Radiation Physics and Engineering
A peer-reviewed journal published by K. N. Toosi University of Technology

Determination of the neutron and gamma dose distribution due to the operation of vertical neutron beam lines

Articles in Press

Document Type : Research Article

Authors

Mohammad Hossein Choopan Dastjerdi 1
Javad Mokhtari 1
Maryam Hassanvand 2
Elham Maleki 2

1 Reactor and Nuclear Safety Research School, Nuclear Science and Technology Research Institute, AEOI, Iran

2 Department of Physics, Isfahan University of Technology, Isfahan, Iran

https://doi.org/10.22034/rpe.2026.580550.1352
Abstract
In this study, the effect of external neutron beam tubes of MNSR research reactor on increasing the neutron and gamma dose rates in different zones of the reactor building was investigated and the dose distribution was determined through calculation and measurements. This study was conducted to investigate the radiation protection conditions at different operation conditions of these beam tubes and to ensure the radiation safety of the reactor operators and researchers. The results showed that when both beam tubes are operated simultaneously, the average total dose rate in the reactor hall, pneumatic room and corridors increases to 4.58 μSv.h-1, 1.7 μSv.h-1 and 4.9 μSv.h-1, respectively at the maximum power of reactor, i.e. 30 kW. The major part of the dose rate of neutrons and gamma rays distributed in the environment is caused by the neutron radiography channel, and more than 80% of the dose rate is related to gamma rays. On the other hand, the performance of the neutron radiography beam tube radiation protection system showed that even when the reactor is at its maximum power and these beam tubes are inactive, the total dose at the edges of the reactor pool is about 2% of the annual dose limit. This indicates that the radiation protection of the beam tube has a good performance in preventing the increase in the dose rate when the beam tube is deactivated.

Highlights

  • Dose rates at different zones of reactor have been determined for different modes of neutron beamlines.
  • The performance of the neutron radiography beam tube radiation protection system has been investigated.
  • The average difference between the simulation results and experimental results was below 5%.
  • More than 80% of cumulative dose rate was due to the gamma rays.

Keywords

MNSR
Neutron beamline
Dose rate
Beam tube
Shielding
Subjects

Copyright
RPE is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License (CC BY-NC 4.0).

Conflict of Interest
The authors declare no potential conflict of interest regarding the publication of this work‎.

Funding
‎The authors declare that no funds‎, ‎grants‎, ‎or other financial support were received during the preparation of this manuscript‎.

Radiation Physics and Engineering

Articles in Press, Accepted Manuscript
Available Online from 24 June 2026

  • Receive Date 05 May 2026
  • Revise Date 15 June 2026
  • Accept Date 22 June 2026

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