429:(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 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."
289:) 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.
394:(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.
472:– "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. The release of molten core materials into the 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."
1009:
As designed, it shut itself down, in about 300 seconds, as soon as the temperature rose to a point designed as higher than proper operation would require. This was well below the boiling point of the unpressurised liquid metal coolant, which had entirely sufficient cooling ability to deal with the heat of fission product radioactivity, by simple convection. The second test, deliberate shut-off of the secondary coolant loop that supplies the generators, caused the primary circuit to undergo the same safe shutdown. This test simulated the case of a water-cooled reactor losing its steam turbine circuit, perhaps by a leak.
320:
441:– "In less than half an hour, the peak core temperature would reach 1,100 K (830 °C). 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."
1285:, which stated, "It melts right down through the bottom of the plant—theoretically to China, but of course, as soon as it hits ground water, it blasts into the atmosphere and sends out clouds of radioactivity. The number of people killed would depend on which way the wind was blowing, rendering an area the size of Pennsylvania permanently uninhabitable." The actual threat of this was coincidentally tested just 12 days after the release of the film when a meltdown at Pennsylvania's Three Mile Island Plant 2 (
717:(or AGR), 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.
942:
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.
458:– "When the temperature in the core reaches about 1,700 K (1,430 °C), 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 (1,430 °C), the core temperature may escalate in a few minutes to the melting point of zircaloy due to increased oxidation rate. When the oxidized cladding breaks, the molten zircaloy, along with dissolved UO
57:
2810:
594:
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 debated positive effect of the corium falling into water is that it is cooled and returns to a solid state.
841:, the resultant hydrogen burns explosively. If oxygen contacts hot graphite, it will burn. 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.
2800:
894:
rapid shutdown system. The passive emergency cooling system uses reliable natural phenomena to cool the core, rather than depending on motor-driven pumps. The containment structure is designed to withstand severe stress and pressure. In the event of a pipe break of a cooling-water channel, the channel can be isolated from the water supply, preventing a general failure.
74:
680:'s fact sheet). The Three Mile Island accident provided real-life experience with an actual molten core: the 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.
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the fuel into tankage, which not only prevents further fission but draws decay heat away statically, and by drawing off the fission products (which are the source of post-shutdown heating) incrementally. The ideal is to have reactors that fail-safe through physics rather than through redundant safety systems or human intervention.
505:, 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.
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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).
606:
the reactor pressure vessels, leading to explosions inside the reactor buildings in units 1, 3 and 4 that damaged structures and equipment and injured personnel. Radionuclides were released from the plant to the atmosphere and were deposited on land and on the ocean. There were also direct releases into the sea.
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inside the reactor core. Other reactor designs, such as
Integral Fast Reactor model EBR II, had been explicitly engineered to be meltdown-immune. It was tested in April 1986, just before the Chernobyl failure, to simulate loss of coolant pumping power, by switching off the power to the primary pumps.
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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. Liquid fueled reactors can be stopped by draining
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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
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The RBMK tends towards dangerous power fluctuations. 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
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vault). 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
605:
In the
Fukushima incident, however, this design failed. Despite the efforts of the operators at the Fukushima Daiichi nuclear power plant to maintain control, the reactor cores in units 1–3 overheated, the nuclear fuel melted and the three containment vessels were breached. Hydrogen was released from
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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 event of lower plenum failure, debris at varied temperatures can be expected to be projected into the cavity below the core. The containment may be
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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
728:
Recently heavy liquid metal, such as lead or lead-bismuth, has been proposed as a reactor coolant. Because of the similar densities of the fuel and the HLM, an inherent passive safety self-removal feedback mechanism due to buoyancy forces is developed, which propels the packed bed away from the wall
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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
300:
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
945:
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 multiple redundant and diversified components. In addition, passive safety features such as 900-tonne ice condensers
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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
848:
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
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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
398:
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
941:
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 operated by former Soviet bloc countries have
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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 abandon the reactors
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than marginal containments, some have quality ECCS systems, and some have been upgraded to international standards of control and instrumentation. Present generations of VVERs (starting from the VVER-1000) are built to
Western-equivalent levels of instrumentation, control, and containment systems.
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An array of improvements make the MKER's safety comparable to
Western Generation III reactors: improved quality 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
541:
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
964:
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
821:, found only in Russia and other post-Soviet states and now shut down everywhere except Russia, do not have containment buildings, are naturally unstable (tending to dangerous power fluctuations), and have emergency cooling systems (ECCS) considered grossly inadequate by Western safety standards.
609:
As the natural decay heat of the corium eventually reduces to an equilibrium with convection and conduction to the containment walls, it becomes cool enough for water spray systems to be shut down and the reactor to be put into safe storage. The containment can be sealed with release of extremely
1309:. However, this concern was proven to be unfounded as (unknown to those at the time) the corium already contacted the reservoir before it could be drained, where instead of creating a steam explosion it harmlessly cooled rapidly and created a light-brown ceramic pumice that floated on the water.
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the phrasing is metaphorical; there is no way a core could penetrate the several-kilometer thickness of the Earth's crust, and even if it did melt to the center of the Earth, it would not travel back upwards against the pull of gravity. Moreover, any tunnel behind the material would be closed by
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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
601:
These procedures are intended to prevent release of radioactivity. 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
593:
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
585:
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" that would melt, dilute the core and increase the heat conductivity, and finally the diluted core can be cooled down by
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mass from the melting core began to breach the concrete floor of the reactor vessel, which was situated above the bubbler pool (a large water reservoir for emergency pumps and to contain any steam pipe rupture). There was concern that a steam explosion would have occurred if the hot corium made
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Several unique features of the MKER's design make it a credible and interesting option. The reactor remains online during refueling, ensuring outages only occasionally for maintenance, with uptime up to 97-99%. The moderator design allows the use of less-enriched fuels, with a high burnup rate.
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Western aid has been given to provide certain real-time safety monitoring capacities to the operating 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
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inside the containment are designed to prevent this. In Fukushima, the containments were filled with inert nitrogen, which prevented hydrogen from burning; the hydrogen leaked from the containment to the reactor building, however, where it mixed with air and exploded. During the 1979 Three Mile
268:
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
890:
Neutronics characteristics have been optimized for civilian use, for superior fuel fertilization and recycling; and graphite moderation achieves better neutronics than is possible with light water moderation. The lower power density of the core greatly enhances thermal regulation.
1265:, 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
649:
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
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when certain threshold of temperature is attained and the bed becomes lighter than the surrounding coolant, thus preventing temperatures that can jeopardize the vessel’s structural integrity and also reducing the recriticality potential by limiting the allowable bed depth.
