Vanadium, rhodium, silver and cobalt self-powered neutron detector calculations by RAST-K v2.0

Abstract

Vanadium, rhodium, silver and cobalt Self-Powered Neutron Detectors (SPNDs) are evaluated and compared in this study, including their characteristic response time. The module for response calculations of different SPNDs has been programmed and added to RAST-K v2.0 (Reactor Analysis code for Steady-state and Transient). For simplification purposes and running time minimization, previously studies have often adopted the simplified depletion chain of the SPNDs. The isomers are often neglected in the detectors studies because of their low levels of contribution to the final signal. Besides, few published documents can be found for comparisons of the behavior of different emitters in normal power changes, especially for silver and cobalt emitters. In this paper, the full depletion chains for different emitters are adopted, and the isomers’ contributions are calculated. A new method for detector response calculation based on Chebyshev Rational Approximation Method (CRAM) is used as the depletion method. It is shown that the response of silver SPND is very similar to that of rhodium SPND and can be considered as an alternate emitter material for light water reactors. This study can contribute to the selection of proper SPNDs in specific applications.