The kick-off meetings of the WP5 (Corium and Debris Coolability), WP6 (molten-core-concrete-interaction) and WP7 (containment) were hosted by FZK in Karlsruhe, covering 5 days at a whole.

Some details are given below for the WP5 and WP7, for illustration of the work under way.

In the WP5, the major objective is to investigate the cooling possibilities for the core and structural materials during a severe accident for in-vessel and ex-vessel situations. Three sub-WP investigate respectively: the cooling of a degraded core, the remelting of debris and in-vessel melt pool formation, and the ex-vessel debris coolability. This separation allows an in-depth analysis of all possible core configurations during the accident progression. This is supported by an extensive experimental programme to validate and improve the existing models of available computer codes. The 4th sub-WP will derive conclusions to adequately model the reactor case based on the gained results of the first 3 sub-WPs. These applications to plant conditions will be mainly performed with the ASTEC integral code (see below the article on ASTEC). A joint workshop on In-vessel Coolability of OECD and SARNET2 will be organised at the NEA Headquarter from 12 to 14 October 2009. It is expected that participants will come from utilities, vendors, safety authorities, technical support organisations and research institutes not only from Europe but as well from other OECD countries (see as well under “Forthcoming events”).

In the WP7, the 3 sub-WPs were discussed at the kick-off meeting. Within the “Ex-vessel Fuel-Coolant Interaction” sub-WP, analytical work will be continued, with complementary analyses of experiments that are performed within the OECD SERENA2 project. Within the “Hydrogen Mixing and Combustion in Containment” sub-WP, benchmarks are being or will be started on the topics of containment sprays, hydrogen combustion and condensation modelling. In addition, experiments on direct containment heating are being prepared. Within the “Bringing Research Results into Reactor Application” sub-WP, the emphasis was on the start of the development of a model of a “generic” containment. The model will be used in further work, on one hand to compare the results obtained by different computer codes on the same model, and on the other hand to investigate the long-pending issue of scaling, so that experimental results, obtained on scaled-down containment experimental facilities, could be applied to actual plants.

The WP8 “Source term” kick-off meeting was hosted by JRC/IE in Petten (The Netherlands) on April 30, just before the periodic meetings of the Phebus.FP ands ISTP (International Source Term Program) programs. The work in WP8 is divided in three sub-WPs. The first sub-WP focuses on the possible release of fission product ruthenium in highly oxidising conditions and from HBU and MOX fuels. In the second sub-WP the behaviour of iodine is studied. The role of the third sub-WP is then to bring the results to reactor applications.