Pressure-Tube Reactor Coolant Plenum for Supercritical Fluids
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Solution Overview
Problem
Existing pressure tube nuclear reactors are not suited for use with supercritical fluids due to material limitations and design constraints, which lead to increased corrosion, wear, and maintenance challenges when exposed to high pressures and temperatures.
Innovation Solution
A pressure-tube nuclear reactor design featuring vertically oriented pressure tubes with a coolant plenum system that maintains coolant fluid at a higher pressure than the moderator, using ceramic insulators to inhibit heat transfer and accommodate thermal expansion, and employing materials like zirconium alloys to handle supercritical flow conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If existing pressure tube designs are used with supercritical fluids, then the reactor can operate at high temperatures and pressures, but the pressure tubes suffer from increased corrosion and wear
Solution Approach 1:
A calandria tube is introduced as an intermediary component between the pressure tube and the moderator. The calandria tube forms a pressure boundary that separates the high-pressure coolant environment from the low-pressure moderator, protecting the pressure tube from direct exposure to corrosive supercritical conditions while maintaining the thermal and pressure functions
2Stress or pressure
If the size or thickness of pressure tubes is increased to withstand high pressures, then the pressure tubes can handle supercritical fluid conditions, but tube spacing requirements are affected and reactor efficiency decreases
Solution Approach 1:
The pressure containment function is segmented between two separate components: the pressure tube (containing the coolant) and the calandria tube (providing the pressure boundary). This segmentation allows the pressure tube to maintain its original dimensions for optimal reactor efficiency while the calandria tube assumes the role of withstanding external pressures
3Stress or pressure
If pressure vessels are increased in size or thickness to withstand high pressures, then the reactor can operate with supercritical fluids, but manufacturing costs and difficulty increase
Solution Approach 1:
The design employs thin-walled calandria tubes that provide the necessary pressure boundary function without requiring thick, heavy construction. The calandria tube acts as a flexible pressure-containing shell that protects the pressure tube from external pressures while maintaining manufacturability and cost-effectiveness
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
Enables efficient operation with supercritical fluids, reducing maintenance needs and extending reactor lifespan by withstanding high pressures and temperatures while minimizing heat transfer and corrosion.
Implementation Method 1
Each pressure tube includes an insulator configured to inhibit heat transfer between the coolant fluid and the pressure tube
Implementation Method 2
A coolant fluid is circulated through the pressure tube and is heated by nuclear fission
Data Source
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AI summary
A pressure-tube nuclear reactor can include an outer shell having an interior to contain a moderator at a first pressure and a coolant plenum to receive the coolant fluid at a second pressure, the second pressure being greater than the first pressure. The reactor also includes a plurality of pressure tubes. Each pressure tube is received within and extends through a corresponding shell tube and is configured to releasably retain at least one fuel bundle. A first end of each pressure tube being coupled to the plenum tubesheet in fluid communication with the plenum chamber and a second end of each pressure tube fluidly connected to a coolant conduit to enable the coolant fluid to flow between the coolant plenum and each pressure tube and to flow from the nuclear reactor for further processing.