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Nuclear meltdown is an informal term for a severe nuclear reactor accident that results in core damage from overheating. The term is not officially defined by the International Atomic Energy Agency or by the U.S. Nuclear Regulatory Commission. However, it has been defined to mean the accidental melting of the core of a nuclear reactor, and is in common usage a reference to the core's either complete or partial collapse. "Core melt accident" and "partial core melt" are the analogous technical terms for a meltdown.
A core melt accident occurs when the heat generated by a nuclear reactor exceeds the heat removed by the cooling systems to the point where at least one nuclear fuel element exceeds its melting point. This differs from a fuel element failure, which is not caused by high temperatures. A meltdown may be caused by a loss of coolant, loss of coolant pressure, or low coolant flow rate or be the result of a criticality excursion in which the reactor is operated at a power level that exceeds its design limits. Alternately, in a reactor plant such as the RBMK-1000, an external fire may endanger the core, leading to a meltdown.
Once the fuel elements of a reactor begin to melt, the fuel cladding has been breached, and the nuclear fuel (such as uranium, plutonium, or thorium) and fission products (such as cesium-137, krypton-88, or iodine-131) within the fuel elements can leach out into the coolant. Subsequent failures can permit these radioisotopes to breach further layers of containment. Superheated steam and hot metal inside the core can lead to fuel-coolant interactions, hydrogen explosions, or water hammer, any of which could destroy parts of the containment. A meltdown is considered very serious because of the potential, however remote, that radioactive materials could breach all containment and escape (or be released) into the environment, resulting in radioactive contamination and fallout, and potentially leading to radiation poisoning of people and animals nearby.
Nuclear power plants generate electricity by heating fluid via a nuclear reaction to run a generator. If the heat from that reaction is not removed adequately, the fuel assemblies in a reactor core can melt. A core damage incident can occur even after a reactor is shut down because the fuel continues to produce decay heat.
A core damage accident is caused by the loss of sufficient cooling for the nuclear fuel within the reactor core. The reason may be one of several factors, including a loss-of-pressure-control accident, a loss-of-coolant accident (LOCA), an uncontrolled power excursion or, in reactors without a pressure vessel, a fire within the reactor core. Failures in control systems may cause a series of events resulting in loss of cooling. Contemporary safety principles of defense in depth ensure that multiple layers of safety systems are always present to make such accidents unlikely.
The containment building is the last of several safeguards that prevent the release of radioactivity to the environment. Many commercial reactors are contained within a 1.2-to-2.4-metre (3.9 to 7.9 ft) thick pre-stressed, steel-reinforced, air-tight concrete structure that can withstand hurricane-force winds and severe earthquakes.
- In a loss-of-coolant accident, either the physical loss of coolant (which is typically deionized water, an inert gas, NaK, or liquid sodium) or the loss of a method to ensure a sufficient flow rate of the coolant occurs. A loss-of-coolant accident and a loss-of-pressure-control accident are closely related in some reactors. In a pressurized water reactor, a LOCA can also cause a "steam bubble" to form in the core due to excessive heating of stalled coolant or by the subsequent loss-of-pressure-control accident caused by a rapid loss of coolant. In a loss-of-forced-circulation accident, a gas cooled reactor's circulators (generally motor or steam driven turbines) fail to circulate the gas coolant within the core, and heat transfer is impeded by this loss of forced circulation, though natural circulation through convection will keep the fuel cool as long as the reactor is not depressurized.
- In a loss-of-pressure-control accident, the pressure of the confined coolant falls below specification without the means to restore it. In some cases this may reduce the heat transfer efficiency (when using an inert gas as a coolant) and in others may form an insulating "bubble" of steam surrounding the fuel assemblies (for pressurized water reactors). In the latter case, due to localized heating of the "steam bubble" due to decay heat, the pressure required to collapse the "steam bubble" may exceed reactor design specifications until the reactor has had time to cool down. (This event is less likely to occur in boiling water reactors, where the core may be deliberately depressurized so that the Emergency Core Cooling System may be turned on). In a depressurization fault, a gas-cooled reactor loses gas pressure within the core, reducing heat transfer efficiency and posing a challenge to the cooling of fuel; however, as long as at least one gas circulator is available, the fuel will be kept cool.
- In an uncontrolled power excursion accident, a sudden power spike in the reactor exceeds reactor design specifications due to a sudden increase in reactor reactivity. An uncontrolled power excursion occurs due to significantly altering a parameter that affects the neutron multiplication rate of a chain reaction (examples include ejecting a control rod or significantly altering the nuclear characteristics of the moderator, such as by rapid cooling). In extreme cases the reactor may proceed to a condition known as prompt critical. This is especially a problem in reactors that have a positive void coefficient of reactivity, a positive temperature coefficient, are overmoderated, or can trap excess quantities of deleterious fission products within their fuel or moderators. Many of these characteristics are present in the RBMK design, and the Chernobyl disaster was caused by such deficiencies as well as by severe operator negligence. Western light water reactors are not subject to very large uncontrolled power excursions because loss of coolant decreases, rather than increases, core reactivity (a negative void coefficient of reactivity); "transients," as the minor power fluctuations within Western light water reactors are called, are limited to momentary increases in reactivity that will rapidly decrease with time (approximately 200% - 250% of maximum neutronic power for a few seconds in the event of a complete rapid shutdown failure combined with a transient).
- Core-based fires endanger the core and can cause the fuel assemblies to melt. A fire may be caused by air entering a graphite moderated reactor, or a liquid-sodium cooled reactor. Graphite is also subject to accumulation of Wigner energy, which can overheat the graphite (as happened at the Windscale fire). Light water reactors do not have flammable cores or moderators and are not subject to core fires. Gas-cooled civilian reactors, such as the Magnox, UNGG, and AGCR type reactors, keep their cores blanketed with non reactive carbon dioxide gas, which cannot support a fire. Modern gas-cooled civilian reactors use helium, which cannot burn, and have fuel that can withstand high temperatures without melting (such as the High Temperature Gas Cooled Reactor and the Pebble Bed Modular Reactor).
- Byzantine faults and cascading failures within instrumentation and control systems may cause severe problems in reactor operation, potentially leading to core damage if not mitigated. For example, the Browns Ferry fire damaged control cables and required the plant operators to manually activate cooling systems. The Three Mile Island accident was caused by a stuck-open pilot-operated pressure relief valve combined with a deceptive water level gauge that misled reactor operators, which resulted in core damage.
Light water reactors (LWRs)
Before the core of a light water nuclear reactor can be damaged, two precursor events must have already occurred:
- A limiting fault (or a set of compounded emergency conditions) that leads to the failure of heat removal within the core (the loss of cooling). Low water level uncovers the core, allowing it to heat up.
- Failure of the Emergency Core Cooling System (ECCS). The ECCS is designed to rapidly cool the core and make it safe in the event of the maximum fault (the design basis accident) that nuclear regulators and plant engineers could imagine. There are at least two copies of the ECCS built for every reactor. Each division (copy) of the ECCS is capable, by itself, of responding to the design basis accident. The latest reactors have as many as four divisions of the ECCS. This is the principle of redundancy, or duplication. As long as at least one ECCS division functions, no core damage can occur. Each of the several divisions of the ECCS has several internal "trains" of components. Thus the ECCS divisions themselves have internal redundancy – and can withstand failures of components within them.
The Three Mile Island accident was a compounded group of emergencies that led to core damage. What led to this was an erroneous decision by operators to shut down the ECCS during an emergency condition due to gauge readings that were either incorrect or misinterpreted; this caused another emergency condition that, several hours after the fact, led to core exposure and a core damage incident. If the ECCS had been allowed to function, it would have prevented both exposure and core damage. During the Fukushima incident the emergency cooling system had also been manually shut down several minutes after it started.
If such a limiting fault were to occur, and a complete failure of all ECCS divisions were to occur, both Kuan, et al and Haskin, et al describe six stages between the start of the limiting fault (the loss of cooling) and the potential escape of molten corium into the containment (a so-called "full meltdown"):
- Uncovering of the Core – In the event of a transient, upset, emergency, or limiting fault, LWRs are designed to automatically SCRAM (a SCRAM being the immediate and full insertion of all control rods) and spin up the ECCS. This greatly reduces reactor thermal power (but does not remove it completely); this delays core becoming uncovered, which is defined as the point when the fuel rods are no longer covered by coolant and can begin to heat up. As Kuan states: "In a small-break LOCA with no emergency core coolant injection, core uncovery [sic] generally begins approximately an hour after the initiation of the break. If the reactor coolant pumps are not running, the upper part of the core will be exposed to a steam environment and heatup of the core will begin. However, if the coolant pumps are running, the core will be cooled by a two-phase mixture of steam and water, and heatup of the fuel rods will be delayed until almost all of the water in the two-phase mixture is vaporized. The TMI-2 accident showed that operation of reactor coolant pumps may be sustained for up to approximately two hours to deliver a two phase mixture that can prevent core heatup."
- Pre-damage heat up – "In the absence of a two-phase mixture going through the core or of water addition to the core to compensate water boiloff, the fuel rods in a steam environment will heat up at a rate between 0.3 °C/s (0.5 °F/s) and 1 °C/s (1.8 °F/s) (3)."
- Fuel ballooning and bursting – "In less than half an hour, the peak core temperature would reach 1,100 K (1,520 °F). At this temperature the zircaloy cladding of the fuel rods may balloon and burst. This is the first stage of core damage. Cladding ballooning may block a substantial portion of the flow area of the core and restrict the flow of coolant. However complete blockage of the core is unlikely because not all fuel rods balloon at the same axial location. In this case, sufficient water addition can cool the core and stop core damage progression."
- Rapid oxidation – "The next stage of core damage, beginning at approximately 1,500 K (2,240 °F), is the rapid oxidation of the Zircaloy by steam. In the oxidation process, hydrogen is produced and a large amount of heat is released. Above 1,500 K (2,240 °F), the power from oxidation exceeds that from decay heat (4,5) unless the oxidation rate is limited by the supply of either zircaloy or steam."
- Debris bed formation – "When the temperature in the core reaches about 1,700 K (2,600 °F), molten control materials [1,6] will flow to and solidify in the space between the lower parts of the fuel rods where the temperature is comparatively low. Above 1,700 K (2,600 °F), the core temperature may escalate in a few minutes to the melting point of zircaloy [2,150 K (3,410 °F)] due to increased oxidation rate. When the oxidized cladding breaks, the molten zircaloy, along with dissolved UO2 [1,7] would flow downward and freeze in the cooler, lower region of the core. Together with solidified control materials from earlier down-flows, the relocated zircaloy and UO2 would form the lower crust of a developing cohesive debris bed."
- (Corium) Relocation to the lower plenum – "In scenarios of small-break LOCAs, there is generally a pool of water in the lower plenum of the vessel at the time of core relocation. Release of molten core materials into water always generates large amounts of steam. If the molten stream of core materials breaks up rapidly in water, there is also a possibility of a steam explosion. During relocation, any unoxidized zirconium in the molten material may also be oxidized by steam, and in the process hydrogen is produced. Recriticality also may be a concern if the control materials are left behind in the core and the relocated material breaks up in unborated water in the lower plenum."
At the point at which the corium relocates to the lower plenum, Haskin, et al relate that the possibility exists for an incident called a fuel-coolant interaction (FCI) to substantially stress or breach the primary pressure boundary when the corium relocates to the lower plenum of the reactor pressure vessel ("RPV"). This is because the lower plenum of the RPV may have a substantial quantity of water - the reactor coolant - in it, and, assuming the primary system has not been depressurized, the water will likely be in the liquid phase, and consequently dense, and at a vastly lower temperature than the corium. Since corium is a liquid metal-ceramic eutectic at temperatures of 2,200 to 3,200 K (3,500 to 5,300 °F), its fall into liquid water at 550 to 600 K (530 to 620 °F) may cause an extremely rapid evolution of steam that could cause a sudden extreme overpressure and consequent gross structural failure of the primary system or RPV. Though most modern studies hold that it is physically infeasible, or at least extraordinarily unlikely, Haskin, et al state that that there exists a remote possibility of an extremely violent FCI leading to something referred to as an alpha-mode failure, or the gross failure of the RPV itself, and subsequent ejection of the upper plenum of the RPV as a missile against the inside of the containment, which would likely lead to the failure of the containment and release of the fission products of the core to the outside environment without any substantial decay having taken place.
Breach of the Primary Pressure Boundary
There are several possibilities as to how the primary pressure boundary could be breached by corium.
- Steam Explosion
As previously described, FCI could lead to an overpressure event leading to RPV fail, and thus, primary pressure boundary fail. Haskin, et al. report that in the event of a steam explosion, failure of the lower plenum is far more likely than ejection of the upper plenum in the alpha-mode. In the even of lower plenum failure, debris at varied temperatures can be expected to be projected into the cavity below the core. The containment may be subject to overpressure, though this is not likely to fail the containment. The alpha-mode failure will lead to the consequences previously discussed.
- Pressurized Melt Ejection (PME)
It is quite possible, especially in pressurized water reactors, that the primary loop will remain pressurized following corium relocation to the lower plenum. As such, pressure stresses on the RPV will be present in addition to the weight stress that the molten corium places on the lower plenum of the RPV; when the metal of the RPV weakens sufficiently due to the heat of the molten corium, it is likely that the liquid corium will be discharged under pressure out of the bottom of the RPV in a pressurized stream, together with entrained gases. This mode of corium ejection may lead to direct containment heating (DCH).
Severe Accident Ex-Vessel Interactions and Challenges to Containment
Haskin, et al identify six modes by which the containment could be credibly challenged; some of these modes are not applicable to core melt accidents.
- Dynamic pressure (shockwaves)
- Internal missiles
- External missiles (not applicable to core melt accidents)
Standard failure modes
If the melted core penetrates the pressure vessel, there are theories and speculations as to what may then occur.
In modern Russian plants, there is a "core catching device" in the bottom of the containment building, the melted core is supposed to hit a thick layer of a "sacrificial metal" which would melt, dilute the core and increase the heat conductivity, and finally the diluted core can be cooled down by water circulating in the floor. However there has never been any full-scale testing of this device.
In Western plants there is an airtight containment building. Though radiation would be at a high level within the containment, doses outside of it would be lower. Containment buildings are designed for the orderly release of pressure without releasing radionuclides, through a pressure release valve and filters. Hydrogen/oxygen recombiners also are installed within the containment to prevent gas explosions.
In a melting event, one spot or area on the RPV will become hotter than other areas, and will eventually melt. When it melts, corium will pour into the cavity under the reactor. Though the cavity is designed to remain dry, several NUREG-class documents advise operators to flood the cavity in the event of a fuel melt incident. This water will become steam and pressurize the containment. Automatic water sprays will pump large quantities of water into the steamy environment to keep the pressure down. Catalytic recombiners will rapidly convert the hydrogen and oxygen back into water. One positive effect of the corium falling into water is that it is cooled and returns to a solid state.
Extensive water spray systems within the containment along with the ECCS, when it is reactivated, will allow operators to spray water within the containment to cool the core on the floor and reduce it to a low temperature.
These procedures are intended to prevent release of radiation. In the Three Mile Island event in 1979, a theoretical person standing at the plant property line during the entire event would have received a dose of approximately 2 millisieverts (200 millirem), between a chest X-ray's and a CT scan's worth of radiation. This was due to outgassing by an uncontrolled system that, today, would have been backfitted with activated carbon and HEPA filters to prevent radionuclide release.
However in case of Fukushima incident this design also at least partially failed: large amounts of highly radioactive water were produced and nuclear fuel has possibly melted through the base of the pressure vessels.
Cooling will take quite a while, until the natural decay heat of the corium reduces to the point where natural convection and conduction of heat to the containment walls and re-radiation of heat from the containment allows for water spray systems to be shut down and the reactor put into safe storage. The containment can be sealed with release of extremely limited offsite radioactivity and release of pressure within the containment. After a number of years for fission products to decay - probably around a decade - the containment can be reopened for decontamination and demolition.
Unexpected failure modes
Another scenario sees a buildup of hydrogen, which may lead to a detonation event, as happened for three reactors during Fukushima incident. Catalytic hydrogen recombiners located within containment are designed to prevent this from occurring; however, prior to the installation of these recombiners in the 1980s, the Three Mile Island containment (in 1979) suffered a massive hydrogen explosion event in the accident there. The containment withstood the pressure and no radioactivity was released. However, in Fukushima recombiners did not work due the absence of power and hydrogen detonation breached the containment.
Speculative failure modes
One scenario consists of the reactor pressure vessel failing all at once, with the entire mass of corium dropping into a pool of water (for example, coolant or moderator) and causing extremely rapid generation of steam. The pressure rise within the containment could threaten integrity if rupture disks could not relieve the stress. Exposed flammable substances could burn, but there are few, if any, flammable substances within the containment.
Another theory called an 'alpha mode' failure by the 1975 Rasmussen (WASH-1400) study asserted steam could produce enough pressure to blow the head off the reactor pressure vessel (RPV). The containment could be threatened if the RPV head collided with it. (The WASH-1400 report was replaced by better-based[original research?] newer studies, and now the Nuclear Regulatory Commission has disavowed them all and is preparing the overarching State-of-the-Art Reactor Consequence Analyses [SOARCA] study - see the Disclaimer in NUREG-1150.)
It has not been determined to what extent a molten mass can melt through a structure (although that was tested in the Loss-of-Fluid-Test Reactor described in Test Area North's fact sheet). The Three Mile Island accident provided some real-life experience, with an actual molten core within an actual structure; the molten corium failed to melt through the Reactor Pressure Vessel after over six hours of exposure, due to dilution of the melt by the control rods and other reactor internals, validating the emphasis on defense in depth against core damage incidents. Some believe a molten reactor core could actually penetrate the reactor pressure vessel and containment structure and burn downwards into the earth beneath, to the level of the groundwater.
By 1970, there were doubts about the ability of the emergency cooling systems of a nuclear reactor to prevent a loss of coolant accident and the consequent meltdown of the fuel core; the subject proved popular in the technical and the popular presses. In 1971, in the article Thoughts on Nuclear Plumbing, former Manhattan Project (1942–1946) nuclear physicist Ralph Lapp used the term "China syndrome" to describe a possible burn-through, after a loss of coolant accident, of the nuclear fuel rods and core components melting the containment structures, and the subsequent escape of radioactive material(s) into the atmosphere and environment; the hypothesis derived from a 1967 report by a group of nuclear physicists, headed by W. K. Ergen.
The geographic, planet-piercing concept of the China syndrome derives from the misperception that China is the antipode of the United States; to many Americans, it is the “the other side of the world”. Moreover, the hypothetical transit of a meltdown product to the other side of the Earth (i.e. China) ignores the fact that the Earth's gravity tends to pull all masses towards its center. Assuming a meltdown product could persist in a mobile molten form for long enough to reach the center of the Earth; gravity would prevent it continuing to the other side.
Other reactor types
Other types of reactors have different capabilities and safety profiles than the LWR does. Advanced varieties of several of these reactors have the potential to be inherently safe.
CANDU reactors
CANDU reactors, Canadian-invented deuterium-uranium design, are designed with at least one, and generally two, large low-temperature and low-pressure water reservoirs around their fuel/coolant channels. The first is the bulk heavy-water moderator (a separate system from the coolant), and the second is the light-water-filled shield tank. These backup heat sinks are sufficient to prevent either the fuel meltdown in the first place (using the moderator heat sink), or the breaching of the core vessel should the moderator eventually boil off (using the shield tank heat sink). Other failure modes aside from fuel melt will probably occur in a CANDU rather than a meltdown, such as deformation of the calandria into a non-critical configuration. All CANDU reactors are located within standard Western containments as well.
Gas-cooled reactors
One type of Western reactor, known as the advanced gas-cooled reactor (or AGCR), built by the United Kingdom, is not very vulnerable to loss-of-cooling accidents or to core damage except in the most extreme of circumstances. By virtue of the relatively inert coolant (carbon dioxide), the large volume and high pressure of the coolant, and the relatively high heat transfer efficiency of the reactor, the time frame for core damage in the event of a limiting fault is measured in days. Restoration of some means of coolant flow will prevent core damage from occurring.
Other types of highly advanced gas cooled reactors, generally known as high-temperature gas-cooled reactors (HTGRs) such as the Japanese High Temperature Test Reactor and the United States' Very High Temperature Reactor, are inherently safe, meaning that meltdown or other forms of core damage are physically impossible, due to the structure of the core, which consists of hexagonal prismatic blocks of silicon carbide reinforced graphite infused with TRISO or QUADRISO pellets of uranium, thorium, or mixed oxide buried underground in a helium-filled steel pressure vessel within a concrete containment. Though this type of reactor is not susceptible to meltdown, additional capabilities of heat removal are provided by using regular atmospheric airflow as a means of backup heat removal, by having it pass through a heat exchanger and rising into the atmosphere due to convection, achieving full residual heat removal. The VHTR is scheduled to be prototyped and tested at Idaho National Laboratory within the next decade (as of 2009) as the design selected for the Next Generation Nuclear Plant by the US Department of Energy. This reactor will use a gas as a coolant, which can then be used for process heat (such as in hydrogen production) or for the driving of gas turbines and the generation of electricity.
