Nuclear Reactor Shutdown System Using Thermal Release Mechanism
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Solution Overview
Problem
Conventional nuclear reactor shutdown systems are not easily adaptable for use in small-sized nuclear reactors, which lack a primary cooling system and rely on solid-state heat conduction.
Innovation Solution
A nuclear reactor shutdown system comprising a shielded path, a neutron absorber, an elastic member, and a braking part, where the elastic member is released from a compressed state when the braking part reaches a threshold temperature, allowing the neutron absorber to enter the reactor core and shut down the nuclear reaction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional nuclear reactor shutdown systems are used, then the system is proven reliable for large reactors, but it cannot be adapted for small-sized reactors without modification
Solution Approach 1:
The shutdown system is designed with universal components that can function in both large and small-sized reactors. The neutron absorber, elastic member, and braking part configuration can be scaled and adapted to different reactor types while maintaining the core shutdown mechanism, allowing the same basic design to serve multiple reactor size categories.
Solution Approach 2:
The system allows for parameter changes in the elastic member's elastic force and the braking part's threshold temperature based on the specific reactor size and requirements. By adjusting these parameters, the same shutdown system design can be optimized for different reactor configurations, from small modular reactors to larger conventional reactors.
2Speed
If the neutron absorber is released to enter the reactor core, then the shutdown is quick and effective, but the system must be held in a ready state that requires activation
Solution Approach 1:
The neutron absorber is preliminarily positioned outside the reactor core and held in place by the elastic member in a compressed state. This preliminary positioning allows the shutdown mechanism to be ready for immediate action without requiring complex real-time control systems. The system is pre-configured so that upon activation, the neutron absorber can quickly enter the core without delay.
Solution Approach 2:
The elastic member automatically urges the neutron absorber into the reactor core when the braking part releases it, without requiring external mechanical intervention or complex control mechanisms. The system uses the stored elastic energy to self-drive the shutdown action, simplifying the overall system complexity while maintaining rapid response capability.
3Loss of time
If the elastic member is kept in a compressed state to enable quick shutdown, then the shutdown response is fast, but the system requires a braking mechanism to maintain readiness
Solution Approach 1:
The braking part utilizes a phase transition material that changes state at a specific threshold temperature. This phase transition allows the braking mechanism to automatically release the elastic member when the reactor temperature exceeds the threshold, providing fast shutdown response without requiring complex active control systems. The passive thermal response simplifies the overall braking mechanism while ensuring rapid activation.
Solution Approach 2:
The system replaces complex active mechanical control systems with a passive thermal-mechanical mechanism. Instead of using motors, sensors, and control circuits to trigger the shutdown, the system uses temperature-induced phase transition in the braking part to automatically release the elastic member. This substitution reduces device complexity while maintaining fast shutdown response.
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 enables safe and quick shutdown of small-sized nuclear reactors without requiring significant modifications, ensuring effective neutron absorption and reactor inhibition.
Implementation Method 1
an elastic member that is configured to urge the neutron absorber in a direction entering inside from the opening of the shielded path by being released from a compressed state
Implementation Method 2
a braking part that is disposed so as to maintain the compressed state of the elastic member and is configured to release the elastic member from the compressed state when the braking part reaches or exceeds a threshold temperature
Implementation Method 3
a neutron absorber that is allowed to enter from the opening of the shielded path
Data Source
AI summary
A nuclear reactor shutdown system includes a shielded path that passes through a reactor core fuel housed in a nuclear reactor vessel in a hermetically sealed manner, one end of the shielded path having an opening and another end of the shielded path being closed; a neutron absorber that is allowed to enter from the opening of the shielded path; an elastic member that is configured to urge the neutron absorber in a direction entering inside from the opening of the shielded path by being released from a compressed state; and a braking part that is disposed so as to maintain the compressed state of the elastic member and is configured to release the elastic member from the compressed state when the braking part reaches or exceeds a threshold temperature.