Severe fuel damage experiments performed in the QUENCH facility with 21-rod bundles of LWR-type

The objective of the QUENCH experimental program at the Karlsruhe Research Center is to investigate core degradation and the hydrogen source term that results from quenching/flooding an uncovered core, to examine the physical/chemical behavior of overheated fuel elements under different flooding conditions, and to create a data base for model development and improvement of severe fuel damage (SFD) code systems. The large-scale 21-rod bundle experiments conducted in the QUENCH out-of-pile facility are supported by an extensive separate-effects test program, by modeling activities as well as application and improvement of SFD code systems. International cooperations exist with institutions mainly within the European Union but, e.g. also with the Russian Academy of Science (IBRAE, Moscow) and the CSARP program of the USNRC.So far, 11 experiments have been performed, two of them with B4C absorber material. Experimental parameters were: the temperature at initiation of reflood, the degree of pre-oxidation, the quench medium, i.e. water or steam, and its injection rate, the influence of a B4C absorber rod, the effect of steam-starved conditions before quench, the influence of air oxidation before quench and boil-off behavior of a water-filled bundle with subsequent quenching.The work is focused on severe fuel damage behavior for assemblies with and without the B4C absorber. An overview of the QUENCH program with its organizational structure and the description of the test facility is also presented.