An Evaluation of the Integrity of the Reactor Vessel Support System for a Postulated Reactor Vessel Closure Head Drop Accident of KSNP+

The integrity of the RV support system of the Korean Standard Nuclear Plant Plus (KSNP+) is investigated for a postulated RV closure head drop accident. This was considered due to the adoption of the IHA (Integrated Head Assembly) in KSNP+ reactor design, which causes the increase of the weight of the RV closure head assembly. The head drop accident could be anticipated during the RV head handling process. The drop event may cause an impact load on the RV and support system. Three different scenarios and three different analysis models were considered and developed for the head drop analysis. The entire reactor vessel and support system are modeled by using lumped masses and beam elements. The nonlinear elasto-plastic dynamic analyses were performed using a commercial code to evaluate the time-dependent behavior of the support columns. The analysis results show that the local plastic deformation occurs in the columns, but the plastic deformation in overall cross section does not occur. As a result, the RV support system would remain intact, and continue to support the reactor vessel in such an accident.