Analysis of fission product release from vented LMFBR fuel pins

The venting device operation appears quite sensitive to the pressure and, perhaps, temperature conditions, so the final demonstration of feasibility has to be obtained in fast reactor environment and in reference conditions. Nevertheless the VN experiments gave a series of highly positive answers. The DISCA venting device performed satisfactorily in steady-state conditions up to high burn-up. No plugging problems arose in the venting device nor in the integrated vibrocompacted blanket. Reduction in the released activity was consistent for short-lived fission gases and can be improved for 133Xe if the pin operates at reactor pressure conditions. The coolant contamination by 137Cs and 131I was kept at extremely low level. Non-steady-state operation and mild overpower transient appear to have little influence on release of activity and on coolant contamination