Passive Nuclear Reactor Cooling via Rupture Disks and Gravity Injection
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Solution Overview
Problem
During extreme transient scenarios, actively- and passively-powered cooling systems may become inoperable or insufficient, leading to reactor heat-up and increased pressure, making forced coolant injection difficult and risking reactor failure, especially if containment pressure cannot be vented.
Innovation Solution
A compact, simplified boiling water reactor system with a smaller containment structure made of resilient materials, featuring a rupture disk for passive depressurization and a gravity-driven coolant system, eliminating the need for complex active systems and minimizing the risk of leakage and radioactive release.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If active cooling systems and power-operated valves are used to maintain reactor pressure and coolant flow, then reactor safety can be maintained under normal conditions, but during extreme transients these systems may become inoperable or insufficient, leading to reactor heat-up and increased pressure
Solution Approach 1:
The cooling system is segmented into multiple independent passive cooling loops, each capable of operating autonomously. The containment structure is divided into separate zones with independent cooling paths, ensuring that failure of one segment does not compromise the entire system. This segmentation provides redundancy without requiring complex centralized control systems.
Solution Approach 2:
The cooling system is designed to be self-activating through passive mechanisms that automatically respond to reactor conditions without external control. Thermal convection currents naturally drive coolant flow when temperature differentials exist, and pressure differential mechanisms automatically open cooling pathways when pressure increases, eliminating the need for powered valves and pumps during normal and transient conditions.
2Temperature
If forced coolant injection systems are used to maintain cooling during transients, then reactor temperature can be controlled, but system complexity increases and the systems may become inoperable when power is lost
Solution Approach 1:
Mechanical pump-based coolant injection systems are replaced with passive convection-driven flow mechanisms. The system utilizes natural thermal convection where heated coolant rises and cooler coolant sinks, creating continuous circulation without mechanical pumps. This substitution eliminates complex mechanical injection systems while maintaining effective temperature control through thermally-driven fluid motion.
Solution Approach 2:
The system changes operational parameters from active mechanically-controlled flow to passive thermally-driven flow. By designing coolant channels with specific geometries and thermal properties, the system exploits natural convection parameters (temperature differentials, density gradients) to maintain coolant circulation and temperature control without requiring external power or complex control systems.
3Stress or pressure
If containment pressure is not vented during transients, then reactor pressure increases leading to failure risk, but if vented through active systems these may become inoperable
Solution Approach 1:
The system employs disposable rupture disks as pressure relief mechanisms. These simple, inexpensive mechanical elements are designed to fail in a controlled manner when pressure exceeds predetermined thresholds, providing reliable passive depressurization. The rupture disks are replaced after use, but their simplicity ensures they remain functional without complex control systems or power sources during transients.
Solution Approach 2:
The containment structure incorporates pre-designed pressure relief pathways and rupture mechanisms that are activated automatically when pressure reaches critical levels. These preliminary anti-actions counteract the harmful pressure buildup before it can cause catastrophic failure, using passive mechanical mechanisms that are predetermined to activate under specific pressure conditions without requiring external control.
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 prevents reactor pressure from exceeding safe limits during transients, allowing for passive depressurization and continuous coolant injection without relying on active valves or power, reducing the risk of overheating and radioactive release, and simplifying the reactor design and operation.
Implementation Method 1
A compact, simplified boiling water reactor system with a smaller containment structure made of resilient materials, featuring a rupture disk for passive depressurization
Implementation Method 2
A compact, simplified boiling water reactor system with a smaller containment structure made of resilient materials, featuring a rupture disk for passive depressurization and a gravity-driven coolant system
Implementation Method 3
A compact, simplified boiling water reactor system with a smaller containment structure made of resilient materials, featuring a rupture disk for passive depressurization and a gravity-driven coolant system
Data Source
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AI summary
Simplified nuclear reactors include depressurization systems or gravity -driven injection systems or both. The systems depressurize and cool the reactor without operator intervention and power. An underground containment building may be used with the depressurization and injection systems passing through the same from above ground. Depressurization systems may use a rupture disk, relief line, pool, and filter to open the reactor and carry coolant away for condensation and exhausting. Injection systems may use a coolant tank above the nuclear reactor to inject liquid coolant by gravity into the reactor through an injection line and valve. The rupture disk and valve may be integral with the reactor and use penetration seals where systems pass through containment. Rupture disks and valves can actuate passively, at a pressure setpoint or other condition, through fluidic controls, setpoint failure, etc. The depressurization system and injection system together feed- and-bleed coolant through the reactor.