Combining effective chemical decontamination and comprehensive radioactive assay to decommission gloveboxes from ILW (PCM) or TRU waste to LLW waste.
Two legacy gloveboxes that were used for alpha contaminated material (plutonium) work were scheduled for decommissioning at the Argonne National Laboratory (ANL) near Chicago. They were initially classified as transuranic (TRU) waste. [This is equivalent to Intermediate Level Waste (ILW) with plutonium contaminated materials (PCM) in the UK.] A pilot project was established with the aim of decommissioning the two gloveboxes in the hope that the TRU activity could be reduced so that they could be reclassified as Low Level Waste (LLW).
The cost of TRU or ILW (PCM) disposal is substantial. It requires that gloveboxes be dismantled and placed in 55-gallon (200 litre) drums. In the US it must be characterised as TRU and shipped to the Waste Isolation Pilot Plant (WIPP). In the UK it must be characterised as ILW (PCM) and placed in interim storage. LLW waste disposal costs are much lower.
The LLW sentencing levels for alpha contaminated waste in the US and the UK are very similar. In the US the TRU-LLW threshold is 100 nCi/g (3,700 Bq/g). In the UK the ILW (PCM)-LLW threshold is 4,000 Bq/g (108 nCi/g).
Glovebox Decontamination and Decommissioning
ANTECH, Environmental Alternatives (EAI) and InstaCote worked together as a team with ANL staff to deactivate, deinventory and survey the gloveboxes prior to decontamination activities.
EAI led the decontamination process utilising “Rad Release” solution. It was sprayed onto the internal surfaces of the gloveboxes, scrubbed lightly with scotch-brite and allowed to stand for typically 30-minutes. After three successive applications over the course of 5 days the resulting decontamination alpha activity reduction factor was approximately 104, or a factor of 10,000.
After the decontamination process ANTECH assayed the gloveboxes and provided measurement documentation to establish that the activity concentration was significantly lower than 100 nCi/g. This provided the necessary justification for the reclassification of the gloveboxes as LLW. The assay also provided the data to satisfy the US Department of Transport regulations.
Once the gloveboxes were reclassified as LLW, InstaCote sealed the internal surfaces of the gloveboxes to fix any remaining alpha contamination. They then filled the gloveboxes with a BASF structural foam that would take up the volume and make each glovebox an acceptable waste package to be transported whole as LLW for final disposition.
The two gloveboxes were duly reclassified as LLW and are being transported to the Nevada Nuclear Security Site (NNSS) [formerly the Nevada Test Site (NTS)] for final disposal. A significant reduction in the volume of the TRU waste and a significant cost saving have been achieved a result of the reclassification.
Following this success ANTECH, AEI and InstaCote formed a partnership to apply this process to the decommissioning of legacy alpha contaminated gloveboxes at other sites and laboratories.
Pa13a D. Pancake, C. M. Rock, R. Creed, T. Donohoue, E. R. Martin, J. A. Mason, C. J. Norton, D. Crosby and T. J. Nachtman, “A Novel and Cost Effective Approach to the Decommissioning and Decontamination of Legacy Glove Boxes: Minimizing TRU Waste and Maximizing LLW Waste – 13634”, WM2013 Conference, February 24 – 28, 2013, Phoenix, Arizona, USA. (WM13-13634)