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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.
S. B. Gunst, J. C. Connor, D. E. Conway
Nuclear Science and Engineering | Volume 58 | Number 4 | December 1975 | Pages 387-413
Technical Paper | doi.org/10.13182/NSE75-A26795
Articles are hosted by Taylor and Francis Online.
Samples of 233U and of natural thorium have been irradiated in high neutron-flux facilities, in both soft and hard neutron spectra, and for both short and long exposure times. Included are exposures resulting in depletions of more than 90% of the 233U in the fissile material and burnups of more than 30 000 MWd/MT in the fertile material. Postirradiation mass analyses of the total and the isotopic uranium, of 137Cs, and of the neodymium isotopes generally agree within a few percent with corresponding calculations based on measured exposure histories. Reactivity measurements between irradiation cycles provide experimental results for the fissile content and fission-product poisoning as functions of both irradiation and cooling time. Corresponding results obtained from calculated concentrations agree with measurements to ∼1% for the fissile content and 3% for the effective one-group fission-product poison cross section. However, fission-product poison cross sections in two energy groups (thermal and epithermal) exhibit differences between measurement and calculation that are believed to be attributable to a lack of adequate information on important fission products in the literature. Experimental results for transient absorbers in irradiated 233U give at least 20 000 b for the neutron absorption resonance integral of 149Pm. This is a factor of 15 higher than that obtained by a 1/v extrapolation of the thermal cross section. For transient 135Xe, the measured absorption is 7.5% higher than that calculated using ENDF/B-IV data. Information is also provided concerning such matters as fission yields and neutron absorption of neodymium isotopes, the existence of significant transient fission-product poisons other than 135Xe and 149Sm, and the shielding of 233U by 232Th. Such shielding suggests the need for a change in the energy dependence of the 232Th thermal-neutron cross section.