SEDL / STP / STP1228-EB / STP15107S

Fluence Surveillance by Scraping Samples from the Inner Surface of the Thermal Shield in the Nuclear Power Plant Obrigheim in Germany (KWO).

Polke, E
Dipl. Phys., SIEMENS AG Power Generation Group (KWU), Erlangen,

Pages: 8    Published: Jan 1994

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Abstract

To reduce the end of life fluence of the KWO rpv, the core loading was modified in different steps. The influence of different core loading strategies on the neutron flux distribution at the inner rpv surface was determined by neutron transport calculations with the code DOT in (R-θ)-geometry and by analysis of samples scraped from the inner surface of the thermal shield. Samples were taken during the 7^th, 9^th, 11^th, 18^th, and 22^nd refueling outages. Up to 38 samples from different azimuthal and axial positions were collected during each sampling campaign. The fluences determined by the Mn54 and Nb93m activities were in good agreement with the corresponding theoretically calculated fluences.