Core Catcher Bottom Cooling Channels for Nuclear Containment
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Solution Overview
Problem
The existing core catcher systems in nuclear reactors face inefficiencies in cooling core debris, particularly when the deposition thickness of corium is large, leading to insufficient cooling of the core debris at the bottom, which can result in high temperatures and erosion of the containment vessel's concrete floor, potentially causing radioactive material leakage.
Innovation Solution
A core catcher design with a steel main body and integrated cooling fins, where cooling water is supplied through a network of channels to efficiently cool the core debris from the bottom, utilizing a heat-resistant material layer and sacrifice concrete layer to manage heat transfer and prevent direct contact with the concrete, allowing for effective heat dissipation and reduced structural requirements for the containment vessel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If cooling water is supplied only over the top surface of the core debris, then the top surface of the core debris can be cooled, but the bottom of the core debris cannot be cooled sufficiently when deposition thickness is large
Solution Approach 1:
The core catcher is divided into multiple cooling channels (first cooling channels and second cooling channels) that distribute cooling water to different regions. The first cooling channels cool the central region while the second cooling channels cool the peripheral region, ensuring comprehensive cooling of the core debris throughout its deposition area.
Solution Approach 2:
The invention transitions from single-top-surface cooling to multi-dimensional cooling by adding bottom cooling through the cooling channels formed in the core catcher structure. This allows cooling water to reach the core debris from both top and bottom surfaces, effectively cooling thick deposits that would be inaccessible from top cooling alone.
2Temperature
If the floor area of the containment vessel is expanded to reduce core debris deposition thickness, then cooling efficiency improves, but the structural design and cost of the containment vessel increase
Solution Approach 1:
The core catcher structure segments the cooling function into multiple independent cooling channels distributed across the existing floor area. This allows efficient cooling of core debris without requiring expansion of the overall containment vessel floor, as the cooling capability is enhanced through structural segmentation rather than area expansion.
Solution Approach 2:
The core catcher acts as an intermediary structure between the containment vessel floor and the core debris. It provides integrated cooling channels that actively remove heat from the core debris, allowing the system to maintain effective cooling on the existing floor area without direct contact between core debris and the containment vessel floor.
3Device complexity
If core debris contacts directly with the concrete floor, then the containment vessel structure is simpler, but the concrete floor erodes due to high temperatures and radioactive material may leak
Solution Approach 1:
The core catcher serves as an intermediary structure positioned between the core debris and the concrete floor of the containment vessel. It prevents direct contact between the hot core debris and the concrete, eliminating thermal erosion and radioactive contamination of the floor while maintaining structural integrity and preventing leakage.
Solution Approach 2:
The core catcher integrates its own cooling system with cooling channels that actively cool the core debris as it accumulates. This self-cooling capability prevents the core debris from reaching temperatures that would cause concrete erosion, allowing the system to protect itself and the containment vessel without external intervention.
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
This design enhances the cooling efficiency of core debris, reduces the risk of radioactive material leakage, and minimizes the structural demands on the containment vessel, effectively managing heat transfer and preventing concrete erosion, thus ensuring safer containment of radioactive materials.
Implementation Method 1
cooling water is supplied through a network of channels to efficiently cool the core debris from the bottom
Implementation Method 2
cooling water is supplied through a network of channels to efficiently cool the core debris from the bottom
Implementation Method 3
utilizing a heat-resistant material layer and sacrifice concrete layer to manage heat transfer and prevent direct contact with the concrete
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
Core debris generated during a molten reactor core in a reactor containment vessel penetrating the reactor containment vessel is configured to be caught by a core catcher located beneath the reactor containment vessel which has a main body (20) having first stage cooling water channels (21 a) and second stage (21 b) surrounded by cooling fins (31) extending radially. The number of the second stage cooling channels (21 b) is larger than that of the first stage cooling channels (21a). Cooling water is supplied from a cooling water injection opening (22) and distributed to the first cooling water channels (21 a) at a distributor (10). An intermediate header (21) is formed between the first and the second cooling water channels (21 a, 21 b), and the cooling water is distributed to the second cooling water channels (21 b) uniformly.