Analysis of Tritium Production and Distribution in HTR-PM

The research on radiological impact of tritium is highly concerned in high temperature gas-cooled reactors. In order to better assess the environmental performance of HTR-PM (HTR demonstration project with 2 × 250MW plants), analysis of tritium behavior in HTR-PM is conducted in this paper. The main production sources of tritium are the ternary fission in the fuel and neutron capture reactions of some nuclides. Based on the tight interactions between tritium sources and sinks, differential equations are built to describe tritium behavior in primary and secondary loop. Specific analysis is conducted to tritium permeation through heat exchanger walls to secondary loop, considering the oxidation of alloys used for heat exchanger. Applied with the parameters of HTR-PM, tritium concentration in primary and secondary loop is calculated, and the amount of tritium released to the environment is evaluated. The evaluation shows that the amount of tritium released to the environment is less than the limit value prescribed by Chinese regulation on radiation protection. The calculation results can also be applied to the safety analysis and used to guide the design of relevant systems and equipments for the HTR-PM.