Verification and further development of a predictive multidimenional model for hydrogen deflagration in a multiple compartment LWR-containment (BASSIM-verfication). Final report

During severe accidents in light water reactors, the integrity of the containment building can be threatened as a result of hydrogen deflagrations. The present work reports on a mechanistic multidimensional calculation method for H2-deflagrations in a multiroom LWR-containment building. The prediction capability of the calculation procedure is shown by performing verification calculations for a number of H2-deflagration experiments. Basic conservation equations, models for turbulence and premixed combustion rate and the solution procedure are described. 23 experiments in the Battelle model containment and HDR facilities with different conditions with respect to room configuration, initial gas composition, turbulence generating obstacles, ignition location etc. have been post computed. Results of these computations along with the experimental data are presented. A few experiments in smaller facilities (smaller than 1 m3) were simulated as well and the results are presented here. The computer code BASSIM-H2, developed in this work, has been coupled to the Lumped Parameter Code RALOC, in order to simulate the complete containment building effectively. (orig.)