Detailed assessment of the Heiss Dampf Reaktor hydrogen-mixing experimentsE11

Whereas all previous presentations on the Heiss Dampf Reaktor hydrogen dist ribution experiments E11, concerning data versus code predictions, concentr ated on the blind posttest efforts, this presentation focuses on the result s of the comparisons with parametric, best-estimate, open posttest predicti ons for experiments E11.2 and E11.4 with the containment analysis computer codes RALOC, WAVCO, CONTAIN, MELCOR, and GOTHIC. The results of these comparisons shaw the following after correcting a numb er of deficient input parameters previously supplied by the Kernforschungsz entrum Karlsruhe/Heiss Dampf Reaktor Project as specifications): E11.4: 1. Standard lumped-parameter codes are able to predict H-2 mixing and distr ibution phenomena when H-2 is injected into a well-mixed atmosphere in lowe r zones of the containment with excellent agreement in most of the importan t quantities. 2. A few discrepancies remain, dependent on the codes' modeling methodologi es and the impact of incorrect specifications. E11.2: 1. Accounting for the corrections substantially improves the agreements com pared to the blind posttest predictions. 2. However; concerning the predictions of the thermal stratification patter n and the H-2 distribution, more or less large discrepancies still remain. 3. Parametric changes of input parameters lead to improvement of agreement in some quantities but at the same time worsen others. 4. "lnnovative" concepts of changing certain input parameters beyond curren t practice improve the quality of the predicted H-2 concentrations.