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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.
Seungjin Kim, Kennard Callender, Gunol Kojasoy
Nuclear Technology | Volume 167 | Number 1 | July 2009 | Pages 20-28
Technical Paper | NURETH-12 / Thermal Hydraulics | doi.org/10.13182/NT09-A8848
Articles are hosted by Taylor and Francis Online.
The present study develops an interfacial area transport equation applicable to an air-water horizontal bubbly flow with a flow restriction. The experiments are performed in a round glass pipe of 50.3-mm inner diameter, along which a 90-deg elbow is installed at L/D = 206.6 from the two-phase mixture inlet. In total, 15 different flow conditions in the bubbly flow regime are studied. The detailed local two-phase flow parameters are acquired by a double-sensor conductivity probe at four different axial locations. The effect of the elbow is evident in the distribution of local parameters as well as in the development of interfacial structures. The elbow clearly promotes bubble interactions resulting in significant changes in both the void fraction and interfacial area concentration. In the present study, the elbow is found to promote the coalescence mechanism while reducing the disintegration mechanism. These geometric effects are also reflected in the axial development of one-dimensional two-phase flow parameters. In the present analysis, the interfacial area transport equation is developed in one-dimensional form via area-averaging based on the existing model for vertical flow. In the averaging process, characteristic nonuniform distributions of the two-phase flow parameters in horizontal two-phase flow are treated mathematically by covariance calculations. Furthermore, the change in pressure due to the minor loss of the elbow is taken into consideration by using a newly developed correlation analogous to Lockhart and Martinelli's. In total, 60 area-averaged data points are employed to benchmark the present model. The present model predicts the data well with an average percent difference of approximately ±10%.