664:
used the term "China syndrome" to describe a possible burn through of 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
492:, 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 (1,930 to 2,930 °C), its fall into liquid water at 550 to 600 K (277 to 327 °C) may cause an
618:
Island accident, a hydrogen bubble formed in the pressure vessel dome. There were initial concerns that the hydrogen might ignite and damage the pressure vessel or even the containment building; but it was soon realized that lack of oxygen prevented burning or explosion.
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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; as long as at least one gas circulator is available, however, the fuel will be kept
451:
by steam. In the oxidation process, hydrogen is produced and a large amount of heat is released. Above 1,500 K (1,230 °C), the power from oxidation exceeds that from decay heat (4,5) unless the oxidation rate is limited by the supply of either zircaloy or
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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.
435:– "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)."
634:) 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 newer studies, and now the
973:
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
916:
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 1–2 inches (2.5–5.1 cm) in thickness, grossly insufficient by Western standards.
33:
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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,
1972:
F.J Arias. The Phenomenology of Packed Beds in Heavy Liquid Metal Fast Reactors During Postaccident Heat Removal: The Self-Removal Feedback Mechanism. Nuclear Science and Engineering / Volume 178 / Number 2 / October 2014 / Pages
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overheated because the cooling systems failed after a tsunami flooded the power station, causing core meltdowns. This was compounded by hydrogen gas explosions and the venting of contaminated steam that released large amounts of
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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
488:("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
597:
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.
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250:. 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
927:
Apparently steam generator loops can be isolated, however, 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.
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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.
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only have one division and little redundancy within that division. Though the large core of the RBMK is less energy-dense than the smaller Western LWR core, it is harder to cool. The RBMK is moderated by
399:
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
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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.
1212:
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 (figuratively) through the
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.
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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.
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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
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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.
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contact with the water, resulting in more radioactive materials being released into the air. Due to damages from the accident, three station workers manually operated the valves necessary to
261:, a loss-of-coolant accident (LOCA), an uncontrolled power excursion. Failures in control systems may cause a series of events resulting in loss of cooling. Contemporary safety principles of
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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.
961:
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.
763:
744:) 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.
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688:
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.
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Though it might be possible to stop a loss-of-coolant event prior to core damage occurring, any core damage incidents will probably allow massive release of radioactive materials.
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limited offsite radioactivity and release of pressure. After perhaps a decade for fission products to decay, the containment can be reopened for decontamination and demolition.
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462:(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 UO
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1064:, in 1979, referred to in the press as a "partial core melt", led to the total dismantlement and the permanent shutdown of reactor 2. Unit 1 continued to operate until 2019.
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has commented on the TMI-2 accident, that despite melting of about one-third of the fuel, the reactor vessel itself maintained its integrity and contained the damaged fuel.
1954:
Allen, P.J.; J.Q. Howieson; H.S. Shapiro; J.T. Rogers; P. Mostert; R.W. van Otterloo (April–June 1990). "Summary of CANDU 6 Probabilistic Safety Assessment Study Results".
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is a modern Russian-engineered channel type reactor that is a distant descendant of the RBMK, designed to optimize the benefits and fix the serious flaws of the original.
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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
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897:
The greatly enhanced safety and unique benefits of the MKER design enhance its competitiveness in countries considering full fuel-cycle options for nuclear development.
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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
1710:"ANS : Public Information : Resources : Special Topics : History at Three Mile Island : What Happened and What Didn't in the TMI-2 Accident"
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was an experimental nuclear reactor that operated from 1957 to 1964 and was the first commercial power plant in the world to experience a core meltdown in July 1959.
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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
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1297:. Thus, the TMI-2 reactor fuel and fission products breached the fuel rods, but the melted core itself did not break the containment of the reactor vessel.
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2268:"Человек широкой души: Вот уже девятнадцатая годовщина Чернобыльской катастрофы заставляет нас вернуться в своих воспоминаниях к апрельским дням 1986 года"
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2270:[A man of broad souls: The nineteenth anniversary of the Chernobyl catastrophe forces us to return to our memories of the April days of 1986].
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subject to overpressure, though this is not likely to fail the containment. The alpha-mode failure will lead to the consequences previously discussed.
198:) within the fuel elements can leach out into the coolant. Subsequent failures can permit these radioisotopes to breach further layers of containment.
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disks could not relieve the stress. Exposed flammable substances could burn, but there are few, if any, flammable substances within the containment.
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669:. Some fear that a molten reactor core could penetrate the reactor pressure vessel and containment structure and burn downwards to the level of the
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Emergency Core Cooling, Report of Task Force Established by the US Atomic Energy Commission to Study Fuel Cooling Systems of Nuclear Power Plants
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reactor designs may be more susceptible to meltdown than other reactor types, due to their larger quantity of fissile material and the higher
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in March 2011, three of the power plant's six reactors suffered meltdowns. Most of the fuel in the reactor No. 1 Nuclear Power Plant melted.
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the primary coolant loop—the product of the slow corrosion of the RPV. This model is viewed as having inadequate process control systems.
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identify six modes by which the containment could be credibly challenged; some of these modes are not applicable to core melt accidents.
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The SNAP8DR reactor at the Santa Susana Field Laboratory experienced damage to approximately a third of its fuel in an accident in 1969.
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Has no ECCS. Can survive at most one 4 in (10 cm) pipe break (there are many pipes greater than that size within the design).
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Even with these positive developments, however, certain older VVER models raise a high level of concern, especially the VVER-440 V230.
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As previously described, FCI could lead to an overpressure event leading to RPV fail, and thus, primary pressure boundary fail. Haskin
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experimental fast breeder reactor, in 1966, required the reactor to be repaired, though it never achieved full operation afterward.
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into tanks where it will cool in a non-critical configuration. Since the core is liquid, and already melted, it cannot be damaged.
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870:, deemed totally incompatible with European nuclear safety standards. The country planned to replace them with safer reactors at
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214:, any of which could destroy parts of the containment. A meltdown is considered very serious because of the potential for
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447:– "The next stage of core damage, beginning at approximately 1,500 K (1,230 °C), is the rapid oxidation of the
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are designed so that complete loss of coolant for an indefinite period does not result in the reactor overheating. The
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751:, a larger-scale mobile version of the TRIGA for power generation in disaster areas and on military missions, and the
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380:
281:
In a loss-of-coolant accident, either the physical loss of coolant (which is typically deionized water, an inert gas,
170:
Once the fuel elements of a reactor begin to melt, the fuel cladding has been breached, and the nuclear fuel (such as
1799:
965:
radioactive material, a meltdown alone should not lead to significant radioactivity release or danger to the public.
