BWR Fuel Assembly Interaction Device for Lower Tie Plate Sealing
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Solution Overview
Problem
In Boiling Water Reactors, the 'bundle-in-basket' design allows for easier maintenance but results in water flow lifting the lower tie plate, potentially compromising the fuel assembly's operation and integrity, and the lower tie plate's debris filtering function is not effectively sealed, leading to potential damage.
Innovation Solution
A configurable interaction device on the lower tie plate that can be activated or deactivated, either automatically by temperature or manually, to establish an axial connection or seal with the fuel channel, preventing the lower tie plate from lifting and ensuring water does not bypass the filter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the lower tie plate is axially connected to the fuel channel to prevent lifting, then the reliability of the fuel assembly is improved, but the ease of maintenance deteriorates
Solution Approach 1:
The interaction device is designed to be configurable between an active state (providing axial connection) and an inactive state (allowing removal). This dynamic capability enables the system to adapt its configuration based on operational requirements - maintaining reliability during operation while enabling maintenance when needed
Solution Approach 2:
The interaction device is implemented as a separate, removable component mounted on the lower tie plate. This segmentation allows the device to be independently activated or deactivated without affecting the entire fuel assembly structure, enabling selective connection to the fuel channel
2Ease of repair
If the lower tie plate is not axially connected to the fuel channel, then the ease of maintenance is improved, but the reliability deteriorates due to water flow lifting
Solution Approach 1:
The interaction device is configured to automatically activate when water flows through the lower tie plate, utilizing the water flow itself to trigger the connection mechanism. This self-activating feature ensures reliable sealing without requiring external control systems
Solution Approach 2:
The interaction device serves as an intermediary element between the lower tie plate and the fuel channel. When activated, it provides the necessary axial connection and sealing function that directly links these two components, preventing water bypass while maintaining the ability to disconnect for maintenance
3Reliability
If the interaction device is activated to seal the gap between the lower tie plate and fuel channel, then the reliability is improved by preventing water bypass, but the device complexity increases
Solution Approach 1:
The interaction device utilizes changes in physical parameters (such as temperature or water flow) to automatically transition between active and inactive states. This parameter-driven activation eliminates the need for complex control mechanisms while ensuring reliable sealing when needed
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 interaction device maintains the lower tie plate's position and prevents water bypass, enhancing the fuel assembly's reliability and integrity during operation while allowing for easy maintenance by switching between active and inactive configurations.
Implementation Method 1
The interaction device is configured to switch between the inactive configuration and the active configuration as a function of temperature
Data Source
AI summary
A BWR fuel assembly is elongated along a fuel assembly axis and comprises a lower tie plate, an upper tie plate axially spaced from the lower tie plate, a bundle of fuel rods extending axially between the lower tie plate and the upper tie plate, and a tubular fuel channel extending from the lower tie plate to the upper tie plate with encasing the fuel rods. The fuel assembly comprises an interaction device mounted on the lower tie plate and configured to interact with the fuel channel. The interaction device has an inactive configuration and an active configuration.