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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.
Tomio Okawa, Akio Kotani, Naoya Shimada, Isao Kataoka
Nuclear Technology | Volume 158 | Number 2 | May 2007 | Pages 304-313
Technical Paper | Nuclear Reactor Thermal Hydraulics | doi.org/10.13182/NT07-A3844
Articles are hosted by Taylor and Francis Online.
The critical heat flux in an annular two-phase flow regime is influenced significantly by an obstacle placed in a flow channel. Since the transition to critical heat flux condition in this flow regime is caused by the depletion of liquid film, it is probable that the flow obstacle has a notable influence on the rate of droplet deposition and, consequently, the film flow rate in the annular regime. Also, the obstacle's effect on the deposition rate would be important in predicting the critical heat flux in a boiling water reactor core because the grid spacer can be regarded as a flow obstacle placed in the subchannel. The obstacle effect was studied experimentally for vertical upward air-water annular flow; placing 12 small tubes of different cross sections concentrically in the test section tube one by one, the influence of obstacle geometry on the deposition rate was investigated. The rate of droplet deposition markedly increased if the present tubular obstacle was placed; the rate of increase was between ~30 and 200% and depended primarily on the obstacle shape. Using the experimental data, an empirical correlation to account for the obstacle's effect was proposed.