Reactor production of 32P for medical applications: an assessment of 32S(n,p)32P and 31P(n,γ)32P methods

The article describes a comparative study carried out on the reactor production of 32 P by two different processes, namely, 32 S(n,p) 32 P and 31 P(n,γ) 32 P with a view to determine the merits and bottlenecks of each method and assess the usefulness of 32 P obtained from each of the processes. In a typical batch, 250 g of elemental sulfur when irradiated at a fast neutron flux of ~8 × 10 11 n cm −2 s −1 for 60 days, after chemical processing provided about 150 GBq(4.05Ci) of 32 P having specific activity of 200TBq(5500Ci)/mmole. On the other hand, irradiation of 0.35 g of red phosphorus at a fast neutron flux of ~7.5 × 10 13 n cm −2 s −1 for a period of 60 days gave 75 GBq(2.02Ci) of 32 P of specific activity 7 GBq(190mCi)/mol -1 . While the specific activity of 32 P obtained from 32 S(n,p) 32 P is superior to that obtained from the 3l P(n,γ) 32 P process, the requirement of elaborate target processing steps involving distillation and purification emerged as a deterrent that limits its widespread adaptability. Both the production routes offer 32 P of acceptable quality amenable for medical applications although their specific activity differs.