Radiation exposure from fission product release

VII. RISKS TO THE INDIVIDUAL AND TO THE POPULATION FROM RADIATION EXPOSURE DUE TO FISSION PRODUCT RELEASE... 

Radioiodine is also identified as one of the most important fission products that can be released from nuclear facilities, particularly under accident conditions, in terms of its radiological effects on the environment, especially human exposure. A large amount of I delivered to the thyroid almost always leads to hypothyroidism, because of permanent radiation-induced destruction of thyroid cells. The use of potassium iodide (KI) helps in preventing such harmful effects. 

The MARS safety concept provides for retaining of radionuclides in the fuel both in normal operation and accidents, so that radiation exposure of the personnel and population around the NPP falls within the limits prescribed by the regulations. Barriers to the release of fission products from fuel are provided primarily by the coatings applied to each fuel particle. The required retention of radioactivity is ensured by the long-term operability of the fUel elements, which maintain their performance at temperatures up to 1250 C with the fast neutron (E>0.18 MeV) fluence to the coatings of up to 2.2 10 cm, and by quality assurance during fuel fabrication. 

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