RESPONSE OF A SPHERICAL NEUTRON SURVEY METER

Calibration data for the spherical Harwell neutron survey meter (type 95/0075) have been reviewed and reassessed using conversion factors from ICRP Publication 21. It is found that, although the instrument has an over-response to intermediate-energy neutrons (by up to a factor of 4.9 at 10 keV), it neither over-reads nor under-reads by more than ±40% for a very wide range of calculated and measured shielded fission neutron spectra. For 14 MeV neutron sources shielded by concrete, the instrument under-reads by about 50%, and it is recommended that near such installations instrument readings should be multiplied by two. © 1979.