Radiation effects in solidified high-level waste. Part I. Stored energy

Buildup and release behavior of radiation-induced stored energy was investigated for several synthetic solidified high-level waste forms: two borosilicate glass formulations, calcine, calcine on Al$sub 2$O$sub 3$, and a hot press compact of 50 percent waste oxide--50 percent quartz. Fused silica and Al$sub 2$O$sub 3$, without waste oxides, were also investigated. Average heat capacities of some of the materials were also measured. The materials were irradiated either by internal alpha radiation $sup 244$Cm or by neutron irradiation in ORR. The irradiations simulated the effects resulting from self- irradiation of the waste for storage periods up to nearly 1000 years for wastes from PWR-UO$sub 2$ fuel [equivalent to periods of approximately 10 years for mixed wastes from UO$sub 2$ fuel ($sup 2$/$sub 3$) and plutonium recycle fuel ($sup 1$/$sub 3$)]. Results showed that the amounts of stored energy over a period of about 10 years at relatively low storage temperatures following reprocessing are such that only moderate temperature increases (less than 200$sup 0$C) in the wastes would occur in the event of sudden release of the stored energy. Extrapolation to longer storage times in a geologic repository indicated that saturation of energy storage would occur at 50 cal/g or less for each of the waste types; the $delta$T corresponding to release of 50 cal/g would be about 250$sup 0$ for most of the waste types. The experimental results also showed no apparent way in which a sudden release could occur except as a result of sudden large increases in waste temperature caused by a heat source other than the stored energy