Analysis of Ice Formation During Spent Fuel Cask Vacuum Drying Operations

Spent Fuel Assemblies are loaded in so-called spent fuel cask for temporary storage or shuttles for transport to disposal or reprocessing facilities. These spent fuel packages are loaded in the spent fuel pools under water to protect from the radiation and to assure adequate cooling. However, the currently used technology relies on so-called dry-packages where the inner atmosphere is dry during storage and transport. As such the water must be drained, whilst assuring only a limited amount of water remaining in the spent fuel package cavity and the seals to prevent hydrogen accumulation and a degradation of the inner surfaces. 

To assure this, the cask cavity, the inter-seal spaces and the fuel assemblies are vacuum dried. However, during vacuum drying ice formation cannot be excluded, potentially impacting the drying operations and drying time, which impact the fuel cladding temperature. The drying system contains a vacuum pump, valves, bends, ducts, and tubes. 

To better understand the physics of vacuum drying a thermodynamic model must be established of the drying system, potentially identifying locations susceptible for ice formation and defining potential improvements to the system.

The minimum diploma level of the candidate needs to be

• Master of sciences in engineering

The candidate needs to have a background in

• Physics
• An engineering student with a good background in thermodynamics, for which a knowledge of Dutch (preferred) or French is mandatory in view of an intervention during cask loading.

Estimated duration

Integrated in the BNEN programme.