Sacrificial Concrete for Core Catcher High-Temperature Resistance
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Solution Overview
Problem
Current sacrificial concrete used in core catchers for nuclear power plants exhibits poor high-temperature resistance, leading to reduced residual compressive strength, shortened service life, and increased risk of radioactive material leakage during severe accidents due to high porosity and melting rates.
Innovation Solution
A sacrificial concrete formulation comprising specific proportions of aluminate cement, high-quality quartz sand, hematite ore, water, a polycarboxylate superplasticizer, and strontium oxide, with a preparation method involving mixing and curing steps, enhancing workability, compressive strength, and high-temperature resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional sacrificial concrete is used in core catchers, then the basic structural function is provided, but the high-temperature resistance is poor leading to reduced residual compressive strength and shortened service life
Solution Approach 1:
The patent changes the chemical composition parameters of the concrete by using aluminate cement with high Al2O3 content (≥75%) and low SiO2 content (≤0.5%), combined with specific proportions of quartz sand, hematite ore, and water. This parameter optimization enables the concrete to maintain residual compressive strength above 30% after exposure to 1000°C for 2 hours, significantly improving high-temperature resistance and extending service life
Solution Approach 2:
The patent creates a composite material system combining aluminate cement, quartz sand, hematite ore, and water-reducing agents. This composite formulation leverages the high melting point of aluminate cement and the thermal stability of quartz sand and hematite ore to achieve superior high-temperature performance, with residual strength retention exceeding conventional concrete by more than 10 percentage points
2Reliability
If conventional sacrificial concrete is used, then the basic cooling and localization function is provided, but the internal porosity increases leading to high melting rate and increased risk of radioactive material leakage
Solution Approach 1:
The patent optimizes the water-cement ratio and uses polycarboxylate superplasticizer to control the hydration process, reducing internal porosity. The high Al2O3 content aluminate cement forms a denser microstructure that resists melting at high temperatures, thereby containing radioactive materials more effectively and reducing melting rate
Solution Approach 2:
The sacrificial concrete is designed as a disposable safety barrier that sacrificially melts to absorb and contain corium. By improving its high-temperature resistance and reducing porosity, the concrete can serve its sacrificial function more reliably, containing radioactive materials during the critical accident phase before being replaced
3Strength
If conventional concrete formulation is used, then the basic workability is achieved, but the compressive strength is insufficient and durability is reduced
Solution Approach 1:
The patent uses polycarboxylate superplasticizer with specific properties (density 1.05-1.15 g/ml, solid content ≥40%, pH 4±2, water reducing rate ≥30%) to optimize the concrete mixture. This chemical additive allows for reduced water content while maintaining workability, resulting in higher compressive strength and improved durability without significantly complicating the mixing process
Solution Approach 2:
The patent employs high-quality quartz sand with SiO2 content ≥99% and controlled particle size (0-5mm), and hematite ore with Fe2O3 content ≥92% and specific particle size (5-8mm). These locally optimized aggregate properties improve the overall concrete strength and durability while maintaining workability through proper grading and distribution
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 improved concrete exhibits significantly higher compressive strength and residual compressive strength at elevated temperatures, prolonging service life and reducing radioactive substance release, thus enhancing safety and durability in nuclear power plant applications.
Implementation Method 1
cement, 575 ̃625 parts; water, 200 ̃220 parts
Implementation Method 2
a water-reducing agent, 7 ̃10 parts
Implementation Method 3
a water-reducing agent, 7 ̃10 parts
Implementation Method 4
a quartz sand, 1200 ̃1300 parts; a hematite ore, 700 ̃800 parts
Data Source
AI summary
A sacrificial concrete for a core catcher and a preparation method thereof are provided. The sacrificial concrete includes raw materials in parts by weight as follows: cement, 575˜625 parts; a quartz sand, 1200˜1300 parts; a hematite ore, 700˜800 parts; water, 200˜220 parts; a water reducing agent, 7˜10 parts; and strontium oxide, 0˜10 parts. The process of the preparation method is simple, and the sacrificial concrete with excellent performances of fluidity, strength and high-temperature resistance can be prepared by the known mixing technology. The sacrificial concrete can reduce releasing of radioactive substances 89Sr and 90Sr, so as to improve safety of nuclear power plants in case of a severe accident. Moreover, the sacrificial concrete can be used not only in a core catcher of current third generation nuclear power plant, but also in a core catcher of future fourth generation nuclear power plant, and has widespread engineering application value.