Reaction Behavior of B₄C Absorber Material with Stainless Steel and Zircaloy in Severe Light Water Reactor Accidents

The chemical reaction behavior of B₄C absorber material with stainless steel 1.4919 (Type 316) and Zircaloy-4 is studied in the 800 to 1600 C temperature range. The reaction kinetics for both systems can be described by parabolic rate laws. Above 1000°C, the reaction zone growth rates in the B₄C/stainless steel system are about two orders of magnitude higher than those in the B₄C/Zircaloy-4 system. The compatibility specimens are quickly and completely liquefied at temperatures ≥1250°C for the B₄C/stainless steel reaction couples and temperatures ≥1650°C for the B₄C/Zircaloy-4 reaction couples. In both reaction systems, liquefaction occurs below the melting points of the components.