Melting Gate Member for Passive Nuclear Reactor Shutdown

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Solution Overview

Problem

Current nuclear reactor shutdown systems rely on mechanical components prone to failure, are costly, and not suitable for compact or horizontal reactor designs, lacking versatility across different reactor types and coolant systems.

Innovation Solution

A solid-state emergency core shutdown system using a housing with a gate member and neutron absorbing material, actuated by a predetermined melting point or electrical power, which segregates compartments to disperse neutron absorbing material into the reactor core, applicable to any nuclear reactor regardless of coolant type or size.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If mechanical components are used in shutdown systems, then the system can be operated and controlled, but the reliability decreases due to component failure and the device complexity increases

Engineering Contradiction:

Improveshutdown system reliabilityVSAvoidshutdown system complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent replaces mechanical shutdown components with a solid-state system using phase change materials (PCM) that automatically transition from solid to liquid at a predetermined temperature, mechanically closing the control rod without requiring mechanical actuators, motors, or complex control mechanisms during shutdown

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The shutdown system uses the reactor's own heat generation to trigger the phase change material, which automatically melts and releases the control rod when temperature exceeds the PCM's melting point, eliminating the need for external power sources, control systems, or mechanical operation during emergency shutdown

Inventive Principle:

Principle #25Self-service

2Reliability

If passive shutdown features using gravity or potential energy are implemented, then the reliability improves, but the device complexity and size increase making them unsuitable for compact reactor designs

Engineering Contradiction:

Improvepassive shutdown reliabilityVSAvoidshutdown system volume

Core Design Contradiction:

ReliabilityVSVolume of moving object

Solution Approach 1:

The patent changes the triggering parameter from gravitational potential energy to thermal energy, using the reactor's operating temperature to melt the phase change material and activate shutdown, enabling a compact design without large gravity-based mechanisms

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The system uses phase transition of the control rod from solid to liquid state at a predetermined temperature to trigger automatic shutdown, eliminating the need for large mechanical components while maintaining passive safety

Inventive Principle:

Principle #36Phase transitions

3Adaptability or versatility

If existing shutdown mechanisms are used, then the system can be operated, but the adaptability decreases as they are design-specific and cannot be applied to other reactor types

Engineering Contradiction:

Improveshutdown system adaptabilityVSAvoidshutdown system design complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent creates a universal shutdown mechanism based on phase change materials that can be applied to any reactor design regardless of size, orientation, or specific configuration, as it relies on fundamental thermal properties rather than design-specific mechanical systems

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 provides a reliable, compact, and versatile shutdown solution that can be actively or passively activated, ensuring reactor safety without mechanical failures, meeting IAEA passive safety category B standards.

Implementation Method 1

the gate member comprising a material having a predetermined melting point

Methodology Applied

Scientific EffectMelting: Melting

Implementation Method 2

The gate member may comprise a number of heater coils embedded in the material that are structured to melt the material upon actuation by an electrical current

Methodology Applied

Scientific EffectJoule heating: Joule Heating

Implementation Method 3

a neutron absorbing material disposed within the first compartment

Methodology Applied

Scientific EffectNeutron absorption: Absorption (physical)

Data Source

PatentUS11289215B2Reactor shutdown system with melting gate member for segregating neutron absorbing material compartment from core

Publication Date: 2022.03.29 WESTINGHOUSE ELECTRIC CORP

AI summary

A system for use in shutting down a nuclear reactor includes a housing that defines a region therein sealed from an ambient environment and a gate member disposed within the region in a manner such that the gate member segregates the region into a first compartment and a second compartment isolated from the first compartment. The gate member is formed from a material having a predetermined melting point. The system further includes a neutron absorbing material disposed within the first compartment and a dispersion mechanism disposed within the region. The dispersion mechanism structured to encourage the neutron absorbing material from the first compartment into the second compartment.