Actinide partitioning-transmutation program final report. I. Overall assessment

Abstract

The actinide partitioning flowsheets resulting from this program have two fundamental steps: (1) extraction of the actinides from the waste, and (2) recovery of the actinides. Processing of high-level waste to sake the actinides extractable is unnecessary since most of the actinides contained therein are amenable to extraction. In the case of solid wastes such as dissolver solids and cladding, the acti nides are solubilized into an extractable form with a nitric acid-hydro fluoric acid leach. The actinides present in HEPA filters and incinerator ashes are solubilized using a eerie nitrate-nitric acid solution to promote dissolution. Nonstrippable actinides are separated from salt wastes, such as solvent cleanup wastes, by acidification followed by contact with an alcohol [2-ethylhexanol (2-EHOH)]. The extractable actinides from these operations are then sent to actinide recovery, which consists of (1) recovering uranium, neptunium, and plutonium using Purex (TBP) extraction (not required for HLLW); (2) coextracting the remaining actinides plus lanthanidec using a bidentate (a neutr.il organophosphorus compound) extractant; and (3) separating the actinides from the lanthanides using cation exchange chromatography. The partitioning of actinides appears to be feasible based on the use of processing technology that has been experimentally verified at least at the laboratory level. Some of the partitioning processes, such as T3P extraction and acid leaching, have been demonstrated on a large scale in actual production operations. The partitioning of iodine also appears to be feasible using any of a variety of proven technologies. Although the partitioning of technetium was not specifically investigated, there is no known reason why it should not be feasible. Calculational actinide transmutation studies indicate that actinide transmutation rates range from 5 to 11% per full-power year, with fast reactors having the higher rates. The effects of actinide recycle on uranium enrichment requirements and the fast reactor breeding ratio were small, except in the first two actinide recycles in the LWR. Power peaking is a consideration in the LWR, but not in the LMFBR. Overall, LMFBRs are better actinide transmutation devices, but not substantially so. The effect of higher-than-normal amounts of neptunium, americium, XV and curium or fuel performance has not been determined. Technetium can be transmuted at the rate of 11~ per full-power year in a PWR; iodine transmutation rates are about 3Z per full-power year. The transmutation of the actinides appears to be feasible in both thermal and fast reactors, subject to the acceptability of reactor fuels with higher-than-normal concentrations of the recycled actinides. Tech netium transmutation also appears to be feasible, subject to the identifi cation of a satisfactory form for incorporation into a rod (the metal may be satisfactory). Iodine transmutation is marginally feasible at best because of its low transmutation rate, the high volatility of iodine compounds at reactor operatin...

Nuclear fuel cycle-oriented actinides separation in China

“…More than 100 000-year safeguard of the repository is required because of the presence of minor actinides Am, Cm and Np. In order to reduce the volume of HLW glass, a method was presented to separate minor actinides from HLW and to transmute them in Accelerator Driven System (ADS) or Generation IV reactors, so called "Partitioning and Transmutation" (P&T) [35]. In the past decades, several partitioning processes were developed all over the world.…”

CURE: Clean use of reactor energy

“…Tabulated data listed in Croff et al (1980) lead to the conclusion that essentially all of the residual risk of disposal of HLW in a deep geologic repository located in salt strata was from 99Tc and 1291.…”

“…The studies cited by Croff et al (1980) and by Wachter and Croff (1980) considered transmutation o f the 99Tc and 1291 in 1 ight-water reactors (LWR), with transmutation rates of 11 percent/yr and 3 percent/yr, respectively.…”

Available options for waste disposal

“…In the U.S.A. the Oak Ridge National Laboratory (ORNL) coordinated a study, with the participation of several national laboratories and private enterprises, in the period 1977-80 (Croff et al 1980). Chemical separation studies dealt with all types of waste from the fuel cycle, but only experiments at tracer levels were done.…”