SiC Gamma Detector Arrays for In-Core Fuel Bundle Leak Triangulation
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Solution Overview
Problem
Current methods for detecting leaks in fuel bundles within CANDU-style nuclear reactors are complex, expensive, and imprecise, with conventional detectors providing delayed signaling and uncertainty in identifying the exact location of defective fuel bundles, which complicates fuel channel power management and fission product contamination control.
Innovation Solution
A method using an array of solid-state radiation detectors with a silicon carbide substrate, epitaxial silicon carbide layer, and Schottky contact, configured to detect gamma radiation from fission products, allowing for continuous monitoring and triangulation of radiation readings to precisely locate leaks in fuel bundles by identifying changes in gamma radiation levels and time-dependent changes along the fuel channels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional detectors (rhodium-based or vanadium flux detectors) are used to monitor fuel bundles, then detection coverage is provided, but the signaling is delayed and location precision is insufficient
Solution Approach 1:
The detector is segmented into multiple independent solid state radiation detection elements arranged in a two-dimensional array, where each element can independently detect and signal radiation events. This segmentation allows for precise spatial localization of leaks while maintaining prompt signaling capability, as each segment operates autonomously to provide both timing and position information.
Solution Approach 2:
The invention transitions from conventional single-point or linear detector arrangements to a two-dimensional array of solid state detection elements. This dimensional expansion enables simultaneous determination of both the timing and spatial coordinates (x, y, z) of radiation events, thereby achieving precise location identification without sacrificing response speed.
2Loss of information
If conventional detection methods are used, then fuel bundle leak detection is achieved, but the exact location identification is uncertain and complex
Solution Approach 1:
The invention replaces complex mechanical sampling and analysis systems with a streamlined electronic detection system based on solid state radiation detectors. The direct electronic signaling capability of these detectors eliminates the need for physical coolant sampling, transport, and laboratory analysis, thereby reducing system complexity while improving location information accuracy through precise spatial mapping of detection events.
Solution Approach 2:
The system incorporates real-time feedback through electronic signaling from the solid state detection elements, which immediately communicate radiation event location and intensity to the control system. This feedback mechanism enables continuous monitoring and precise location tracking without the delays and complexities of conventional sampling methods, allowing for dynamic adjustment of fuel channel power management.
3Reliability
If delayed signaling detectors are used, then power measurement is provided, but prompt leak detection and response is not achieved
Solution Approach 1:
The solid state radiation detection elements provide continuous monitoring of radiation levels in each fuel bundle, maintaining constant vigilance without interruption or delay. This continuous detection capability ensures that leaks are identified immediately upon occurrence, enabling prompt response while maintaining reliable detection coverage throughout the reactor core.
Solution Approach 2:
The system performs preliminary detection and signaling actions directly at the source of radiation events through the solid state detection elements embedded in or near the fuel bundles. This preliminary action occurs at the moment of leak occurrence, eliminating subsequent delays associated with sample transport, processing, and analysis, thereby achieving both high reliability and rapid response.
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 prompt and precise detection of fuel bundle leaks, reducing uncertainty and operational costs by providing immediate signaling of radiation leaks, allowing for effective fuel channel power management and minimizing coolant contamination.
Implementation Method 1
solid state detectors being comprised of a silicon carbide substrate having a first side and a second side, an epitaxial silicon carbide layer on the first side of the substrate, a Schottky contact covering at least a portion of the epitaxial layer, an electron emitter material spaced from the Schottky contact and defining a gap therebetween, each of the gap and the electron emitter material configured to a depth effective for detecting radiation above the base line level
Data Source
AI summary
The method is well-suited for use in a reactor having a plurality of cladding tubes housed in a plurality of linearly arranged channels for flowing coolant past the cl adding tubes. The method includes monitoring channels for the occurrence of an increase in radiation above selected base lines indicative of the presence of at least one fission product in the coolant in at least one of the plurality7 of channels, monitoring the channels for the occurrence of time dependent changes in the strength of radiation in the coolant above the base line along the length of at least one of the plurality of channels. The leak location is calculated by triangulating the radiation readings from a fixed linear array of detectors positioned adjacent to the channel s to determine the location of the strongest radiation reading and the location along the length of the channel where the increase in radiation occurred.