Philippine Journal of Science
153 (S1): 15-26, Nuclear Science and Technology
ISSN 0031 – 7683
Date Received: 13 Jul 2023
Response Evaluation of Neutron Dose Meters in Modified Neutron Fields
Eric M. Inocencio1*, Alvie Asuncion-Astronomo2, Charlotte Balderas2, Rafael Miguel dela Cruz2, Cheri Anne M. Dingle2, Marianna Lourdes Marie L. Grande2, and Roland Christopher F. Caballar3
1Department of Physical Sciences and Mathematics, College of Arts and Sciences, University of the Philippines, Manila, NCR 1000 Philippines 2Philippine Nuclear Research Institute, Department of Science and Technology, Diliman, Quezon City, NCR 1101 Philippines 3Department of Mathematics and Physics, College of Science, University of Santo Tomas, Manila, NCR 1008 Philippines
*Corresponding author: eminocencio@up.edu.ph 1D. de Asis is a Health Physicist II at the FDA-CDRRHR
Inocencio E et al. 2024. Response Evaluation of Neutron Dose Meters in Modified Neutron Fields. Philipp J Sci 153(S1): 15–26.
ABSTRACT
Commercial neutron dose meters (NDMs) provide estimates of neutron doses that may be inaccurate due to varying energy distribution of neutrons in workplace radiation fields. In this study, two NDMs (RadEye and DINEUTRON) were investigated by comparing their responses to a calibrated NDM (ELSE-Nuclear), which is traceable to a primary standards laboratory, and a validated 3 He-based multishell neutron spectrometer (He-MuNS). The instruments were first calibrated using a Cf-252 reference field at the DOST-PNRI Neutron Laboratory (PNL). The Cf-252 field was then modified by introducing materials (concrete, aluminum, graphite, lead, polyethylene, and water phantom) to simulate workplace radiation fields. Calibration factors that were obtained using ELSE-Nuclear were found to be insufficient, as they presented different doses after the field was modified. Hence, He-BSS was used to derive correction factors (CF) for the three NDMs. Only concrete, aluminum, and graphite were selected for experimentation due to their significant results from computational studies of neutron modification, their undeniable presence in medical LINAC facilities, and their interaction with neutrons (Astronomo et al. 2021; Roslan et al. 2019; Borrelli et al. 2020). Results show that for facilities with neutron fields comparable to the concrete-modified field (58.8% thermal, 1.8% epithermal, and 39.4% fast), CF for RadEye, DINEUTRON, and ELSE-Nuclear are (0.493), (2.058), and (0.920), respectively. For the aluminum-modified field (15.5% thermal, 8.1% epithermal, and 76.4% fast), the CFs are (1.212), (1.894), and (0.872) respectively. Lastly, for the graphite-modified field (26.7% thermal, 16.3% epithermal, and 57% fast), the CFs are (0.785), (2.415), and (0.865), respectively. The results of this study can be applied by NDM users to facilitate more accurate neutron monitoring for radiation protection purposes. Keywords: neutron dose meter calibration, neutron dosimetry, radiation protection