URANIUM DIOXIDE FUEL PELLET Russian patent published in 2003 - IPC

FIELD: nuclear power engineering. SUBSTANCE: fuel pellet designed for example to charge fuel elements for nuclear power reactors is produced with defective factor and level of its parameters sufficient to ensure uranium burn-out of minimum 50-60 MWD/kg. Fuel pellet has following defective factors and level, %: density, g/cu.cm, 10.4-10.6; defective factor, 3.5; diameter, mm, 7.535-7.570; defective factor, 1.0; height, mm, 9-11; defective factor, 1.0; mass proportion of uranium isotopes mixture, % ≥87,9; deviation of uranium-235 mass proportion from rating, %, 0.03; after-sintering ability, %, 0.0-0.3; defective factor, 4; open porosity, %, 0.5; mean nominal grain size, mcm, 10-25; proportion of 1-10 mcm pores, %, ≥90; maximal pore size, mcm, 100; mean effective pore size, mcm, 3-5; uranium gas content, ml/g, 40; hydrogen content at 1800 C, 0.7 ppm; roughness, mcm, max. 1.8. Fuel elements charged with proposed pellets will operate trouble-free for five years and more. EFFECT: improved quality of fuel pellet. 2 tbl