A similar highly advanced gas cooled reactor originally designed by West Germany (the AVR reactor) and now developed by South Africa is known as the Pebble Bed Modular Reactor. It is an inherently safe design, meaning that core damage is physically impossible, due to the design of the fuel (spherical graphite "pebbles" arranged in a bed within a metal RPV and filled with TRISO (or QUADRISO) pellets of uranium, thorium, or mixed oxide within). A prototype of a very similar type of reactor has been built by the Chinese, HTR-10, and has worked beyond researchers' expectations, leading the Chinese to announce plans to build a pair of follow-on, full-scale 250 MWe, inherently safe, power production reactors based on the same concept. (See Nuclear power in the People's Republic of China for more information.)
Experimental or conceptual designs
Some design concepts for nuclear reactors emphasize resistance to meltdown and operating safety.
The PIUS (process inherent ultimate safety) designs, originally engineered by the Swedes in the late 1970s and early 1980s, are LWRs that by virtue of their design are resistant to core damage. No units have ever been built.
Power reactors, including the Deployable Electrical Energy Reactor, a larger-scale mobile version of the TRIGA for power generation in disaster areas and on military missions, and the TRIGA Power System, a small power plant and heat source for small and remote community use, have been put forward by interested engineers, and share the safety characteristics of the TRIGA due to the uranium zirconium hydride fuel used.
The Hydrogen Moderated Self-regulating Nuclear Power Module, a reactor that uses uranium hydride as a moderator and fuel, similar in chemistry and safety to the TRIGA, also possesses these extreme safety and stability characteristics, and has attracted a good deal of interest in recent times.
The liquid fluoride thermal reactor is designed to naturally have its core in a molten state, as a eutectic mix of thorium and fluorine salts. As such, a molten core is reflective of the normal and safe state of operation of this reactor type. In the event the core overheats, a metal plug will melt, and the molten salt core will drain into tanks where it will cool in a non-critical configuration. Since the core is liquid, and already melted, it cannot be damaged.
Advanced liquid metal reactors, such as the U.S. Integral Fast Reactor and the Russian BN-350, BN-600, and BN-800, all have a coolant with very high heat capacity, sodium metal. As such, they can withstand a loss of cooling without SCRAM and a loss of heat sink without SCRAM, qualifying them as inherently safe.
Soviet Union-designed reactors
Soviet designed RBMKs, found only in Russia and the CIS and now shut down everywhere except Russia, do not have containment buildings, are naturally unstable (tending to dangerous power fluctuations), and also have ECCS systems that are considered grossly inadequate by Western safety standards. The reactor from the Chernobyl Disaster was a RBMK reactor.
RBMK ECCS systems only have one division and have less than sufficient redundancy within that division. Though the large core size of the RBMK makes it less energy-dense than the Western LWR core, it makes it harder to cool. The RBMK is moderated by graphite. In the presence of both steam and oxygen, at high temperatures, graphite forms synthesis gas and with the water gas shift reaction the resultant hydrogen burns explosively. If oxygen contacts hot graphite, it will burn. The RBMK tends towards dangerous power fluctuations. Control rods used to be tipped with graphite, a material that slows neutrons and thus speeds up the chain reaction. Water is used as a coolant, but not a moderator. If the water boils away, cooling is lost, but moderation continues. This is termed a positive void coefficient of reactivity.
Control rods can become stuck if the reactor suddenly heats up and they are moving. Xenon-135, a neutron absorbent fission product, has a tendency to build up in the core and burn off unpredictably in the event of low power operation. This can lead to inaccurate neutronic and thermal power ratings.
The RBMK does not have any containment above the core. The only substantial solid barrier above the fuel is the upper part of the core, called the upper biological shield, which is a piece of concrete interpenetrated with control rods and with access holes for refueling while online. Other parts of the RBMK were shielded better than the core itself. Rapid shutdown (SCRAM) takes 10 to 15 seconds. Western reactors take 1 - 2.5 seconds.
Western aid has been given to provide certain real-time safety monitoring capacities to the human staff. Whether this extends to automatic initiation of emergency cooling is not known. Training has been provided in safety assessment from Western sources, and Russian reactors have evolved in result to the weaknesses that were in the RBMK. However, numerous RBMKs still operate.
It is safe to say that it might be possible to stop a loss-of-coolant event prior to core damage occurring, but that any core damage incidents will probably assure massive release of radioactive materials. Further, dangerous power fluctuations are natural to the design.
Lithuania joined the EU recently, and upon acceding, it has been required to shut the two RBMKs that it has at Ignalina NPP, as such reactors are totally incompatible with the nuclear safety standards of Europe. It will be replacing them with some safer form of reactor.
The MKER is a modern Russian-engineered channel type reactor that is a distant descendant of the RBMK. It approaches the concept from a different and superior direction, optimizing the benefits, and fixing the flaws of the original RBMK design.
There are several unique features of the MKER's design that make it a credible and interesting option: One unique benefit of the MKER's design is that in the event of a challenge to cooling within the core - a pipe break of a channel, the channel can be isolated from the plenums supplying water, decreasing the potential for common-mode failures.
The lower power density of the core greatly enhances thermal regulation. Graphite moderation enhances neutronic characteristics beyond light water ranges. The passive emergency cooling system provides a high level of protection by using natural phenomena to cool the core rather than depending on motor-driven pumps. The containment structure is modern and designed to withstand a very high level of punishment.
Refueling is accomplished while online, ensuring that outages are for maintenance only and are very few and far between. 97-99% uptime is a definite possibility. Lower enrichment fuels can be used, and high burnup can be achieved due to the moderator design. Neutronics characteristics have been revamped to optimize for purely civilian fuel fertilization and recycling.
Due to the enhanced quality control of parts, advanced computer controls, comprehensive passive emergency core cooling system, and very strong containment structure, along with a negative void coefficient and a fast acting rapid shutdown system, the MKER's safety can generally be regarded as being in the range of the Western Generation III reactors, and the unique benefits of the design may enhance its competitiveness in countries considering full fuel-cycle options for nuclear development.
The VVER is a pressurized light water reactor that is far more stable and safe than the RBMK. This is because it uses light water as a moderator (rather than graphite), has well understood operating characteristics, and has a negative void coefficient of reactivity. In addition, some have been built with more than marginal containments, some have quality ECCS systems, and some have been upgraded to international standards of control and instrumentation. Present generations of VVERs (the VVER-1000) are built to Western-equivalent levels of instrumentation, control, and containment systems.
However, even with these positive developments, certain older VVER models raise a high level of concern, especially the VVER-440 V230.
The VVER-440 V230 has no containment building, but only has a structure capable of confining steam surrounding the RPV. This is a volume of thin steel, perhaps an inch or two in thickness, grossly insufficient by Western standards.
- Has no ECCS. Can survive at most one 4 inch pipe break (there are many pipes greater than 4 inches within the design).
- Has six steam generator loops, adding unnecessary complexity.
- However, apparently steam generator loops can be isolated, in the event that a break occurs in one of these loops. The plant can remain operating with one isolated loop - a feature found in few Western reactors.
The interior of the pressure vessel is plain alloy steel, exposed to water. This can lead to rust, if the reactor is exposed to water. One point of distinction in which the VVER surpasses the West is the reactor water cleanup facility - built, no doubt, to deal with the enormous volume of rust within the primary coolant loop - the product of the slow corrosion of the RPV. This model is viewed as having inadequate process control systems.
Bulgaria had a number of VVER-440 V230 models, but they opted to shut them down upon joining the EU rather than backfit them, and are instead building new VVER-1000 models. Many non-EU states maintain V230 models, including Russia and the CIS. Many of these states - rather than abandoning the reactors entirely - have opted to install an ECCS, develop standard procedures, and install proper instrumentation and control systems. Though confinements cannot be transformed into containments, the risk of a limiting fault resulting in core damage can be greatly reduced.
The VVER-440 V213 model was built to the first set of Soviet nuclear safety standards. It possesses a modest containment building, and the ECCS systems, though not completely to Western standards, are reasonably comprehensive. Many VVER-440 V213 models possessed by former Soviet bloc countries have been upgraded to fully automated Western-style instrumentation and control systems, improving safety to Western levels for accident prevention - but not for accident containment, which is of a modest level compared to Western plants. These reactors are regarded as "safe enough" by Western standards to continue operation without major modifications, though most owners have performed major modifications to bring them up to generally equivalent levels of nuclear safety.
During the 1970s, Finland built two VVER-440 V213 models to Western standards with a large-volume full containment and world-class instrumentation, control standards and an ECCS with multiply redundant and diversified components. In addition, passive safety features such as 900-tonne ice condensers have been installed, making these two units safety-wise the most advanced VVER-440's in the world.
The VVER-1000 type has a definitely adequate Western-style containment, the ECCS is sufficient by Western standards, and instrumentation and control has been markedly improved to Western 1970s-era levels.
Chernobyl disaster
In the Chernobyl disaster the fuel became non-critical when it melted and flowed away from the graphite moderator - however, it took considerable time to cool. The molten core of Chernobyl (that part that did not vaporize in the fire) flowed in a channel created by the structure of its reactor building and froze in place before a core-concrete interaction could happen. In the basement of the reactor at Chernobyl, a large "elephant's foot" of congealed core material was found. Time delay, and prevention of direct emission to the atmosphere, would have reduced the radiological release. If the basement of the reactor building had been penetrated, the groundwater would be severely contaminated, and its flow could carry the contamination far afield.
The Chernobyl reactor was an RBMK type. The disaster was caused by a power excursion that led to a meltdown and extensive offsite consequences. Operator error and a faulty shutdown system led to a sudden, massive spike in the neutron multiplication rate, a sudden decrease in the neutron period, and a consequent increase in neutron population; thus, core heat flux very rapidly increased to unsafe levels. This caused the water coolant to flash to steam, causing a sudden overpressure within the reactor pressure vessel (RPV), leading to granulation of the upper portion of the core and the ejection of the upper plenum of said pressure vessel along with core debris from the reactor building in a widely dispersed pattern. The lower portion of the reactor remained somewhat intact; the graphite neutron moderator was exposed to oxygen containing air; heat from the power excursion in addition to residual heat flux from the remaining fuel rods left without coolant induced oxidation in the moderator; this in turn evolved more heat and contributed to the melting of the fuel rods and the outgassing of the fission products contained therein. The liquefied remains of the fuel rods flowed through a drainage pipe into the basement of the reactor building and solidified in a mass later dubbed corium, though the primary threat to the public safety was the dispersed core ejecta and the gasses evolved from the oxidation of the moderator.
Although the Chernobyl accident had dire off-site effects, much of the radioactivity remained within the building. If the building were to fail and dust was to be released into the environment then the release of a given mass of fission products which have aged for twenty years would have a smaller effect than the release of the same mass of fission products (in the same chemical and physical form) which had only undergone a short cooling time (such as one hour) after the nuclear reaction has been terminated. However, if a nuclear reaction was to occur again within the Chernobyl plant (for instance if rainwater was to collect and act as a moderator) then the new fission products would have a higher specific activity and thus pose a greater threat if they were released. To prevent a post-accident nuclear reaction, steps have been taken, such as adding neutron poisons to key parts of the basement.
The effects of a nuclear meltdown depend on the safety features designed into a reactor. A modern reactor is designed both to make a meltdown unlikely, and to contain one should it occur.
In a modern reactor, a nuclear meltdown, whether partial or total, should be contained inside the reactor's containment structure. Thus (assuming that no other major disasters occur) while the meltdown will severely damage the reactor itself, possibly contaminating the whole structure with highly radioactive material, a meltdown alone should not lead to significant radiation release or danger to the public.
In practice, however, a nuclear meltdown is often part of a larger chain of disasters (although there have been so few meltdowns in the history of nuclear power that there is not a large pool of statistical information from which to draw a credible conclusion as to what "often" happens in such circumstances). For example, in the Chernobyl accident, by the time the core melted, there had already been a large steam explosion and graphite fire and major release of radioactive contamination (as with almost all Soviet reactors, there was no containment structure at Chernobyl). Also, before a possible meltdown occurs, pressure can already be rising in the reactor, and to prevent a meltdown by restoring the cooling of the core, operators are allowed to reduce the pressure in the reactor by releasing (radioactive) steam into the environment. This enables them to inject additional cooling water into the reactor again.
Reactor design
Although pressurized water reactors are more susceptible to nuclear meltdown in the absence of active safety measures, this is not a universal feature of civilian nuclear reactors. Much of the research in civilian nuclear reactors is for designs with passive nuclear safety features that may be less susceptible to meltdown, even if all emergency systems failed. For example, pebble bed reactors are designed so that complete loss of coolant for an indefinite period does not result in the reactor overheating. The General Electric ESBWR and Westinghouse AP1000 have passively activated safety systems. The CANDU reactor has two low-temperature and low-pressure water systems surrounding the fuel (i.e. moderator and shield tank) that act as back-up heat sinks and preclude meltdowns and core-breaching scenarios.
Fast breeder reactors are more susceptible to meltdown than other reactor types, due to the larger quantity of fissile material and the higher neutron flux inside the reactor core, which makes it more difficult to control the reaction.
Accidental fires are widely acknowledged to be risk factors that can contribute to a nuclear meltdown.
United States
There have been at least eight meltdowns in the history of the United States. All are widely called "partial meltdowns."
- BORAX-I was a test reactor designed to explore criticality excursions and observe if a reactor would self limit. In the final test, it was deliberately destroyed and revealed that the reactor reached much higher temperatures than were predicted at the time.
- The reactor at EBR-I suffered a partial meltdown during a coolant flow test on November 29, 1955.
- The Sodium Reactor Experiment in Santa Susana Field Laboratory was an experimental nuclear reactor which operated from 1957 to 1964 and was the first commercial power plant in the world to experience a core meltdown in July 1959.
- Stationary Low-Power Reactor Number One (SL-1) was a United States Army experimental nuclear power reactor which underwent a criticality excursion, a steam explosion, and a meltdown on January 3, 1961, killing three operators.
- The SNAP8ER reactor at the Santa Susana Field Laboratory experienced damage to 80% of its fuel in an accident in 1964.
- The partial meltdown at the Fermi 1 experimental fast breeder reactor, in 1966, required the reactor to be repaired, though it never achieved full operation afterward.
- The SNAP8DR reactor at the Santa Susana Field Laboratory experienced damage to approximately a third of its fuel in an accident in 1969.
- The Three Mile Island accident, in 1979, referred to in the press as a "partial core melt," led to the permanent shutdown of that reactor.
Soviet Union
In the most serious example, the Chernobyl disaster, design flaws and operator negligence led to a power excursion that subsequently caused a meltdown. According to a report released by the Chernobyl Forum (consisting of numerous United Nations agencies, including the International Atomic Energy Agency and the World Health Organization; the World Bank; and the Governments of Ukraine, Belarus, and Russia) the disaster killed twenty-eight people due to acute radiation syndrome, could possibly result in up to four thousand fatal cancers at an unknown time in the future and required the permanent evacuation of an exclusion zone around the reactor.
During the Fukushima I nuclear accidents, three of the power plant's six reactors reportedly suffered meltdowns. Most of the fuel in the reactor No. 1 Nuclear Power Plant melted. TEPCO believes No.2 and No.3 reactors were similarly affected. On May 24, 2011, TEPCO reported that all three reactors melted down.
Meltdown incidents
- There was also a fatal core meltdown at SL-1, an experimental U.S. military reactor in Idaho.
Large-scale nuclear meltdowns at civilian nuclear power plants include:
- the Lucens reactor, Switzerland, in 1969.
- the Three Mile Island accident in Pennsylvania, U.S.A., in 1979.
- the Chernobyl disaster at Chernobyl Nuclear Power Plant, Ukraine, USSR, in 1986.
- the Fukushima I nuclear accidents following the earthquake and tsunami in Japan, March 2011.
Other core meltdowns have occurred at:
- NRX (military), Ontario, Canada, in 1952
- BORAX-I (experimental), Idaho, U.S.A., in 1954
- EBR-I (military), Idaho, U.S.A., in 1955
- Windscale (military), Sellafield, England, in 1957 (see Windscale fire)
- Sodium Reactor Experiment, (civilian), California, U.S.A., in 1959
- Fermi 1 (civilian), Michigan, U.S.A., in 1966
- Chapelcross nuclear power station (civilian), Scotland, in 1967
- Saint-Laurent Nuclear Power Plant (civilian), France, in 1969
- A1 plant, (civilian) at Jaslovské Bohunice, Czechoslovakia, in 1977
- Saint-Laurent Nuclear Power Plant (civilian), France, in 1980
China Syndrome
The China syndrome (loss-of-coolant accident) is a fictional nuclear reactor operations accident characterized by the severe meltdown of the core components of the reactor, which then burn through the containment vessel and the housing building, then notionally through the crust and body of the Earth until reaching the other side, which in the United States is jokingly referred to as being China.
The system design of the nuclear power plants built in the late 1960s raised questions of operational safety, and raised the concern that a severe reactor accident could release large quantities of radioactive materials into the atmosphere and environment. By 1970, there were doubts about the ability of the emergency cooling systems of a nuclear reactor to prevent a loss of coolant accident and the consequent meltdown of the fuel core; the subject proved popular in the technical and the popular presses. In 1971, in the article Thoughts on Nuclear Plumbing, former Manhattan Project (1942–1946) nuclear physicist Ralph Lapp used the term "China syndrome" to describe a possible burn-through, after a loss of coolant accident, of the nuclear fuel rods and core components melting the containment structures, and the subsequent escape of radioactive material(s) into the atmosphere and environment; the hypothesis derived from a 1967 report by a group of nuclear physicists, headed by W. K. Ergen. In the event, Lapp’s hypothetical nuclear accident was cinematically adapted as The China Syndrome (1979).
The geographic, planet-piercing concept of the China syndrome derives from the misperception that China is the antipode of the United States; to many Americans, it is the “the other side of the world”. Moreover, the hypothetical transit of a meltdown product to the other side of the Earth (i.e. China) ignores the fact that the Earth's gravity tends to pull all masses towards its center. Assuming a meltdown product could persist in a mobile molten form for long enough to reach the center of the Earth; momentum loss due to friction (fluid viscosity) would prevent it continuing to the other side.
See also
- Behavior of nuclear fuel during a reactor accident
- Chernobyl compared to other radioactivity releases
- Chernobyl disaster effects
- High-level radioactive waste management
- International Nuclear Event Scale
- List of civilian nuclear accidents
- Lists of nuclear disasters and radioactive incidents
- Nuclear fuel response to reactor accidents
- Nuclear safety
- Nuclear power
- Nuclear power debate
- Martin Fackler (June 1, 2011). "Report Finds Japan Underestimated Tsunami Danger". New York Times.
- International Atomic Energy Agency (IAEA) (2007). IAEA Safety Glossary: Terminology Used in Nuclear Safety and Radiation Protection (2007edition ed.). Vienna, Austria: International Atomic Energy Agency. ISBN 92-0-100707-8. Retrieved 2009-08-17.
- United States Nuclear Regulatory Commission (NRC) (2009-09-14). "Glossary". Website. Rockville, Maryland, USA: Federal Government of the United States. pp. See Entries for Letter M and Entries for Letter N. Retrieved 2009-10-03.
- Reactor safety study: an assessment of accident risks in U.S. commercial nuclear power plants, Volume 1
- Hewitt, Geoffrey Frederick; Collier, John Gordon (2000). "4.6.1 Design Basis Accident for the AGR: Depressurization Fault". Introduction to nuclear power (in Technical English). London, UK: Taylor & Francis. p. 133. ISBN 978-1-56032-454-6. Retrieved 2010-06-05.
- "Earthquake Report No. 91". JAIF. May 25, 2011. Retrieved May 25, 2011.
- Kuan, P.; Hanson, D. J., Odar, F. (1991). Managing water addition to a degraded core. Retrieved 2010-11-22.
- Haskin, F.E.; Camp, A.L. (1994). Perspectives on Reactor Safety (NUREG/CR-6042) (Reactor Safety Course R-800), 1st Edition. Beltsville, MD: U.S. Nuclear Regulatory Commission. p. 3.1–5. Retrieved 2010-11-23.
- Haskin, F.E.; Camp, A.L. (1994). Perspectives on Reactor Safety (NUREG/CR-6042) (Reactor Safety Course R-800), 1st Edition. Beltsville, MD: U.S. Nuclear Regulatory Commission. pp. 3.5–1 to 3.5–4. Retrieved 2010-12-24.
- Haskin, F.E.; Camp, A.L. (1994). Perspectives on Reactor Safety (NUREG/CR-6042) (Reactor Safety Course R-800), 1st Edition. Beltsville, MD: U.S. Nuclear Regulatory Commission. pp. 3.5–4 to 3.5–5. Retrieved 2010-12-24.
- ANS : Public Information : Resources : Special Topics : History at Three Mile Island : What Happened and What Didn't in the TMI-2 Accident
- Nuclear Industry in Russia Sells Safety, Taught by Chernobyl
- 'Melt-through' at Fukushima? / Govt. suggests situation worse than meltdown http://www.yomiuri.co.jp/dy/national/T110607005367.htm
- Test Area North
- Walker, J. Samuel (2004). Three Mile Island: A Nuclear Crisis in Historical Perspective (Berkeley: University of California Press), p. 11.
- Lapp, Ralph E. "Thoughts on nuclear plumbing." The New York Times, 12 December 1971, pg. E11.
- "China Syndrome". Merriam-Webster. Retrieved December 11, 2012.
- Presenter: Martha Raddatz (15 March 2011). "ABC World News". ABC.
- Allen, P.J.; J.Q. Howieson, H.S. Shapiro, J.T. Rogers, P. Mostert and R.W. van Otterloo (April–June 1990). "Summary of CANDU 6 Probabilistic Safety Assessment Study Results". Nuclear Safety 31 (2): 202–214.
- http://www.insc.anl.gov/neisb/neisb4/NEISB_1.1.html INL VVER Sourcebook
- Partial Fuel Meltdown Events
- ANL-W Reactor History: BORAX I
- Wald, Matthew L. (2011-03-11). "Japan Expands Evacuation Around Nuclear Plant". The New York Times.
- The Chernobyl Forum: 2003-2005 (2006-04). "Chernobyl’s Legacy: Health, Environmental and Socio-economic Impacts". International Atomic Energy Agency. p. 14. Retrieved 2011-01-26.
- The Chernobyl Forum: 2003-2005 (2006-04). "Chernobyl’s Legacy: Health, Environmental and Socio-Economic Impacts". International Atomic Energy Agency. p. 16. Retrieved 2011-01-26.
- Hiroko Tabuchi (May 24, 2011). "Company Believes 3 Reactors Melted Down in Japan". The New York Times. Retrieved 2011-05-25.


