Uncertainty analysis for the weighted least square fitted buildup factors in the point kernel module

Point kernel method for nuclear power plant shielding analysis is widely used due to the simplicity of its application, implementation, and their fast solution. Point kernel method is mainly used to estimate an initial guess for the shielding design including material selection and shielding thickness. The buildup factor of point kernel method is of importance, which depends on photon energy and material attenuation parameter. In this paper, buildup factors of the point kernel method are put together from literature survey and a weighted least square fitting approach is used to provide more accurate results of the point kernel method. Uncertainties are evaluated when applying buildup factors based on the error propagation approach. Furthermore, a simple point kernel module is applied in the spherical geometry in order to test the fitted build up factors. Monte Carlo results are also used to validate the point kernel results with the least square fitted buildup factor in multi-layer test problems.