In its standard ISO 8529 the International Organization
for Standardization (ISO) recommends different radionuclide neutron sources for the
calibration of measuring instruments for use in radiation protection. An irradiation device using such sources (252Cf (unmoderated and moderated by 15 cm D2O), 241Am-Be) is available at the PTB. Here calibrations of area monitors and irradiation of personal neutron dosemeters, which have been approved for official use, are carried out at regular intervals. The measurands are the ambient and the personal dose equivalent. Furthermore, spectrometers and neutron detectors are examined and calibrated with respect to neutron fluence.
The properties of the radiation fields are exactly known; the strengths of the neutron sources were determined at the NPL by the manganese bath method, the spectral neutron fluence at the place of measurement was measured with spectrometers and determined by neutron transport calculations. The relative standard uncertainty for the neutron fluence is 0.7% to 2.3%, depending on the neutron source. The neutron fluence also serves to determine dose equivalent quantities (e.g. the ambient dose equivalent) using recommended conversion coefficients.
Literature:
Kluge,H (1998): Irradiation facility with radioactive reference neutron sources: Basic principles: a status report. PTB-Report N-34. Physikalisch-Technische Bundesanstalt, Braunschweig.
Contact
Dr. Andreas Zimbal
Phone: +49 (0) 531-592-6530
e-mail: Andreas.Zimbal@ptb.de
