Qualification of MELCOR and RELAP5 models for EU HCPB TBS accident analyses

Abstract

The F4E, Amec Foster Wheeler and INL comprehensive methodology for fusion breeding blanket accident analysis, published last year, consists of several phases. Following the selection of the reference accident scenarios, development of detailed accident analysis specifications and assessment of the analysis codes, the Test Blanket Systems (TBS) models are constructed using the selected codes and modelling approaches. The models are then qualified according to a test matrix by comparison with Test Blanket Module (TBM) finite element design analyses, code-to-code comparisons of TBS normal operation and transient cases and sensitivity studies of accident scenarios. The test cases executed gradually move from qualification of separate systems models to complete TBS models and from the simulation of steady state and normal plasma pulses operation to consideration of power excursion, operational transients and accident events. Finally, both qualified models are used to analyse a selected accident scenario of 32h loss-of-offsite power with sensitivity studies dedicated to the uncertainty evaluation. This step completes the qualification process. The qualification results obtained for the EU Helium-Cooled Pebble-Bed (HCPB) TBS models are reported in the paper.