484:
to substantially stress or breach the primary pressure boundary when the corium relocates to the lower plenum of the
414:
describe six stages between the start of the limiting fault (the loss of cooling) and the potential escape of molten
2586:
2514:
2245:
1328:
1225:
1061:
748:
329:
1728:
582:
If the melted core penetrates the pressure vessel, there are theories and speculations as to what may then occur.
319:
2804:
2740:
2649:
1078:
1040:
756:
223:
81:
1841:
1394:
501:
state that there exists a remote possibility of an extremely violent FCI leading to something referred to as an
1774:
1301:
1290:
1258:
509:
415:
406:
If such a limiting fault were to occur, and a complete failure of all ECCS divisions were to occur, both Kuan,
203:
160:
41:
590:
and filters. Hydrogen/oxygen recombiners also are installed within the containment to prevent gas explosions.
147:
A core meltdown accident occurs when the heat generated by a nuclear reactor exceeds the heat removed by the
2765:
2755:
2081:"TEPCO admits nuclear meltdown occurred at Fukushima reactor 16 hours after quake - the Mainichi Daily News"
1294:
1249:
built in the late 1960s raised the concern that a severe reactor accident could release large quantities of
485:
49:
45:
2760:
2561:
1570:
1413:
1086:
975:
1685:
1660:
1632:
2618:
2026:
1082:
782:
302:
164:
425:– In the event of a transient, upset, emergency, or limiting fault, LWRs are designed to automatically
978:
features that may be less susceptible to meltdown, even if all emergency systems failed. For example,
2750:
2612:
2383:
1363:
1250:
1230:
586:
water circulating in the floor. There has never been any full-scale testing of this device, however.
520:
There are several possibilities as to how the primary pressure boundary could be breached by corium.
247:
215:
156:
125:
89:
2084:
2735:
2537:
1441:
1246:
1242:
741:
301:
specifications until the reactor has had time to cool down. (This event is less likely to occur in
231:
227:
219:
85:
37:
946:
have been installed, making these two units safety-wise the most advanced VVER-440s in the world.
265:
ensure that multiple layers of safety systems are always present to make such accidents unlikely.
2643:
2606:
2543:
2115:
1713:
1306:
1300:
A similar concern arose during the Chernobyl disaster. After the reactor was destroyed, a liquid
1281:
1272:
979:
786:
737:
Some design concepts for nuclear reactors emphasize resistance to meltdown and operating safety.
666:
207:
144:, however, and is in common usage a reference to the core's either complete or partial collapse.
1428:
403:
the emergency cooling system had also been manually shut down several minutes after it started.
2177:
2110:
1414:"Reactor Safety Study: An Assessment of Accident Risks in U.S. Commercial Nuclear Power Plants"
56:
2745:
2708:
2205:
2043:
1899:
1613:
1536:
1445:
1022:
655:
199:
2199:
1893:
857:
response to the weaknesses that were in the RBMK. Nonetheless, numerous RBMKs still operate.
2631:
1873:
1217:
983:
489:
183:
2137:
1289:) created a molten core that moved 15 millimetres (0.59 inches) toward "China" before the
1213:
1209:
838:
767:
677:
658:
493:
141:
1687:
Perspectives on Reactor Safety (NUREG/CR-6042) (Reactor Safety Course R-800), 1st Edition
1662:
Perspectives on Reactor Safety (NUREG/CR-6042) (Reactor Safety Course R-800), 1st Edition
1634:
Perspectives on Reactor Safety (NUREG/CR-6042) (Reactor Safety Course R-800), 1st Edition
1476:
1253:
into the atmosphere and environment. By 1970, there were doubts about the ability of the
2770:
2637:
2602:
2596:
2275:
2106:
1353:
1160:
1118:
2240:[Memoirs of the senior engineer-mechanic of reactor shop №2 Alexey Ananenko].
1987:
1926:
1506:
2826:
2308:
2009:
1358:
1266:
1224:, presumed to be in "China". While the antipodes of China include Argentina with its
701:
293:
286:
152:
93:
2713:
2659:
2654:
1199:
1026:
1005:
1001:
863:
Upon entering the EU in 2004, Lithuania was required to phase out its two RBMKs at
211:
167:
in which the reactor is operated at a power level that exceeds its design limits.
44:. After reaching an extremely high temperature, the nuclear fuel and accompanying
17:
1430:
IAEA Safety Glossary: Terminology Used in Nuclear Safety and Radiation Protection
2785:
1122:
1075:
833:. In the presence of both steam and oxygen at high temperatures, graphite forms
670:
187:
66:
2775:
2238:"Воспоминания старшего инженера-механика реакторного цеха №2 Алексея Ананенка"
1156:
661:
643:
274:
251:
195:
191:
1690:. Beltsville, MD: U.S. Nuclear Regulatory Commission. pp. 3.5–4 to 3.5–5
1665:. Beltsville, MD: U.S. Nuclear Regulatory Commission. pp. 3.5–1 to 3.5–4
2567:
1221:
1152:
631:
297:
270:
175:
1412:
Commission, U. S. Nuclear Regulatory; Rasmussen, Norman C. (18 June 1975).
1036:
suffered a partial meltdown during a coolant flow test on 29 November 1955.
163:, loss of coolant pressure, or low coolant flow rate or be the result of a
2357:
Nuclear and radioactive disasters, former facilities, tests and test sites
159:, which is not caused by high temperatures. A meltdown may be caused by a
32:
2438:
1170:
864:
830:
448:
2237:
476:
At the point at which the corium relocates to the lower plenum, Haskin,
368:
Coating of previously molten material on bypass region interior surfaces
73:
1139:
1051:
613:
Another scenario sees a buildup of potentially explosive hydrogen, but
179:
171:
2047:
2039:
1729:"After Chernobyl, Russia's Nuclear Industry Emphasizes Reactor Safety"
1617:
1261:
and the consequent meltdown of the fuel core. In 1971, in the article
1029:
defect caused one fuel element (out of over 200) to overheat and melt.
630:
Another theory, called an "alpha mode" failure by the 1975 Rasmussen (
140:. It has been defined to mean the accidental melting of the core of a
1437:
993:
834:
797:
793:
789:
1877:
1870:
Emergency core-cooling systems for light-water-cooled power reactors
849:
the RBMK were shielded better than the core itself. Rapid shutdown (
546:
Severe accident ex-vessel interactions and challenges to containment
1637:. Beltsville, MD: U.S. Nuclear Regulatory Commission. p. 3.1–5
96:. Unit 2, which suffered a partial core melt, is in the background.
