Читать книгу Industrial and Medical Nuclear Accidents - Jean-Claude Amiard - Страница 19

Smythe [SMY 11] proposed a new quantitative scale of nuclear accident magnitude (NAMS). To do this, he used the event magnitude approach by calculating the magnitude of the accident (M) from wider releases of radionuclides (R). This radioactivity parameter is normalized in iodine 131 equivalents and expressed in TBq. The magnitude is calculated according to the following equation: M = log (20R).

Using this NAMS, the distribution between frequency and amplitude has been observed for 33 quantified events over the past 60 years. It follows a reverse power law, as in the case of earthquakes. However, the NAMS shows four exceptional accidents that have values 2–3 orders of magnitude higher than other accidents. These four accidents are, in decreasing order of severity, Chernobyl (NAMS 8.0), Three Mile Island (NAMS 7.9), Fukushima Daiichi (NAMS 7.5) and Kyshtym (NAMS 7.3). According to Smythe [SMY 11], such catastrophic accidents can occur every 12–15 years.