Characterization of the National Research Experimental Reactor Stack (NRX) For AECL
NMNTI obtained samples from the concrete stack sections and analyzed these samples in close proximity to sampling operations. The purpose was to provide the necessary gamma radiochemical fingerprinting to properly identify and quantify the waste radiochemical activities of stack section concretes in cross sectional profile and estimate waste masses. The field work occurred at the Chalk River Laboratories (CRL) Waste Management Area C (WMA C) located at the Atomic Energy of Canada Limited’s (AECL) Chalk River Laboratories, Chalk River, Ontario, Canada.
NMNTI provided materials and labor, obtaining 320 separate discrete incremental samples (consisting of 16 samples per stack section) including powdered concrete at depth from the NRX stack structures. Included in this sampling and characterization activity were associated site evaluations, day to day sampling and documented reporting. Sampling was in the horizontal direction (i.e., through the stack section walls and voids) to obtain samples from inaccessible depths within the stack pieces. All of the retrieved powdered samples were measured quantitatively for gamma radionuclide activities (Bq/g) of interest, specifically fission products and activation products Cs-137, Co-60, Eu-152, Eu-154, Eu-155, and Am-241.
TruPro® sampling & characterization successfully achieved the following:
- Operated without the use of water, to retrieve dry representative powdered samples,
- Was powered by a mobile field generator coupled to 50 meters electrical extension cables,
- Removed incremental depths of potentially highly contaminated concrete from predetermined sampling points sequentially to depth,
- Collected all concrete particulate from sampling operations into specialized filter units with no risk or spread of contamination, and
- Produced representative samples of 380 mm or less (determined from drawings of wall thicknesses for each stack section), 1 mm, 6 mm, 6 mm, 6 mm, 12 mm, 25 mm, 50 mm, and 275 mm incremental sampling depths where necessary in a powdered form ready for immediate analysis and for optimal counting by gamma spectrometry.
The results were used by site operations to make informed decisions regarding the concrete removal & storage approach and on contamination control practices.