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Current Concepts Short-Term and Long-Term Health Risks of Nuclear-Power-Plant Accidents

Mon, 05/02/2011 - 09:02 — Yuriawati
2 May 2011

 

John P. Christodouleas, Robert D. Forrest, Christopher G. Ainsley, Zelig Tochner, Stephen M. Hahn, Eli Glatstein [Departments of Radiation Oncology and Radiation Safety, University of Pennsylvania, Philadelphia]
 
N Engl J Med 2011, published online first on April 20, 2011
 
Free full text: www.nejm.org/doi/pdf/10.1056/NEJMra1103676
 
 
On March 11, 2011, a 9.0-magnitude earthquake struck the east coast of Japan. The total number of people who died in the earthquake and the tsunami that it generated is still being assessed, but the official estimation already exceeds 14,000.1 The natural disaster also caused substantial damage to the Fukushima Daiichi nuclear power plant, the consequences of which are still unclear. The purpose of this review is to put the emergency at the Japanese power plant, even as it is evolving, into the context of the extensive literature on nuclear reactor accidents by analyzing the mechanisms and major short-term and long-term health risks of radiation exposure. In addition, we briefly discuss the accidents at Three Mile Island in Pennsylvania in 1979 and at Chernobyl in Ukraine in 1986 because they illustrate the broad range of potential outcomes.
 
Mechanisms of Exposure
Reactor Accidents and the Release of Radioactive Materials
In a nuclear power plant, the fuel, an isotope of either uranium or plutonium, undergoes fission to produce the energy that is used to heat water and turn steam-driven turbine generators. In addition to the release of energy, the split fuel creates radioactive fission products. In the event of an accident, the primary concern is that the support structure (core) containing the fuel and the fission products may become damaged and allow radioactive elements to escape into the environment. One mechanism by which this can happen is failure of the core cooling system. In such a circumstance, the reactor core and even the fuel itself can partially or completely melt. Elevated temperatures and pressures can result in explosions within the reactor, dispersing radioactive material. In most plants, the potential effects of a cooling system failure are minimized by surrounding the reactor core with a steel-walled vessel, which in turn is surrounded by an airtight, steel-reinforced concrete containment structure that is designed to contain the radioactive material indefinitely. Of note, the explosions that have been seen in reactor accidents are not the same as those seen after the detonation of a nuclear weapon, since the latter requires highly enriched uranium or plutonium isotopes in concentrations and configurations that are not present in power plants.