Effect of axial burnup on power distribution and isotope inventory for a PWR fuel assembly

Abstract EN

Axial burnup is an important factor in criticality safety and thermo-hydraulic calculation.

In the present study, the effect of axial distribution of burnup on power distribution and isotope inventory were evaluated using combination of the WIMSD-5B and MCNP5 codes for PWR fuel rods assembly.

The fuel rods of assembly were divided into 5, 8 and 10 zones.

The system was normalized to the total thermal power 16.89172 MWth, which was derived using the fuel assembly load of 458.599 kg.

The MCNP5 code has been used to perform three dimensional neutron physics analysis while WIMSD-5B was used for generation of number densities at various stages of fuel burnup.

The results were compared with data from the Takahama-3 Benchmark.

The calculated-to-experimental and previous calculated results for ratios of U-235, U-236, U-238 and many important nuclides show good agreement.

Both results for the isotopic inventory and the power distribution emphasize the importance of considering the axial variation of burnup.