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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.
Brian R. Nease, Taro Ueki
Nuclear Science and Engineering | Volume 157 | Number 1 | September 2007 | Pages 51-64
Technical Paper | doi.org/10.13182/NSE07-A2712
Articles are hosted by Taylor and Francis Online.
A coarse-mesh projection method has been developed for the Monte Carlo calculation of dominant eigenvalue ratio [dominance ratio (DR)]. The first step of the method consists of the regression analysis of the multivariate time series from the coarse-mesh binning of the Monte Carlo fission source distribution. The second step is computation of the eigenvectors of the adjoint matrix of noise propagation. In general, projections on these eigenvectors can be utilized to compute important characteristics of the eigenmodes of fission source distribution. In this work, it has been proven that if the eigenvector corresponding to the largest eigenvalue of the aforementioned adjoint matrix is taken to be the vector for projection, the projected scalar time series follows the autoregressive process of order one with the root of characteristic polynomial, i.e., the autocorrelation coefficient, being the DR of fission source distribution. Numerical results are presented for four problems including one-energy-group checkerboard-type problems, a one-energy-group cube problem and a continuous-energy pressurized water reactor core problem. The strength of the method is twofold; (a) the elimination of the use of autoregressive moving average fitting, and (b) no need to optimize the order of fitting.