Volume 3, Issue 4 (April 2006)

    Retrospective Measurement of Neutron Activation within the Pressure Circuit Steelwork of a Magnox Reactor and Comparison with Prediction

    (Received 20 June 2005; accepted 25 October 2005)

    CODEN: JAIOAD

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    Abstract

    This paper describes a retrospective measurement of neutron activation rates within steel standpipe penetrations of the pressure circuit of the Wylfa nuclear power plant. This was carried out in support of neutron dose calculations. Samples were taken from a length of irradiated thermocouple cable and counted for the fast neutron reactions 54Fe(n,p) 54Mn, and 58Ni(n,p) 58Co, and the thermal neutron reactions 59Co(n,γ) 60Co, 58Fe(n,γ) 59Fe, and 50Cr(n,γ) 50Cr. By isolating clean sheath material and performing elemental analysis, it was possible to obtain absolute neutron flux data from the measurements over a broad range of locations. The measured data were compared with results obtained from a Monte Carlo calculation performed with the code MCBEND. Structure observed within the measured and calculated thermal neutron flux distributions was used to confirm the position of the thermocouple samples relative to the reactor geometry. The measurements show that the calculations consistently over-predict fast and thermal neutron reactions. It is concluded that the model predicts spectra without significant bias, and consequently, that the standpipe dose recommendations are similarly over-predicted.


    Author Information:

    Thornton, DA
    British Nuclear Group, Berkeley Centre, Berkeley, Gloucestershire

    Thiruarooran, C
    British Nuclear Group, Berkeley Centre, Berkeley, Gloucestershire

    Allen, DA
    British Nuclear Group, Berkeley Centre, Berkeley, Gloucestershire

    Harris, AM
    British Nuclear Group, Berkeley Centre, Berkeley, Gloucestershire

    Holmes, CG
    Nexia Solutions, Springfields, Salwick, Preston, Lancashire

    Harvey, CR
    Nexia Solutions, Springfields, Salwick, Preston, Lancashire


    Stock #: JAI13451

    ISSN: 1546-962X

    DOI: 10.1520/JAI13451

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    Author
    Title Retrospective Measurement of Neutron Activation within the Pressure Circuit Steelwork of a Magnox Reactor and Comparison with Prediction
    Symposium Reactor Dosimetry, 12th Volume, 2005-05-13
    Committee E10