Occupational exposure to Am-Be neutron calibration source mounted in OB26 shielding container
Laboratory for Dosimetric and Radon Instruments Calibration which is a part of Central Laboratory for Radiological Protection (CLRP) in Warsaw is equipped with 241Am-Be neutron calibration source with activity of 185 GBq since 1999. The capsule was mounted in the OB26 type shielding container. The control room is separated from the above source by a concrete wall of 0.5 m in thickness. The calibration hall is adjacent to one side of the offi ce room. To comply with the requirements of the radiological protection system, the occupational exposure of persons that are working both in the offi ce and control room needs to be assessed. Two methods were involved for ambient dose equivalent rate determination. The active instrument measurements (AIMs) performed with the Berthold LB6411 neutron probe and the Monte Carlo simulation method (MCS) based on MCNP5 code. These estimations were completed for fi ve reference points. Additionally the γ radiation component was measured by RSS131 ionisation chamber. An increased value of the ambient dose equivalent rate from neutrons was observed in two reference positions. The fi rst observation was done in the control room while the second one in the offi ce room. Expected individual dose equivalents were evaluated based on the results of the AIM and on the expected working time in particular reference points. The annual individual dose equivalent associated with calibration activities using mentioned neutron source was estimated at maximum 0.8 mSv.
- Central Laboratory for Radiological Protection, 7 Konwaliowa Str., 03-194 Warsaw, Poland, Tel.: +48 22 811 0011, Fax: +48 22 811 0016, email@example.com
- Institute of Plasma Physics and Laser Microfusion, EURATOM Association, 23 Hery Str., 01-497 Warsaw, Poland
- 1. International Organization for Standardization. (2001). Reference neutron radiations, part 1: Characteristics and methods of production. Geneva, Switzerland. (ISO 8529-1).
- 2. Jozefowicz, K., Golnik, N., & Zielczynski, M. (2004). Standard fi elds of old neutron sources - parameters and traceability. Radiat. Prot. Dosim., 110(1/4), 107-110.
- 3. Jozefowicz, K., Golnik, N., Tulik, P., & Zielczynski, M. (2007). Radionuclide neutron sources in calibration laboratory - neutron and gamma doses and their changes in time. Radiat. Prot. Dosim., 126(1/4), 134-137.[WoS]
- 4. Schuhmacher, H. (2004). Neutron calibration facilities. Radiat. Prot. Dosim., 110(1/4), 33-42.
- 5. Mazrou, H., Sidahmed, T., & Allab, M. (2010). Monte Carlo investigation of radiation beam quality of the CRNA neutron irradiator for calibration purposes. Appl. Radiat. Isot., 68(10), 1915-1921.[WoS]
- 6. X-5 Monte Carlo Team. (2003). MCNP - A General Monte Carlo N-Particle Transport Code. Version 5. Volume I: Overview and theory. Los Alamos: Los Alamos National Laboratory.
- 7. Mazrou, H., Sidahmed, T., & Allab, M. (2010). Neutron fi eld characterisation of the ob26 crna irradiator in view of its use for calibration purposes. Radiat. Prot. Dosim., 141(2), 114-126.[WoS]
- 8. McConn Jr, R. J., Gesh, C. J., Pagh, R. T., Rucker, R. A., & Williams III, R. G. (2011). Compendium of material composition data for radiation transport modeling - radiation portal monitor project. Washington: Pacifi c Northwest National Laboratory Richland.
- 9. Berthold Technologies. (1996). Neutron probe LB6411 - operating manual. Bad Wildbag, Germany.
- 10. Blizard, E. P., & Miller, J. M. (1958). Radiation attenuation characteristics of structural concrete. Oak Ridge: Oak Ridge National Laboratory. (ORNL-2193).
- 11. Murata, I., Tsuda, I., Nakamura, R., Nakayama, S., Matsumoto, M., & Miyamaru, H. (2014). Neutron and gamma-ray source-term characterization of AmBe sources in Osaka University. Progress in Nuclear Science and Technology, 4, 345-348.