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CNL Awards of Excellence/Distinguished Merit Award: Tile hole drying system

Distinguished Merit Award: Tile hole drying system

Anders Barvestal, Giles Danis, Jon Sanders, Jonathan Bartley, Jonathan Fitzpatrick, Josh McLellan, Kapil Vaidya, Ken Landreau, Kris Penner, Roman Lungu, and Tibor Molnar

For the design and operation of the tile hole drying system.

Used nuclear fuel has been stored within storage containers placed in below grade tile holes at the CRL Waste Management Areas (WMA) since the 1960s. As part of the Fuel Packaging and Storage (FPS) project pre-retrieval field activities, one tile hole was confirmed to contain a storage container that was stuck within its storage position, and had become degraded.

A Best Available Technique approach was employed to determine the method of addressing the degraded fuel and the selected method was in situ stabilisation and liquid removal. A multi-disciplinary team from the Fluids Engineering branch was assembled to develop an appropriate drying capability, taking into consideration a number of constraints, including limited access to the tile hole due to space constraints, high levels of radiological contamination, significant uranium fuel degradation and the potential for hydrogen generation.

Through extensive collaboration between design teams and operations, the Tile Hole Drying System (THDS) concept was developed. The drying system consists of a closed loop argon recirculation system employing a positive displacement blower for process flow, a dehumidifier to condense and remove moisture, HEPA filters to remove any contaminants that become entrained with the carrier gas, compressed argon supply, and an oxygen tile hole through a custom interface and the system is leak checked to ensure minimal argon leakage. Electrical resistance heaters heat the argon gas prior to entering the in-ground storage structure.

Maintaining this degraded tile hole in a dry state significantly reduces AECL’s legacy liability by reducing any potential environmental impacts until such a time that capabilities are available to remove entire tile hole contents. WMA Operations conducted an additional follow up fiber optic camera inspection in 2023 July and confirmed tile hole conditions have not changed and the tile hole remains dry. The THDS remains available for future deployment should any water in the tile hole be observed in the future.