Nuclear Reactor Suppression Pool Cooling via Segmented Heat Exchange

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Solution Overview

Problem

Existing cooling systems for reactor suppression pools do not adequately address the need for enhanced safety margins during events exceeding postulated initiating events or when the residual heat removal system fails.

Innovation Solution

A cooling system incorporating a heat exchanger that can cool suppression pool water by performing heat exchange with a coolant, which is then returned to the pool, and includes alternative cooling configurations such as service water, alternative reactor building closed cooling water units, cooling towers, and air fin coolers to ensure stable cooling.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the residual heat removal system is used to cool suppression pool water, then cooling function is provided under normal postulated initiating events, but the system becomes insufficient when events surpassing postulated initiating events occur or when the system fails

Engineering Contradiction:
Improvecooling system reliabilityVSAvoidcooling system adaptability
Core Design Contradiction:
ReliabilityVSAdaptability or versatility

Solution Approach 1:

The cooling system is segmented into multiple independent cooling paths: the residual heat removal system for normal operation and alternative cooling systems (service water system, air cooler system) for emergency situations. This segmentation allows each subsystem to be optimized for specific scenarios while maintaining overall system reliability through diversity.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The system changes operational parameters by switching between different cooling modes based on temperature conditions and system availability. The control unit monitors suppression pool water temperature and activates alternative cooling systems when temperature exceeds predetermined thresholds or when the residual heat removal system is unavailable, thereby adapting to varying operational states.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If alternative cooling systems are added to improve safety margins, then defense in depth is reinforced, but system complexity increases

Engineering Contradiction:
Improvereactor safetyVSAvoidcooling system complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The alternative cooling systems utilize existing multi-functional infrastructure within the nuclear power plant. The service water system, originally designed for other purposes, is repurposed for suppression pool cooling. Similarly, air coolers serve both normal and emergency cooling functions. This multi-functionality reduces the need for entirely new dedicated systems, thereby limiting complexity increase while improving reliability.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

A control unit acts as an intermediary between the temperature sensing system and the various cooling systems. It automatically monitors suppression pool water temperature and selectively activates appropriate cooling systems based on predetermined criteria, simplifying operator decision-making and reducing control complexity while maintaining enhanced safety capabilities.

Inventive Principle:
Principle #24Intermediary (Mediator)

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 system effectively cools suppression pool water, improving reactor safety and reinforcing defense-in-depth measures even during extreme events or when the residual heat removal system is non-functional, ensuring stable and reliable cooling operations.

Implementation Method 1

A cooling system incorporating a heat exchanger that can cool suppression pool water by performing heat exchange with a coolant

Methodology Applied
Scientific EffectHeat exchange: Heat Exchanger

Implementation Method 2

cool suppression pool water by performing heat exchange with a coolant

Methodology Applied
Scientific EffectThermal energy transfer: Conduction (thermal)

Implementation Method 3

cooling towers

Methodology Applied
Scientific EffectEvaporative cooling: Evaporative Cooler

Implementation Method 4

air fin coolers

Methodology Applied
Scientific EffectConvection: Convection

Implementation Method 5

air fin coolers

Methodology Applied
Scientific EffectThermal radiation: Thermal Radiation

Data Source

PatentEP3067896B1Cooling system for nuclear reactor suppression pool
Publication Date: 2018.07.04 HITACHI GE NUCLEAR ENERGY LTD
  • EP3067896B1 patent drawingFigure 1
  • EP3067896B1 patent drawingFigure 2
  • EP3067896B1 patent drawingFigure 3~4

AI summary

To provide a cooling system of a reactor suppression pool capable of cooling suppression pool water and improving the safety of a reactor in the case where an event surpassing a postulated initiating event occurs, or in the case where cooling of the suppression pool water by a residual heat removable system does not function. A cooling system of a reactor suppression pool according to the present invention includes a heat exchanger for cooling suppression pool water installed in the middle of a suppression pool water cooling line, operating when the temperature of the suppression pool water reaches a given temperature, performing heat exchange with the suppression pool water from a suppression pool water cleanup system suction line to cool the water, and returning the cooled suppression pool water to the suppression pool through a suppression pool water cleanup system discharge line.