By Serena Gordon
MONDAY, Nov. 16 (HealthDay News) -- Pediatric food allergies, which can sometimes be life-threatening, are increasing at a dramatic rate in the United States, new research shows.
But the study authors aren't sure if the rise in reports of food allergies reflects an increase in actual prevalence or if better awareness has led more people to seek treatment for their symptoms.
Whatever the cause, it's clear that the number of children with food allergies has gone up 18 percent and the number seeking treatment for food allergy at emergency departments or hospitals has tripled since 1993.
"People are more aware of food allergies today, and that could have something to do with it," said study author, Amy Branum, a health statistician for the U.S. Centers for Disease Control and Prevention. "But, when we looked at health-care surveys filled out by parents and those from the health-care sector, we saw the increase across the surveys so this may be more than just increased awareness."
Results of the study were published online Nov. 16 and will appear in the December print issue of Pediatrics.
Although many people think of allergies as more of a nuisance than a serious health issue, food allergy in particular can be very serious, even life-threatening. The most common foods that people are allergic to include peanuts, tree nuts, milk, eggs, soy, shellfish, fish and wheat, according to the Food Allergy & Anaphylaxis Network.
Symptoms often appear minutes after people eat a food that they're allergic to, but it can sometimes take several hours before a reaction begins, according to the network. Typical symptoms of a food allergy include a tingling sensation in the mouth, swelling of the tongue or throat, trouble breathing, hives, stomach cramping, vomiting or diarrhea.
In the current study, the researchers used information from four different national data sources to assess the current rate of food allergies in the United States. The surveys included information from parents and from health-care providers, according to Branum.
The researchers found that between 1997 and 2007, the incidence of food allergy went up by 18 percent. Parents of almost 4 percent of U.S. children reported a food or digestive allergy in their child, the study authors noted.
There was also an increase in the rates of parent-reported skin allergy (eczema) during the same time period. Approximately 8.9 percent of U.S. children had experienced skin allergy in 2007, compared with 7.9 percent in 1997.
Health-care providers, on the other hand, reported that the number of children being treated for food allergies had tripled, the study found. Data from health-care providers was from 1993 to 2006.
Data included testing for immunoglobulin E, or IgE, antibodies in the blood for various foodstuffs, which can indicate an allergy. The percentage of children who tested positive for IgE antibodies for peanut allergy was 9 percent; for egg allergy, 7 percent; milk, 12 percent; and shrimp, 5 percent, the study found.
Though IgE antibodies can indicate a potential food allergy, the test is often better at ruling out who does not have an allergy, Branum said. A positive test doesn't mean that someone definitely has a food allergy, but suggests that the potential is there.
The researchers also noted that Hispanic children had the lowest overall prevalence of food allergy but the greatest increases over time of parent-reported incidences of food allergy.
"People should be aware that food allergy may really be increasing," Branum said. "If small children have symptoms when they eat a particular food, have that child checked out, particularly if they have co-occurring conditions like asthma and eczema."
"Food allergies are real," said Dr. Jennifer Appleyard, chief of allergy and immunology at St. John Hospital and Medical Center in Detroit. "And it appears that the prevalence is rising."
This will present various challenges, she noted. One is that there's already a shortage of allergy specialists in many areas, Appleyard said. Another is that schools will have to gear up to take care of additional children with food allergy to ensure their safety during the school day and on field trips, she said.
Parents who suspect their child has a food allergy should first talk with the child's primary care physician about symptoms. The problem could be a food intolerance rather than an allergy, she said, but the child might need to be tested by an allergy specialist to get a definitive diagnosis.
The Food Allergy & Anaphylaxis Network has more on food allergies.
Copyright © 2011 HealthDay. All rights reserved.


