Nuclear Fuel Docking Device with Hydraulic Bellows Sealing

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Solution Overview

Problem

Existing docking devices for irradiated fuel containers in nuclear facilities face challenges such as the need for precise and complex adjustments, high construction costs, and reduced safety due to the weight and size of the containers, as well as inadequate sealing during earthquakes.

Innovation Solution

A docking device with a metal bellows and cylinders that transmit translational movement to a docking flange with controlled locks, allowing for secure sealing without lifting the container, and featuring a hydraulic control system to maintain constant pressure on the seal carrier flange, ensuring sealing even during axial offsets and earthquakes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a motor system with screwdrivers and spring boxes is used to lower the metal bellows, then the seal continuity between pit and container is ensured, but the device becomes extremely complex and expensive with difficult troubleshooting

Engineering Contradiction:
Improveseal continuityVSAvoiddevice complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent extracts and eliminates the complex screwdriver and spring box mechanism from the system. Instead of using this complicated motor-driven system to lower the metal bellows, the invention directly uses hydraulic cylinders to achieve the same sealing function with much simpler components, thereby reducing device complexity while maintaining seal continuity.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent introduces hydraulic cylinders as the actuating mechanism to lower the metal bellows and ensure seal continuity. This hydraulic system replaces the mechanical screwdriver and spring box system, providing a more reliable and easier-to-maintain solution that achieves the same sealing function with reduced complexity.

Inventive Principle:
Principle #29Pneumatics and hydraulics

2Manufacturing precision

If precise adjustment of the container on the trolley is performed, then the seal alignment is improved, but the adjustment operations become very long and reduce productivity

Engineering Contradiction:
Improveseal alignmentVSAvoidadjustment time
Core Design Contradiction:
Manufacturing precisionVSProductivity

Solution Approach 1:

The patent creates a system where the metal bellows and sealing flanges are designed to automatically align and equalize any minor positioning differences between the container and penetration. The flexible nature of the bellows and the locking mechanism work together to compensate for misalignment, eliminating the need for lengthy precise adjustment operations while maintaining good seal alignment.

Inventive Principle:
Principle #12Equipotentiality

3Area of stationary object

If the diameter of the penetration is increased, then the docking capacity is improved, but more return springs are required which increases the diameter further and creates substantial efforts in screwdrivers and docking nuts

Engineering Contradiction:
Improvepenetration diameterVSAvoidforce on screwdrivers and docking nuts
Core Design Contradiction:
Area of stationary objectVSForce

Solution Approach 1:

The patent uses hydraulic cylinders to provide the force needed to lower the metal bellows and apply the sealing flange to the container. This hydraulic actuation system replaces the mechanical advantage system using screwdrivers and return springs, allowing for larger penetration diameters without creating excessive forces on mechanical components, as the hydraulic system can directly generate the required force.

Inventive Principle:
Principle #29Pneumatics and hydraulics

4Reliability

If the container is lifted to ensure seal tightness, then the sealing is improved, but the lifting of heavy containers exceeds 100 tons and reduces operating safety

Engineering Contradiction:
Improveseal tightnessVSAvoidoperating safety
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

Instead of lifting the heavy container to ensure seal tightness, the patent inverts the approach by lowering the sealing system (metal bellows with sealing flange) to meet the container at its original position. The locking mechanism then secures the seal in place, achieving reliable sealing without the safety risks associated with lifting extremely heavy containers.

Inventive Principle:
Principle #13The other way round (Inversion)

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 solution simplifies the docking process, reduces construction costs, and maintains a secure seal during earthquakes by eliminating the need for precise container alignment and using fewer components, while maintaining constant pressure on the seal carrier flange.

Implementation Method 1

a metal bellows housed in the penetration, making it possible to ensure the continuity of the seal between the pit and the container

Methodology Applied
Scientific EffectElasticity: Elasticity

Implementation Method 2

at least two cylinders positioned in the penetration and capable of lowering the lower end of the metal bellows

Methodology Applied
Scientific EffectHydraulic pressure: Hydraulic Press

Implementation Method 3

the docking flange comprises at least two controlled locks capable of locking the docking flange to the container in the lower position to hold the seal carrier flange in sealing support

Methodology Applied
Scientific EffectMechanical force: Mechanical Force

Data Source

PatentEP3084772B1Device for mating with an irradiated fuel container under a nuclear facility pit and containing irradiated fuel
Publication Date: 2018.08.29 CONSTRUCTIONS IND DE LA M DITERRAN E - CNIM
  • EP3084772B1 patent drawingFigure 1
  • EP3084772B1 patent drawingFigure 2
  • EP3084772B1 patent drawingFigure 3

AI summary

The present invention relates to a device for mating with an irradiated fuel container under a pit of a nuclear facility and containing irradiated fuel. According to the invention, the mating device is characterized in that it comprises a mating flange (15) secured to the lower end of the metallic bellows (6) and actuators (10) are interposed between the structure (7) of the penetration (3) and the mating flange (15) in order to transmit the translational movement of the actuators (10) to the bottom end of the metallic bellows (6) and to the gasket-bearing flange (11), and the mating flange (15) comprises at least two controlled latches (24) able to lock the mating flange (15) to the container (2) when the bottom end of the bellows(6) is in the lowered position so as to keep the gasket-bearing flange (11) pressed hermetically against the top surface of the container (2).