Fuel Assembly Descender With Vacuum-Assisted Leak Detection

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Existing leak testing methods for nuclear fuel assemblies in nuclear reactors are costly due to the use of old, expensive fixed or mobile penetrant cells, and there is a need to reduce these costs while maintaining test reliability.

Innovation Solution

A device comprising a descender with a guidance system, nacelle, cover, sampling, depressurization, and analysis systems that allows for leak testing by vacuuming and analyzing fission products without the need for conventional penetrant cells, using a sampling system to take water and gas samples for radioactivity detection.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional fixed or mobile penetrant cells are used for leak testing, then reliable detection of fission products is achieved, but the cost of testing increases significantly

Engineering Contradiction:

Improvedetection reliabilityVSAvoidtesting cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent extracts the essential leak detection function from expensive dedicated penetrant cells and implements it within the existing descender structure. The sampling system, depressurization system, and analysis system are integrated into the descender, allowing leak testing to be performed using the same equipment that already handles fuel assemblies, thereby eliminating the need for separate costly penetrant cells while maintaining detection reliability

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The descender is transformed into a multi-functional device that performs both fuel assembly handling and leak testing functions. By equipping the descender with sampling ports, depressurization capability, and radioactivity analysis systems, it can execute leak tests during normal fuel assembly operations without requiring dedicated testing equipment, thus reducing overall testing costs while preserving detection effectiveness

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Adaptability or versatility

If mobile penetrant cells are used instead of fixed ones, then installation flexibility is improved, but installation and removal costs increase

Engineering Contradiction:

Improveinstallation flexibilityVSAvoidinstallation cost

Core Design Contradiction:

Adaptability or versatilityVSEase of manufacture

Solution Approach 1:

The descender utilizes its own inherent mobility and positioning capabilities to perform leak testing operations at various locations within the pool. The sampling system is integrated into the descender structure itself, allowing it to autonomously conduct tests by simply positioning the fuel assembly within the descender's sampling zone, eliminating the need for separate mobile penetrant cell installations and removals

Inventive Principle:

Principle #25Self-service

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 efficient and cost-effective leak testing of nuclear fuel assemblies by eliminating the need for fixed or mobile penetrant cells, ensuring reliable detection of fission products and maintaining the integrity of the testing process.

Implementation Method 1

by causing a relative increase in the internal pressure of the nuclear fuel rods of a nuclear fuel assembly compared to the external pressure, or an increase in the volume of fluids inside the nuclear fuel rods

Methodology Applied

Scientific EffectPressure difference: Pressure Gradient

Implementation Method 2

The device comprises a sampling system for taking at least one water sample from the housing, for the purpose of detecting fission products from the rods

Methodology Applied

Scientific EffectRadioactivity detection: Radioactive Decay

Data Source

PatentEP4449448B1Device for raising or lowering a nuclear fuel assembly out of and into a pool of a nuclear facility

Publication Date: 2025.10.22 FRAMATOME SA

Figure 1
Figure 2

AI summary

The invention relates to a device (10) for raising or lowering a nuclear fuel assembly (12) out of and into a pool (14) of a nuclear facility, comprising: - a guide system (20); and - a vertically movable gondola (22) that defines a housing (24) for accommodating the nuclear fuel assembly and water; - a movable cover (28) for closing the gondola (22) in a watertight manner, the housing (24) containing a gas layer (44), or for allowing loading of the nuclear fuel assembly; - at least one sampling system (30) for providing at least one water sample (32) taken from the housing; and - a depressurization system (34) for extracting some of the gas layer and lowering the pressure in the housing (24) when the cover is closed.