New arrangements of FAs at BNPP's reactor: PPF and burnup calculations

In this work, the two assemblies named 16B36 and 36B20, and two arrangements named B and C, were introduced. The current arrangement of assemblies (named arrangement A) in the core of the BNPP reactor, was changed and the new assemblies were replaced, while the main characteristics of the core were maintained unchanged. The new arrangements and new assemblies were simulated in the MCNPX.2.6.0 code. For each arrangement, some parameters were calculated like: the effective multiplication factor, power peaking factor (PPF), energy deposition, average linear power density, maximum linear heat rate in hot rod, and the burnup after 300 operation days. According to the obtained results, arrangement C was suggested for use in BNPP at the first cycle of reactor operation, because in arrangement C, the burnup increases to about 3.3 GWd/MTU, the linear power density increases about 29%, and the radial power distribution becomes significantly flattened, while the safety margin, including the maximum heat rate in hot rod, is maintained. The maximum heat rate in the hot rod was 35.95 kw/m which is below the allowed value (44.8 kw/m) reported in FSAR.