Effect of BC absorber material on melt progression and chemical forms of iodine or cesium under severe accident conditions

Hidaka, Akihide

Nihon Genshiryoku Gakkai Wabun Rombunshi, 14(1), p.51 - 61, 2015/03

https://doi.org/10.3327/taesj.J14.021

BC used mainly for BWR and EPR absorbers could cause phenomena which never happen in PWR with Ag-In-Cd absorbers during severe accident. BC would make a eutectic interaction with stainless steel and enhance melt relocation. Boron oxidation could increase H generation and change of liberated carbon to CH could enhance CHI generation. HBO generated during BC oxidation could be changed to CsBO by combining with Cs. This may increase Cs deposition in reactor coolant system. There could be differences in configuration, surface area, stainless steel-BC weight ratio between BC powder and pellet absorbers. Present issue is to clarify effect of these differences on full scale melt progression, BC oxidation and source term. Advancement of this research domain could contribute to further sophistication of prediction tool for melt progression and source terms, and treatment of organic iodide formation in safety evaluation.