.alpha. and .beta. Radiolysis of plutonium hexafluoride vapor

Abstract

The ..cap alpha.. and ..beta.. radiolysis of PuF/sub 6/ vapor was studied at 22/sup 0/C in passivated aluminum vessels at pressures from 5 to 50 torr. The plutonium itself served as the radiation source. For ..cap alpha.. radiolysis, plutonium that was 4.8% /sup 238/Pu was used to prepare the PuF/sub 6/. For ..beta.. radiolysis, the plutonium was 73% /sup 241/Pu. PuF/sub 6/ decomposition rates were measured from the uv absorbance of the PuF/sub 6/. The amount of ..cap alpha.. and ..beta.. energy absorbed was calculated from stopping power for PuF/sub 6/. With ..cap alpha.. radiolysis, the decomposition followed a first-order reversible mechanism, indicating a back reaction between the products F/sub 2/ and PuF/sub 4/. The G value for the ..cap alpha.. particle decomposition of PuF/sub 6/, G(-PuF/sub 6/), was 2.2 +- 0.7 molecules/100 eV. With ..beta.. radiolysis, the decomposition rate was dependent only on the dose rate; evidence for the back reaction was not observed. For ..beta.. decomposition, G(-PuF/sub 6/) was 1.0 +- 0.3 molecules/100 eV. The difference between the G values may be due to the higher fraction of ..cap alpha.. energy compared to ..beta.. energy being absorbed at the wall of the reaction vessel. G(-PuF/sub 6/) for ..beta..more » radiolysis was independent of PuF/sub 6/ pressure and dose rate. G(-PuF/sub 6/) for ..cap alpha.. was less precise but did not exhibit a significant effect of pressure. 9 figures, 6 tables.« less