Classification of Burns
What are the classifications of burns?
Burns are classified as first-, second-, or third-degree, depending on how deep and severe they penetrate the skin's surface.
First-degree (superficial) burns
First-degree burns affect only the epidermis, or outer layer of skin. The burn site is red, painful, dry, and with no blisters. Mild sunburn is an example. Long-term tissue damage is rare and usually consists of an increase or decrease in the skin color.
Second-degree (partial thickness) burns
Second-degree burns involve the epidermis and part of the dermis layer of skin. The burn site appears red, blistered, and may be swollen and painful.
Third-degree (full thickness) burns
Third-degree burns destroy the epidermis and dermis. Third-degree burns may also damage the underlying bones, muscles, and tendons. The burn site appears white or charred. There is no sensation in the area since the nerve endings are destroyed.


These energy saving tips will show you how to reduce your impact on both the environment and your energy bills.
1. Turn out the lights when you leave a room. This is probably the easiest thing you can do to save energy – just flip the switch on your way out.
2. Turn off electronic devices when you are not using them. This includes TVs, computers, DVD players, stereos, and any other electronic devices. If you’re not using it, why leave it on? To take this one step further, you can also unplug devices like cell phone chargers when they are not in use. They still use a small amount unless they are completely unplugged, even if they do not appear to be in use.
3. Invest in energy-efficient light bulbs, such as compact fluorescent bulbs. These are slowly replacing regular incandescent bulbs, and they use significantly less energy.
4. In the winter, wear extra layers around the house. Simply turning up the thermostat seems so easy, but putting on a sweater uses a lot less energy. Try to have an extra-comfy sweater or sweatshirt handy that you can throw on over anything when you get cold. Wearing long underwear, tights or leggings under your pants can also be helpful if it is particularly chilly.
5. During the winter, open shades during the day; during the summer, close them. Sunlight can have a powerful effect on the temperature of a room, especially if that room faces south and receives more sun. Use this to your advantage by keeping your living space warmer in the winter and cooler in the summer.
6. Block the bottoms of doors in winter to prevent heat from escaping. You can buy a door draft snake or make one yourself.
7. Hang clothes to dry rather than use a dryer. This is very easy to do and will even make your clothes last longer; using a dryer causes clothes to shrink and lose their shape. You can buy a rack to hang them on at places like Bed Bath and Beyond. Be careful about using hangers to dry clothes, as they may stretch some fabrics.
Hope these tips help you to save energy!