1368:
1286:
1033:
986:
850:
752:
696:
426:
318:
72:
55:
31:
1529:"4.6.1 Design Basis Accident for the AGR: Depressurization Fault"
853:) takes 10 to 15 seconds. Western reactors take 1 - 2.5 seconds.
383:
can be damaged, two precursor events must have already occurred:
151:
to the point where at least one nuclear fuel element exceeds its
2624:
1775:"The Fukushima Daiichi Accident. Report by the Director General"
906:
883:
814:
466:
would form the lower crust of a developing cohesive debris bed."
2329:
305:, where the core may be deliberately depressurized so that the
218:
to breach all containment and escape (or be released) into the
1135:
924:
Has six steam generator loops, adding unnecessary complexity.
282:
1825:
Three Mile Island: A Nuclear Crisis in Historical Perspective
1487:. pp. See Entries for Letter M and Entries for Letter N
1279:
The real scare, however, came from a quote in the 1979 film
480:
relate that the possibility exists for an incident called a
1986:. Timetravel.mementoweb.org. 31 August 2010. Archived from
1895:
Catastrophe: A Guide to World's Worst Industrial Disasters
1527:
Hewitt, Geoffrey Frederick; Collier, John Gordon (2000).
567:
External missiles (not applicable to core melt accidents)
1747:"Fukushima Daiichi Accident - World Nuclear Association"
638:
has disavowed them all and is preparing the overarching
764:
Hydrogen Moderated Self-regulating Nuclear Power Module
1835:
1833:
2300:
Annotated bibliography on civilian nuclear accidents
1371:
or SCRAM, an emergency shutdown of a nuclear reactor
1349:
Lists of nuclear disasters and radioactive incidents
418:
into the containment (a so-called "full meltdown"):
2679:
2496:
2363:
1025:suffered partial core damage in 1960 when a likely
845:to inaccurate neutronic and thermal power ratings.
2111:"Company Believes 3 Reactors Melted Down in Japan"
1827:(Berkeley: University of California Press), p. 11.
1427:International Atomic Energy Agency (IAEA) (2007).
1395:"Report Finds Japan Underestimated Tsunami Danger"
1324:Chernobyl compared to other radioactivity releases
1319:Behavior of nuclear fuel during a reactor accident
1535:. London, UK: Taylor & Francis. p. 133.
781:Advanced liquid metal reactors, such as the U.S.
2042:(Report). Division of Reactor Development, AEC.
1800:"Backgrounder on the Three Mile Island Accident"
2063:"Japan Expands Evacuation Around Nuclear Plant"
2603:Thor missile launch failures at Johnston Atoll
1522:
1520:
2404:Nuclear and radiation accidents by death toll
2399:Nuclear and radiation accidents and incidents
2341:
1802:. United States Nuclear Regulatory Commission
640:State-of-the-Art Reactor Consequence Analyses
242:Nuclear power plants generate electricity by
8:
2388:
1872:(Technical report). Oak Ridge National Lab.
1654:
1652:
1603:
1601:
1599:
1597:
1595:
1593:
1591:
78:Three Mile Island Nuclear Generating Station
2526:1996 San Juan de Dios radiotherapy accident
2409:Nuclear and radiation fatalities by country
2315:"The world's worst nuclear power disasters"
2274:(in Russian). 16 April 2005. Archived from
2162:Presenter: Martha Raddatz (15 March 2011).
1473:United States Nuclear Regulatory Commission
138:United States Nuclear Regulatory Commission
2348:
2334:
2326:
2040:SOME ASPECTS OF THE WTR AND SL-1 ACCIDENTS
1780:. International Atomic Energy Agency. 2015
1610:Managing water addition to a degraded core
1608:Kuan, P.; Hanson, D. J.; Odar, F. (1991).
713:One type of Western reactor, known as the
202:and hot metal inside the core can lead to
36:A simulated animation of a core melt in a
2694:Vulnerability of nuclear plants to attack
2671:Atomic bombings of Hiroshima and Nagasaki
2591:Three Mile Island accident health effects
1898:. Vij Books India Pvt Ltd. pp. 25–.
1819:
1817:
1081:experienced nuclear meltdowns, including
48:liquefies and flows to the bottom of the
2689:International Nuclear Event Scale (INES)
2532:Clinic of Zaragoza radiotherapy accident
2304:Alsos Digital Library for Nuclear Issues
1949:
1947:
27:Reactor accident due to core overheating
2731:International Day against Nuclear Tests
2379:Crimes involving radioactive substances
1485:Federal Government of the United States
1385:
1334:High-level radioactive waste management
516:Breach of the primary pressure boundary
470:(Corium) Relocation to the lower plenum
2521:Instituto Oncológico Nacional#Accident
1444:: International Atomic Energy Agency.
2204:. Butterworth-Heinemann. p. 37.
1769:
1767:
1416:. W.S. Hein – via Google Books.
819:Reaktor Bolshoy Moshchnosti Kanalnyy)
724:Lead and lead-bismuth-cooled reactors
7:
2726:History of the anti-nuclear movement
2248:from the original on 8 November 2018
749:Deployable Electrical Energy Reactor
2384:Criticality accidents and incidents
1727:Kramer, Andrew E. (22 March 2011).
1569:. JAIF. 25 May 2011. Archived from
700:light-water-filled shield tank (or
359:Possible region depleted in uranium
2488:Nuclear power accidents by country
2178:"Safety of nuclear Power Reactors"
2061:Wald, Matthew L. (11 March 2011).
1840:Lapp, Ralph E (12 December 1971).
1344:List of civilian nuclear accidents
1101:Fukushima Daiichi nuclear disaster
733:Experimental or conceptual designs
134:International Atomic Energy Agency
128:damage from overheating. The term
25:
2720:Bulletin of the Atomic Scientists
1712:. 30 October 2004. Archived from
1684:Haskin, F.E.; Camp, A.L. (1994).
1659:Haskin, F.E.; Camp, A.L. (1994).
1631:Haskin, F.E.; Camp, A.L. (1994).
1339:International Nuclear Event Scale
1184:Saint-Laurent Nuclear Power Plant
1167:Chapelcross nuclear power station
615:passive autocatalytic recombiners
259:loss-of-pressure-control accident
132:is not officially defined by the
2843:Civilian nuclear power accidents
2809:
2808:
2798:
2581:Kramatorsk radiological accident
1208:(loss-of-coolant accident) is a
742:process inherent ultimate safety
246:via a nuclear reaction to run a
2483:List of orphan source incidents
2038:Tardiff, A. N. (1 April 1962).
