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ANS Student Conference 2025
April 3–5, 2025
Albuquerque, NM|The University of New Mexico
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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.
B. Grimeland and G. Seierstad
Nuclear Science and Engineering | Volume 23 | Number 4 | December 1965 | Pages 339-343
Technical Paper | doi.org/10.13182/NSE65-A21070
Articles are hosted by Taylor and Francis Online.
Small crystals of NaI(TI) were exposed to (D, D) neutrons slowed down in a paraffin moderator. The crystals were either enclosed in cadmium or placed inside a small cadmium box filled with the moderator material. The activities induced in iodine at different positions were measured. Now let the normalized activities obtained with the detectors enclosed in cadmium be A1 and let those obtained with the detectors placed inside the cadmium box be A2. It is assumed that the difference A2 − A1 is proportional to q(0.5 eV)-the slowing down density at an energy of 0.5 eV-and from the measured quantities A2(r) and A1(r) the slowing down age has been determined. Bare crystals were also irradiated and the induced activities measured. Let these activities be A3. Then the difference A3 − A1 will give a measure of the density of thermal neutrons and the migration area can be determined. With migration area and slowing down age known, the diffusion length of thermal neutrons could be determined too. The result obtained was L = (2.86 ± 0.16)cm compared to a calculated value of (2.60 ± 0.01)cm. The discrepancy might indicate that the neutron temperature in the paraffin is about 400 °K. Paraffin was used as moderator material because this greatly facilitated the experiment. It is never used as a reactor material and knowledge of the measured quantities may be of minor importance. The method, however, might possibly be of some interest.
