Describe the dry cask storage mechanism for spent fuel and its shielding principle.

Describe the dry cask storage mechanism for spent fuel and its shielding principle.

• A. Liquid immersion cooling
• B. Shielded steel-concrete containers with natural convection cooling
• C. Air cooling with fins
• D. On-site open racks

Answer: (B)

Dry cask storage relies on a robust, passive setup that both shields radiation and removes heat without active systems. Spent fuel is placed in a sealed steel canister, which is then surrounded by a heavy shield overpack made of concrete or steel-concrete. The dense materials attenuate gamma rays and slow neutrons, greatly reducing radiation levels at the outside. Heat from the decaying fuel is carried away by natural convection: air moves around the shield, picking up heat and exiting without pumps or moving parts. This combination—strong shielding plus passive air-based cooling—defines the dry cask approach. Other methods either involve liquids for cooling or lack the heavy shielding, such as open racks used in some wet storage scenarios.

Dry cask storage relies on a robust, passive setup that both shields radiation and removes heat without active systems. Spent fuel is placed in a sealed steel canister, which is then surrounded by a heavy shield overpack made of concrete or steel-concrete. The dense materials attenuate gamma rays and slow neutrons, greatly reducing radiation levels at the outside. Heat from the decaying fuel is carried away by natural convection: air moves around the shield, picking up heat and exiting without pumps or moving parts. This combination—strong shielding plus passive air-based cooling—defines the dry cask approach. Other methods either involve liquids for cooling or lack the heavy shielding, such as open racks used in some wet storage scenarios.