Tub-Type Meltdown Retaining Device for Nuclear Reactors
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Solution Overview
Problem
Existing solutions for managing a core meltdown in nuclear power plants face challenges in effectively capturing and dissipating extreme heat without destroying the facility and releasing radioactive radiation.
Innovation Solution
A trough-like restraining device with a multi-layer lining, including a sacrificial layer for heat absorption and endothermic reactions, a ceramic bonded molded part layer for mechanical stability, and a high thermal conductivity filling layer, positioned below the reactor pressure vessel to absorb and transfer the core melt safely.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a single-layer refractory lining is used in the containment device, then high temperature resistance is achieved, but heat dissipation efficiency is insufficient
Solution Approach 1:
The containment device is divided into multiple functional layers: an inner sacrificial layer (20-80 cm thick) for heat absorption and endothermic reactions, a middle molded part layer for structural stability, and an outer filling layer with high thermal conductivity for efficient heat dissipation. This segmentation allows each layer to optimize its specific function rather than requiring a single material to fulfill all requirements.
Solution Approach 2:
The invention uses a composite multi-layer structure combining different materials with complementary properties: the sacrificial layer uses concrete or refractory concrete for heat absorption, the molded part layer uses ceramic-bonded materials for mechanical strength, and the filling layer uses materials with high thermal conductivity for heat transfer. This composite approach resolves the contradiction between temperature resistance and heat dissipation efficiency.
2Temperature
If extreme cooling measures are applied to the core melt, then temperature reduction is achieved, but structural integrity of the containment device is compromised
Solution Approach 1:
The sacrificial layer is pre-positioned inside the containment device before the meltdown occurs. This layer is designed to be consumed in advance during the meltdown process, absorbing heat and undergoing endothermic reactions before the core melt reaches the structural molded part layer. This preliminary action protects the structural integrity while achieving temperature reduction.
Solution Approach 2:
The sacrificial layer acts as an intermediary between the core melt and the structural containment device. It absorbs the thermal energy and chemical interaction first, preventing direct contact between the extreme heat and the structural molded part layer, thereby maintaining structural integrity while achieving cooling.
3Volume of moving object
If the containment device is positioned offset to the side of the pressure vessel, then space for melt distribution is provided, but immediate heat capture capability is reduced
Solution Approach 1:
Instead of positioning the containment device offset to the side as in previous designs, this invention inverts the approach by placing the containment device immediately below the pressure vessel. The pressure vessel protrudes into the retention basin, allowing the core melt to be captured vertically at the point of failure rather than requiring lateral redistribution.
4Temperature
If a thick sacrificial layer is used for heat absorption, then temperature reduction is improved, but device complexity and material consumption increase
Solution Approach 1:
The invention optimizes the thickness parameter of the sacrificial layer to be within 20-80 cm, providing a quantitative range that balances heat absorption capability with device complexity. This parameter optimization allows sufficient heat absorption through endothermic reactions while maintaining reasonable structural complexity and material consumption.
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 device efficiently reduces the temperature of the core melt, stabilizes the containment, and facilitates controlled transfer to downstream components, effectively managing the meltdown scenario while minimizing radioactive release.
Implementation Method 1
It is within the meaning of the invention to form the sacrificial layer from a material which not only absorbs stored heat when it comes into contact with a core meltdown, but also leads to endothermic reactions, ie reactions in which additional heat is consumed.
Implementation Method 2
The sacrificial layer absorbs heat from the core melt without extreme cooling
Implementation Method 3
This so-called filling layer is created with the help of a monolithic mass, which can consist of a material with high thermal conductivity. In this way, the heat dissipation from the molded part layer in front is promoted or accelerated.
Data Source
AI summary
The invention relates to a tub-type meltdown retaining device comprising an outer envelope, the inside of which is provided with a multilayer lining. Said lining encompasses, from the inside out, a monolithic sacrificial layer, a layer made from high temperature-resistant molded parts, and a monolithic filling layer between the envelope and the layer made from molded parts.