MODELING OF SWELLING AND TRITIUM RELEASE IN IRRADIATED BERYLLIUM

The most important effects of neutron irradiation on beryllium are swe lling, embrittlement and tritium retention. The helium produced by the Be-9(n, 2n)2(4)He reaction is the cause of beryllium swelling and, at high neutron fluences, the main cause of tritium retention which is p roduced by simultaneous reactions. It was, therefore, decided to devel op a computer code capable of describing the helium and tritium behavi our in beryllium. The approach used was to modify an existing code ava ilable for the modelling of fission gas behaviour in UO2 irradiated in fission reactors. A new model describing the trapping effects on trit ium due to chemical reactions and capture in helium-bubbles has been i ncluded in the code. The resulting code ANFIBE (ANalysis of Fusion Irr adiated BEryllium) allows the calculation of gas distribution, induced swelling and helium and tritium release from beryllium. Good agreemen t between experimental and calculated swelling and tritium release has been found.