PENGARUH DENSITAS URANIUM TERHADAP UMUR BAHAN BAKAR NUKLIR DI DALAM REAKTOR RSG-GAS DITINJAU DARI ASPEK NEUTRONIK

Abstract

Material Testing Reactor (MTR) is a research reactor with characteristics: small power, high thermal neutron flux and short life time fuel. Reaktor Serba Guna G.A. Siwabessy (RSG-GAS) located in Serpong is an MTR type reactor initially operated with dispersion fuel of U₃O₈/Al with uranium enrichment of 19.75 % ²³⁵U and uranium density of 2.96 gU/cm³. In an effort to increase the lifetime of nuclear fuel, BATAN has done research on high density uranium fuel starting from U₃Si₂/Al fule and continued with UMo based fuel in line with investigations performed by worldwide researchers in the field of research reactors. Fuel of U₃Si₂/Al with a density of 2.96 gU/cm³ has been successfully manufactured and utilized as fuel for RSG-GAS to substitute the U₃O₈/Al fuel. Post irradiation examination has also been done for U₃Si₂/Al with a density of 4.8 gU/cm³ up to a burn up of 60 %, while research on UMo with 7 gU/cm³ density has been progressing into mini plate fabrication. Research on high density fuel has been focused on fabrication process, while little has been done on lifetime calculation or utilization period. Therefore, this research has performed a calculation on nuclear fuel lifetime using a paired program of ORIGEN and MCNP. The calculation results show that an increase in uranium density will extend the lifetime of fuel exponentially. The longest lifetime is achieved by UMo type, which extends to 651 days, and this relates to a lifetime extension of 219 days if the RSG-GAS is operated with UMo fuel.