The Evolution of SPODE: A Monte Carlo Computer Code for Self-Powered Detector Response Calculations

Abstract

The computer program SPODE has been devised to facilitate the design and development of self powered, in-core, reactor flux detectors. Using Monte Carlo techniques, the program evaluates the electrical current generated in a given detector once the surrounding neutron and gamma field is specified. SPODE embraces detailed neutron, photon and electron transport and the degree of detail appropriate for electron transport in these calculations has been formally investigated. Using our most detailed electron transport model, based on the Goudsmit-Saunderson formulation for angular distributions of electrons emerging from foils, the calculated transmissions for 960 keV electrons through either lead or aluminum agree well with experimental results. The agreement between the calculated and experimental detector responses is within 10% for a wide range of materials and geometries exposed to a variety of radiation conditions. It is anticipated that the introduction of the most detailed electron scattering model (referred to above) would improve to some extent the calculational accuracy. However, the agreement may still be limited by the quality of the input nuclear data used in SWDE or the experimental uncertainties.