Nuclear Debris Trap with Passive Bypass Flowpath
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Solution Overview
Problem
Emergency Core Cooling Systems (ECCS) in nuclear power plants face issues with fine debris passing through strainers, potentially damaging components and causing head loss, which can lead to insufficient cooling water flow.
Innovation Solution
A debris trap with filter media that defines both filtration and bypass flowpaths, allowing flow to transition passively from filtration to bypass paths as debris accumulates, reducing head loss and ensuring efficient debris collection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ECCS strainers with small hole diameters (0.035-0.125 inch) are used to stop debris, then large debris is prevented from reaching pumps and components, but fine debris can still pass through and cause damage or head loss
Solution Approach 1:
The debris trap divides the filtration system into multiple stages: a first strainer with larger holes (0.035-0.125 inch) for coarse debris, and a second strainer with smaller holes (0.004-0.035 inch) for fine debris. This segmentation allows each stage to handle specific debris sizes, preventing fine debris from passing through while maintaining reliable protection against large debris.
2Reliability
If filter media with small pore sizes is used to capture fine debris, then debris collection efficiency improves, but head loss increases significantly
Solution Approach 1:
The system segments the filtration function across two strainers with different pore sizes. The first strainer with larger holes handles the bulk of debris removal with minimal head loss, while the second strainer with smaller holes captures fine debris. This segmentation allows efficient fine debris collection while preventing excessive head loss that would occur with a single fine-mesh filter.
Solution Approach 2:
The debris trap includes a bypass flowpath that provides partial flow around the filter media. When the filter media becomes clogged with debris, increasing head loss, the bypass allows excess flow to circumvent the restricted filtration path. This ensures continuous cooling water flow to the reactor while maintaining debris collection capability.
3Device complexity
If a single strainer is used for all debris sizes, then device complexity is reduced, but the ability to effectively capture both large and fine debris is compromised
Solution Approach 1:
The debris trap employs two strainers with different hole sizes arranged in series, with the first strainer having larger holes (0.035-0.125 inch) for coarse debris and the second strainer having smaller holes (0.004-0.035 inch) for fine debris. This segmentation enables effective filtration across multiple debris size ranges while maintaining a relatively simple overall device structure.
Solution Approach 2:
The debris trap serves multiple functions: the first strainer captures large debris, the second strainer captures fine debris, and the bypass flowpath provides relief when filtration capacity is exceeded. This multi-functionality allows a single device to handle diverse debris sizes and flow conditions effectively.
4Reliability
If filter media collects increasing amounts of debris, then debris capture capability improves, but flow resistance increases and may cause insufficient cooling water flow
Solution Approach 1:
The bypass flowpath provides an alternative route for cooling water when the filtration path becomes restricted by debris accumulation. As the filter media collects more debris and flow resistance increases, the bypass allows sufficient water flow to reach the reactor, preventing insufficient cooling while maintaining debris capture capability.
Solution Approach 2:
The system provides passive feedback through head loss measurement across the filter media. When debris accumulation increases resistance to flow, the resulting head loss signals the need for bypass activation or filter replacement. This feedback mechanism ensures cooling water flow remains sufficient while maintaining effective debris capture.
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 debris trap effectively captures fine debris while minimizing head loss, ensuring safe operation of ECCS by automatically adjusting flow to prevent damage to downstream components.
Implementation Method 1
filter media that defines both filtration and bypass flowpaths
Implementation Method 2
the filtration and bypass flowpaths have relatively low and relatively high head loss, respectively
Data Source
AI summary
In a debris trap that may be used in an Emergency Core Cooling System of a nuclear power plant, the filter media is arranged to define both filtration and bypass flowpaths that are in fluid communication with one another. At least initially, each of the filtration and bypass flowpaths are open, and the filtration and bypass flowpaths have relatively low and relatively high head loss, respectively. The debris trap is operative so that flow through the debris trap may passively, and typically gradually, transition from the filtration flowpaths to the bypass flowpath in response to the filter media collecting increasing amounts of debris. More specifically, initially substantially all of the flow may be through the filtration flowpaths, and thereafter the filtration flowpaths may become substantially obstructed so that substantially all of the flow is through the bypass flowpath.