Changes of the surface-to-volume ratio and diffusion coefficient of fission gas in fuel pellets during irradiation

• Published in: Journal of nuclear materials Vol. 402; no. 2; pp. 108 - 115
• Main Authors: Amaya, Masaki, Grismanovs, Viktors, Tverberg, Terje
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 31.07.2010; Elsevier
• Subjects: Applied sciences; Company structure; Controled nuclear fusion plants; Diffusion coefficient; Energy; Energy. Thermal use of fuels; Exact sciences and technology; Fission; Fission nuclear power plants; Fuels; Installations for energy generation and conversion: thermal and electrical energy; Irradiation; MOX; Nuclear fission; Nuclear fuels; Pellets; Preparation and processing of nuclear fuels; Gaseous diffusion; Gas release; Flow measurement; Heavy water reactor; Mixed fuel; Diffusion coefficient; Burnup; Uranium dioxide; Fission gas; Fuel pellet; Nuclear reactor
• ISSN: 0022-3115; 1873-4820
• DOI: 10.1016/j.jnucmat.2010.05.004

Short-lived fission gas release from fuel pellets during irradiation was investigated based on the experimental results of the gas-flow rigs irradiated in the Halden Heavy Water Reactor (HBWR). The release-to-birth ( R/ B) rates of short-lived fission gas were measured by means of gas-flow measurement during the irradiation experiments. Surface-to-volume ( S/ V) ratios of fuel pellets and diffusion coefficients of short-lived fission gas release were evaluated from the obtained ( R/ B) values. The increase of ( S/ V) ratio agreed well with the point where the fuel temperature exceeded the threshold of 1% fission gas release. This indicates that the interlinkage of fission gas bubbles occurred there. The evaluated diffusion coefficients scattered in the range between 10 −23 and 10 −17 m 2/s, and the effects of fuel type (UO 2 or MOX) were not clearly observed. In addition, it is likely that the restructuring effect of fuel pellet on the diffusion coefficients of short-lived fission gas at least in the fuel pellet matrix is negligible in high burnup region where the rim structure forms in the fuel pellet.