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The new version of the International Reactor Dosimetry File IRDF-90 (called “Version April 1993”) has been tested by calculatio of average cross-sections and their uncertainties in a coarse three energy group structure and by neutron spectrum adjustments in reference neutron spectra. This paper presents the results and compares them with the corresponding ones of the old Reactor Dosimetry File IRDF-85 and with the data of the Nuclear Data Guide for Reactor Neutron Metrology. Finally, the applicability of the new library in the field of neutron metrology is discussed.

Foil irradiation experiments were carried out at LFR (ECN. Petten) and WWR-SM (KFKI, Budapest). The effect of boron covers on the activation and fission detector response regions has been investigated. Fluence rate perturbation due to the applied B4C box in graphite or water was determined by means of transport calculations. Neutron spectrum adjustments were performed by the SAND-II and STAY'SL codes. The B4C cover shifts the response regions of the resonance reactions from the thermal region to the 0.1 keV to 1.0 MeV interval. Where boron-covered reactions are used in a least squares spectrum adjustment procedure, the uncertainty of the spectrum is reduced significantly in the intermediate energy region.