Application of Different Nuclides in Retrospective Dosimetry

Activities of nuclides produced by neutron irradiation of reactor-pressure-vessel (RPV) steel are used to validate respective fluence calculations. Niobium, nickel and technetium isotopes from RPV trepans of the decommissioned NPP Greifswald (VVER-440) have been analyzed. The activities were determined by TRAMO (Monte-Carlo) fluence calculations,,newly applying 640 neutron-energy groups and ENDF/B7 data. Compared to former results, up to 20% higher fluences have been computed, leading to somewhat better agreement of measurement and calculation, particularly in case of Tc-99.