Nuclear Fuel Storage Capsule with Forced Gas Dehydration
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Solution Overview
Problem
The storage and transport of damaged nuclear fuel rods pose challenges due to high dose rates and water penetration through cladding defects, making traditional drying and encapsulation methods inefficient and difficult.
Innovation Solution
A nuclear fuel storage system comprising a capsule with vertically oriented fuel rod storage tubes and a lid that uses inert forced gas dehydration techniques to dry and store damaged fuel rods, ensuring a gas-tight seal and efficient moisture removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If traditional vacuum drying is used to dry damaged fuel after removal from reactor pool, then drying process is simple, but water can penetrate through cladding defects and become trapped inside the cladding materials making drying exceedingly challenging
Solution Approach 1:
The capsule is divided into separate functional zones: an upper drying chamber for forced gas dehydration and a lower containment chamber for water collection. This segmentation allows the drying process to occur in a controlled environment separate from the water collection system, preventing water re-entry during drying while maintaining simple overall operation.
Solution Approach 2:
A gas-tight seal and forced gas dehydration system act as intermediaries between the external environment and the trapped water within cladding defects. The inert gas flow penetrates through the cladding defects via the same pathways water would use, displacing water vapor without requiring direct contact with liquid water, thus achieving reliable drying while maintaining process simplicity.
2Ease of operation
If damaged fuel assemblies are stored without encapsulation in secondary capsule, then storage and transport is straightforward, but storage and transport regulations do not allow storage or transport of damaged fuel assemblies without encapsulation
Solution Approach 1:
The capsule serves multiple functions simultaneously: it provides regulatory-compliant encapsulation for damaged fuel assemblies, enables forced gas dehydration for drying, contains water collection during storage, and facilitates secure transport. This multi-functionality eliminates the need for separate encapsulation and drying systems, maintaining operational simplicity while ensuring regulatory compliance.
Solution Approach 2:
The capsule is pre-configured with gas-tight seals, forced gas dehydration systems, and water collection mechanisms before damaged fuel assemblies are loaded. This preliminary preparation ensures that regulatory requirements for encapsulation are met from the outset, while the built-in drying and containment systems maintain operational simplicity throughout storage and transport.
3Reliability
If individual damaged fuel rods are removed from fuel assembly and stored separately in secondary capsules, then storage compliance is improved, but the process becomes more complex and time-consuming
Solution Approach 1:
Multiple damaged fuel rods are combined and stored together within a single capsule in their original fuel assembly configuration, rather than being separated into individual capsules. This merging approach maintains storage compliance for damaged fuel while significantly reducing processing complexity and time requirements for removal, storage, and subsequent drying operations.
Solution Approach 2:
The capsule is pre-prepared with gas-tight seals and forced gas dehydration systems before fuel rods are loaded, allowing multiple rods to be stored and dried simultaneously in a single unit. This preliminary configuration enables compliant storage of multiple damaged fuel rods without requiring separate processing for each rod, thereby reducing overall complexity while maintaining regulatory compliance.
4Object-affected harmful factors
If encapsulation is done underwater to protect from high dose rates, then radiation protection is improved, but subsequent drying becomes exceedingly challenging due to water penetration through cladding defects
Solution Approach 1:
The capsule separates the encapsulation function (providing radiation protection) from the drying function (removing water). The upper drying chamber provides forced gas dehydration while the lower chamber collects water, allowing the capsule to provide radiation protection during storage while enabling effective drying without the water penetration problems of traditional underwater encapsulation methods.
Solution Approach 2:
Forced gas dehydration using inert gas acts as an intermediary drying mechanism that can effectively remove water from cladding defects without requiring the capsule to be opened or exposed to atmospheric conditions. The gas flow penetrates through cladding defects, displacing water vapor, thereby enabling easy drying while maintaining the radiation protection benefits of encapsulation.
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 system effectively dries and stores multiple damaged fuel rods simultaneously, improving safety and efficiency by preventing water penetration and allowing for secure transport and storage.
Implementation Method 1
drying the internal cavity of the capsule and fuel rods stored therein using known inert forced gas dehydration (FGD) techniques or other methods
Data Source
AI summary
A fuel storage system for storing and drying nuclear fuel rods includes a vertically oriented capsule defining an internal cavity. A plurality of fuel rod storage tubes is disposed in the cavity. In one embodiment, each storage tube has a transverse cross section configured and dimensioned to hold no more than one fuel rod. Intact or damaged fuel rods may be stored in the storage tubes. After the fuel rods are loaded into the capsule, a lid is attached to a previously open top end of the capsule. In one embodiment, the lid may be sealed welded to the capsule for forming a gas tight enclosure. The interior of the capsule and multiple fuel rods contained therein may be dried together simultaneously via flow conduits formed in the lid that can be fluidly connected to a suitable drying process such as a forced gas dehydration system.