SEDL / STP / STP1001-EB / STP10100S

Application of LEPRICON Methodology to LWR Pressure Vessel Surveillance Dosimetry

Maerker, RE
Research Staff, Oak Ridge National Laboratory, Oak Ridge, TN

Pages: 10    Published: Jan 1989

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Abstract

A second example of applying the LEPRICON methodology to an existing pressurized water reactor is described. The present application is an analysis of ad hoc dosimetry inserted into the H. B. Robinson-2 reactor to monitor the effects on pressure vessel fluence produced by the introduction of a low-leakage fuel management scheme during Cycle 9. The use of simultaneous dosimetry at both a downcomer location and in the reactor cavity allows a quantitative evaluation to be made by the LEPRICON procedure of the relative merits of each location; the cavity location is found to be superior. Unfolded results using the dosimetry indicate that the cumulative neutron fluence above 1.0 MeV originally calculated for the critical lower circumferential weld in the pressure vessel during Cycle 9, 7.2 × 10¹⁷,” n/cm² ± 15.9%, should be adjusted upward by about one standard deviation to a value of 8.8 × 10¹⁷ n/cm² with a reduced uncertainty of 10.9%.