Analysis of tritium behaviors on VHTR and forward osmosis integration system

Highlights: • Tritium behaviour analysis code named BOTANIC is developed for VHTR-FO desalination system. • The code is verified using the analytical solutions based on Peach Bottom core 2 operation data. • Using BOTANIC code, the tritium behaviour in VHTR-FO integrated system is analysed. • Based on the sensitivity analyses, the tritium mitigation concepts have been suggested. - Abstract: Recently, a novel concept of integrating Very High Temperature Reactor (VHTR) waste heat to Forward Osmosis (FO) system has been proposed. The proposed nuclear desalination system possesses a significantly higher energy utilization rate, however at the same time introduces a tritium exposure issue. This is especially critical as the VHTR integrated FO system produces potable water since tritium is especially hazardous when ingested. In this study, a numerical code named BOTANIC is developed using a chemical process analysis code, gProms, in order to understand tritium behaviors in the VHTR-FO system and migration of tritium to downstream processes. The code involves tritium generation, sorption, leakage, purification, recombination, dissociation, permeation, trapping, release models. The developed code is verified using the analytical solutions and the benchmark code in stepwise approach. Using the developed BOTANIC code, tritium behavior in the proposed VHTR-FO system is analyzed and sensitivity analysis is extensively conducted in order to figure out the effective measures for reducing tritium level in the final product. Based on the sensitivity analysis results, two mitigation concepts are suggested and investigated; (1) protective barrier in PHX and (2) ceramic PHX.