Backup Water Injection for Boiling Water Nuclear Reactors

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Solution Overview

Problem

In a boiling water type nuclear power plant, there is a challenge in reliably supplying cooling water to the reactor pressure vessel and reactor containment vessel from a back-up building due to the need for valve operations and potential abnormalities in the water supply piping.

Innovation Solution

The implementation of an external, independently powered back-up building with a pump and alternative water injection pipes connected to the reactor pressure vessel or containment vessel, which allows for secure water injection without requiring operations within the nuclear reactor building, utilizing check and gate valves to ensure continuous water supply during severe accidents.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If water injection is performed from the back-up building using existing piping, then cooling water can be supplied during severe accidents, but valve operations are required and piping abnormalities may prevent reliable water supply

Engineering Contradiction:

Improvereliability of cooling water supplyVSAvoidease of water injection operation

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The invention segments the water supply system by providing separate, dedicated water injection pipes for the back-up building that bypass the complex valve systems of the existing piping. This segmentation allows independent water supply paths that are simpler to operate and less susceptible to abnormalities in the main piping system.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention introduces an intermediary water supply path through dedicated pipes that connect the back-up building directly to the reactor pressure vessel and containment vessel. This intermediary path avoids the need to operate valves in the existing complex piping system, thereby improving both reliability and ease of operation.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Adaptability or versatility

If complex valve operations are required for water supply routing, then water can be directed to different components, but operational complexity increases and reliability decreases during severe accidents

Engineering Contradiction:

Improveversatility of water supply routingVSAvoidreliability of water supply

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The invention provides separate dedicated water injection pipes for different targets (reactor pressure vessel and containment vessel), segmenting the water supply paths. This eliminates the need for complex valve operations to route water, as each pipe is dedicated to a specific target, thereby maintaining versatility while improving reliability.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The dedicated water injection pipes are pre-configured and positioned to directly connect to the targets they serve. This preliminary arrangement of water paths eliminates the need for complex routing operations during accidents, ensuring that water can be supplied reliably to the required components.

Inventive Principle:

Principle #10Preliminary action

3Reliability

If the back-up building is positioned at a fixed distance from the reactor building, then safety is enhanced through physical separation, but water supply distance increases requiring more powerful pumps

Engineering Contradiction:

Improvesafety through physical separationVSAvoidpower of water injection pump

Core Design Contradiction:

ReliabilityVSPower

Solution Approach 1:

The invention optimizes the spatial arrangement of water injection pipes by extending them vertically and horizontally to reach the reactor pressure vessel and containment vessel from the back-up building. This dimensional optimization allows the pump to operate at efficient pressure levels while maintaining the safety benefits of physical separation.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

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

This solution enhances the safety of the boiling water type nuclear power plant by ensuring reliable cooling water supply to critical components during severe accidents, reducing the need for on-site operations and preventing radioactive substance leakage, thus improving containment and operator safety.

Implementation Method 1

a pump installed inside the external building, alternative water injection pipes configured to perform water injection from the pump

Methodology Applied

Scientific EffectPump: Pump

Data Source

PatentUS10446279B2Boiling water type nuclear power plant

Publication Date: 2019.10.15 HITACHI GE NUCLEAR ENERGY LTD

AI summary

To more reliably supply cooling water to a reactor pressure vessel and a reactor containment vessel using a back-up building if a severe accident should occur, a boiling water type nuclear power plant includes a nuclear reactor building including a reactor containment vessel, and an external building, which is installed independently outside the nuclear reactor building and which has an anti-hazard property. The external building has a power source and an operating panel independent of the nuclear reactor building. The boiling water type nuclear power plant includes a water injection pump installed inside the external building, an alternative water injection pipe performing water injection at least on a reactor pressure vessel or the reactor containment vessel in the nuclear reactor building from the water injection pump, and a valve connected to the alternative water injection pipe, making it possible to perform alternative water injection if a severe accident occurs.