99Tcm generators: the influence of the radiation dose on the elution yield

Abstract The elution yields of high activity 99 Mo 99 Tc m generators prepared by several different techniques were found to be a function of the self-irradiation dose caused by the decay of the 99 Mo. The absorbed dose was both calculated and measured; more than 95% of it was found to arise from short-range particulate radiation. The elution yield began to decrease with an absorbed dose of 50 krad and continued to decrease up to 900 krad, after which there was no further effect. Externally irradiated generators loaded with tracer levels of 99 Mo showed a similar behavior but the threshold dose was 200 instead of 50 krad. Radiolysis of pertechnetate solutions containing no alumina did not exhibit any reduction at doses up to 1000 krad.