Isotopically pure Pu-236 (>99.999% by activity) has been produced by i
rradiating U (95% U-235) With He-4 ions and refining the product by el
ectromagnetic mass separation. Further developments in the production
of Pu-237 are also reported, giving material containing, by activity,
only 3 x 10(-6)% Pu-236 and probably only similar to 10(-5)% Pu-238.