Use of IDRA Code for Calculation of Fission Product Transport and Retention in the Containment: Comparison with National and International Experimental Results

Abstract

IDRA is a recent fast-running computer code for calculating fission product transport and retention in a multicompartment system. The utility of a fast running code is both the drastically reduction of time-running costs and the possibility for a lot of users to gain easily the due experience useful to perform the works requiring the use of highly sophisticated codes. The fission products can occur in the form of incondensable, volatile and aerosol materials. Because of the strongly differences between gas and aerosol products behaviour, the calculations are performed making use of independent algorithms. The containment can be divided up to 30 compartments (cells). The code models solve for each cell a time dependent disappearance/production balance processing previous input data containing information about specific parameters of gases, vapours and aerosols. The performance of containment engineered safety features and the effects of aerosol depletion processes can also be taken into account. An example of IDRA application on a containment accidental event is here reported and discussed. All the hypotheses, type of materials involved, the cell interconnections and other necessary assumptions made during the problem elaboration, were finalized to reach an objective comparison between the program output and the already existing national and international experimental results. Information obtained from LACE research program have largely been used. A satisfactory code response for gases and an acceptable representation of aerosols behaviour was noticed.