Neutron streaming through plenum in fast reactor core subassembly - comparison of calculations with measurements

Full text: In a typical transport calculation with 2-D SN codes, the plenum region in the subassemblies is homogenised with the steel present in the pins. This approximation generally leads to under-prediction of fluxes at the grid plate. To estimate the correction factor to be used to take into account this approximation, experiment on neutron streaming through lower axial plenum region in fast reactor core subassemblies has been carried out in shielding comer of Apsara. Analysis has been done with 1D, 2D transport codes and using Monte Carlo simulation with MCNP. The comparison between measured and calculated values of reaction rate attenuation is within 50% in most of the cases