title: Results of field trials using the NPL simulated reactor neutron field facility.
abstract: The NPL simulated reactor neutron field facility provides neutron spectra similar to those found in the environs of UK gas-cooled reactors. Neutrons are generated by irradiating a thick lithium-alloy target with monoenergetic protons between 2.5 and 3.5 MeV (depending on the desired spectrum), and then moderated by a 40-cm diameter sphere of heavy water. This represents an extremely soft workplace field, with a mean neutron energy of 25 keV and, more significantly, a mean fluence to ambient dose equivalent conversion coefficient of the order of 20 pSv cm(2), approximately 20 times lower than those of the ISO standard calibration sources (252)Cf and (241)Am-Be. Results of field trials are presented, including readings from neutron spectrometers, personal dosimeters (active and passive) and neutron area survey meters, and issues with beam monitoring are discussed.
authors.affiliation: Neutron Metrology Group, DQL, National Physical Laboratory, Teddington, Middlesex, TW11 0LW, UK. graeme.taylor@npl.co.uk
authors.forename: G C
authors.initials: GC
authors.lastname: Taylor
authors.forename: D J
authors.initials: DJ
authors.lastname: Thomas
authors.forename: A
authors.initials: A
authors.lastname: Bennett
mesh_terms: D003198:Computer Simulation; D017076:Computer-Aided Design; D004867:Equipment Design; D019544:Equipment Failure Analysis; D008962:Models, Theoretical; D009502:Neutrons; D009688:Nuclear Reactors; D010315:Particle Accelerators / Q000295:instrumentation*; D011829:Radiation Dosage; D011874:Radiometry / Q000379:methods*; D014480:United Nations