Membrane Degassing for Nuclear Reactor Coolant
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Solution Overview
Problem
Current reactor coolant degassing systems in nuclear power plants require significant energy, space, and maintenance due to their complex design and multiple components, making them costly and inefficient for removing dissolved hydrogen and radioactive gases.
Innovation Solution
A sub-system utilizing gas membranes with a vacuum generator and an inert gas sweep system to efficiently remove radioactive and hydrogen gases from reactor coolant, with contactors aligned in series and/or parallel configurations to minimize the number of components and enhance gas removal efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional volume control tank systems are used for degassing reactor coolant, then hydrogen and radioactive gases can be removed from the coolant, but the system requires significant energy consumption, large space, and complex maintenance
Solution Approach 1:
The patent employs a hollow fiber membrane contactor where dissolved gases permeate through thin hydrophobic membrane walls. The membrane acts as a selective barrier that allows gas molecules to pass from the liquid phase on one side to the vacuum side, replacing complex bulk degassing equipment with a compact membrane-based separation system.
Solution Approach 2:
The hollow fiber membranes used in the contactor are porous materials with specific pore structures that enable gas permeation while maintaining structural integrity. The porous nature of the hydrophobic membrane allows dissolved gases to diffuse through the wall thickness, achieving efficient gas removal in a compact configuration.
2Reliability
If vacuum pumps are used to draw vacuum on the outlet chamber for gas extraction, then dissolved gases can be removed from the reactor coolant, but energy consumption increases
Solution Approach 1:
The system uses a jet pump that operates on the principle of momentum transfer and pressure differential created by high-velocity fluid flow. By changing the operational parameters from traditional vacuum pump suction to jet-induced vacuum, the system achieves gas removal with reduced energy input, leveraging the kinetic energy of the sweep gas flow rather than continuous mechanical vacuum pumping.
Solution Approach 2:
The jet pump mechanism utilizes pneumatic principles where a high-velocity inert gas stream creates a vacuum region that draws dissolved gases through the membrane. This pneumatic vacuum generation method replaces mechanical vacuum pumps, reducing moving parts and energy consumption while maintaining effective degassing.
3Productivity
If inert gas sweep system is implemented to enhance gas removal, then gas separation efficiency is improved, but the number of components and system complexity increases
Solution Approach 1:
The inert gas sweep system serves multiple functions simultaneously: it creates the vacuum necessary for gas permeation through the membrane, provides a driving force for gas transport across the membrane, and acts as a carrier gas to transport removed gases to the vacuum source. This multi-functionality reduces the need for separate vacuum generation equipment, offsetting the added complexity with operational efficiency.
Solution Approach 2:
The inert gas acts as an intermediary medium that facilitates the transfer of dissolved gases from the coolant through the membrane to the vacuum side. By introducing this intermediate sweep gas, the system enables efficient gas removal without requiring direct contact between the coolant and vacuum pump, simplifying the overall gas extraction mechanism despite the additional component.
4Productivity
If membrane contactors with series and parallel configurations are used, then gas removal efficiency is enhanced, but capital costs increase
Solution Approach 1:
The membrane contactor system is divided into multiple hollow fiber elements that can be arranged in series or parallel configurations. This segmentation allows the system to be scaled to match specific degassing requirements, with each module providing a standardized unit of gas removal capacity. The modular nature enables cost-effective manufacturing and deployment.
Solution Approach 2:
The system uses a relatively small flow of inert sweep gas to achieve effective degassing, rather than requiring large volumes of gas or high-energy vacuum pumping. This partial action approach, where minimal sweep gas flow is sufficient to maintain the vacuum and drive gas permeation, reduces operational costs and allows for more economical system design while maintaining high gas removal efficiency.
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 approach simplifies the design, reduces energy consumption, and decreases capital and maintenance costs while effectively removing dissolved gases, improving the degassing process by using a membrane-based system with a vacuum and inert gas sweep to enhance gas separation.
Implementation Method 1
the membrane has pores that pass the radioactive and the hydrogen gases from the inlet chamber to the outlet chamber, but prevent the reactor coolant from passing through to the outlet chamber
Implementation Method 2
A vacuum generator is connected to the outlet chamber for drawing a vacuum on the outlet chamber
Implementation Method 3
In one embodiment, a 'sweep' gas system is connected to the outlet chamber for supplying a relatively small inert gas purge flow in the outlet chamber
Data Source
AI summary
An in-line dissolved gas removal membrane-based apparatus for removing dissolved hydrogen and fission gases from the letdown stream from a reactor coolant system.