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Nuclear Criticality Safety
NCSD provides communication among nuclear criticality safety professionals through the development of standards, the evolution of training methods and materials, the presentation of technical data and procedures, and the creation of specialty publications. In these ways, the division furthers the exchange of technical information on nuclear criticality safety with the ultimate goal of promoting the safe handling of fissionable materials outside reactors.
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ANS Student Conference 2025
April 3–5, 2025
Albuquerque, NM|The University of New Mexico
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Latest News
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.
Minoru Yamada, Ikuo Kinoshita, Toshihide Torige, Michio Murase, Yoshitaka Yoshida, Hideo Nakamura
Nuclear Technology | Volume 200 | Number 2 | November 2017 | Pages 125-143
Technical Paper | doi.org/10.1080/00295450.2017.1362940
Articles are hosted by Taylor and Francis Online.
Application of the statistical safety evaluation method to the analysis for reflux cooling in the loss of residual heat removal system (RHR) event during mid-loop operation was conducted with RELAP5/MOD3.2 as the best-estimate code. The evaluation parameters for this event are the reactor coolant system (RCS) pressure and reactor vessel (RV) water level. A phenomena identification and ranking table was developed previously to identify important phenomena that have a large influence on the evaluation parameters. The uncertainties of the analytical models which are related to the important phenomena were quantified to use as input for the statistical analysis. Actual plant sensitivity analyses were carried out to confirm the influence of the uncertainty which was quantified. Validation analysis of the RELAP5/MOD3.2 code was carried out for the reflux cooling test conducted with the ROSA-IV Large-Scale Test Facility to confirm that the experimental RCS pressure results were within the range of the uncertainty of the analytical models. A statistical analysis for 93 cases was carried out for a four-loop plant to evaluate the RV water level in the steady state and the maximum RCS pressure with 95% cumulative probability and 95% confidence. As a result, it was confirmed that reflux cooling using two cooling steam generators was successful.
