Flow Tripping Device for BWR Fuel Channel CPR Enhancement
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Solution Overview
Problem
Machining flow tripping features in the channel walls of boiling water reactors is costly and requires specialized equipment, limiting the design of periphery rods and affecting critical power ratio (CPR) performance.
Innovation Solution
A flow tripping device with a peripheral band and extending flow tabs and finger structures that apply a spring force to the fuel channel, minimizing bypass flow and accommodating in-service changes, while maintaining contact with the channel walls to enhance CPR performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If flow tripping features are machined in the channel walls, then CPR performance of periphery rods is improved, but manufacturing cost increases and specialized equipment is required
Solution Approach 1:
The flow tripping function is extracted from the channel wall and transferred to a separate removable device that can be installed in the fuel bundle. This allows the channel wall to remain simple and inexpensive to manufacture, while the flow tripping device provides the necessary CPR enhancement through its tab and finger structure configuration.
Solution Approach 2:
The flow tripping device uses simple, inexpensive materials such as stainless steel or Inconel for the tabs and fingers, which can be easily fabricated and replaced if needed. This approach is more cost-effective than permanently machining expensive channel walls, as the simple device can be manufactured at lower cost and installed as needed.
2Reliability
If flow tripping features are machined in the channel walls, then CPR performance is improved, but manufacturing complexity and inspection difficulty increase
Solution Approach 1:
The complex flow tripping geometry is extracted from the channel wall and implemented as a separate device with tabs and fingers that can be independently manufactured and assembled. This simplifies the channel wall design while providing the necessary flow control functionality through the removable device configuration.
Solution Approach 2:
The flow tripping device is segmented into multiple tabs and fingers that can be independently formed and assembled. This modular approach simplifies manufacturing compared to machining complex features in the channel wall, as each tab and finger can be produced separately and then assembled into the final configuration.
3Manufacturing precision
If rigid flow tripping features are used, then flow control is precise, but adaptability to channel distortions is reduced
Solution Approach 1:
The finger structures are designed with spring-like properties that allow them to flex and adapt to channel wall distortions while maintaining contact. This dynamic capability enables the device to accommodate thermal expansion, irradiation-induced swelling, and other in-service changes without losing flow control effectiveness.
Solution Approach 2:
The tab and finger structures utilize flexible metallic materials that can bend and conform to channel wall irregularities. This flexibility allows the device to maintain precise flow control geometry even when the channel distorts during reactor operation, combining precision with adaptability.
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 flow tripping device improves CPR performance by redirecting water flow, increasing power output and reducing fuel cycle costs, while being cost-effective and adaptable to channel distortions.
Implementation Method 1
a plurality of finger structures extending from a lower portion of the peripheral band, each of the plurality of finger structures extending upward and back towards the peripheral band
Data Source
Figure 1A
Figure 1B
Figure 1C
AI summary
A flow tripping device (100) according to a non-limiting embodiment of the present invention may include a peripheral band (102) surrounding a central space. A plurality of flow tabs (104) may extend from an upper portion of the peripheral band (102) toward the central space. A plurality of finger structures (106) may extend from a lower portion of the peripheral band (102). When installed in a fuel channel (112) of a boiling water reactor (BWR), the critical power ratio (CPR) performance of the periphery rods may be increased, thereby also increasing overall performance. Consequently, the increased power translates to lower fuel cycle costs.