Nuclear Fuel Pool Lock Automatic Closure Mechanism

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Solution Overview

Problem

In nuclear power plants, manual operation of the lock between the reactor pit and the fuel element storage pool can lead to failure to close the lock during a leak, causing water level drops and increased radiation exposure, making it difficult or impossible to cool spent fuel elements effectively.

Innovation Solution

An automatic locking mechanism is implemented, triggered by a float-based signal transmitter when the water level falls below a predetermined limit, using a network-independent energy source such as a mechanical or pneumatic system to ensure the lock closes independently, maintaining adequate water coverage for the fuel elements.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If manual operation of the contactor is used to close the lock, then operational simplicity is maintained, but reliability deteriorates because the contactor may remain open during a leak

Engineering Contradiction:
Improvemanual operation simplicityVSAvoidlock closing reliability
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The system uses a float that automatically detects water level drop and triggers the contactor closure without human intervention. The float mechanism self-activates when the water level falls below the limit, ensuring the lock closes reliably during leaks without requiring manual operation.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The float provides continuous feedback about the water level condition. When the water level drops below the predetermined limit, the float moves to trigger the contactor, creating a feedback loop that automatically responds to the leak condition and closes the lock to prevent further water loss.

Inventive Principle:
Principle #23Feedback

2Reliability

If automatic float-based locking is implemented, then reliability of lock closure is improved, but device complexity increases

Engineering Contradiction:
Improvelock closure reliabilityVSAvoidautomatic locking mechanism complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The control logic is extracted from complex electronic systems and implemented using a simple mechanical float mechanism. The float directly translates water level position into contactor activation, eliminating the need for complex sensors, processors, and control circuits while maintaining high reliability.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent replaces potential electrical or electronic automatic control systems with a purely mechanical float-based system. This mechanical substitution simplifies the device by using straightforward mechanical buoyancy and contact principles instead of complex electromechanical systems.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

3Ease of operation

If network-dependent electrical drive is used for the contactor, then ease of operation is improved, but reliability deteriorates during power failures

Engineering Contradiction:
Improveelectrical drive operationVSAvoidoperation during power failure
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The patent replaces network-dependent electrical drives with a mechanical float-driven system. The float mechanism uses buoyancy forces to directly actuate the contactor closure, eliminating dependency on external power networks while maintaining operational capability during power failures or network outages.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The mechanical float system is self-powered by the buoyancy force of water itself. It does not require external electrical energy or network connection to operate, making it autonomously functional during power failures and network outages while maintaining reliability.

Inventive Principle:
Principle #25Self-service

4Ease of operation

If the lock remains open during a leak, then accessibility to the fuel storage pool is maintained, but water coverage of fuel elements deteriorates

Engineering Contradiction:
ImproveaccessibilityVSAvoidwater coverage
Core Design Contradiction:
Ease of operationVSQuantity of substance

Solution Approach 1:

The float provides real-time feedback on water level conditions. When the water level drops below the safe threshold, the float triggers the contactor to close the lock, automatically preventing further water loss and maintaining adequate water coverage of the fuel elements without requiring manual monitoring or intervention.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The system takes preliminary action by closing the lock automatically when the water level first drops below the limit. This preemptive closure prevents further water loss and maintains adequate water coverage before the situation becomes critical, protecting the fuel elements from insufficient cooling.

Inventive Principle:
Principle #9Preliminary anti-action

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

Ensures continuous water coverage and facilitates safe cooling of fuel elements even during accidents or power failures, preventing radiation exposure and maintaining operational accessibility.

Implementation Method 1

the signal transmitter comprises a float for falling below the limit value and for triggering the closing movement of the contactor

Methodology Applied
Scientific EffectBuoyancy: Archimedes' Principle (Buoyancy)

Implementation Method 2

a passive drive system with a network-independent energy store is provided for driving the contactor during automatic locking

Methodology Applied
Scientific EffectMechanical energy storage: Mechanical Accumulator

Implementation Method 3

a pretensioned spring or a pneumatic energy store, which is coupled directly to the contactor without an electrical drive

Methodology Applied
Scientific EffectElastic potential energy: Spring

Implementation Method 4

a pretensioned spring or a pneumatic energy store, which is coupled directly to the contactor

Methodology Applied
Scientific EffectPneumatic energy storage: Hydraulic Accumulator

Data Source

PatentEP2845199B1Fuel pool of a nuclear power plant
Publication Date: 2016.03.30 AREVA GMBH
  • EP2845199B1 patent drawingFigure 1
  • EP2845199B1 patent drawingFigure 2~3
  • EP2845199B1 patent drawingFigure 4~6

AI summary

The invention relates to a nuclear power plant in which the sluice (10) between a fuel pool (4) and a reactor cavity (2) is provided with a contactor (36), with which the sluice (10) is automatically locked when the water level (h) in the fuel pool (4) falls under a predetermined threshold value (hG).