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Norway’s Halden reactor takes first step toward decommissioning
The government of Norway has granted the transfer of the Halden research reactor from the Institute for Energy Technology (IFE) to the state agency Norwegian Nuclear Decommissioning (NND). The 25-MWt Halden boiling water reactor operated from 1958 to 2018 and was used in the research of nuclear fuel, reactor internals, plant procedures and monitoring, and human factors.
Gunzo Uchiyama, Sachio Fujine, Shinobu Hotoku, Mitsuru Maeda
Nuclear Technology | Volume 102 | Number 3 | June 1993 | Pages 341-352
Technical Paper | Enrichment and Reprocessing System | doi.org/10.13182/NT93-A17033
Articles are hosted by Taylor and Francis Online.
A new neptunium, plutonium, and uranium separation process using n- and iso-butyraldehydes as reductantsfor Np(VI) and Pu(IV), respectively, is described for nuclear fuel reprocessing. A kinetics study and a chemical flow sheet study are conducted to develop the selective separation process for neptunium, plutonium, and uranium. In the kinetics study, it is found that n-butyraldehyde reduces Np(VI) to Np(V) in the Purex solution but does not reduce Pu(IV) and U(VI), and iso-butyraldehyde reduces Np(VI) and Pu(IV) but does not reduce U(VI). Based on these results, a new process to separate neptunium, plutonium, and uranium selectively is proposed. The process consists mainly of three steps: the codecontamination step, the neptunium separation step [in which Np(VI) extracted by a solvent of 30% tri-n-butyl phosphate (TBP)/n-dodecane together with Pu(IV) and U(VI) is reduced to Np(V) by n-butyraldehyde and is back-extracted from the solvent], and the uranium/plutonium (U/Pu) partition step using iso-butyraldehyde as a Pu(IV) reductant. In the chemical flow sheet study, the effectiveness of the separation process is demonstrated by the use of miniature mixer-settlers. In the neptunium separation step, ∼99.98% of the neptunium extracted by the 30% TBP/n-dodecane solvent along with U(VI) in the uranium/neptunium coextraction step is reduced by n-butyraldehyde and separated from the uranium stream. In the U/Pu partition step, >99% of the plutonium is reduced by iso-butyraldehyde and separated from the uranium stream.
