Proceedings of the 11th international QUENCH workshop

An important accident management measure for controlling severe accident transients in light water reactors (LWRs) is the injection of water to cool the degrading core. Flooding of the overheated core, which causes quenching of the fuel rods, is considered a worst-case scenario regarding hydrogen generation rates which should not exceed safety-relevant critical values. Before the water succeeds in cooling the uncovered core, there could be an enhanced oxidation of the Zircaloy cladding and other core materials that in turn causes a sharp increase in temperature, hydrogen production, and fission product release. The complex physico-chemical processes during quenching and their mutual influence is not yet sufficiently known. So, the OECD/NEA International Standard Problem (ISP) No. 45 on Quench (Test QUENCH-06) has shown that the codes still have difficulties to predict correctly the bundle behaviour during reflood. Topics of the 11th International QUENCH Workshop have been the discussion of the available experimental data base and the status of the modelling activities on quenching in various countries. The results of pre-tests for the recent bundle test QUENCH-11 on boil-off as well as the post-test examination of QUENCH-08 and QUENCH-10 and the B4C behaviour in experiments QUENCH-07 and QUENCH-09 have been presented in detail. The Code Application session contained post-test calculations of various QUENCH tests. Additionally; new model developments including new results on oxidation of metal melts and oxidation in air atmosphere were presented in the Modelling session. Further presentation have been devoted to recent studies on core degradation and chemical interactions of core materials under severe accident conditions, with the oxidation of Zircaloy atmospheres containing air, hydrogen absorption by zirconium alloys and VVER quench tests as topics among others. The presentation of the planned CODEX Cleaning Tank Experiment in Hungary and various pre-test studies for the next QUENCH experiment (boil-off test QU-11) provided an outlook on future activities in this field. More than 50 scientists from 10 countries took part in the workshop. This CD contains abstracts and copies of handouts of all presentations given at the workshop, the final agenda and the list of participants as well as a number of photo pictures taken during the workshop. (orig.)