Gas emission from the UO2 samples, containing fission products and burnable absorber

10th International School-Conference on Materials for Extreme Environment: Development, Production and Application

Kopytin, V.P.^1 ; Baranov, V.G.^1 ; Burlakova, M.A.^1 ; Tenishev, A.V.^1 ; Kuzmin, R.S.^1 ; Pokrovskiy, S.A.^1 ; Mikhalchik, V.V.^1

National Research Nuclear University MEPhI, Moscow Engineering Physics Institute, Kashirskoe Highway 31, Moscow

115409, Russia^1

关键词: Bonding energies;    Burnable absorber;    Cladding material;    Material structure;    Neutron absorbers;    Sample heating;    Temperature range;    Transport process;   

Others  :  https://iopscience.iop.org/article/10.1088/1757-899X/130/1/012020/pdf
DOI  :  10.1088/1757-899X/130/1/012020

来源: IOP

【 摘 要 】

The process gas released from the fuel pellets of uranium fuel during fuel burn-up reduces the thermal conductivity of the rod-shell gap, enhances hydrogen embrittlement of the cladding material, causes it's carbonization, as well as transport processes in the fuel. In this study a technique of investigating the thermal desorption of gases from the UO2fuel material were perfected in the temperature range 300-2000 K for uniform sample heating rate of 15 K/min in vacuum. The characteristic kinetic dependences are acquired for the gas emission from UO2samples, containing simulators of fission products (SFP) and the burnable neutron absorber (BNA). Depending on the amount of SFP and BNA contained in the sample thermal desorption gas spectra (TDGS) vary. The composition of emitted gas varies, as well as the number of peaks in the TDGS and the peaks shift to higher temperatures. This indicates that introduction of SFPs and BNA alters the sample material structure and cause the creation of so- called traps which have different bonding energies to the gases. The traps can be a grid of dislocations, voids, and contained in the UO2matrix SFP and BNA. Similar processes will occur in the fuel pellets in the real conditions of the Nuclear Power Plant as well.