THE SIGNIFICANCE OF SEQUENTIAL CHARGED-PARTICLE REACTIONS IN THE ACTIVATION OF VANADIUM ALLOYS

The significance of sequential charged particle activation in the elem ents vanadium, chromium, titanium and silicon and in selected alloys o f these elements during fusion neutron exposure is examined. No apprec iable charged particle activation is found in titanium or silicon. In chromium, enhanced Mn-53 production leads to a 40-fold relative increa se in activity after a 200 y postexposure time, raising the level to o nly 6 kBq kg(-1) without any effect on gamma-dose rate. In vanadium, g eneration of additional Mn-53 and Mn-54 increases the long term activi ty by a large factor but only to the practically insignificant level o f 30 Bq kg(-1). Although Mn-54 strongly enhances the gamma-dose rate i n the period 0.5-20 y, the increase is likely to be overshadowed by co ntributions from impurities. The overall influence of charged particle activation is diminished on alloying and it is concluded that its eff ect in alloys of the type V-15Cr-5Ti and V-3Ti-1Si is negligible.