1222:until reaching the opposite end
775:liquid fluoride thorium reactor
537:Pressurized melt ejection (PME)
362:Ablated incore instrument guide
2010:"Partial Fuel Meltdown Events"
1866:(undocumented, see summary in
1842:"Thoughts on nuclear plumbing"
1393:Martin Fackler (1 June 2011).
1257:to cope with the effects of a
826:emergency core cooling systems
804:Soviet Union–designed reactors
747:Power reactors, including the
642:study - see the Disclaimer in
482:fuel–coolant interaction (FCI)
234:of people and animals nearby.
1:
2805:Nuclear technology portal
1892:Terra Pitta (5 August 2015).
1880:. ORNL-NSIC-24; OSTI 4825588.
1533:Introduction to nuclear power
1255:emergency core cooling system
1045:Santa Susana Field Laboratory
872:Visaginas Nuclear Power Plant
636:Nuclear Regulatory Commission
561:Dynamic pressure (shockwaves)
392:emergency core cooling system
307:emergency core cooling system
230:, and potentially leading to
2575:Andreev Bay nuclear accident
2562:Chazhma Bay nuclear accident
2309:Partial Fuel Meltdown Events
2242:Exposing the Chornobyl Myths
1483:. Rockville, Maryland, USA:
1263:Thoughts on Nuclear Plumbing
1050:The partial meltdown at the
652:Thoughts on Nuclear Plumbing
439:Fuel ballooning and bursting
2833:Nuclear safety and security
2509:Nyonoksa radiation accident
1475:(NRC) (14 September 2009).
1186:(civilian), France, in 1969
715:advanced gas-cooled reactor
381:light-water nuclear reactor
315:Light-water reactors (LWRs)
2859:
2781:Russell–Einstein Manifesto
2704:Films about nuclear issues
2699:Books about nuclear issues
2587:Three Mile Island accident
2515:Fukushima nuclear accident
2394:Military nuclear accidents
2389:Nuclear meltdown accidents
2198:Gianni Petrangeli (2006).
1823:Walker, J. Samuel (2004).
1564:"Earthquake Report No. 91"
1329:Chernobyl disaster effects
1226:Atucha Nuclear Power Plant
1197:
1062:Three Mile Island accident
353:Previously molten material
296:efficiency (when using an
82:pressurized water reactors
2794:
2741:Nuclear-Free Future Award
2650:Totskoye nuclear exercise
2478:Sunken nuclear submarines
1864:(Technical report). USAEC
1860:Ergen, W.K., ed. (1967).
1041:Sodium Reactor Experiment
757:uranium zirconium hydride
622:Speculative failure modes
494:extremely rapid evolution
224:radioactive contamination
204:fuel–coolant interactions
60:Three of the reactors at
1735:– via NYTimes.com.
1507:"Definition of MELTDOWN"
1259:loss of coolant accident
1159:, England, in 1957 (see
839:water gas shift reaction
510:American Nuclear Society
273:-force winds and severe
122:nuclear reactor accident
42:loss-of-coolant accident
2756:Nuclear power phase-out
1295:reactor pressure vessel
486:reactor pressure vessel
50:reactor pressure vessel
2838:Nuclear reactor safety
2761:Nuclear weapons debate
1105:earthquake and tsunami
976:passive nuclear safety
766:, a reactor that uses
578:Standard failure modes
423:Uncovering of the Core
376:
303:boiling water reactors
155:. This differs from a
97:
88:, each inside its own
70:
69:material into the air.
53:
2619:K-19 nuclear accident
2414:Nuclear weapons tests
2224:Andrew Leatherbarrow
2027:Integral fast reactor
1984:"INL VVER Sourcebook"
1868:Lawson, C.G. (1968).
1751:www.world-nuclear.org
1293:at the bottom of the
1251:radioactive materials
783:Integral Fast Reactor
379:Before the core of a
322:
216:radioactive materials
165:criticality excursion
76:
59:
35:
2751:Nuclear power debate
2613:Cuban Missile Crisis
2464:in the United States
1364:Nuclear power debate
1247:nuclear power plants
1231:lithostatic pressure
456:Debris bed formation
365:Hole in baffle plate
157:fuel element failure
90:containment building
86:Babcock & Wilcox
2736:Nuclear close calls
1990:on 22 December 2008
1716:on 30 October 2004.
1511:merriam-webster.com
980:pebble bed reactors
709:Gas-cooled reactors
684:Other reactor types
356:Lower plenum debris
232:radiation poisoning
208:hydrogen explosions
38:light-water reactor
2644:Operation Plumbbob
2607:Operation Fishbowl
2544:Chernobyl disaster
2226:Chernobyl 01:23:40
2116:The New York Times
2067:The New York Times
2014:nucleartourist.com
1846:The New York Times
1733:The New York Times
1399:The New York Times
1282:The China Syndrome
1273:The China Syndrome
1079:nuclear submarines
503:alpha-mode failure
433:Pre-damage heat up
401:Fukushima incident
377:
110:core melt accident
98:
71:
54:
18:Core melt accident
2820:
2819:
2746:Nuclear-free zone
2709:Anti-war movement
2665:Rocky Flats Plant
2321:. 7 October 2013.
