Ventilated Transfer Cask with Integrated Trunnions
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Solution Overview
Problem
Current transfer casks for spent nuclear fuel are too heavy and large for efficient handling and transportation, often exceeding the lifting capacity of cranes and storage pool dimensions, necessitating additional radiation shielding and cumbersome cooling systems.
Innovation Solution
A transfer cask design featuring a cylindrical inner shell with concentric intermediate and outer shells, integrated trunnions for stronger lifting, and ventilation channels to enhance cooling through ambient air, reducing weight and size while maintaining effective radiation shielding and impact protection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If additional radiation shielding is added to transfer casks to contain neutrons and gamma photons, then radiation containment is improved, but weight and size increase making the casks too heavy for crane lifting
Solution Approach 1:
The transfer cask is divided into multiple functional segments: an inner canister for fuel storage, an intermediate shell for gamma radiation shielding, and an outer shell for structural integrity and additional shielding. This segmentation allows each component to be optimized independently for its specific function while maintaining overall weight manageability for crane lifting.
2Reliability
If transfer cask size is increased to provide adequate radiation shielding, then radiation shielding effectiveness is improved, but the cask becomes too large to fit in storage pools
Solution Approach 1:
The transfer cask employs a nested structure where the inner canister containing spent fuel assemblies is placed within the intermediate shell, which is itself contained within the outer shell. This nested arrangement maximizes radiation shielding effectiveness within a compact volume that fits within storage pool dimensions.
3Device complexity
If passive air cooling is implemented instead of active water cooling, then device complexity is reduced, but cooling effectiveness may be insufficient for high heat loads
Solution Approach 1:
The transfer cask incorporates passive air cooling features including ventilation channels and heat dissipation surfaces that enable the system to cool itself without external active cooling equipment. Natural convection currents drawn through the ventilation channels provide sufficient cooling for the heat loads encountered during transfer operations, eliminating the need for complex active water cooling systems.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The design allows for safer, more efficient handling and transportation of spent nuclear fuel by reducing weight and size, improving lifting capabilities, and simplifying cooling through passive or forced air ventilation, while maintaining adequate radiation shielding and impact protection.
Implementation Method 1
The annulus is ventilated with ambient air to cool the canister
Implementation Method 2
the gamma radiation emitted by spent nuclear fuel is blocked by placing mass in its way, the greater the density and thickness of the blocking mass, the more effective the attenuation of the gamma radiation
Implementation Method 3
the neutrons emitted by spent nuclear fuel are blocked by placing a neutron absorbing material in their path. Any material rich in hydrogen serves as an effective neutron shield
Data Source
AI summary
An apparatus for transferring spent nuclear fuel in the form of a cask having a cylindrical inner shell forming a cavity configured to receive a canister containing spent nuclear fuel, an intermediate shell disposed concentrically around and spaced apart from the inner shell and an outer shell disposed concentrically around and spaced apart from the intermediate shell. A bottom flange is affixed to bottoms of each of the shells, and a bottom lid is removably affixed to the bottom flange. A top flange is affixed to tops of each of the shells, and a top lid is seated on the top flange. An annulus for air flow may be formed between the inner shell and the canister; the bottom lid may include an impact zone including impact absorbing structure; and the top flange may have integrally formed trunnions.