Thermodynamics Study on Liquid Phase Catalytic Exchange for Water Detritiation

Peilong Li,Bin Yu,Wenhua Luo,Xin Zhang,Fei Jiang,Yan Shi,Min Chen,Jiangfeng Song,Ming Wen,Zexuan Zhang,F.-N Shi,Y.-L Lin,J.-S Li,G Korotcenkov,D Dobrota,R Dastjerdi

doi:10.1051/e3sconf/202129901007

Abstract

Liquid phase catalytic exchange (LPCE) is one of the key technologies for tritium removal of tritiated water, such as effluents from Fukushima nuclear power plant. Although former researchers have widely studied this process theoretically, the reported results differ from each other due to different assumptions and parameters adopted. In this work, the principle of Gibbs free energy minimization is applied, with only basic physical properties and no more other assumptions involved. The predictions of isotope exchange are more accurate, and the average error between calculation results and experimental data reduces from 4.45%~6.65% to 2.17%. Then the catalytic exchange behaviors are systematically investigated in the protium-deuterium (H-D) system, and the influence of the cascade processes are emphatically analyzed. The method established in this paper could be applied to catalytic exchange systems for tritium separation, which is essential for the development of water detritiation.

Highlights

Tritium is a radioactive isotope of hydrogen, which is hazardous to the human body and the environment
A theoretical study about the thermodynamic characteristics of liquid phase catalytic exchange (LPCE) of protium-deuterium (H-D) system was firstly carried out based on the mentioned principle, and much higher prediction accuracy was achieved to benefit for the design of this process
As we mainly concerns the reduction of deuterium or tritium in hydrogen, we introduce the dedeuterium factor (DF) here, defining as the ratio of CD in inlet hydrogen to that in outlet

Summary

Introduction

Tritium is a radioactive isotope of hydrogen, which is hazardous to the human body and the environment. The disposal of tritiated water is a crucial important technology to the development of nuclear power and fusion energy [1,2,3]. It has aroused wide attention and discussion that Japanese Government decides to discharge the wastewater of Fukushima nuclear power plant, in which tritium is the most important radionuclide. It is significant to carry out indepth theoretical research on LPCE and establish a method that can accurately forecast the catalytic exchange performance of all hydrogen isotopes. A theoretical study about the thermodynamic characteristics of LPCE of protium-deuterium (H-D) system was firstly carried out based on the mentioned principle, and much higher prediction accuracy was achieved to benefit for the design of this process. The research method established in this paper can be further extended to tritium systems, which shows obvious significance for the future application, and the results for the tritium-containing system would be discussed in our follow-up work

LPCE reaction and equilibrium constant

Principle of Thermodynamic Equilibrium Calculation

Theoretical calculation and verification

Cascade process of LPCE

Conclusion