scholarly journals Characteristics of Simulated Workplace Neutron Standard Fields

2020 ◽  
Vol 30 (1) ◽  
pp. 71
Author(s):  
Le Ngoc Thiem ◽  
Nguyen Ngoc Quynh ◽  
Dang Thi My Linh ◽  
Phan Thi Huong
Keyword(s):  
Standard Uncertainty ◽  
International Standard Organization ◽  
Dose Equivalent ◽  
Bonner Sphere ◽  
Ambient Dose Equivalent ◽  
Conversion Coefficients ◽  
Standard Organization ◽  
Spectrometer System ◽  
Ambient Dose

This paper presents the development of simulated workplace neutron standard fields at the Institute for Nuclear Science and Technology with the 241Am-Be source moderated by polyethylene spheres with diameters of 15 cm and 30 cm. The characterization of the standard fields (in terms of neutron fluence rates and neutron ambient dose equivalent rates) was performed using Bonner sphere spectrometer system together with MAXED and FRUIT unfolding codes. The related quantities such as neutron dose equivalent-averaged energies and fluence-to-ambient dose equivalent conversion coefficients were also determined. The discrepancies of values are satisfied the standard uncertainty criteria as recommended by the International Standard Organization 12789 series. It implies that the simulated workplace neutron standard fields can be applied in the practical works for calibration purposes.

NEUTRON SPECTRUM UNFOLDING USING VARIOUS COMPUTER CODES: A COMPARISON

2021 ◽  
pp. 128-133
Author(s):  
Thiệm
Keyword(s):  
Neutron Spectrum ◽  
Neutron Fluence ◽  
Dose Equivalent ◽  
Spectrum Unfolding ◽  
Bonner Sphere ◽  
Ambient Dose Equivalent ◽  
Computer Codes ◽  
Neutron Spectrum Unfolding ◽  
Spectrometer System ◽  
Ambient Dose

Dosimetric quantities at various distances from a 30 cm diameter polyethylene sphere moderated 241Am-Be source were investigated using the Bonner sphere spectrometer system. The different international commercial unfolding codes were applied to unfold the neutron spectrum, and their shapes were compared to each other. Additionally, the integrated neutron fluence rates overall spectrum and fractional neutron fluence rates were deduced and compared between the results obtained from different unfolding codes. As an important quantity applying in radiation safety assessment, the neutron ambient dose equivalent rates were also calculated and compared to each other to verify the utility feasibilities of the codes.

DEVELOPMENT OF A NEW SECONDARY STANDARD FOR H*(10)

2020 ◽  
Vol 188 (3) ◽  
pp. 378-382
Author(s):  
K Bairlein ◽  
B Behnke ◽  
O Hupe
Keyword(s):  
Ionization Chamber ◽  
Secondary Standard ◽  
Dose Equivalent ◽  
Air Kerma ◽  
Radiation Fields ◽  
Ambient Dose Equivalent ◽  
Conversion Coefficients ◽  
Aluminium Coating ◽  
Pulsed Fields ◽  
Ambient Dose

Abstract A secondary standard for ambient dose equivalent, H*(10), is necessary for the dissemination of the unit Sievert (Sv), but there is no such standard commercially available currently. Furthermore, the measurement of H*(10) instead of calculating H*(10) from air kerma and conversion coefficients is needed for unknown radiation fields. We developed a prototype of a new secondary standard for H*(10) based on a spherical 1 l ionization chamber for air kerma. This chamber was modified with copper wires at the inner surface to adjust the response of the chamber according to H*(10). Additionally, a Makrolon shell and an aluminium coating were added to optimize the response at energies below 50 keV. The prototype fulfils the requirements given in ISO 4037-2 in the energy range from 12 keV to 7 MeV. In combination with an electrometer, it can be used as area dosemeter, suitable for pulsed fields and for low energy radiation.

scholarly journals Neutron spectrometry at low fluence rates for radiation protection at the AMANDE facility

2020 ◽  
Vol 225 ◽  
pp. 05005
Author(s):  
V. Lacoste ◽  
M. Petit ◽  
V. Gressier
Keyword(s):  
Radiation Protection ◽  
Control Room ◽  
Dose Equivalent ◽  
Neutron Spectrometry ◽  
Concrete Wall ◽  
Experimental Hall ◽  
Bonner Sphere ◽  
Ambient Dose Equivalent ◽  
Ambient Dose ◽  
Made In

A neutron spectrometry campaign was carried out in the AMANDE accelerator control room. These measurements had several objectives, one of which was to verify the possibility of determining, with the HERMEIS Bonner sphere system, very low fluence and ambient dose equivalent rates. These measurements were also expected to provide comparison values with calculations, performed with MCNPX 2.6.0, used for modeling the whole facility and to verify the radiological zoning implemented. Neutrons of 3.3 MeV then 15 MeV were produced in the experimental hall of AMANDE and measurements were made in the control room, behind a 40 cm thick concrete wall. The ambient dose equivalent rates derived from the measured spectra are respectively of the order of 0.2 and 10 μSv/h, which are in agreement with a LB6411 surveymeter data also involved.

scholarly journals Characterization of an ²⁴¹Am-Be neutron irradiation facility at Institute for Nuclear Science and Technology

2021 ◽  
Vol 7 (2) ◽  
pp. 16-24
Author(s):  
Ngoc Toan Tran ◽  
Vu Long Chu ◽  
Duc Ky Bui ◽  
Duc Kien Nguyen ◽  
Duc Tam Nguyen
Keyword(s):  
Science And Technology ◽  
Neutron Field ◽  
Dose Equivalent ◽  
Neutron Fluence Rate ◽  
Nuclear Science ◽  
Equivalent Rate ◽  
Ambient Dose Equivalent ◽  
Spectral Unfolding ◽  
Ambient Dose

An automated panoramic irradiator with a 241Am-Be neutron source of 5 Ci is installed in a bunker-type medium room at the Institute for Nuclear Science and Technology (INST) for calibration of neutron devices. Bonner Sphere Spectrometer (BSS) formed by 6 spheres plus bare detector, with cylindrical, almost point like, 6LiI(Eu) scintillator and 2 different spectral unfolding FRUIT and BUNKIUT codes are used to characterize the neutron field in different measurement points along the irradiation bench. The neutron field is also simulated by MCNP5 software and compared with measurements performed by the BSS. The paper shows the main results obtained in terms of neutron spectra at fixed distances from the source as well as their neutron fluence rate (totaland direct) and ambient dose equivalent rate. These values measured by the BSS with two unfolding FRUIT and BUNKIUT codes are in good agreement with that of simulated by MCNP5 within 10%.

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