Assessment of liquid radioactive effluents from the Philippine Nuclear Power Plant-1 (PNPP-1): A comparative study using GALE-PWR 3.2

Abstract

This study assessed the environmental impact of rehabilitating the Philippine Nuclear Power Plant-1 (PNPP-1) by comparing liquid effluent source terms using the updated GALE-PWR 3.2 code and ANSI/ANS-18.1-1999 standard against legacy data from the PNPP-1 Final Safety Analysis Report (FSAR), which used ANSI/ANS-18.1-1984. The updated analysis revealed a broader range of radionuclides, including Na-24, Zn-65, and Ni-63, which were either omitted or grouped under the "All Others" category in the FSAR, reported at a combined activity of 3.6×10⁻⁵ Ci/yr. Detergent wastes such as Ni-63 and P-32 were assigned fixed values of 1.7×10⁻³ and 1.8×10⁻⁴ Ci/yr, respectively. Corrosion and activation products, notably Co-58 and Co-60, showed higher release rates in the current model due to revised assumptions and improved detection of neutron activation products. In contrast, fission product releases such as Cs and I isotopes were lower in the updated model, reflecting improved fuel performance. The study also highlighted key parent-daughter relationships like Cs-137/Ba-137m and Ru-106/Rh-106, which were previously unaccounted for. Overall, the updated methodology provided more detailed and conservative effluent estimates, offering a stronger technical basis for evaluating PNPP-1's environmental viability.