Radioprotection 2025, 60( 1), 84 – 90 © N. T. Le, Published by EDP Sciences, 2025 https:// doi. org / 10.1051 / radiopro / 2024020
Available online at: www. radioprotection. org
ARTICLE
Parameter of neutron calibration field in Viet Nam following international standard
N. T. Le *
Institute for Nuclear Science and Technology, 179 Hoang Quoc Viet � Cau Giay, Hanoi, Viet Nam. Received: 12 January 2024 / Accepted: 27 May 2024
Abstract – This paper presents the technical parameters of neutron calibration fields available in Viet Nam for calibrations of neutron measuring meters( i. e., neutron ambient dose equivalent / rate meters and / or neutron personal dose equivalent / rate meters � referred to neutron meters). The technical parameters of neutron calibration fields, in this work, consist of physical quantity( i. e., the integrated neutron fluence rate over a neutron spectrum, f); operational dosimetric quantities( i. e., ambient dose equivalent rate, _ H ð10ÞÞ and radiation quantities( i. e., fluence-spectrum-averaged energies, E; fluence-to-ambient dose equivalent conversion coefficient, h *). The technical parameters of neutron reference fields were reported for different radiation beam qualities following the ISO-8529 and the ISO-12789 series( i. e., for direct neutron component from a neutron reference fields of a bare 241 Am-Be, complied with the ISO-8529 series criteria; and for total neutron component from simulated workplace neutron reference fields of a 241 Am-Be source moderated by different polyethylene spheres and from a neutron reference field of a bare 239 Pu-Be source, complied with the ISO-12789 series criteria). The technical parameters of the ISO-8529 neutron reference field of the bare 241 Am-Be source were theoretically calculated based on the total neutron source strength and presented for direct neutron component. In addition, the technical parameters of the ISO-12789 simulated workplace neutron reference fields of the 241 Am-Be source moderated by different polyethylene spheres as well as of the 239 Pu-Be source were characterized using the Bonner sphere spectrometer system accompanying with the FRUIT neutron spectrum unfolding code for the total neutron component. The technical parameters as well as their combined standard uncertainties of neutron fields were also presented in conjunction with different distances from the sources’ centers.
Keywords: Quantities / operational dosimetric / reference fields
1 Introduction
There are various types of neutron measuring devices( referred to neutron meters) to be used for measuring neutron physical quantity( i. e., integrated neutron fluence rate, f) and / or neutron operational dosimetric quantities( i. e., ambient dose equivalent rate, _ H ð10Þ; personal dose equivalent rate, _ H p ð10Þ) for the purposes of radiation protection and safety
assessment. For different purposes of measurements, neutron meters are maybe in active( Fuji Electric; Model 12-4-Ludlum; VF Nuclear) and / or in passive( The Thermo Fisher Scientific) types.
For ensuring the proper operations of neutron meters, calibrations must be done prior to, and periodically after their first use( IAEA, 2000). In a calibration certificate, in term of physical quantity( i. e., f) and / or operational dosimetric
* Corresponding author: LnThiem @ vinatom. gov. vn quantities( i. e., _ H ð10Þ; _ H p ð10Þ), radiation quantities( i. e., neutron fluence-spectrum-averaged energies, E and / or fluenceto-ambient dose equivalent conversion coefficient, h *) must be mentioned since indicators of neutron meters are dependent on those quantities. Recent years, neutron reference fields have been established for calibrations of neutron meters, in worldwide( Mazrou et al., 2008; Guzman-Garcia et al., 2015; Vykydal et al., 2015; Vega-Carrillo and Martinez-Ovalle, 2016) as well as in Viet Nam( Le et al., 2016, 2017, 2018, 2019, 2024; Nguyen et al., 2024).
In this work, technical parameters( including physical, operational dosimetric, and radiation quantities) were presented at different distances from the sources’ centers. The technical parameters were respectively presented in manners of theoretical calculations( i. e., for the ISO-8529 neutron reference field of a bare 241 Am-Be source) and of experimental data using the Bonner sphere spectrometer( BSS) system( i. e., for the ISO-12789 simulated workplace neutron reference fields of the 241 Am-Be source moderated by different
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