Liquid-Metal Reactor Inner Lid for Reduced Sloshing and Vessel Height
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Solution Overview
Problem
Liquid metal cooled nuclear reactors face challenges with seismic loading, sloshing, and high construction costs due to the large dead weight and fluid level differences between the hot and cold legs, as well as vulnerability to earthquakes and reduced lifespan of primary circulation pumps.
Innovation Solution
A nuclear reactor design incorporating an inner lid beneath the reactor lid to create overpressure in one leg, reducing fluid level differences and vessel height, with pressure relief mechanisms and labyrinth seals to protect components from liquid coolant.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the reactor vessel height is increased to accommodate large fluid level differences between hot and cold legs, then the pumps can operate effectively, but the construction cost and seismic vulnerability increase
Solution Approach 1:
The patent applies parameter changes by introducing overpressure (0.5-10 bar) in the cold leg to alter the fluid level difference between hot and cold legs. This pressure parameter modification allows the pumps to operate effectively without requiring excessive vessel height, thereby reducing construction costs while maintaining pump effectiveness.
Solution Approach 2:
The inner lid acts as an intermediary component that creates and maintains the overpressure zone in the cold leg. This intermediate structure enables the pressure differential necessary for reduced fluid level difference without requiring the entire reactor vessel to be taller, thus solving the contradiction between pump operation and construction cost.
2Ease of operation
If the reactor vessel height is increased to accommodate large fluid level differences, then pump operation is maintained, but seismic vulnerability and sloshing problems worsen
Solution Approach 1:
By changing the pressure parameter in the cold leg through the inner lid, the fluid level difference is reduced, which in turn reduces the height of the reactor vessel. A shorter vessel experiences less seismic loading and reduced sloshing effects, thereby improving seismic stability while maintaining pump operation through the overpressure mechanism.
3Ease of manufacture
If the reactor vessel height is reduced to decrease construction cost, then manufacturing becomes more economical, but fluid level difference and pump operation become problematic
Solution Approach 1:
The patent resolves this contradiction by introducing overpressure (0.5-10 bar) in the cold leg, which reduces the fluid level difference between hot and cold legs. This allows the reactor vessel to be shorter and more economical to construct, while the pumps continue to operate effectively due to the maintained pressure differential created by the inner lid.
Solution Approach 2:
The inner lid serves as an intermediary that creates the overpressure zone, enabling the system to achieve both reduced vessel height (lower construction cost) and maintained pump operation effectiveness through the pressure differential it establishes.
4Ease of operation
If the pump shaft length is increased to reach deeper pump positions, then pumps can be positioned optimally, but vibrations increase and lifespan decreases
Solution Approach 1:
By changing the pressure parameter in the cold leg, the fluid level difference is reduced, allowing pumps to be positioned higher in the vessel. This shorter pump shaft length reduces vibrations and increases pump lifespan, while the overpressure mechanism ensures optimal pump operation is maintained.
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
Reduces reactor vessel height and construction costs, enhances seismic stability, prolongs pump lifespan, and minimizes sloshing by covering a large portion of the pool, while protecting components from corrosion and wear.
Implementation Method 1
The inner lid enables the covered leg to have an over pressure in relation to the other leg. This reduces the fluid level difference between the cold leg and the hot leg
Implementation Method 2
at least one heat exchanger having an inlet from the hot leg and outlet to the cold leg for transferring the heat from the primary fluid to a secondary fluid of an externally connecting circuit
Implementation Method 3
a core submerged in the hot leg for heating the primary fluid
Implementation Method 4
at least one primary fluid circulation pump or circulating the primary fluid in the main vessel and pressurising one of the legs
Data Source
AI summary
A liquid-metal-cooled nuclear reactor includes a main vessel containing a primary fluid and a cylindrical separation structure, separating a hot leg from a cold leg. The cold leg encompasses the hot leg. At least one opening is provided in the cylindrical separation structure to enable the primary fluid to flow from the cold leg to the hot leg. A core is submerged in the hot leg. The reactor also includes at least one heat exchanger having an inlet from the hot leg and an outlet to the cold leg for transferring heat from the primary fluid to a secondary fluid of an externally connecting circuit. A reactor lid covers the main vessel. A gas plenum is disposed beneath the reactor lid and above the hot leg. An inner lid is disposed beneath the reactor lid covering the cold leg. The hot leg is open ended towards the gas plenum.