Clarification of rim structure effects on properties and behaviour of LWR UO{sub 2} fuels and gadolinia doped fuels

Conference · Sun Jul 01 04:00:00 EDT 2007

OSTI ID:21229298

Sonoda, T; Kameyama, T; Sasahara, A; Kitajima, S; Nauchi, Y; Kinoshita, M ^[1]; Rondinella, V V; Wiss, T; Hiernaut, J P; Papaioannou, D; Sheindlin, M; Staicu, D ^[2]

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1. Central Research Institute of Electric Power Industry (CRIEPI), 2-11-1 Iwado-kita, Komae-shi 201-8511, Tokyo (Japan)
2. European Commission, Joint Research Centre, Institute for Transuranium Elements (ITU), P.O. Box 2340, 76125 Karlsruhe (Germany)

At the peripheral region of high burnup fuel pellets, a crystallographic re-structuring is observed, commonly called the 'rim structure', which is characterized by the existence of highly dense small sub-grains, whose size is approximately 100 nm, and the accumulation of small pores with average size around 1 {mu}m. This restructuring can influence the fuel performance including, e.g. fission gas release behaviour, temperature, hardness and density. In order to clarify the threshold burnup and temperature of rim structure formation and fuel performances of LWR UO{sub 2} fuels and gadolinia-doped ((U,Gd)O{sub 2}) fuels whose usage is increasing for higher burnup in LWR, several post irradiation examinations such as scanning electron microscope (SEM) /transmission electron microscope (TEM) observation, density measurements, hot cell annealing and thermal diffusivity measurements are done. By SEM and TEM observations, it is clarified that the microstructure evolution and the burnup and temperature threshold of rim structure formation of (U,Gd)O{sub 2} fuels is not different from that of UO{sub 2} fuels. The density change of UO{sub 2} and (U,Gd)O{sub 2} fuels is almost similar, and the irradiation temperature does not affect the density change significantly. Fission gas release behaviour can be classified by the existence of rim structure, and the release behaviour between UO{sub 2} and (U, Gd)O{sub 2} fuels is almost same. The thermal diffusivity behavior of (U, Gd)O{sub 2} fuels is similar to that of UO{sub 2} fuels, and the decrease rate of thermal diffusivity is prevented in burnup range of 50-70 MWd/kgU. (authors)

• Research Organization: American Nuclear Society, 555 North Kensington Avenue, La Grange Park, IL 60526 (United States)
• OSTI ID: 21229298
• Country of Publication: United States
• Language: English

Related Subjects

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS
36 MATERIALS SCIENCE
ANNEALING
BURNUP
CRYSTALLOGRAPHY
DENSITY
DOPED MATERIALS
FISSION PRODUCT RELEASE
FUEL PELLETS
HARDNESS
HOT CELLS
MICROSTRUCTURE
NUCLEAR FUELS
PERFORMANCE
POST-IRRADIATION EXAMINATION
SCANNING ELECTRON MICROSCOPY
THERMAL DIFFUSIVITY
TRANSMISSION ELECTRON MICROSCOPY
URANIUM DIOXIDE