A Plant data evaluation for Fukushima-Daiichi NPP Unit 3

Sato, Ikken 

The PCV pressure measurement of Fukushima-Daiichi NPP Unit 3 showed cyclic pressure up and down. Although some early pressure changes of them can be regarded as consequence of venting actions, later changes are not likely due to venting nor significant leakage through the PCV boundary. In this study, preliminary correction for pressure measurement data was applied based on assumed consistency among different pressure measurement data. With this correction, subtle pressure differences among RPV, D/W and S/C became visible and information related to accident progression was obtained. With this knowledge, possible mechanism of PCV pressure decrease by itself will be reported.