Depletion and Decay Analysis of Pakistan Research Reactor-2 (PARR-2) with HEU and LEU Fuel

Abstract

Fuel depletion and decay calculations have been performed for the existing aluminium clad high enriched uranium (HEU) aluminium alloy fuel and the projected zirc-alloy clad low enriched uranium (LEU) oxide fuel of Pakistan Research Reactor-2 (PARR-2). Analysis has been performed by accommodating operating history of PARR-2. ORIGEN-2 code has been used in this analysis. Calculations have been carried out for the decay parameters including radioactivity, decay heat and inventory of heavy metals in the core. Variation of decay parameters has been studied up to 1000 days after shut down of the reactor at present burnup status. Decay heat and radioactivity calculations have been carried out for actinides, fission products and structural materials for both HEU & LEU fuels of PARR-2. Analysis indicates that for same operation history of both fuels, radioactivity of actinides is higher for LEU fuel. Immediately after reactor shut down radioactivity of structural materials is higher for HEU fuel while for longer decay time LEU fuel has higher values for radioactivity. This is due to different structural and clad materials of these fuels. Radioactivity of fission products remains approximately same for both fuels. Decay heat profile of fission products, actinides and structural materials also follow the above trend as described for radioactivity. U consumption is slightly low for LEU fuel due to contribution of plutonium fission in this fuel.