Radiation Protection Design of the TEC-Laboratory
Marcin Latocha, Michael Wind, Peter Beck
Seibersdorf Laboratories, Seibersdorf, Austria
Abstract
Radiation protection design of the TEC-Laboratory has been performed according to applicable legal requirements [1, 2, 3] that lay down the annual effective dose limits for both occupationally exposed workers (20 mSv/year) and public (1 mSv/year). The TEC-Laboratory is equipped with a 74 TBq (2kCi) Cobalt-60 source which is located in a large exposure room. The size of the exposure room allows realization of all dose rate ranges specified in the European Space Agency’s standards [4]. For radiation protection purposes, the irradiation room is accessible through a radiation protection door (3 mm lead) and a labyrinth.
The controlled area is defined behind the radiation protection door that is in the labyrinth and irradiation room. The laboratory is designed in such a way that outside the controlled area (either outside or inside of the laboratory) ambient dose equivalent, H*(10), does not exceed the limit of 0.5 μSv/h (40 hours workweek). This specification has been achieved by constructing the concrete shielding walls with an appropriate thicknesses. The efficiency of the shielding was simulated with FLUKA [5, 6] Monte Carlo code. These simulations were part of the design phase of the TEC-Laboratory.
Three scenarios has been investigated: (1) no scattering bodies – to test the thickness of the front wall, (2) several printed circuits boards as scattering bodies – for a typical operational case, and (3) seven steel plates (2 cm thick each) – for the worst case backscattering scenario. All scenarios showed that outside the laboratory the H*(10) does not exceed the limit of 0.5 μSv/h. Scenario (3) showed also that the radiation protection door with 3 mm lead efficiently shields the backscattered radiation so that H*(10) is below 0.1 μSv/h outside the door. Measurements in various positions inside and outside of the laboratory were conducted. Measurements confirmed the simulated results, showing that H*(10) outside the controlled area is below 0.1 μSv/h [7].
References
[1] BGBl. Nr.227/1969, BGBl. I Nr. 146/2002, BGBl. I Nr. 137/2004, BGBl. II Nr. 191/2006.
[2] ÖNORM S 5265-2:2006-06-01, 2006.
[3] EU Directive 96/29/EURATOM, 1996
[4] ESA, ESCC Basic Specification No. 22900, Issue 4, 2010.
[5] G. Battistoni et al., “The FLUKA code: Description and benchmarking“, AIP Conference Proceeding 896,
31-49, 2007.
[6] A. Ferrari et al., „FLUKA: a multi-particle transport code”, CERN-2005-10, INFN/TC_05/11, SLAC-R-773, 2005.
[7] Accredited Testing Laboratory Nr.312, Laboratory Report Nr. LG-P998-1/15, 2015.