ANALYSIS OF A LOAD REJECTION EVENT AT THE NUCLEAR POWER PLANT GOESGEN WITH COUPLED NEUTRONIC/THERMAL-HYDRAULIC CODE SYSTEMS

摘要

The use of coupled 3-D neutron kinetics/thermal-hydraulic system codes is becomingrnincreasingly important as a means to accurately simulate plant transients and to analyze complexrnaccident sequences which are characterized by a significant change in the power distribution ofrnthe reactor core and by interaction between the core and the plant. In the development of thesernlarge computer codes the verification and validation procedure is vital to establish how well therncodes perform. Part of the code verification includes the comparison of results with those ofrnother codes. This can most easily be done through the calculation of benchmark problems, butrnthe accuracy of the results can only be determined through comparisons with experimental data.rnSince only a few adequate experimental data exist to validate coupled codes an inadvertent eventrnat the NPP Goesgen - a load rejection to auxiliary power supply - was used for the validation ofrnRELAP5/PANBOX. The comparison of calculated and measured data shows the ability ofrnRELAP5/PANBOX to analyze this type of transient and validates in-core and ex-core detectorrnmodels and certain aspects of the coupled core and thermal-hydraulic models. Similarrninvestigations are being performed with TRAC-PF1/NEM. Code-to-code comparisons withrnRELAP5/PANBOX will help to estimate and further reduce modeling uncertainties.