Relap5 / Mod 3.3 を使用した冷却材喪失事故の統計的安全性解析

抄録

The Best-Estimate Plus Uncertainty (BEPU) is applied as Deterministic Approach for safety analysis of Nuclear Power Plant using the system analysis code such as Relap5. Thus, it is necessary to verify the applicability of a system analysis code that is able to predict accurately the two-phase flow such as interfacial shear between two phases: liquid and gases. It is also important to know the prediction uncertainty due to the constitutive relation in order to close the twofluid model equation. In PWR’s Small-Break LOCA (SB-LOCA) accident, the loop-seal clearing is important phenomena where liquid inventory going into the reactor core from Steam Generator known as the inherent safety feature of PWR. The prediction of thermal-hydraulic system code is necessary to be verified. In order to investigate this phenomenon, the experimental data is used to compare with simulation results in order to validate the computer code. In this work, the UPTF-TRAM simulated the counter-current flow between vapor and liquid in Loop-seal during SB- LOCA which is used to verify the applicability of Relap5/Mod3.3. Moreover, the uncertainty of simulation results is also quantified by using the statistical method. Therefore, the uncertainty quantification of interfacial shear stress is reported for loop-seal clearing phenomena.