Header Sampling for Fuel Leak Detection in CANDU Reactors
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Solution Overview
Problem
Current systems for detecting fuel leaks in heavy water-moderated nuclear reactors are inefficient, time-consuming, and costly, often requiring reactor shutdowns and extensive modifications, which can lead to increased operating costs and reduced power output.
Innovation Solution
A system and method for detecting fuel leaks using a test tool and container that can be integrated with existing fueling machines in heavy water-moderated reactors, allowing for sampling of primary fluid from fuel channels while the reactor is online, without disrupting operations or requiring piping modifications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If neutron monitoring systems with bleed lines are installed in each fuel channel, then detection precision is improved, but device complexity and cost increase significantly
Solution Approach 1:
The patent combines multiple sampling functions into a single header sampling system. Instead of installing separate bleed lines and detectors in each fuel channel, the invention merges all channel sampling through common headers, reducing device complexity while maintaining detection capability through the centralized sampling approach
Solution Approach 2:
The sampling system serves multiple fuel channels simultaneously through a single header connection. The header sampling apparatus is designed to be universal, capable of detecting leaks across numerous channels without requiring individual specialized equipment for each channel, thereby reducing overall system complexity
2Measurement precision
If feeder scanning with detector is used, then detection precision is improved, but loss of time increases due to reactor shutdown requirement
Solution Approach 1:
The system performs preliminary sampling of primary fluid from headers during normal reactor operation. By continuously or periodically sampling the fluid before a potential leak becomes critical, the system enables early detection without requiring reactor shutdown, thus maintaining both detection precision and operational continuity
Solution Approach 2:
The header sampling system operates continuously during reactor operation, maintaining constant monitoring capability. This continuous sampling action eliminates the need for periodic shutdowns required by traditional feeder scanning methods, ensuring both precision detection and uninterrupted power generation
3Loss of time
If main header sampling is performed, then loss of time is reduced, but measurement precision deteriorates due to inability to locate specific fuel channel
Solution Approach 1:
The header sampling system is segmented into multiple sampling points corresponding to different fuel channel groups. By dividing the header into distinct sampling zones and analyzing fission product concentrations at each zone, the system can pinpoint the specific fuel channel or group containing a leak, thereby maintaining both rapid detection and precise location capability
Solution Approach 2:
Different sections of the header are sampled with different characteristics to identify local leak sources. The sampling system incorporates localized detection capabilities at specific header sections, allowing precise identification of which fuel channel feeds into which header section, thus resolving the location precision issue while maintaining rapid screening capability
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 rapid detection of fuel leaks within 4 to 6 hours, allowing for maximum reactor operation and reducing the risk of power de-rating, with the ability to test up to 16 fuel channels per machine trip, and is transferable to any CANDU reactor site without modifications.
Implementation Method 1
the internal volume of the test container is configured to receive primary fluid from the reactor when the test tool is disposed within the corresponding fuel channel of the reactor
Data Source
AI summary
A defective fuel bundle location system for use with a heavy water moderated nuclear fission reactor having a fueling machine, including a test tool defining an internal volume, the test tool being configured to be received within both the fueling machine and a corresponding fuel channel of the reactor, and a test container defining an internal volume, wherein the test container is configured to be received within the internal volume of the test tool and the internal volume of the test container is configured to receive primary fluid from the reactor when the test tool is disposed within the corresponding fuel channel of the reactor.