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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.
HyeonTae Kim, Woosong Kim, Yonghee Kim
Nuclear Science and Engineering | Volume 193 | Number 5 | May 2019 | Pages 441-452
Technical Paper | doi.org/10.1080/00295639.2018.1542867
Articles are hosted by Taylor and Francis Online.
This paper suggests novel approaches to generate exact discontinuity factors (DFs) for transverse-integrated nodal analyses with a two-by-two node configuration in a homogenized fuel assembly (FA). We have shown that the conventional DF calculation scheme cannot generate exact DFs with the nodal expansion method (NEM) calculation when a FA is subdivided into two-by-two nodes due to the inherent discrepancy between the transport-based heterogeneous analysis and the diffusion-based NEM calculation. In order to overcome the difference, an iterative, two-node NEM sweeping method is proposed. In addition, three different formulations to define a single representative DF per assembly surface for the two-by-two NEM are suggested for convenient application for the existing nodal codes while maintaining enough accuracy. Numerical assessments with a colorset model and small modular reactor cores with 16 × by × 16 FAs show that the iterative two-node NEM sweep method successfully corrects the error caused by an inherent discrepancy between the transport and the diffusion method. Among the candidates of a single representative DF, the net current weighted average DFs are found to be the most adequate.