Assessment of tornado hazard in the nuclear facilities siting areas

Abstract

The potential hazard of destructive tornado effects on nuclear facilities determines the necessity to study the climatic regime of tornado passage and arrange the appropriate protection of these facilities in conformity with the national and international radiation safety standards. One of the most characteristic features of the climate in recent decades is a significant increase in the number of dangerous meteorological events, including tornadoes. The purpose of this study is to assess the level of tornadoes hazard for nuclear facilities and to determine the design characteristics of tornadoes. The data on the tornado passage through the tornado-hazardous subzone A-L on the territory of the former USSR made it possible to estimate the probability of tornadoes passing through a hypothetical nuclear facility site, showing that it does not exceed the probability of the criterion in force in Russia ? the threshold probability of 10?4 per reactor per year. It is shown that such a threshold probability can be achieved if two or more tornadoes of intensity class F5 on the Fujita scale would pass through subzone A-L. For such a hypothetical scenario, the design characteristics of a probable tornado were determined. The need to improve the regulatory and technical base in the field of nuclear facilities safety is noted to ensure their reliable protection from the effects of tornadoes.