ナトリウム冷却高速炉の崩壊熱除去システム運用時の原子炉容器内熱流動解析評価手法整備

In the sodium-cooled fast reactor (SFR), decay heat removal system under natural circulation (NC-DHRS) using dipped type direct heat exchanger (D-DHX) installed in the upper plenum of the reactor vessel is considered as one of the most effective methods to enhance the safety. The numerical estimation method which can predict thermal hydraulic phenomena in operation of the NC-DHRS with the D-DHX under various plant operating conditions including the severe accident is required. The numerical analysis model named RV-CFD is being developed for the computational fluid dynamics (CFD) code. The numerical analysis of a sodium test conducted at the scaled sodium experimental facility named PLANDTL-2 was implemented to validate the RV-CFD model. The predicted characteristic phenomena in the RV during the D-DHX operation were discussed and the numerical results were compared with the experimental results. The applicability of the RV-CFD for the sodium test simulating the NC-DHRS operation with the D-DHX was confirmed.