Spent Fuel Transfer Cask Buoyancy Shielding
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Solution Overview
Problem
Current transfer casks for spent nuclear fuel lack adequate radiation shielding throughout all stages of the transfer procedure, particularly when the weight of the payload varies, as increasing thickness and density for better shielding exceeds the crane's lifting capacity, and existing solutions are cumbersome and increase radiation exposure.
Innovation Solution
A transfer cask design featuring a gamma radiation-absorbing body with a surrounding neutron-absorbing fluid jacket and baffles to create a thermosiphon circulation for enhanced cooling and shielding, allowing for adjustable radiation shielding based on payload weight and utilizing buoyancy for efficient handling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the thickness and density of shielding materials are increased to provide better radiation shielding, then radiation shielding is improved, but the weight of the cask exceeds the crane's lifting capacity
Solution Approach 1:
The cask employs a composite shielding structure combining gamma radiation-absorbing materials (lead, steel, or concrete) and neutron-absorbing materials (water or boron-rich substances). This composite approach provides effective radiation shielding while controlling overall weight compared to using a single dense material throughout.
Solution Approach 2:
Different regions of the cask are assigned different shielding properties based on local requirements. The gamma shielding layer and neutron shielding layer are positioned strategically to provide optimal radiation protection where needed, rather than uniformly distributing shielding materials throughout the entire cask structure.
2Weight of moving object
If the weight of the cask is reduced to fit within crane capacity, then ease of handling is improved, but radiation shielding becomes inadequate
Solution Approach 1:
The system allows for adjustable shielding parameters including the thickness of gamma and neutron shielding layers, which can be modified based on the payload weight and radiation requirements. This enables optimization of shielding effectiveness while maintaining compliance with crane lifting capacity limits.
Solution Approach 2:
By using composite materials with different density and shielding characteristics, the design achieves adequate radiation protection with reduced overall weight compared to traditional homogeneous shielding structures, making the cask handleable within crane capacity constraints.
3Object-affected harmful factors
If additional radiation shielding is added during transport and preparation stages, then radiation shielding is improved, but device complexity and handling difficulty increase
Solution Approach 1:
The gamma and neutron shielding functions are merged into an integrated cask structure rather than using separate shielding components. This unified design provides comprehensive radiation protection while simplifying the overall structure and reducing handling complexity during transport and preparation operations.
Solution Approach 2:
The cask structure is designed to serve multiple functions simultaneously: containing the spent nuclear fuel, providing gamma radiation shielding, providing neutron radiation shielding, and facilitating safe handling. This multi-functional design eliminates the need for additional separate shielding components during transport and preparation stages.
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
Provides maximum radiation shielding throughout the transfer process without exceeding crane capacity, minimizing weight and radiation exposure, and facilitating efficient handling and cooling of spent nuclear fuel.
Implementation Method 1
baffles to create a thermosiphon circulation for enhanced cooling and shielding
Implementation Method 2
heat emanating from the radioactive materials warms the neutron absorbing fluid in the inner region so as to cause the neutron absorbing fluid to flow upward in the inner region
Implementation Method 3
shielding of gamma radiation requires large amounts of mass. Gamma rays are best absorbed by materials with a high atomic number and a high density, such as concrete, lead, and steel
Implementation Method 4
shielding of neutron radiation requires a large mass of hydrogen-rich material. One such material is water, which can be further combined with boron for a more efficient absorption of neutron radiation
Implementation Method 5
utilizing buoyancy for efficient handling
Data Source
AI summary
A system, apparatus and method of processing and/or removing radioactive materials from a body of water that utilizes the buoyancy of the water itself to minimize the load experienced by a crane and/or other lifting equipment. In one aspect, the invention is a method comprising: a) submerging a container having a top, a bottom, and a cavity in a body of water having a surface level, the cavity filling with water; b) positioning radioactive material within the cavity of the submerged container; c) raising the submerged container until the top of the containment apparatus is above the surface level of the body of water while a major portion of the container remains below the surface level of the body of water; and d) removing bulk water from the cavity while the top of the container remains above the surface level of the body of water and a portion of the container remains submerged. The bulk water can be added back into the cavity to add neutron shielding after the container is placed in a staging area and prior to personnel performing the desired operations to the container. As a result, gamma radiation and neutron shielding of the container can be maximized for any crane capacity.