Application of FELTRAN to NEACRP TN12 shipping cask benchmark

Abstract The finite element technique has received attention as a method of solving the Boltzmann equation in one, two and three spatial dimensions. In particular much work has been published concerning the geometrical flexibility, speed and accuracy of the method. British Nuclear Fuels plc and Imperial College have collaborated in developing the finite element code FELTRAN to near production code status. FELTRAN solves the even parity form of the Boltzmann equation using a functional approach. The solution is found in one or two spatial dimensions using various orders of finite elements to specify the problem geometry. The angular dependence of the even parity flux is expressed using spherical harmonics. FELTRAN has been interfaced to ANISN formatted nuclear data libraries such as CASK and BUGLE. Anisotropic scattering may be specified to any order. Methods have been incorporated within the code to analyse systems with voids. FELTRAN is currently undergoing further development as part of a BNFL sponsored MSc research programme at the University of Salford. The purpose of this paper is to consider the application of FELTRAN to a practical shield design problem. The OECD have adopted a benchmark experiment to measure the neutron and gamma ray radiation dose rates around a spent fuel transport flask. As part of an international collaboration the physical details of the flask design and contents have been provided to the nuclear industry. The objective is to perform an international comparison of the methods used in the analysis of cask shielding. BNFL is one of the companies involved, using the well established codes RANKERN and MCBEND. The FELTRAN calculations are performed using the same source and geometry data and equivalent angular flux expansions as for these two codes. FELTRAN is then compared with experimental and calculated results.