Reduction of conservatisms in the treatment of some aspects of aerosol behaviour following a large loss of coolant accident
The report identifies the major uncertainties in the calculational methods of the Reactor Safety Working Group (RSWG) and recommends that various studies be undertaken. This report addresses two of these, namely iodine release from the coolant in the vessel after reflood and the size of the aerosol containing fission products in the atmosphere of the reactor building. The object of the work is to apply a more realistic analysis in order to reduce the calculated release of radioactivity to the environment following a design basis large loss of coolant by accident. A kinetic model for the mass transfer of volatile fission products to the steam released from the reactor vessel following the reflood phase of an accident shows that the concentration of iodine species in the steam is close to equilibrium. A simple model to predict aerosol growth by condensation in the atmosphere of the reactor building results in higher calculated aerosol removal rates, compared with the recommendations in Stephenson et al. This leads to reductions in the quantity of non-volatile fission products released to the environment. The reduction in the calculated release of iodine species is less marked due to the formation of volatile species in the reactor building.
Bibliographic Reference: EUR 15721 EN (1994) 51 pp., FS, ECU 7
ISBN: ISBN 92-826-8577-2
Record Number: 199410717 / Last updated on: 1994-12-06
Original language: en
Available languages: en