파단 열림시간과 면적에 따른 동하중 변화에 대한 민감도연구

Integral effect tests using the ATLAS facility were performed to investigate the blowdown load behavior during a feedwater line break accident of a steam generator. As a sensitivity study, the break opening time and the break area were varied in the tests. After the break of the feedwater line, propagation of the pressure wave along the distance from the break location inside the steam generator was clearly and pertinently observed in all the tests. As the break opening time became shorter and the broken area became larger, the dynamic pressures were measured to be significant values in the tests. Based on the present experimental data, an analysis was performed using the best-estimate thermal-hydraulic system code, MARS 3.1 with an aim of qualitatively validating the test results and also evaluating the blowdown load prediction capability of the best-estimate system code in the simulation of steam generator feedwater line break. Calculation results on overall trends of the dynamic pressure behavior were comparable with the test results which indicated a feasibility of dynamic load prediction using the MARS code.