Radiation Protection Dosimetry Vol. 110 Nos. 1-4 © Oxford University Press 2004; all rights reserved
Neutron spectra and angular distributions of concrete-moderated neutron calibration fields at JAERI
1 Japan Atomic Energy Research Institute, Tokai, Naka-gun, Ibaraki, 319-1195, Japan
2 Institute of Radiation Measurements, Tokai, Naka-gun, Ibaraki, 319-1106, Japan
* Corresponding author: myoshi{at}popsvr.tokai.jaeri.go.jp
The Facility of Radiation Standards of Japan Atomic Energy Research Institute has been equipped with concrete-moderated neutron calibration fields as simulated workplace neutron fields. The fields use an 241AmBe neutron source placed in the narrow space surrounded by concrete bricks, walls and floor. The neutron spectra and the neutron fluence rates of the fields were measured with the Bonner multi-sphere spectrometer system (BMS), spherical recoil-proton proportional counters, and a liquid scintillation counter (NE-213). The results were compared with each other. The reference values of H*(10) were determined from the results of BMS. The angular distributions of neutron fluence were calculated using MCNP-4B2 to obtain the reference values of Hp(10). The calculated results show that the scattered neutrons have a wide range of incident angles. The reference Hp(10) values considered the angular distribution were found to be 1018% smaller than those without consideration.