Hot Weather Gets Scientists' Attention
Originally published on Wed July 11, 2012 5:30 am
RENEE MONTAGNE, HOST:
Across America people are sweltering through extreme heat this year, continuing a long-term trend of rising temperatures. Inevitably, many are wondering if the scorching heat is due to global warming. Scientists are expected to dig into the data and grapple with that in the months to come. They've already taken a stab at a possible connection with last year's extreme weather events, like the blistering drought in Texas. NPR's Richard Harris reports.
RICHARD HARRIS, BYLINE: Weather researchers from around the world are now taking stock of what happened in 2011. It was not the hottest year on record, but it was still in the top 15. Jessica Blunden from the National Climatic Data Center says 2011 had its own memorable characteristics.
JESSICA BLUNDEN: People may very well remember this year as a year of extreme weather and climate.
HARRIS: There were devastating droughts in Africa, Mexico, and Texas. In Thailand, massive flooding kept people's houses underwater for two months.
BLUNDEN: Here in the United States, we had one of our busiest and most destructive seasons on record in 2011. There were seven different tornado and severe weather outbreaks that each caused more than a billion dollars in damages.
HARRIS: So what's going on here? Federal climate scientist, Tom Karl, said one major feature of the global weather last year was a La Nina event. That's a period of cooler Pacific Ocean temperatures and it has effects around the globe, primarily in producing floods in some parts of the world and droughts in others.
TOM KARL: By no means did it explain all of the activity in 2011, but it certainly influenced a considerable part of the climate and weather.
HARRIS: Karl and Blunden are part of a huge multinational effort to sum up last year's weather and say what it all means. They provided an update by conference call. Clearly, long-term temperature trends are climbing as you'd expect as a result of global warming. Tom Peterson from the Federal Climate Data Center says the effort now is to look more closely at individual events.
TOM PETERSON: You've probably all heard the term you can't attribute any single event to global warming, and while that's true, the focus of the science now is evolving and moving onto how is the probability of event change.
HARRIS: And there researchers report some progress. For example, last year's record-breaking drought in Texas wasn't simply the result of La Nina. Peter Stott from the British Meteorology Office says today's much warmer planet played a huge role as well, according to the study the group released on Tuesday.
PETER STOTT: The result that they find is really quite striking, in that they find that such a heat wave is now about 20 times more likely during a La Nina year than it was during the 1960s.
HARRIS: A second study found that an extraordinary warm spell in London last November was 60 times more likely to occur on our warming planet than it would have been over the last 350 years. But that's not to say everything is related to climate change. There's no clear link between the spate of tornadoes and global warming, and devastating floods in Thailand last year, turn out to be the result of poor land use practices.
Even so, Kate Willett of the British Weather Service says there is a global trend consistent with what scientists expect climate change to bring.
KATE WILLETT: So, in simple terms, we can say that the dry regions are getting drier and the wet regions are getting wetter.
HARRIS: This year's extreme events are different from last year's, but they all fit into a coherent picture of global change. Richard Harris, NPR News. Transcript provided by NPR, Copyright NPR.


