Neutron Depth Profiling Study on 6Lithium and 10Boron Contents of Nuclear Graphite

Abstract

ABSTRACT 6Li and 10B contents in the nuclear graphite need to be calculated and evaluated for 4He and the gaseous nuclear radioactive waste 3H, which should be eliminated to an acceptable low level. Furthermore, it will help analyze the diffusion and adsorption behavior as precursors of 3H and 4He. Based on reactions of 6Li(n,α)3H and 10B(n,α)7Li, we employ Neutron Depth Profiling (NDP) as a non-invasive and versatile technique, providing 6Li and 10B content of three different kinds of nuclear graphite, including fuel element matrix graphite, reflector graphite, and boron-containing carbon bricks in High-temperature Gas Reactor (HTGR). The 6Li depth distributions and total amounts calculated from 4He and 3H are compared with high precision for evaluating gaseous radionuclides release. The calculated 10B content of boron-containing carbon bricks is needed for analyzing the impurity and neutron absorption capacity. We offer a new method to measure the trace content of isotopes along the depth of various nuclear materials, which is important for studying the reactor activation products and supporting the service and safety of reactors.