Calculation and measurement of helium generation and solid transmutants in Cu-Zn-Ni alloys

A method recently proposed by Garner and Greenwood [1] would allow the separation of the simultaneous and possibly synergistic effects of solid and gaseous transmutation in Cu-Zn-Ni alloys. Copper transmutes primarily to Ni and Zn, leading to an accelerated production of helium from the ingrowth of zinc in mixed-spectrum reactors. Adding Zn to Cu alloys eliminates the time required for this ingrowth and leads to accelerated helium rates which are comparable to the well-known effect in Ni. Using a suitable Cu-Zn-Ni alloy matrix in a comparative irradiation of thermal neutron shielded and unshielded specimens, the separate influences of the solid and gaseous transmutants should be distinguishable. To assess the potential of this proposal, it is necessary to show that we can accurately predict the isotopic and elemental evolution of these alloys. In the current study, several different Cu-Zn-Ni alloys, irradiated in the HFIR JP-23 experiment, were characterized by measuring of the helium content as well as the solid transmutants. The measured values are in good agreement with calculations based on neutron dosimetry, therefore allowing the successful design of the transmutation experiment proposed by Garner and Greenwood. (C) 1998 Published by Elsevier Science B.V. All rights reserved.