Session: 05-04: Nuclear Engineering and Safety Analysis

Paper Number: 136160

136160 - Radioactive Source Term of Lead-Bismuth Smr and the Environmental Impact 

Abstract: 

Lead-bismuth fast reactor was selected as one of the undeveloped reactor types of the International Forum on Fourth-generation Reactors (GIF) because of the excellent neutron economic, good thermal conductivity and chemical stability. To realize the fast development as an affordable power source, LFR must satisfy several goals including a high level of public and worker safety, low environmental impact, high operation availability, a closed fuel cycle and the potential to be economically competitive. Yet there are still scientific and technological efforts need to be addressed. A major challenge with LFR is the extreme toxic radioactive nuclide polonium (²¹⁰Po). In cases of cover gas leaks or accidents, ²¹⁰Po may chemically interact with moist air to form volatile compounds. Moreover, radioactive nuclides such as iodine and cesium appear new migration properties in the high temperature liquid lead bismuth environment. And tritium will be also produced in the primary loop by the ternary fission reaction and (n, α) reaction of lithium impurity.

In this presentation, the main radioactive source terms and their migration mechanism in the Lead-Bismuth fast reactor is introduced briefly. And the lasted research progress on the LFR source terms issues in IFCEN-SYSU are summarized:

1) Series testing platforms for LFR source terms were constructed, including the radioactive aerosol from LBE, tritium behavior in LBE, corrosion products transportation, and I/Cs/Te evaporation device.

2) A multi-physics numerical model for the source terms migration had been established. The flow and heat transfer field in the reactor was simulated based on the Finite Element Method (FEM), coupled with the dynamic migration model of source term spices. The influence factors such as nuclide decay, covering gas leakage, containment ventilation and aerosol deposition are comprehensively considered, and the influencing factors are evaluated in detail.

3) Experimental research on key nuclides such as Te/I/Cs/T had been conducted to measure the physical and chemical properties in LBE coolant. The experimental results indicated that the particle size distribution of Te-doped LBE aerosols is mainly at the nanometer level, the chemical form of Te in LBE aerosols is mainly TeO₂. Deuterium (instead of tritium) in the cover gas mainly exists in the form of HD and HDO, and the HDO share reaches more than 90% under various conditions. The transport properties as solubility, diffusivity and permeability of tritium, and the evaporation rate of fission products were also measured in various conditions.

Finally, the key technical challenges for the control and treatment of the source term for LBR are discussed.

Presenting Author: Muyi Ni Sino-French Institute of Nuclear Engineering & Technology, Sun Yat-sen University

Presenting Author Biography: Ph.D. in Nuclear Engineering from the School of Nuclear Science and Technology, University of Science and Technology of China in 2013, and has been engaged in research in the field of nuclear safety and radiation protection. From 2016 to 2017, the Ministry of Science and Technology appointed the International Thermonuclear Fusion Experimental Reactor (ITER) as a Senior Visiting Scholar. Since 2018, he has been employed by ITER International as an ITER Scientific Fellow. He is an expert in radiation protection and environmental impact assessment for the Ministry of Ecology and Environment. He has been awarded the "Doctoral Academic Newcomer Award" by the Ministry of Education and the "Outstanding Youth in Tritium Science" by Chinese Nuclear Society.

Authors:

Muyi Ni Sino-French Institute of Nuclear Engineering & Technology, Sun Yat-sen University
Wei Wang Sino-French Institute of Nuclear Engineering & Technology, Sun Yat-sen University
Man Jiang Huazhong University of Science and Technology
Yuqing Wang Sino-French Institute of Nuclear Engineering & Technology, Sun Yat-sen University
Yingwu Jiang Sino-French Institute of Nuclear Engineering & Technology, Sun Yat-sen University