Gerasymenko T. NPP Environmental Safety Assessment in Case of Exposure of Extreme Natural Phenomena.

The dissertation analyses the main causes and consequences of Fukushima catastrophe, results of National Report on stress tests of safety assessment of Ukrainian NPPs subject to lessons of great accident, and probabilistic and deterministic methods to model accident processes. The dissertation substantiates need to develop and improve a methodology for revaluation of NPP systems and equipment safety in case of combined exposure of beyond design basis extreme natural phenomena. The dissertation develops and realises methods for revaluation of flooding on Fukushima-Daiichi и Zaporizhzhya sites in case of combined exposure of beyond design basis earthquakes, storms and tornados. It is determined that flooding wave on Fukushima-Daiichi site in case of beyond design basis earthquake with magnitude 9 exceeds substantially (3 - 5 times) design statistic and deterministic evaluations. The dissertation determines criteria and conditions for probable flooding on Zaporizhzhya site in case of combined exposure of beyond design basis earthquakes, storms and tornados. The dissertation develops and realises methods for qualification of transport- process equipment and nuclear fuel intermediate storage systems. By example of Zaporizhzhya and South-Ukrainian NPPs, it is determined that these systems and equipment survive in case of beyond design basis earthquakes exceeding design seismic loads by a factor of ten.