The situation at Fukushima, though still in daily flux, will probably end up ranking between these two historical accidents in terms of radiation releases and health consequences. 6,7 The long-term effects of the Chernobyl accident are still being characterized, as we discuss in more detail below. Although the Three Mile Island accident has not yet led to identifiable health effects, 3-5 the Chernobyl accident resulted in 28 deaths related to radiation exposure in the year after the accident. 2 However, there was no such containment structure in place at the Chernobyl reactor - the explosions and the subsequent fire sent a giant plume of radioactive material into the atmosphere. In the partial meltdown at Three Mile Island, the plant's containment structure fulfilled its purpose, and a minimal amount of radiation was released. 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. 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 ( Figure 1). Elevated temperatures and pressures can result in explosions within the reactor, dispersing radioactive material. In such a circumstance, the reactor core and even the fuel itself can partially or completely melt. One mechanism by which this can happen is failure of the core cooling system. 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. In addition to the release of energy, the split fuel creates radioactive fission products. 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. Adapted from the Nuclear Regulatory Commission. In most reactors, the effects of such meltdowns are minimized by surrounding this vessel in an airtight, steel-reinforced concrete containment structure, designed to contain the fuel and fission products indefinitely. However, in the event of a failure of the cooling systems, the water can boil off, with the potential for the temperature to rise sufficiently for the core and the fuel itself to melt partially or completely. The reactor core, which contains the fuel and radioactive fission products, is situated inside a thick-walled steel vessel that houses the cooling water. The resulting steam drives the turbines that generate electricity, while the condensed water is collected, cooled, and returned to the reactor vessel. In a boiling water reactor - the type in use at Fukushima, Japan - water is boiled by the heat produced by nuclear fission. Reactor Accidents and the Release of Radioactive Materials Figure 1. ![]() The most trusted, influential source of new medical knowledge and clinical best practices in the world. Information and tools for librarians about site license offerings. Valuable tools for building a rewarding career in health care. The authorized source of trusted medical research and education for the Chinese-language medical community. The most advanced way to teach, practice, and assess clinical reasoning skills. Information, resources, and support needed to approach rotations - and life as a resident. ![]() The most effective and engaging way for clinicians to learn, improve their practice, and prepare for board exams. NEW! Peer-reviewed journal featuring in-depth articles to accelerate the transformation of health care delivery.Ĭoncise summaries and expert physician commentary that busy clinicians need to enhance patient care. ![]() NEW! A digital journal for innovative original research and fresh, bold ideas in clinical trial design and clinical decision-making.
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