Fast neutron flux and spectrum measurements in HIFAR

Abstract

This report presents the results of measurements on the fast neutron fluxes and energy spectra in the core and 2V experimental facilities of HIFAR using threshold detectors. The following reactions were used: P31(n,p)Si31, S32(n,p)P32, Ni58(n,p)Co58, A127(n,α)Na24. The total fission flux in the flux scanning tubes were found to be 23 ± 3 per cent. of the total effective flux at the same position, having a maximum value of 4.3 x 10 13 neutrons cm-2 sec-1 (approximately 8.3 MW thermal), for a maximum effective flux of 1.7 x 10 14 neutrons cm-1 sec-1. A neutron energy spectrum differing only slightly from a fission spectrum shape was found in all positions. The use of the Ni58(n,p)Co50 reaction as a fast flux monitor is discussed.