Gamma dose rate calculation on ion-exchange resin waste drums at CIRUS using Monte Carlo simulation and study of decay pattern of spent resin

In this paper characterization study of exhausted and removed cation and anion resin in the waste drums was carried out and total activity was estimated. The specific activity of cation resin was found to be 5.04 kBq/g and that of anion resin was 1.34 kBq/g. The major common activation and fission radionuclides contributing to activity in both resins is found to be 51Cr, 144Ce, 58Co. In cation resin 140Ba, 140La, 54Mn, 65Zn also contributed whereas 95Nb, 59Fe contributed in the anion present. Activity in the cation and anion resin drums after 1 y and 5 y of storage is also calculated. Specific activity of resins reduced to approximately 10 % and 2 % in 1 y and 5 y respectively. Theoretical simulation of gamma dose rate on the surface of standard solid waste drums, at 30 cm and at a distance of 1m from the resin drums was carried out using MCNP code. The radiation dose rate at 1 m away from a waste drum is calculated and found to reduce by a factor of 10 and 40-60 after 1 y and 5 y respectively