STP1001

    Correction of Burn-In Effects in Fission Neutron Dosimeters

    Published: Jan 1989


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    Abstract

    When fission neutron dosimeters are applied for neutron dosimetry, such as those used in light-water reactor (LWR) pressure vessel surveillance (PVS), higher order actinide isotopes can be produced in the dosimeter by the neutron field. These higher order actinide isotopes can also undergo fission and thereby contribute to the number of fissions or fission rate that is observed with the dosimeter. This so-called "burn-in" effect can be non-negligible, especially in fission threshold monitors such as those used in LWR-PVS.

    A novel method for correction of this "burn-in" effect is advanced. In this new method, two quantities are measured in order to quantify the "bum-in" contribution, namely the amount of the "in-grown" fissile isotope that is created and the fissions per unit volume produced in the "in-grown" fissile isotope. Monitors used to measure these two quantities must experience the very irradiation that the fission neutron dosimeter undergoes, (i.e., the same location and flux-time history). Conditions are defined under which the "burn-in" effect can be delineated in terms of these two observed quantities. Advantages of this correction method are discussed.

    Keywords:

    fission neutron dosimeters, ,“burn-in,” effect, light water reactor, pressure vessel surveillance


    Author Information:

    Gold, R
    Fellow Scientist, Program Manager, Hanford Engineering Development Laboratory, Westinghouse Hanford Company, Richland, WA

    McElroy, WN
    Fellow Scientist, Program Manager, Hanford Engineering Development Laboratory, Westinghouse Hanford Company, Richland, WA


    Paper ID: STP10128S

    Committee/Subcommittee: E10.07

    DOI: 10.1520/STP10128S


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