Qualifying C8/F9 Spectrum Index Measurements by Using Standard Neutron Fields

摘要

A measurement method for the determination of the spectrum index C8/F9 and, indirectly the F8/F9 spectrum index in LWR fuel assemblies has been qualified. With this method U- and Pu-foils are placed between fuel pellets and irradiated in the VENUS test reactor. After irradiation the foils are dismantled and the produced activation and fission products are measured with the help of gamma-spectrometry. The amounts of activation and fission products are a measure of the reaction rates. A qualification of this method has been performed in the BR1 reactor in a well-known reference neutron spectrum (thermal). The observed deviation from the theoretical value (1.7%) falls within the uncertainty range (1.9%, lσ). In this paper the qualification of the measurement technique, together with the uncertainty analysis, will be reported.