There have been only two major accidents at nuclear power plants, and their impacts have been much less serious than previously feared. Nuclear energy is the safest source of energy that we use anywhere in the world. Immediate health effects for the general public would not be expected from an accident at a nuclear power plant. This is because the amount of radiation present would be too small to cause immediate injury or illness.
However, there is a risk of long-term health effects. Cancer can develop many years after exposure. The VHTR is expected to be prototyped and tested at the Idaho National Laboratory within the next decade (starting in 200), based on the design selected for the Next Generation Nuclear Power Plant by the United States Department of Energy. Studies conducted by, for example, the World Health Organization have concluded that the health effects of nuclear accidents from radiation have been very small.
If the building were to fail and dust were released to the environment, the release of a given mass of fission products that have aged for almost thirty years would have a smaller effect than the release of the same mass of fission products (in the same chemical and physical form) that only experienced a short cooling time (e.g. , an hour) after the nuclear reaction had ended. The most serious nuclear accident occurred on April 26, 1986 at the Chernobyl nuclear power plant in Ukraine (then part of the Soviet Union). The term nuclear fusion is not officially defined by the International Atomic Energy Agency or by the United States Nuclear Regulatory Commission.
To prevent a post-accident nuclear reaction, measures have been taken, such as adding neutron poisons to key parts of the basement. However, a more detailed analysis of the probabilities of nuclear accidents requires more transparency on the part of the IAEA. In a modern reactor, a nuclear fusion, whether partial or total, must be contained within the reactor containment structure. Despite encouraging countries to report nuclear accidents, the agency makes INES information public only for 1 year after its publication.
The main impacts of nuclear accidents were not caused by radiation exposure, but were due to psychological and socio-economic factors resulting from misconceptions and fears about radiation, and could therefore have been largely avoided. The American Nuclear Society has commented on the TMI-2 accident, that despite the melting of approximately one third of the fuel, the reactor vessel itself maintained its integrity and contained the damaged fuel. A core damage accident is caused by the loss of sufficient cooling for the nuclear fuel inside the reactor core. Soon after the Chernobyl accident, it became clear that the main impacts of nuclear accidents are not radiological, but socio-economic and psychological, driven by misconceptions about the health effects of radiation.
If an accident occurs at a nuclear power plant, heat and pressure build up and steam, along with radioactive materials, can be released.