From airport food that is roughly 100 percent sodium to the roof of the plane potentially coming off to a sleeping air traffic controller guiding a plane, you’d think air travel is getting dangerous.
A new study says it may be. Although not in the convertible-plane or narcoleptic-controller sort of way.
The study, released Monday in the Journal of Occupational Health and Environmental Medicine, says that frequent business travelers were more likely to describe their health as “fair” or “poor.”
More than 13,000 subjects were studied from data supplied by a corporate wellness program. It looked at three groups: Non-travelers, occasional travelers (80 percent of those surveyed) and “extensive travelers” who run at the George Clooney in “Up in the Air” pace of 20 or more nights a month on the road.
Those Clooney-esque road warriors are not a healthy bunch. And they certainly don’t look like him. They are 92 percent more likely to be obese, with high blood pressure and unfavorable cholesterol levels.
Several factors could contribute to this, the researchers said, including poor sleep, fattening foods and long periods of inactivity.
We’re no scientists, but we’d guess that doubles-for-$1-extra, migraine-inducing flight delays and blood-pressure-raising bag fees also have something to do with it.
How do you try to stay healthy on the road?


Like other pulmonate land snails, most slugs have two pairs of 'feelers' or tentacles on their head. The upper pair is light sensing, while the lower pair provides the sense of smell. Both pairs are retractable, and can be regrown if lost.
On top of the slug, behind the head, is the saddle-shaped mantle, and under this are the genital opening and anus. On one side (almost always the right hand side) of the mantle is a respiratory opening, which is easy to see when open, but difficult to see when closed. This opening is known as the pneumostome. Within the mantle in some species is a very small, rather flat shell.
Like other snails, a slug moves by rhythmic waves of muscular contraction on the underside of its foot. It simultaneously secretes a layer of mucus on which it travels, which helps prevent damage to the foot tissues. Some slug species hibernate underground during the winter in temperate climates, but in other species, the adults die in the autumn.
In rural southern Italy, the garden slug Arion hortensis was used to treat gastritis, stomach ulcers or peptic ulcers by swallowing it whole and alive. Given that it is now known that most peptic ulcers are caused by Helicobacter pylori, the merit of swallowing a live slug is questionable. A clear mucus produced by the slug is also used to treat various skin conditions including dermatitis, warts, inflammations, calluses, acne and wounds.


Our main goal here is to give a quick visual summary that is at once convincing and data rich. These employ some of the most basic tools of visual data analysis and should probably become form part of the basic vocabulary of an experimental mathematician. Note that traditionally one would run a test such as the Anderson-Darling test (which we have done) for the continuous uniform distribution and associate a particular probability with each of our sets of probability, but unless the probability values are extremely high or low it is difficult to interpret these statistics.
Experimentally, we want to test graphically the hypothesis of normality and randomness (or non-periodicity) for our numbers. Because the statistics themselves do not fall into the nicest of distributions, we have chosen to plot only the associated probabilities. We include two different types of graphs here. A quantile-quantile plot is used to examine the distribution of our data and scatter plots are used to check for correlations between statistics.
The first is a quantile-quantile plot of the chi square base 10 probability values versus a a discrete uniform distribution. For this graph we have placed the probabilities obtained from our square roots and plotted them against a perfectly uniform distribution. Finding nothing here is equivalent to seeing that the graph is a straight line with slope 1. This is a crude but effective way of seeing the data. The disadvantage is that the data are really plotted along a one dimensional curve and as such it may be impossible to see more subtle patterns.
The other graphs are examples of scatter plots. The first scatter plot shows that nothing interesting is occurring. We are again looking at probability values this time derived from the discrete Cramer-von Mises (CVM) test base 10,000. For each cube root we have plotted the point , where is the CVM base 10,000 probability associated with the first 2500 digits of the cube root of i and is the probability associated with the next 2500 digits. A look at the graph reveals that we have now plotted our data on a two dimensional surface and there is a lot more `structure' to be seen. Still, it is not hard to convince oneself that there is little or no relationship between the probabilities of the first 2500 digits and the second 2500 digits.
The last graph is similar to the second. Here we have plotted the probabilities associated with the Anderson-Stephens statistic of the first 10,000 digits versus the first 20,000 digits. We expect to find a correlation between these tests since there is a 10,000 digit overlap. In fact, although the effect is slight, one can definitely see the thinning out of points from the upper left hand corner and lower right hand corner.
Figure 1: Graphs 1-3


