Analysis of fission product gas pressure and radioactivity in SAMOP reactor experimental facility

Abstract

The fission-product gas pressure and radioactivity analysis of a subcritical assembly for 99Mo production (SAMOP) experimental facility have been done. SAMOP reactor is fueled with low enriched uranyl nitrate solution UO2(NO3)2 of 300 g U/L, the reactor core is in the form an annular tube surrounded by a ring of fuel tubes. The SAMOP system is designed to be operated at 100 to 120 hours periodic operation per batch. The analysis method is done by using ORIGEN2 computer code, at the condition of the maximum fuel temperature of 54 °C, 120 hours reactor operating time, and neutron flux varied from 1010 to 1012 n/cm2s. The result show that the inventory of the gaseous fission products is dominantly consisted of the xenon, radium, helium, and tritium isotopes with the total activity of 1.3775x1013 Bq (372.29 Ci) and total gas volume of 0.0986 cm3 or giving a total gas pressure of 5.78 kPa. The isotopes of xenon and krypton are the major contributors to the total gas pressure. The analysis result shows that the gas pressure of the fission products is very small, therefore the pressure monitoring in the SAMOP reactor core is not necessary.