Neutron Depth Profiling Study On (6)Lithium And (10)Boron Contents Of Nuclear Graphite

Li-6 and B-10 contents in the nuclear graphite need to be calculated and evaluated for He-4 and the gaseous nuclear radioactive waste H-3, which should be eliminated to an acceptable low level. Furthermore, it will help analyze the diffusion and adsorption behavior as precursors of H-3 and He-4. Based on reactions of Li-6(n,alpha)H-3 and B-10(n,alpha)Li-7, we employ Neutron Depth Profiling (NDP) as a non-invasive and versatile technique, providing Li-6 and B-10 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 Li-6 depth distributions and total amounts calculated from He-4 and H-3 are compared with high precision for evaluating gaseous radionuclides release. The calculated B-10 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.