1920:"Test Area North"
1905:978-93-85505-17-1
1576:on 3 January 2012
1542:978-1-56032-454-6
1451:978-92-0-100707-0
1142:, Canada, in 1952
1023:Westinghouse TR-2
659:nuclear physicist
656:Manhattan Project
564:Internal missiles
371:Upper grid damage
347:Loose core debris
326:Three Mile Island
200:Superheated steam
118:partial core melt
80:consisted of two
16:(Redirected from
2850:
2812:
2811:
2803:
2802:
2801:
2632:Kyshtym disaster
2627:nuclear meltdown
2554:Related articles
2538:Goiânia accident
2350:
2343:
2336:
2327:
2322:
2319:Power Technology
2288:
2287:
2285:
2283:
2278:on 26 April 2016
2264:
2258:
2257:
2255:
2253:
2234:
2228:
2222:
2216:
2215:
2195:
2189:
2188:
2182:
2174:
2168:
2167:
2159:
2153:
2152:
2150:
2148:
2138:"China Syndrome"
2134:
2128:
2127:
2125:
2123:
2103:
2097:
2096:
2094:
2092:
2083:. Archived from
2077:
2071:
2070:
2058:
2052:
2051:
2035:
2029:
2024:
2018:
2017:
2006:
2000:
1999:
1997:
1995:
1980:
1974:
1970:
1964:
1963:
1951:
1942:
1941:
1939:
1937:
1931:
1925:. Archived from
1924:
1916:
1910:
1909:
1889:
1883:
1881:
1865:
1857:
1855:
1853:
1837:
1828:
1821:
1812:
1811:
1809:
1807:
1796:
1790:
1789:
1787:
1785:
1779:
1771:
1762:
1761:
1759:
1757:
1743:
1737:
1736:
1724:
1718:
1717:
1706:
1700:
1699:
1697:
1695:
1681:
1675:
1674:
1672:
1670:
1656:
1647:
1646:
1644:
1642:
1628:
1622:
1621:
1605:
1586:
1585:
1583:
1581:
1575:
1568:
1560:
1554:
1553:
1551:
1549:
1524:
1515:
1514:
1503:
1497:
1496:
1494:
1492:
1469:
1463:
1462:
1460:
1458:
1435:
1424:
1418:
1417:
1409:
1403:
1402:
1390:
984:General Electric
813:Soviet-designed
328:reactor 2 after
263:defense in depth
184:fission products
130:nuclear meltdown
124:that results in
102:nuclear meltdown
84:manufactured by
21:
2858:
2857:
2853:
2852:
2851:
2849:
2848:
2847:
2823:
2822:
2821:
2816:
2799:
2797:
2790:
2766:Peace activists
2681:
2675:
2500:
2498:
2492:
2370:
2368:
2366:
2359:
2354:
2313:
2296:
2291:
2281:
2279:
2266:
2265:
2261:
2251:
2249:
2236:
2235:
2231:
2223:
2219:
2212:
2197:
2196:
2192:
2180:
2176:
2175:
2171:
2161:
2160:
2156:
2146:
2144:
2142:Merriam-Webster
2136:
2135:
2131:
2121:
2119:
2109:(24 May 2011).
2105:
2104:
2100:
2090:
2088:
2079:
2078:
2074:
2060:
2059:
2055:
2037:
2036:
2032:
2025:
2021:
2008:
2007:
2003:
1993:
1991:
1982:
1981:
1977:
1971:
1967:
1953:
1952:
1945:
1935:
1933:
1932:on 13 June 2011
1929:
1922:
1918:
1917:
1913:
1906:
1891:
1890:
1886:
1878:10.2172/4825588
1867:
1859:
1851:
1849:
1839:
1838:
1831:
1822:
1815:
1805:
1803:
1798:
1797:
1793:
1783:
1781:
1777:
1773:
1772:
1765:
1755:
1753:
1745:
1744:
1740:
1726:
1725:
1721:
1708:
1707:
1703:
1693:
1691:
1683:
1682:
1678:
1668:
1666:
1658:
1657:
1650:
1640:
1638:
1630:
1629:
1625:
1607:
1606:
1589:
1579:
1577:
1573:
1566:
1562:
1561:
1557:
1547:
1545:
1543:
1526:
1525:
1518:
1505:
1504:
1500:
1490:
1488:
1471:
1470:
1466:
1456:
1454:
1452:
1433:
1426:
1425:
1421:
1411:
1410:
1406:
1392:
1391:
1387:
1383:
1378:
1315:
1307:drain this pool
1239:
1210:nuclear reactor
1202:
1196:
1190:
1180:
1149:
1132:
1114:
1096:
1071:
1032:The reactor at
1018:
1012:
971:
959:
953:
903:
880:
811:
806:
768:uranium hydride
735:
726:
720:
711:
694:
686:
678:Test Area North
624:
580:
548:
524:Steam explosion
518:
465:
461:
445:Rapid oxidation
390:Failure of the
375:
374:
333:
317:
240:
222:, resulting in
161:loss of coolant
149:cooling systems
142:nuclear reactor
28:
23:
22:
15:
12:
11:
5:
2856:
2854:
2846:
2845:
2840:
2835:
2825:
2824:
2818:
2817:
2795:
2792:
2791:
2789:
2788:
2783:
2778:
2773:
2771:Peace movement
2768:
2763:
2758:
2753:
2748:
2743:
2738:
2733:
2728:
2723:
2716:
2711:
2706:
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2696:
2691:
2685:
2683:
2677:
2676:
2674:
2673:
2667:
2662:
2657:
2652:
2646:
2640:
2638:Windscale fire
2634:
2628:
2621:
2615:
2609:
2599:
2597:Lucens reactor
2593:
2583:
2577:
2571:
2564:
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2557:
2556:
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2454:United Kingdom
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2330:
2324:
2323:
2311:
2306:
2295:
2294:External links
2292:
2290:
2289:
2272:Post Chernobyl
2259:
2244:(in Russian).
2229:
2217:
2210:
2201:Nuclear safety
2190:
2169:
2164:ABC World News
2154:
2129:
2107:Hiroko Tabuchi
2098:
2087:on 20 May 2011
2072:
2053:
2030:
2019:
2001:
1975:
1965:
1956:Nuclear Safety
1943:
1911:
1904:
1884:
1829:
1813:
1791:
1763:
1738:
1719:
1701:
1676:
1648:
1623:
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1516:
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1419:
1404:
1384:
1382:
1379:
1377:
1374:
1373:
1372:
1366:
1361:
1356:
1354:Nuclear safety
1351:
1346:
1341:
1336:
1331:
1326:
1321:
1314:
1311:
1238:
1235:
1206:China syndrome
1195:
1194:China syndrome
1192:
1188:
1187:
1179:
1176:
1175:
1174:
1164:
1161:Windscale fire
1148:
1147:United Kingdom
1145:
1144:
1143:
1131:
1128:
1127:
1126:
1119:Lucens reactor
1113:
1110:
1109:
1108:
1103:following the
1095:
1092:
1091:
1090:
1070:
1067:
1066:
1065:
1058:
1055:
1048:
1037:
1030:
1017:
1014:
970:
969:Reactor design
967:
958:
955:
931:
930:
929:
928:
922:
902:
899:
879:
876:
810:
807:
805:
802:
734:
731:
725:
722:
710:
707:
693:
692:CANDU reactors
690:
685:
682:
623:
620:
579:
576:
575:
574:
571:
568:
565:
562:
559:
547:
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526:
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388:
373:
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342:
339:
335:
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323:
316:
313:
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311:
290:
239:
236:
120:) is a severe
94:cooling towers
92:and connected
26:
24:
14:
13:
10:
9:
6:
4:
3:
2:
2855:
2844:
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2807:
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2793:
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2710:
2707:
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2656:
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2647:
2645:
2641:
2639:
2635:
2633:
2629:
2626:
2622:
2620:
2616:
2614:
2610:
2608:
2604:
2600:
2598:
2594:
2592:
2588:
2584:
2582:
2578:
2576:
2572:
2569:
2565:
2563:
2559:
2555:
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2550:
2547:
2546:
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2518:
2516:
2512:
2510:
2506:
2505:
2503:
2495:
2489:
2486:
2484:
2481:
2479:
2476:
2472:
2471:United States
2469:
2465:
2462:
2460:
2457:
2456:
2455:
2452:
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2447:
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2425:
2422:
2420:
2417:
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2415:
2412:
2410:
2407:
2405:
2402:
2400:
2397:
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2390:
2387:
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2377:
2376:
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2358:
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2328:
2320:
2316:
2312:
2310:
2307:
2305:
2301:
2298:
2297:
2293:
2277:
2273:
2269:
2263:
2260:
2247:
2243:
2239:
2233:
2230:
2227:
2221:
2218:
2213:
2211:0-7506-6723-0
2207:
2203:
2202:
2194:
2191:
2186:
2179:
2173:
2170:
2165:
2158:
2155:
2143:
2139:
2133:
2130:
2118:
2117:
2112:
2108:
2102:
2099:
2086:
2082:
2076:
2073:
2068:
2064:
2057:
2054:
2049:
2045:
2041:
2034:
2031:
2028:
2023:
2020:
2015:
2011:
2005:
2002:
1989:
1985:
1979:
1976:
1969:
1966:
1962:(2): 202–214.
