Nuclear Fuel Assembly Descender with Integrated Leak Testing
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Solution Overview
Problem
Current methods for sealing control of nuclear fuel assemblies in nuclear reactors are costly and inefficient, particularly in older nuclear power plants, as they require expensive maintenance and updates of fixed or mobile lift cells, and do not effectively detect waterproofing defects in irradiated fuel pencils without individual control during reactor shutdowns.
Innovation Solution
A device that includes a nacelle mounted on a guide system for descending and ascending nuclear fuel assemblies, equipped with a heating unit and sampling system to perform sealing control tests by heating the assembly or reducing hydrostatic pressure, allowing for detection of fission products without the need for traditional lift cells, thereby reducing costs and maintaining reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional fixed or mobile lift cells are used for sealing control tests, then leaktightness detection capability is maintained, but maintenance and operational costs increase significantly
Solution Approach 1:
The descender device is designed to perform multiple functions: it serves as both a lowering device for fuel assemblies and a sealing control test device. The nacelle includes a heating unit and sampling system that enable leaktightness detection without requiring separate dedicated test equipment, thereby eliminating the need for expensive fixed or mobile lift cells while maintaining detection capability
Solution Approach 2:
The patent combines the sealing control test functions (heating unit, sampling system) directly into the descender nacelle structure. This merging of functions allows the same device to both lower fuel assemblies and perform leaktightness tests, reducing the need for separate expensive test cells and their associated maintenance costs
2Reliability
If fixed penetrant cells are used in storage pools, then leaktightness testing is reliable, but installation and removal costs are expensive
Solution Approach 1:
The descender provides a dynamic, movable testing solution that can be positioned and operated within the storage pool as needed, replacing the static fixed penetrant cells. The device can be moved to different locations and raised or lowered, eliminating the need for installation and removal while maintaining testing reliability through its integrated heating and sampling capabilities
3Reliability
If mobile penetrant cells are used for leak testing, then earthquake incident resistance is improved, but installation and removal expenses increase
Solution Approach 1:
The descender serves dual purposes as both a fuel assembly handling device and a leak testing device, eliminating the need for separate mobile penetrant cells. This multi-functionality reduces installation and removal expenses while maintaining the ability to perform reliable leak testing in earthquake-prone environments
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
Enables quick and cost-effective sealing tests by heating the nuclear fuel assembly or reducing hydrostatic pressure to detect fission products, eliminating the need for traditional lift cells and maintaining test reliability, thus reducing maintenance and operational costs.
Implementation Method 1
The device 7 advantageously comprises a heating unit 9, in particular fixed to the lower end 36 of the nacelle 22, for heating the water 40 present in the housing 24
Implementation Method 2
The device 7 also comprises a sampling system 62 for taking at least one water sample 68 from the housing 24
Implementation Method 3
a nacelle (22) defining a housing (24) for receiving the nuclear fuel assembly (12) and water (40), the nacelle (22) being mounted movably on the guidance system (20) in translation in the direction (V)
Data Source
Figure 1
Figure 2
AI summary
A device (7) for raising or lowering a nuclear fuel assembly (12) in a pool (14) of a nuclear installation, comprising: - a guiding system (20) intended to be fastened to the pool, and - a basket (22) defining a housing (24) for receiving the nuclear fuel assembly and water (40) around the nuclear fuel assembly, the basket being mounted on the guiding system so as to be able to move translationally in a direction (V) that is intended to be substantially vertical, the basket comprising an upper end (32) defining a passage (33) intended to allow the nuclear fuel assembly to be loaded into the housing from above, and a lateral jacket (34) that is intended to encircle the nuclear fuel assembly about the direction (V) and that is seal-tight to water, and - at least one sampling system (62) suitable for delivering at least one water sample (68) sampled from the housing.