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Members are devoted to applying nuclear science and engineering technologies involving isotopes, radiation applications, and associated equipment in scientific research, development, and industrial processes. Their interests lie primarily in education, industrial uses, biology, medicine, and health physics. Division committees include Analytical Applications of Isotopes and Radiation, Biology and Medicine, Radiation Applications, Radiation Sources and Detection, and Thermal Power Sources.
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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.
Quan Zhou, Rizwan-uddin
Nuclear Science and Engineering | Volume 151 | Number 1 | September 2005 | Pages 95-113
Technical Paper | doi.org/10.13182/NSE05-A2532
Articles are hosted by Taylor and Francis Online.
Stability and bifurcation analyses of boiling water reactors have been carried out using a reduced-order two-channel model developed earlier by Karve et al. To parameterize azimuthal asymmetry in core loading, an amplification factor F is introduced into the model to vary azimuthal mode feedback coefficients. Bifurcation analysis code BIFDD and numerical integration are used to analyze the reduced-order model composed of 22 modified ordinary differential equations. Results are presented for effects of azimuthal asymmetry (as parameterized by the amplification parameter F) on characteristics of oscillations. Analysis of eigenvectors corresponding to the two pairs of complex conjugate eigenvalues with the largest and second largest real parts suggests that one of these pairs is responsible for in-phase oscillations and the other for the out-of-phase oscillations.For a uniform core without azimuthal asymmetry (F = 1), as a bifurcation parameter (total pressure drop) is varied, the pair of eigenvalues corresponding to the fundamental mode first cross the imaginary axis, thus making the system unstable and leading to in-phase oscillations. However, for azimuthally asymmetric cores (corresponding to large values of F) and small inlet subcooling, the pair of eigenvalues corresponding to the first azimuthal mode, whose real part is the second largest for F = 1 case, approach the vertical axis faster (as a bifurcation parameter is varied) than those corresponding to the fundamental mode, thus becoming the dominant pair of eigenvalues. This leads to out-of-phase oscillations. Results of bifurcation analyses show that both sub- and supercritical bifurcation can occur for large as well as small azimuthal asymmetry, depending on values of other operating parameters. Changes in characteristics of oscillations (in-phase or out-of-phase; super- or subcritical bifurcation), therefore, result along the stability boundary. Numerical integrations confirm the results of stability and bifurcation analyses.