Fission Product Release From High Burnup Fuel During Oxidation In Air At 950 Degrees C

Download or read book Fission product release from high burnup fuel during oxidation in air at 950 degrees c written by D. R. Mccracken and published by . This book was released on 1985 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Two mechanistically different regimes have been observed during the oxidation of uo2 in air: at temperatures greater than or equal to 800 degrees c, u3o8 forms large crystals which propagate in a front through the underlying u4o9/uo2; at temperatures less than 700 degrees c, one grain of uo2 ultimately gives one or more grains of u3o8. previous experiments (1) indicated that in this latter temperature zone, releases of fission products are low and probably originate from inventory at grain boundaries. the experiments described here at 950 degrees c using high burnup fuel (445, 465 mw.h/kg u) confirm earlier results obtained with low burnup fuel (2) at 920 degrees c: in this temperature zone, 100 percent of the volatile fission products are released when u3o8 is formed by oxidation of uo2 in air. within experimental error, oxidation rates and corresponding release rates are independent of burnup, so that data on oxidation rates obtained using unirradiated pellets can be used to estimate release rates of fission products during oxidation of irradiated fuel. iodine, in the form of i2, is released from the uranium matrix as readily as the noble gases, but subsequently adsorbs in steel pipework thus reducing its volatility in a real system. cs release was also observed. it lagged behind the iodine, ruling out csi as the volatile species.