K. C. Jagadeesan

Fission Product Yield in the Neutron-Induced Fission of 232Th with Average Energies of 5.42, 7.75, and 10.09 MeV

Abstract The yields of various fission products in the neutron-induced fission of 232Th have been determined a using recoil catcher and off-line gamma-ray spectrometric technique with flux-averaged energies of 5.42, 7.75, and 10.09 MeV. The neutrons were generated using the 7Li(p,n) reaction at the BARC-TIFR [Bhabha Atomic Research Centre–Tata Institute of Fundamental Research] Pelletron facility, Mumbai, India. The fission product–yield data in the 10.09-MeV neutron-induced fission of 232Th are determined for the first time. The yields of the different fission products in the neutron-induced fission of 232Th with flux-averaged energies of 5.42 and 7.75 MeV from the present work have been compared with similar data of comparable neutron energy from the literature and are found to be in good agreement. The effect of nuclear structure on fission product yields as a function of neutron energy has been examined.

Practicality of Production of 32P by Direct Neutron Activation for Its Utilization in Bone Pain Palliation as Na3[32P]PO4

Large-scale production of ³²P for its clinical use in palliative care of painful bone metastasis in the form of Na3[³²P]PO₄ (³²P-sodium orthophosphate) has been practiced for six decades. The classical route of production of ³²P by (n,p) reaction on high purity elemental sulfur yields no-carrier-added (NCA) ³²P. Since high specific activity ³²P is not essential for the formulation of Na₃[³²P]PO₄ for bone pain palliation, an alternate route of production of ³²P by direct neutron capture using elemental phosphorus target [(31)P(n,γ)³²P] was envisaged and its suitability for use in bone pain palliation was evaluated. Toward this, irradiation of elemental red phosphorus target was carried out at a neutron flux of 8×10¹³ n/cm².s for 60 days and this yielded ³²P with a specific activity of 230±15 MBq/mg (6.2±0.4 mCi/mg) having >99.9% radionuclidic purity. About 370-555 MBq (10-15 mCi) doses of Na₃[³²P]PO₄ were formulated in sterile saline (pH 7.4) using the ³²P produced. The radiochemical purity of the formulation was found to be ~99% with respect to PO₄³⁻. The formulation exhibited good in vitro stability in saline and in human serum. Biodistribution studies carried out in normal Wistar rats revealed comparable pharmacokinetic properties of the formulation prepared using (n,γ) produced ³²P with that of NCA ³²P produced by (n,p) route. Besides having the advantages of simplicity in radiochemical processing and minimum radioactive waste generation, use of the proposed production route in place of the traditional ³²S(n,p)³²P route would result in better utilization of irradiation volume of research reactors.