ANALISIS KRITIKALITAS BAHAN BAKAR NUKLIR BEKAS REAKTOR RSG-GAS PADA RAK BERBAHAN ALUMINIUM

Abstract

The use of stainless steel in nuclear spent fuels storage racks of interim storage facility potentially causes galvanic corrosion so material replacement of spent fuels storage racks needs to be considered. Galvanic corrosion is due to interaction between aluminum as in nuclear fuel of Multipurpose Research Reactor - G. A. Siwabessy (RSG-GAS reactor) and stainless steel as storage rack material for nuclear spent fuel. The purpose of this study is to assess the criticality of nuclear spent fuel storage racks using aluminum material to reduce galvanic corrosion effect. criticality guarantee is necessary to maintain the safety of nuclear spent fuel interim storage facility. Optimum criticality of aluminum storage rack is assessed by varying pitch size and calculating neutron absorption rate performed under normal condition (not an accident). Criticality (keff) calculation is performed using Monte Carlo N-Particle version 6 (MCNP6) code. The model used in this study is a 3-dimensional model where racks are filled fully with spent fuels in the storage pool. The calculations show that nuclear spent fuel storage rack stainless steel materials (keff = 0.6810) compared to aluminum (keff = 0.7709) in the size of 127 mm pitch, keff increased by 13.20%, but still within the value of safety requirement (keff ≤ 0.95). keff is affected by pitch size, where the reduction in the size of 1 mm pitch can increase the keffof 14.24%. Neutron absorption rate also affects keff, where neutron absorption rate in aluminum storage racks smaller than stainless steel. Storage racks using aluminum materials meet safety aspect to use as a storage rack in nuclear spent fuel interim storage facility because it has a keff less than 0.95 on a pitch size more than 112 mm (keff = 0.9196).