Standardization of online gamma monitoring system for pool water activity measurements at spent fuel storage facility

Spent Fuel Storage Facility (SFSF) is a under water storage facility for storing and handling of PHWR spent nuclear fuel bundles. During storage and handling of spent fuel, fission product activity gets build up in the pool water in due course of time and the pool water activity concentration is maintained below the approved regulatory limit using a recirculatory type clean up system which removes the radio-isotopes from pool water effectively. ¹³⁷Cs, ¹⁰⁶Ru, ⁹⁰Sr and ³H are the important radionuclides found in pool water. However, ¹³⁷Cs is found to be a major gamma contributor (>90%)