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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.
Young Min Kwon, Chan Eok Park, Jin Ho Song
Nuclear Technology | Volume 122 | Number 3 | June 1998 | Pages 295-305
Technical Paper | Thermal Hydraulics | doi.org/10.13182/NT98-A2871
Articles are hosted by Taylor and Francis Online.
To investigate the realistic behavior of mass and energy release and resultant containment response during a large-break loss-of-coolant accident (LOCA), analyses are performed on the Yonggwang (YGN) 3&4 nuclear power plants using the RELAP5/CONTEMPT4 computer code. Comparative analyses using conservative design computer codes are also performed. The break types analyzed are the double-ended guillotine breaks at the cold leg and hot leg. The design analysis predicts that the containment peak pressure occurs during the postblowdown phase for the cold-leg break. However, RELAP5/CONTEMPT4 analyses show that the containment pressure has a peak during the blowdown phase, thereafter it decreases monotonously without the postblowdown peak. For the hot-leg break, revised design analysis shows a much lower pressure than that reported in the YGN 3&4 final safety analysis report. The RELAP5/CONTEMPT4 analysis shows a similar trend and confirms that the bypass flow through the broken loop steam generator during postblowdown is negligibly small compared to that of the cold-leg break. In conclusion, realistic analysis by RELAP5/CONTEMPT4 demonstrates that the containment peak pressure occurs during the blowdown phase for both cold- and hot-leg large-break LOCAs, and there is no physical mechanism resulting in mass and energy discharge that can pressurize the containment after end of blowdown for a hot-leg break. Also, it is suggested that the substantial conservatism included in the design analysis should be improved to provide benefits in relaxing the plant technical specifications and reducing the containment design pressure.
