TDCR measurements of ~3H, ~(63)Ni and ~(55)Fe using Hidex 300SL LSC device

摘要

The commercial Hidex LSC system has been used to measure triple to double coincidence ratio (TDCR), experimental counting efficiency (CE) and the absolute activity for radioactive standards of pure beta emitters viz. ~3H, ~(63)Ni and ~(55)Fe, an electron capture nuclide. Colour and chemical quench measurements of ~(63)Ni and ~(55)Fe have been done. An excellent match between TDCR and CE has been obtained for beta emitters, while very large deviations have been observed for ~(55)Fe. The deviation between TDCR and experimental efficiency has been found to be nearly uniform. Based on this, an empirical correction factor for TDCR which gives the correct efficiency has been evaluated, to enable efficient application of this commercial instrument for ~(55)Fe estimation. These TDCR correction factors were further validated by applying for 55Fe activity measurements in ASTM standard steel samples irradiated to a fixed neutron flux in research reactor CIRUS. Finally, ~(55)Fe activity in steel sample from APSARA reactor decommissioning waste was successfully estimated using this modified TDCR.