Vol. 17 Issue 6
One-Legged (Single Limb) Stance Test
The One-Legged Stance Test (OLST)1,2 is a simple, easy and effective method to screen for balance impairments in the older adult population.
You may be asking yourself, "how can standing on one leg provide you with any information about balance, after all, we do not go around for extended periods of time standing on one leg?"
True, as a rule we are a dynamic people, always moving, our world always in motion, but there are instances were we do need to maintain single limb support. The most obvious times are when we are performing our everyday functional activities.
Stepping into a bath tub or up onto a curb would be difficult, if not impossible to do without the ability to maintain single limb support for a given amount of time. The ability to switch from two- to one-leg standing is required to perform turns, climb stairs and dress.
As we know, the gait cycle requires a certain amount of single limb support in order to be able to progress ourselves along in a normal pattern. When the dynamics of the cycle are disrupted, loss of balance leading to falls may occur.
This is especially true in older individuals whose gait cycle is altered due to normal and potentially abnormal changes that occur as a result of aging.
The One-Legged Stance Test measures postural stability (i.e., balance) and is more difficult to perform due to the narrow base of support required to do the test. Along with five other tests of balance and mobility, reliability of the One-Legged Stance Test was examined for 45 healthy females 55 to 71 years old and found to have "good" intraclass correlations coefficients (ICC range = .95 to .099). Within raters ICC ranged from 0.73 to 0.93.3
To perform the test, the patient is instructed to stand on one leg without support of the upper extremities or bracing of the unweighted leg against the stance leg. The patient begins the test with the eyes open, practicing once or twice on each side with his gaze fixed straight ahead.
The patient is then instructed to close his eyes and maintain balance for up to 30 seconds.1
The number of seconds that the patient/client is able to maintain this position is recorded. Termination or a fail test is recorded if 1) the foot touches the support leg; 2) hopping occurs; 3) the foot touches the floor, or 4) the arms touch something for support.
Normal ranges with eyes open are: 60-69 yrs/22.5 ± 8.6s, 70-79 yrs/14.2 ± 9.3s. Normal ranges for eyes closed are: 60-69 yrs/10.2 ± 8.6s, 70-79 yrs/4.3 ± 3.0s.4 Briggs and colleagues reported balance times on the One-Legged Stance Test in females age 60 to 86 years for dominant and nondominant legs.
Given the results of this data, there appears to be some difference in whether individuals use their dominant versus their nondominant leg in the youngest and oldest age groups.
When using this test, having patients choose what leg they would like to stand on would be appropriate as you want to record their "best" performance.
It has been reported in the literature that individuals increase their chances of sustaining an injury due to a fall by two times if they are unable to perform a One-Legged Stance Test for five seconds.5 Other studies utilizing the One-Legged Stance Test have been conducted in older adults to assess static balance after strength training,6 performance of activities of daily living and platform sway tests.7
Interestingly, subscales of other balance measures such as the Tinetti Performance Oriented Mobility Assessment8 and Berg Balance Scale9 utilize unsupported single limb stance times of 10 seconds and 5 seconds respectively, for older individuals to be considered to have "normal" balance.
Thirty percent to 60 percent of community-dwelling elderly individuals fall each year, with many experiencing multiple falls.10 Because falls are the leading cause of injury-related deaths in older adults and a significant cause of disability in this population, prevention of falls and subsequent injuries is a worthwhile endeavor.11
The One-Legged Stance Test can be used as a quick, reliable and easy way for clinicians to screen their patients/clients for fall risks and is easily incorporated into a comprehensive functional evaluation for older adults.
1. Briggs, R., Gossman, M., Birch, R., Drews, J., & Shaddeau, S. (1989). Balance performance among noninstitutionalized elderly women. Physical Therapy, 69(9), 748-756.
2. Anemaet, W., & Moffa-Trotter, M. (1999). Functional tools for assessing balance and gait impairments. Topics in Geriatric Rehab, 15(1), 66-83.
3. Franchignoni, F., Tesio, L., Martino, M., & Ricupero, C. (1998). Reliability of four simple, quantitative tests of balance and mobility in healthy elderly females. Aging (Milan), 10(1), 26-31.
4. Bohannon, R., Larkin, P., Cook, A., & Singer, J. (1984). Decrease in timed balance test scores with aging. Physical Therapy, 64, 1067-1070.
5. Vellas, B., Wayne, S., Romero, L., Baumgartner, R., et al. (1997). One-leg balance is an important predictor of injurious falls in older persons. Journal of the American Geriatric Society, 45, 735-738.
6. Schlicht, J., Camaione, D., & Owen, S. (2001). Effect of intense strength training on standing balance, walking speed, and sit-to-stand performance in older adults. Journal of Gerontological Medicine and Science, 56A(5), M281-M286.
7. Frandin, K., Sonn, U., Svantesson, U., & Grimby, G. (1996). Functional balance tests in 76-year-olds in relation to performance, activities of daily living and platform tests. Scandinavian Journal of Rehabilitative Medicine, 27(4), 231-241.
8. Tinetti, M., Williams, T., & Mayewski, R. (1986). Fall risk index for elderly patients based on number of chronic disabilities. American Journal of Medicine, 80, 429-434.
9. Berg, K., et al. (1989). Measuring balance in the elderly: Preliminary development of an instrument. Physio Therapy Canada, 41(6), 304-311.
10. Rubenstein, L., & Josephson, K. (2002). The epidemiology of falls and syncope. Clinical Geriatric Medicine, 18, 141-158.
11. National Safety Council. (2004). Injury Facts. Itasca, IL: Author.
Dr. Lewis is a physical therapist in private practice and president of Premier Physical Therapy of Washington, DC. She lectures exclusively for GREAT Seminars and Books, Inc. Dr. Lewis is also the author of numerous textbooks. Her Website address is www.greatseminarsandbooks.com. Dr. Shaw is an assistant professor in the physical therapy program at the University of South Florida dedicated to the area of geriatric rehabilitation. She lectures exclusively for GREAT Seminars and Books in the area of geriatric function.
APTA Encouraged by Cap Exceptions
New process grants automatic exceptions to beneficiaries needing care the most
Calling it "a good first step toward ensuring that Medicare beneficiaries continue to have coverage for the physical therapy they need," Ben F Massey, Jr, PT, MA, president of the American Physical Therapy Association (APTA), expressed optimism that the new exceptions process will allow a significant number of Medicare patients to receive services exceeding the $1,740 annual financial cap on Medicare therapy coverage. The new procedure, authorized by Congress in the recently enacted Deficit Reduction Act (PL 109-171), will be available to Medicare beneficiaries on March 13 under rules released this week by the Centers for Medicare and Medicaid Services (CMS).
"APTA is encouraged by the new therapy cap exceptions process," Massey said. "CMS has made a good effort to ensure that Medicare beneficiaries who need the most care are not harmed by an arbitrary cap."
As APTA recommended, the process includes automatic exceptions and also grants exceptions to beneficiaries who are receiving both physical therapy and speech language pathology (the services are currently combined under one $1,740 cap).
"We have yet to see how well Medicare contractors will be able to implement and apply this process. Even if it works well, Congress only authorized this new process through 2006. Congress must address this issue again this year, and we are confident that this experience will demonstrate to legislators that they must completely repeal the caps and provide a more permanent solution for Medicare beneficiaries needing physical therapy," Massey continued.
The therapy caps went into effect on Jan. 1, 2006, limiting Medicare coverage on outpatient rehabilitation services to $1,740 for physical therapy and speech therapy combined and $1,740 for occupational therapy.
The American Physical Therapy Association is a national professional organization representing more than 65,000 members. Its goal is to foster advancements in physical therapy practice, research and education.
New Mouthwash Helps With Pain
Doctors in Italy are studying whether a new type of mouthwash will help alleviate pain for patients suffering from head and neck cancer who were treated with radiation therapy, according to a new study (International Journal of Radiation Oncology*Biology*Physics, Feb. 1, 2006).
Fifty patients, suffering from various forms of head and neck cancer and who received radiation therapy, were observed during the course of their radiation treatment. Mucositis, or inflammation of the mucous membrane in the mouth, is the most common side effect yet no additional therapy has been identified that successfully reduces the pain.
This study sought to discover if a mouthwash made from the local anesthetic tetracaine was able to alleviate the discomfort associated with head and neck cancer and if there would be any negative side effects of the mouthwash. The doctors chose to concoct a tetracaine-based mouthwash instead of a lidocaine-based version because it was found to be four times more effective, worked faster and produced a prolonged relief.
The tetracaine was administered by a mouthwash approximately 30 minutes before and after meals, or roughly six times a day. Relief of oral pain was reported in 48 of the 50 patients. Sixteen patients reported that the mouthwash had an unpleasant taste or altered the taste of their food.


Hypertension is often diagnosed during a visit to your doctor. Blood pressure is measured using a cuff around your arm and a device called a sphygmomanometer. Your doctor may ask you to sit quietly for five minutes before checking your blood pressure.
If your blood pressure reading is high, you will probably be asked to come back for repeat blood pressure checks. If you have three visits with readings over 140/90 mmHG, you will be diagnosed with high blood pressure.
Some people’s blood pressure goes up when they are at the doctor’s office. If your doctor suspects that may be occurring, he or she may ask you to get some blood pressure readings at home. In some cases, he or she may recommend that you wear an ambulatory blood pressure monitor. This device measures your blood pressure regularly throughout the day as you go about your activities. It is usually worn for 24 hours, even while sleeping.
- Reviewer: Michael J. Fucci, DO
- Review Date: 09/2012 -
- Update Date: 00/91/2012 -


When faced with the possibility of cooperating for mutual gain, states that feel insecure must ask how the gain will be divided..
A state worries about a division of possible gains that may favor others more than itself. That is the first way in which the structure of international politics limits the cooperation of states. A state also worries lest it become dependent on others through cooperative endeavors and exchanges of goods and services... The world's well-being would be increased if an ever more elaborate divisions of labor were developed, but states would thereby place themselves in situations of ever closer interdependence...
In an unorganized realm each unit's incentive is to put itself in a position to be able to take care of itself since no one can be counted on to do so. The international imperative is "take care of yourself"! Some leaders of nations may understand that the well-being of all of them would increase in their participation in a fuller division of labor. But to act on the idea would be to act on a domestic imperative, an imperative that does not run internationally...Waltz's argument may not apply perfectly to the EU, since he claims that the fundamental impediment to cooperation is the threat of conflict. The era of European wars is long over, but there may nonetheless be something to Waltz's argument. In the midst of economic crisis, tensions between European countries have hardened, and the crisis has caused bickering among EU member nations.
On another note, a recent FT/Harris poll of the British public found that only one in three Brits wants to remain in the EU.


Analog Input Channels
Temperature is a measure of the average kinetic energy of the particles in a sample of matter expressed in units of degrees on a standard scale. You can measure temperature in many different ways that vary in equipment cost and accuracy. The most common types of sensors are thermocouples, RTDs, and thermistors.
Figure 1. Thermocouples are inexpensive and can operate over a wide range of temperatures.
Thermocouples are the most commonly used temperature sensors because they are relatively inexpensive yet accurate sensors that can operate over a wide range of temperatures. A thermocouple is created when two dissimilar metals touch and the contact point produces a small open-circuit voltage as a function of temperature. You can use this thermoelectric voltage, known as Seebeck voltage, to calculate temperature. For small changes in temperature, the voltage is approximately linear.
You can choose from different types of thermocouples designated by capital letters that indicate their compositions according to American National Standards Institute (ANSI) conventions. The most common types of thermocouples include B, E, K, N, R, S, and T.
For more information on thermocouples, read The Engineer's Toolbox for Thermocouples.
Figure 2. RTDs are made of metal coils and can measure temperatures up to 850 °C.
A platinum RTD is a device made of coils or films of metal (usually platinum). When heated, the resistance of the metal increases; when cooled, the resistance decreases. Passing current through an RTD generates a voltage across the RTD. By measuring this voltage, you can determine its resistance and, thus, its temperature. The relationship between resistance and temperature is relatively linear. Typically, RTDs have a resistance of 100 Ω at 0 °C and can measure temperatures up to 850 °C.
For more information on RTDs, read The Engineer's Toolbox for RTDs.
Figure 3. Passing current through a thermistor generates a voltage proportional to temperature.
A thermistor is a piece of semiconductor made from metal oxides that are pressed into a small bead, disk, wafer, or other shape and sintered at high temperatures. Lastly, they are coated with epoxy or glass. As with RTDs, you can pass a current through a thermistor to read the voltage across the thermistor and determine its temperature. However, unlike RTDs, thermistors have a higher resistance (2,000 to 10,000 Ω) and a much higher sensitivity (~200 Ω/°C), allowing them to achieve higher sensitivity within a limited temperature range (up to 300 °C).
For information on thermistors, read The Engineer's Toolbox for Thermistors.


there is a book called "the Statistics Problem Solver" for $4 (used) on amazon. Buy it! These problem-solver books are great for math & science classes. With thousands of solved problems and the steps for solving them shown, its like having a grad student tutor at your elbow.
You have to use the book correctly, though. The wrong way is to look at your homework problem, thumb thru the book until you see a similar one, then apply it blindly to your HW. A 5th grader could do that. Instead, use the book as a way to get practice until you understand the concepts. Go to the chapter matching your current classwork, cover up the answers and start working problems. If you get it wrong, read the correct steps, cover them up, do it again. Keep working problems until you get it. When you get midterms in class you'll almost be laughing because you know you can do them all.
Keep in mind that a standard expectation for a college class is 2-3 hours outside of the class for every hour in it. Your class will meet 3x a week for an hour, which means you ought to be putting in 6-9 hours outside of class for it. Do this, and use your time effectively, you'll do well in the class.


