Development of a LOCA analysis code for the supercritical-pressure light water cooled reactors

The supercritical-pressure light water cooled reactors aim at cost reduction by system simplification and higher thermal efficiency, and have flexibility for the fuel cycle due to technical feasibility for various neutron spectrum reactors. Since loss-of-coolant accident (LOCA) behavior at supercritical pressure conditions cannot be analyzed with the existing codes for the current light water reactors, a LOCA analysis code for the supercritical-pressure light water cooled reactor is developed in this study. This code, which is named SCRELA, is composed of two parts: the blowdown and reflood analysis modules. The blowdown analysis module is designed based on the homogeneous equilibrium model. The reflood analysis module is modeled by the thermal equilibrium relative velocity model. SCRELA is validated by the REFLA-TRAC code, which is developed in the Japan Atomic Energy Research Institute based on TRAC-PF1. A large break LOCA of the thermal neutron spectrum reactor (SCLWR) is analyzed by SCRELA. The result shows that the peak clad temperature (PCT) is nearly 980 degrees C about 60 s after the break and the PCT position is quenched at 170s This means that PCT is sufficiently lower than the safety limit of 1260 degrees C. In conclusion, the developed code shows the safety of SCLWR under the large break LOCA, and is expected to be applied to LOCA analysis of other types of the supercritical-pressure light water cooled reactors. (C) 1998 Elsevier Science Ltd. All rights reserved.