China syndrome (nuclear meltdown)
The China Syndrome is a term that describes a fictitious result of a severe nuclear meltdown in which molten reactor core components penetrate their containment vessel and building. However the term is misleading, since molten material from such an event could not melt through the crust of the Earth and reach China.[1][2]
History and usage
Nuclear power plants ordered during the late 1960s raised safety questions and created fears that a severe reactor accident could release large quantities of radioactive material into the environment. In the early 1970s, a controversy arose regarding the ability of emergency cooling systems to prevent a core meltdown. This issue was discussed in the popular media and technical journals.[3]
In 1971, nuclear physicist Ralph Lapp used the term China syndrome to describe a possible burn-through, following a loss of coolant accident of the reactor containment structures and the subsequent escape of radioactive material into the environment. His statements were based on the report of a task force of nuclear physicists headed by W. K. Ergen, published in 1967.[4] The dangers of such a hypothetical accident were popularized by the 1979 film, The China Syndrome.
The name itself comes from the mistaken idea that, to many Americans, "the other side of the world" is China.[5] (see Antipodes)
Possible effects of a catastrophic meltdown
The "China Syndrome" refers to a ficticous result of the catastrophic meltdown of a nuclear reactor. The scenario begins when something causes the coolant level in a reactor vessel to drop, uncovering part—or all—of the fuel rod assemblies. Even if the nuclear chain reaction has been stopped through use of control rods or other devices, the fuel continues to produce significant residual heat for a number of days due to further decay of fission products. If not properly cooled, the fuel assemblies may soften and melt, falling to the bottom of the reactor vessel. There, without neutron-absorbing control rods to prevent it, nuclear fission could theoretically resume if fuel is significantly fresh but, in the absence of a neutron moderator or fresh fuel, will not. Regardless, without adequate cooling, the temperature of the molten fuel could increase to the point where it melts through the structures containing it. Although many feel the radioactive slag would stop at or before the the concrete level (as is the case with TMI, Chernobyl and Fukushima in which zero concrete penetration occured since, by design, concrete disipates heat very well and has an extremely high melting point), such a series of events could release varying quantities of radioactive material into the atmosphere, potentially causing damage to the local environment's plant and animal life.[6]
Some claim this damage happened, to an extent, during the Chernobyl disaster. No conclusive research to date has been developed regarding the matter.[7]
New Russian reactors are featuring a core catching technology intended to cool down the molten core in case of a full meltdown[8]
References
- ^ China Syndrome. (2008). In Merriam-Webster Online Dictionary. Retrieved May 26, 2008
- ^ Presenter: Martha Raddatz (2011-03-15). "ABC World News". ABC.
{{cite episode}}: Missing or empty|series=(help) - ^ 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, Dec. 12, 1971, pg. E11.
- ^ China Syndrome. (2008). In Merriam-Webster Online Dictionary. Retrieved May 26, 2008, from http://www.merriam-webster.com/dictionary/China+Syndrome
- ^ NR Publication 1556.2, "Nuclear Power; Separating Popular Science from Research and Development" Washington, DC; March 2009
- ^ Fukushima, ecco i rischi: “L’idrogeno può compromettere l’integrità dell’ultima barriera”, March 18th, 2011 interview to Massimo Zucchetti by Federico Simonelli. quote: " In parte questo successe a Chernobyl, dove si dovette costruire una soletta di cemento per separare il reattore dal terreno, esponendo a dosi letali di radiazioni alcune migliaia di lavoratori." translation: "In part that's what happened at Chernobyl, where they had to build a layer of concrete to separate the reactor from the soil, and so exposing some thousands workers to lethal doses of radiation."
- ^ Nuclear Industry in Russia Sells Safety, Taught by Chernobyl