S. Widodo¹ , M. Muzakky¹ , S. Sukirno¹ , P.I. Wahyono¹ , S. Syarip¹

¹BATAN Indonesia's National Nuclear Energy Agency

Abstract:

As the development of thorium-based nuclear fuels for long-term sustainability of electricity generation have reached a step to closer commercial approval in some countries, the future impacts to the CTBTO's radionuclide monitoring regime need to be taken into account. Its potential sources of radioxenon and other fission products are a real challenge and need to be considered. We have made initial estimation of the products through fission yields of 233U and 235U data. To support and validate this analysis we have made measurement and analysis of 233U from irradiated 0.1g ThO2 samples by using the fission-induced delayed neutron counting method. The amounts of 233U produced was 17.2 +/- 1.9 µg after 50 hours irradiation by the Kartini reactor at an average neutron flux of 10^11 n cm-2 s-1, cooled down for 55 days, and re-irradiated for 100 hours. This value is in a good agreement with the measurement results through the strongest gamma line of 233Pa by using a gamma spectrometry system i.e (16.8 +/- 1.2 µg) and with the calculated amounts of 233U using ORIGEN2 computer code (14.3 µg). For better estimation, the ThO2 samples will be re-irradiated again by the Siwabessy reactor at neutron flux of 10^14 n cm-2 s-1. In future activities, the 135Xe and 233Pa build-up of thorium based fuel will be analyzed.