On the Screening of Other External Events: Explosions and Hazardous Release Evaluation

Wider scope of external events assessment is considering also evaluations of explosions and hazardous chemical release postulated to occur on sites or near nuclear power plants. This is potentially important because it should not affect capability of main control room operators to operate nuclear power plant under the conditions after such events. Major potential source of these danger is from the outside the plant. Namely they are either industry facilities or transportation near the site.This paper is discussing the application of the approach defined by the U.S. Nuclear Regulatory Commission defined in the Regulatory Guide 1.78 'Evaluating Power Plant Control Room During a Postulated Hazardous Chemical Release', and 1.91 'Evaluations of explosions postulated to occur on transportation routes near nuclear power plants'. In the paper most of the screening criteria from the RG 1.78 and 1.91 are applied, and some of necessary simulations are illustrated. Influence of the various assumptions, and differences in the results between simplified calculations and simulations is also investigated.Presented results are showing huge important results and need for improved screening process.(author).