1961:
1957:
1950:
1948:
1944:
1928:
1921:
1915:
1912:
1907:
1901:
1897:
1896:
1888:
1885:
1879:
1875:
1871:
1863:
1848:. p. E11
1847:
1843:
1836:
1834:
1830:
1826:
1820:
1818:
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1801:
1795:
1792:
1776:
1770:
1768:
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1752:
1748:
1742:
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1734:
1730:
1723:
1720:
1715:
1711:
1705:
1702:
1689:
1688:
1680:
1677:
1664:
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1655:
1653:
1649:
1636:
1635:
1627:
1624:
1619:
1615:
1611:
1604:
1602:
1600:
1598:
1596:
1594:
1592:
1588:
1572:
1565:
1559:
1556:
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1523:
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1517:
1512:
1508:
1502:
1499:
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1478:
1474:
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1443:
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1431:
1423:
1420:
1415:
1408:
1405:
1400:
1396:
1389:
1386:
1380:
1375:
1370:
1367:
1365:
1362:
1360:
1359:Nuclear power
1357:
1355:
1352:
1350:
1347:
1345:
1342:
1340:
1337:
1335:
1332:
1330:
1327:
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1322:
1320:
1317:
1316:
1312:
1310:
1308:
1303:
1298:
1296:
1292:
1288:
1284:
1283:
1277:
1275:
1274:
1268:
1264:
1260:
1256:
1252:
1248:
1244:
1243:system design
1236:
1234:
1232:
1227:
1223:
1220:of the Earth
1219:
1215:
1211:
1207:
1201:
1193:
1191:
1185:
1182:
1181:
1177:
1172:
1168:
1165:
1162:
1158:
1154:
1151:
1150:
1146:
1141:
1137:
1134:
1133:
1129:
1124:
1120:
1116:
1115:
1111:
1106:
1102:
1098:
1097:
1093:
1088:
1085:, K-140, and
1084:
1080:
1077:
1073:
1072:
1068:
1063:
1059:
1056:
1053:
1049:
1046:
1042:
1038:
1035:
1031:
1028:
1027:fuel cladding
1024:
1020:
1019:
1016:United States
1015:
1013:
1010:
1007:
1003:
998:
995:
992:
988:
985:
981:
977:
968:
966:
962:
956:
954:
951:
947:
943:
939:
935:
926:
925:
923:
920:
919:
918:
914:
911:
908:
900:
898:
895:
891:
887:
885:
877:
875:
873:
869:
866:
861:
858:
854:
852:
846:
842:
840:
837:and with the
836:
835:synthesis gas
832:
827:
822:
820:
816:
815:RBMK reactors
808:
803:
801:
799:
795:
791:
788:
784:
779:
776:
771:
769:
765:
760:
758:
754:
750:
745:
743:
738:
732:
730:
723:
721:
718:
716:
708:
706:
703:
698:
691:
689:
683:
681:
679:
674:
672:
668:
663:
660:
657:
653:
647:
645:
641:
637:
633:
628:
621:
619:
616:
611:
607:
603:
599:
595:
591:
587:
583:
577:
572:
569:
566:
563:
560:
557:
556:
555:
553:
545:
543:
536:
535:
534:
531:
523:
522:
521:
515:
513:
511:
506:
504:
500:
495:
491:
487:
483:
479:
471:
468:
457:
454:
450:
446:
443:
440:
437:
434:
431:
428:
424:
421:
420:
419:
417:
413:
409:
404:
402:
393:
389:
386:
385:
384:
382:
370:
367:
364:
361:
358:
355:
352:
349:
346:
343:
340:
337:
336:
331:
327:
321:
314:
308:
304:
299:
295:
294:heat transfer
291:
288:
287:liquid sodium
284:
280:
279:
278:
276:
272:
266:
264:
260:
255:
253:
249:
245:
244:heating fluid
237:
235:
233:
229:
225:
221:
217:
213:
209:
205:
201:
197:
193:
189:
185:
181:
177:
173:
168:
166:
162:
158:
154:
153:melting point
150:
145:
143:
139:
135:
131:
127:
123:
119:
115:
111:
107:
106:core meltdown
103:
95:
91:
87:
83:
79:
75:
68:
63:
58:
51:
47:
43:
39:
34:
30:
19:
2796:
2718:
2714:Bikini Atoll
2660:Hanford Site
2655:Bikini Atoll
2459:in Australia
2449:Soviet Union
2444:South Africa
2318:
2280:. Retrieved
2276:the original
2271:
2262:
2250:. Retrieved
2241:
2232:
2225:
2220:
2200:
2193:
2185:npcil.nic.in
2184:
2172:
2163:
2157:
2145:. Retrieved
2141:
2132:
2120:. Retrieved
2114:
2101:
2089:. Retrieved
2085:the original
2075:
2066:
2056:
2033:
2022:
2013:
2004:
1992:. Retrieved
1988:the original
1978:
1968:
1959:
1955:
1934:. Retrieved
1927:the original
1914:
1894:
1887:
1869:
1861:
1858:referencing
1850:. Retrieved
1845:
1824:
1804:. Retrieved
1794:
1782:. Retrieved
1754:. Retrieved
1750:
1741:
1732:
1722:
1714:the original
1704:
1692:. Retrieved
1686:
1679:
1667:. Retrieved
1661:
1639:. Retrieved
1633:
1626:
1609:
1578:. Retrieved
1571:the original
1558:
1546:. Retrieved
1532:
1510:
1501:
1489:. Retrieved
1480:
1467:
1455:. Retrieved
1429:
1422:
1407:
1398:
1388:
1299:
1280:
1278:
1271:
1262:
1240:
1205:
1203:
1200:Core catcher
1189:
1169:(civilian),
1155:(military),
1138:(military),
1074:A number of
1069:Soviet Union
1011:
1006:neutron flux
1002:fast breeder
999:
991:Westinghouse
972:
963:
960:
952:
948:
944:
940:
936:
932:
915:
912:
904:
896:
892:
888:
881:
862:
859:
855:
847:
843:
823:
818:
812:
780:
772:
761:
746:
739:
736:
727:
719:
712:
695:
687:
675:
651:
648:
629:
625:
612:
608:
604:
600:
596:
592:
588:
584:
581:
558:Overpressure
551:
549:
540:
529:
527:
519:
507:
502:
498:
481:
477:
475:
469:
455:
444:
438:
432:
422:
411:
410:and Haskin,
407:
405:
397:
378:
330:the meltdown
267:
256:
241:
212:steam hammer
169:
146:
129:
117:
113:
109:
105:
101:
99:
29:
2786:Smiling Sun
2497:Individual
2434:North Korea
2147:11 December
1994:9 September
1936:7 September
1784:24 February
1694:24 December
1669:24 December
1641:23 November
1267:radioactive
1123:Switzerland
1112:Switzerland
1099:During the
1076:Soviet Navy
759:fuel used.
