[2H01-06] Severe Accident

9:30 AM - 9:45 AM JST(12:30 AM - 12:45 AM UTC)

[2H01] Study on Influence of the RPV Depressurization Timing on the PCV Failure Timing during Severe Accident of the BWR

*Naoki Hattori¹, Akifumi Yamaji¹ (1. Waseda Univ.)

Keywords:

Severe Accident Management,PCV Protection,BWR,Steam Dryer,Accident Analysis,MELCOR

Analyses with MELCOR-2.2 showed the heat transport / transfer mechanisms by which the Reactor Pressure Vessel (RPV) depressurization timing affects the Primary Containment Vessel (PCV) upper boundary overheat failure timing during a BWR severe accident. If the thermal insulation between the RPV upper dome and the PCV top head is lost, the PCV top head may fail by the heat from the RPV upper dome. The Steam Dryer effectively transferred the in-vessel atmosphere heat to the upper dome by radiative heat transfer. Earlier depressurization of the RPV was favorable from the viewpoint of suppressing core oxidation heat, which alternatively led to heat-up of the PCV top head.