Thermodynamic evaluation on effect of sea water to degraded nuclear fuel in severe accident of LWR

Kurata, Masaki ; Shirasu, Noriko  ; Ogawa, Toru*

In the severe accident of Fukushima-Daiichi Nuclear Power Plant, large amount of sea water was introduced into reactor pressure vessels. Not only sodium chloride but also several minor elements contained in sea water possibly reacted with degraded fuel debris or molten corium. Varous concerns are pointed out, such as volatilization of FP, characterization of fuel debris, formation of corrosive gases, and etc. Thermodynamic evaluation can give useful information on the general tendency of these sea-water effects. Volatility of Cs, Sr, and Te is potentially increased due to the change in the chemical species. Corrosive gases, such as HCl, HS, and etc. are possibly generated from sea-water heated at high temperature. These phenomena are predicted to be varied with change in oxygen potential.