The countries of northern Europe have agreed to build a huge network of renewables that will connect offshore wind farms in northern Scotland to solar panels in Germany to wave power and hydroelectricity in Scandinavia.
Offshore wind projects in Europe are expected to generate more than 100 gigawatts of energy, about ten percent of the continent’s demands, in coming years, roughly equivalent to a hundred large coal plants. But unpredictable weather patterns can hamper their ability to deliver reliable energy, and national power grids are too weak to overcome fluctuations in production and demand.
Nine nations, including France, Germany, the Netherlands, Denmark, Sweden, and the UK, have joined forces to lay undersea cables beneath the North Sea in the coming decade. The grid will act as a gigantic battery, storing electricity when demand is reduced.
The North Sea grid could connect to a much larger renewable plan that was launched in Germany last year. The Desertec Industrial Initiative is a $400 billion scheme that aims to deliver 15 percent of Europe’s electricity by 2050 from southern Europe and North Africa. Concentrated solar power will be delivered by power lines that stretch across the Sahara and the Mediterranean. Scientists in the European Commission estimate that just 0.3 percent of the light falling on the deserts of the Sahara and Middle East would be enough to meet all of Europe’s energy needs.


Viticulture - n. : the cultivation or culture of grapes
Enology - n. :a science that deals with wine and wine making
The V&E Department combines the sciences of viticulture and enology in a single research and teaching unit that encompasses all of the scientific disciplines that impact grape growing and winemaking. For over one hundred years the University of California has maintained an active and productive program in research and education in viticulture and enology. The continuing excellence of the Department has enabled California growers and vintners to develop practices that have allowed the Golden State to achieve its potential and become a premier wine-producing region.
The Rhone Rangers Scholarship
The Rhone Rangers is a non-profit educational organization dedicated to the advancing the knowledge and understanding of traditional Rhone grape varieties and the wines produced from those grapes. The Rhone Rangers has adopted the French government's list of approved varieties allowed in the Cote du Rhone as the criteria for winery membership. Today, membership consists of over 125 wineries from California, Washington, and Virginia.
This scholarship is given with a preference to students interested in research involving Rhone grape varieties or Rhone wines produced in the USA. The Rhone Rangers desire to see a deserving student be supported during their studies at UCD.


December 3, 2012 | Politics and Leadership
The Dilma Effect: How Brazil’s Groundbreaking President is Inspiring Other Women to Run
By Maya Popa
“In Portuguese, the term presidente applies to both men and women, and presidenta to women only. When Dilma was elected, people asked her which term she preferred to use and she said presidenta, with the feminine ending.”
“Dilma,” it almost goes without saying, is Dilma Rousseff, voted into office in 2010 as the first woman to lead powerhouse Brazil, the world’s sixth largest economy. For the woman telling that anecdote, thirtysomething Veronica Marques of Rio, it illustrates one of Rousseff’s greatest accomplishments in office: Her ability to motivate other women to succeed, especially in public life. “For me, this simple gesture shows how having a woman as a presidenta can inspire other women not only to seek more space in the political arena, but also through their daily lives,” says Marques, an executive at ELAS, the Women's Social Investment Fund, a nonprofit that invests in women’s empowerment and education.
The Dilma Effect starts at the top: After promising in her inaugural speech “to open doors, so that in the future many other women can also be president,” Rousseff put together a cabinet with three times as many women as the previous administration, giving women nine of the 24 minister-level positions--including such key jobs as ministers of planning, social development and the environment.
And in this macho, macho country, thanks to Rousseff, more women are getting into politics than ever before. "Dilma took several high-profile media opportunities to encourage women to run in the last elections,” says Heather Arnet, CEO of the Women and Girls Foundation of Pennsylvania, which is partnering with ELAS to study the effect of governmental policies on the lives of Brazilian women. The result: A record 48 women sought the chance to head Brazil’s 26 states, a 60 percent increase over the previous contest.
But the fight for gender equality is hardly won. Although Brazil has a 30 percent rule—requiring that 30 percent of candidates for elective office be women—females hold only nine percent of positions in the lower house of parliament and only 36 percent of lawmaker, senior official and managerial jobs, according to a 2011 report by the World Economic Forum. “There is a long way to go to have more women in politics, but we are building step by step,” says Marques. “Maybe, in some years we will have at least 50 percent of women in political positions in Brazil.”
Politics, though, isn’t the only area where Brazilian women are breaking glass ceilings. Earlier this year Maria das Graças Silva Foster was named CEO of Petrobras-Petróleo Brasil--the first woman in the world to head a major oil-and-gas company. According to a recent survey, 80 percent of Brazilian women now aspire to top jobs (compared to 52 percent in the U.S), while 59 percent consider themselves “very ambitious” (compared to 36 percent in the U.S.) Arnet praises government-funded social programs for providing the right conditions for women to succeed: inexpensive, over-the-counter birth control, six months paid maternity leave, efforts to connect rural women to education and healthcare, and the bolsa familia program, compensation for poor women to keeping their children in school. "All of these policies and cultural practices together are creating an environment where women can be more economically sufficient and can take on increasing corporate and political leadership," says Arnet.
Marques, though, has the most personal take on her country’s leader: “When I see myself represented by a woman as presidenta, I see that things are changing. I see that our generation of women and the next generation of women will have more space in the political arena because of her. Achieving in the political arena is not simple. Brazil has to give us—the new generation of women—the space and the opportunity for it. We want to do it, we can do it, we will do it.”
SOLUTIONS FOR BRAZIL: Let’s Go Girls!
The Women and Girls Foundation of Pennsylvania, led by Heather Arnet, is partnering with Veronica Marques at ELAS, on a project called Vamos Meninas! (Let's Go Girls!) to "explore the role that Brazilian voting practices, economic policies, and policies regarding family planning and child care have in fostering a culture for female advancement."
In January 2013, Arnet and ELAS will visit Rio, Sao Paulo, Brasilia and other cities, to better understand the changes occurring in Brazil and their impact on women’s leadership. As Arnet explains: "Together we hope to capture stories of transformation that provide Americans insight into this emerging world economic leader, and inspiration to continue our own pursuit towards gender equity."
Explaining what seems an unlikely pairing, Arnet says that “Brazil and Pennsylvania, historically, have a surprising amount in common. We are both economies which used to rely mainly on coal mining. We are traditionally macho cultures where women stayed home, and had children, and men went to work in the factories. We have had significant racial and class segregation and gender segregation in the workplace. And yet look at Brazil now. From an economic revitalization perspective and gender leadership perspective things are changing in Brazil dynamically.”
A documentary about Vamos Meninas! will premiere on PBS station WQED/Pittsburgh later in 2013. Says Arnet, "We have a lot to learn from Brazil, its people and its leaders, regarding how to transform our culture and our economies for a new century."
Maya Catherine Popa is a writer for the Women in the World Foundation. She is currently completing a Master's in Creative Writing at Oxford University under a Clarendon Scholarship, as well as an MFA in Poetry from NYU. She co-leads a weekly writing workshop for veterans of Iraq & Afghanistan. Her writing appears in The Huffington Post, Locustpoint, and elsewhere.


Not only does it have over 800 illustrations and photographs but it's jam packed, full of
information for your homeschool or any supplement to your children's learning. In my opinion it
would make a great "Summer project" book to keep the kiddos on their toes and help them learn
while having fun!
The World Of Science is broken down into 7 different sections covering topics entitled: Matter and Chemicals - Energy, Motion and Machines - Electricity and Magnetism - Light and Sound - Earth
and Life - Space and Time - and includes over 60 Science experiments.
The photographs and diagrams are just right to help you teach your budding scientists. My 3
scientists range in age from 6 years old to 10 years and the information is shared in such a way
that from my Kindergartner to my 5th grader, they were able to learn, understand, and enjoy
what we've done so far.
We've been studying the atmosphere, covered in the Earth and Life section. One of the things we learned about is the Greenhouse effect. The boys are looking forward to doing more and I have a feeling we'll have conquered all the experiments by the end of the summer. They love this type of learning and it sticks with them so much better than plain questions and answers!
The World Of Science is a wonderful addition to our homeschool curriculum. I highly recommend it. We are using it as a supplement to our main course and it covers enough topics that it would make a nice addition to any curriculum. It reads much like an encyclopedia, thorough yet made for children to easily understand.
The introduction begins with, "In the beginning God Created the Heavens and the Earth." It goes on to explain about the Scientific method, talks about Real science, various fields of science, and even an explanation as to why we should do science. I think every home could benefit by having such a well rounded resource.
We used a tin tray I had on hand with a plastic lid that attaches
recycled toilet paper/ or paper towel rolls for the seed cups
sand and soil from outside & seeds from the dollar store
(you could also use grass with roots or flowers from outside)
1. Place about 1 inch of sand in the bottom of container tray
2. Cut paper rolls down to 2 inches - 2 1/2 inches
3. Places cups in tray and push them down into the sand
4. Fill individual cups with soil
5. Use a finger to make a little hole to drop seeds into
6. Cover back up with the soil - Water them in well
7. Cover with plastic lid and set tray in indirect sunlight
(you don't want to fry your little plants but they do need light - a windowsill is a good spot)
Within just a few minutes the boys noticed that our little
greenhouse was beginning to fog up and collect condensation
on the plastic lid - before we've even sprouted our
little carrots - they're understanding the "greenhouse effect"
From other cool sites:
Check out a couple of really fun ways to make your own
greenhouses - grow some plants - and learn about the
What kind of Science are you doing in your homeschool? Do you have any fun ideas to share?