671:groundwater
667:W. K. Ergen
570:Meltthrough
275:earthquakes
220:environment
188:caesium-137
67:radioactive
62:Fukushima I
2827:Categories
2776:Peace camp
2566:1985–1987
2499:accidents
2367:disasters
2252:8 November
1806:1 December
1477:"Glossary"
1381:References
1291:core froze
1198:See also:
1157:Sellafield
1125:, in 1969.
740:The PIUS (
662:Ralph Lapp
644:NUREG-1150
252:decay heat
196:iodine-131
192:krypton-85
136:or by the
2568:Therac-25
2501:and sites
2371:incidents
2365:Lists of
2302:from the
1491:3 October
1457:17 August
1173:, in 1967
1153:Windscale
702:calandria
654:, former
632:WASH-1400
298:inert gas
271:hurricane
248:generator
186:(such as
176:plutonium
2814:Category
2680:Related
2570:accident
2439:Pakistan
2246:Archived
1756:24 April
1313:See also
1276:(1979).
1229:immense
1171:Scotland
1000:Certain
865:Ignalina
831:graphite
785:and the
449:Zircaloy
341:Inlet 1A
338:Inlet 2B
114:meltdown
46:cladding
40:after a
2549:Effects
2048:4828615
1973:240-249
1618:5642843
1481:Website
1442:Austria
1245:of the
1237:History
1140:Ontario
1052:Fermi 1
957:Effects
787:Russian
550:Haskin
452:steam."
228:fallout
180:thorium
172:uranium
2682:topics
2605:under
2424:France
2208:
2166:. ABC.
2122:25 May
2091:20 May
2046:
1902:
1852:26 May
1616:
1580:25 May
1548:5 June
1539:
1448:
1438:Vienna
1302:corium
1178:France
1130:Canada
994:AP1000
798:BN-800
796:, and
794:BN-600
790:BN-350
573:Bypass
416:corium
344:Cavity
238:Causes
182:) and
2669:1945
2648:1954
2642:1957
2636:1957
2630:1957
2623:1961
2617:1961
2611:1962
2601:1962
2595:1969
2585:1979
2579:1980
2573:1982
2560:1985
2542:1986
2536:1987
2530:1990
2519:2001
2513:2011
2507:2019
2429:India
2419:China
2282:3 May
2181:(PDF)
1930:(PDF)
1923:(PDF)
1778:(PDF)
1574:(PDF)
1567:(PDF)
1434:(PDF)
1376:Notes
1369:Scram
1287:TMI-2
1214:crust
1094:Japan
1087:K-431
1034:EBR-I
987:ESBWR
851:SCRAM
824:RBMK
809:RBMKs
753:TRIGA
697:CANDU
552:et al
530:et al
499:et al
490:phase
478:et al
427:SCRAM
412:et al
408:et al
350:Crust
310:cool.
285:, or
210:, or
194:, or
178:, or
2625:SL-1
2589:and
2369:and
2284:2016
2254:2018
2206:ISBN
2149:2012
2124:2011
2093:2011
2044:OSTI
1996:2019
1938:2008
1900:ISBN
1854:2024
1808:2013
1786:2018
1758:2024
1696:2010
1671:2010
1643:2010
1614:OSTI
1582:2011
1550:2010
1537:ISBN
1493:2009
1459:2009
1446:ISBN
1241:The
1218:body
1216:and
1204:The
1117:The
1083:K-27
1060:The
1039:The
1021:The
989:and
907:VVER
905:The
901:VVER
884:MKER
882:The
878:MKER
773:The
762:The
508:The
324:The
226:and
126:core
1874:doi
1136:NRX
1043:in
868:NPP
646:.)
283:NaK
116:or
2829::
2317:.
2183:.
2140:.
2113:.
2065:.
2012:.
1960:31
1958:.
1946:^
1882:)
1844:.
1832:^
1816:^
1766:^
1749:.
1731:.
1651:^
1612:.
1590:^
1531:.
1519:^
1509:.
1479:.
1440:,
1436:.
1397:.
1233:.
1121:,
874:.
792:,
673:.
277:.
254:.
206:,
190:,
174:,
112:,
108:,
100:A
2349:e
2342:t
2335:v
2286:.
2256:.
2214:.
2187:.
2151:.
2126:.
2095:.
2069:.
2050:.
2016:.
1998:.
1940:.
1908:.
1876::
1856:,
1810:.
1788:.
1760:.
1698:.
1673:.
1645:.
1620:.
1584:.
1552:.
1513:.
1495:.
1461:.
1401:.
1163:)
1089:.
817:(
464:2
460:2
332:.
104:(
52:.
20:)
Text is available under the Creative Commons Attribution-ShareAlike License. Additional terms may apply.
