Preparation and Neutron Counting of ²³⁸PuO₂ Depleted in ¹⁸O

Plutonium-238 dioxide is a potentially useful source of energy for biological purposes such as the cardiac pacemaker. Experiments showed that the neutron contribution to the undesirable external radiation from ²³⁸PuO₂ can be minimized by preparing the compound from oxygen depleted in ¹⁸O. Depleted oxygen for these experiments was prepared in a thermal diffusion column in a two-step operation. The ¹⁸O content was depleted from the natural abundance of 0.204 to 0.0016 ± 0.0005%. A yield of 30 n/(sec 10⁶) alpha particles was found for the (α, n) reaction on ¹⁸O.