Assessment and application of the ROSE code for reactor outage thermal-hydraulic and safety analysis

The currently available tools, such as RELAP5, RETRAN, and others, cannot e asily and correctly perform the task of analyzing the system behavior durin g plant outages. Therefore, a medium-sized program aiming at reactor outage simulation and evaluation, such as midloop operation (MLO) with loss of re sidual heat removal (RHR), has been developed. Important thermal-hydraulic processes involved during MLO with loss of,RHR can be properly, simulated b y the newly developed reactor outage simulation and evaluation (ROSE) code. The two-region approach with a modified two-fluid model has been adopted t o be the theoretical basis of the ROSE code. To verify, the analytical model in the first step, posttest calculations ag ainst the integral midloop experiments with loss of RHR have been performed . The excellent simulation capacity of the ROSE code against the Institute of Nuclear Energy Research Integral System Test Facility test data is demon strated. To further mature the ROSE code in simulating a full-sized pressur ized water reactor, assessment against the WGOTHIC code and the Maanshan mo mentary-loss-of-RHR event has been undertaken. The successfully assessed RO SE code is then applied to evaluate the abnormal operation procedure (AOP) with loss of RHR during MLO (AOP 537.4) for the Maanshan plant. The ROSE co de also has been successfully transplanted into the Maanshan training simul ator to support operator training. How the simulator was upgraded by the RO SE code for MLO will be presented in the future.