Fission Product Analysis Device with Dual-Phase Separation
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Solution Overview
Problem
Current methods for detecting fission products in nuclear fuel rods face challenges, especially during long storage times or in high activity environments, where defects may be difficult to detect due to limited availability of detectable nuclides and high background interference, and gaseous fission products may escape, making reliable leakage detection problematic.
Innovation Solution
A novel analysis device with separate lines for liquid and gas samples, equipped with detectors for gamma and beta radiation measurement, and a separation device to extract gaseous fission products from liquids, allowing for continuous sampling and detection of a broad range of fission products, including krypton and xenon, suitable for various sipping systems and leakage types.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single-phase liquid sampling system is used for fission product detection, then the device complexity is reduced, but the measurement precision and detection reliability deteriorate due to inability to separately analyze gaseous and liquid fission products
Solution Approach 1:
The sampling system is divided into two independent phases: a gas sampling line with a gas detector for detecting gaseous fission products (kr-85, xenon), and a liquid sampling line with a liquid detector for detecting liquid fission products (cs-137, i-131). This segmentation allows each detector to be optimized for its specific phase, improving measurement precision while maintaining manageable system complexity through modular design.
Solution Approach 2:
A separation device is introduced as an intermediary component between the fuel rod environment and the detection system. This device separates gaseous fission products from liquid samples before they reach the detectors, enabling accurate phase-specific detection and resolving the contradiction between simple system structure and precise measurement.
2Reliability
If sampling is performed after long storage times, then the reliability of fuel rod tightness verification is maintained, but the quantity of detectable fission products decreases due to decay of short-lived nuclides
Solution Approach 1:
The dual-phase detection system provides universal detection capability for both short-lived and long-lived fission products across different time periods. By detecting both gaseous products (kr-85, xenon) and liquid products (cs-137, i-131) simultaneously, the system maintains reliability for tightness verification whether sampling occurs immediately after reactor operation or after extended storage periods when only long-lived nuclides remain.
3Device complexity
If gaseous fission products are not separately extracted, then the device complexity is reduced, but the detection reliability deteriorates due to escape of gaseous products from liquid samples
Solution Approach 1:
The system segments the sampling process into separate gas and liquid pathways. The gas sampling line directly extracts gaseous fission products from the fuel rod environment before they can escape into the liquid phase, while the liquid sampling line handles liquid samples independently. This segmentation ensures reliable detection of gaseous products that would otherwise be lost.
Solution Approach 2:
The system performs preliminary separation of gaseous fission products from the fuel rod environment through the dedicated gas sampling line before they have opportunity to dissolve or escape into the liquid coolant. This preliminary action captures volatile radionuclides like kr-85 and xenon that are prone to phase transfer, ensuring they are detected in the gas phase where they belong.
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 reliable detection of fission products across different types of leakage and storage times, independent of decay or storage conditions, by continuously supplying gas and liquid samples to detectors, ensuring accurate identification of defects in fuel rods.
Implementation Method 1
a first detector connected to the first line and designed for measuring the radioactivity of fission products contained in the liquid sample
Implementation Method 2
a second detector connected to the second line and designed for measuring the radioactivity of fission products contained in the gas sample
Implementation Method 3
a separation device is provided for separating gas from the first line carrying the liquid sample
Data Source
AI summary
An analysis device for detecting fission products by measurement of a radioactivity includes a first line for carrying a liquid sample, a first detector connected to the first line and designed for measuring the radioactivity of fission products contained in the liquid sample, a second line for carrying a gas sample and a second detector connected to the second line and designed for measuring the radioactivity of fission products contained in the gas sample. The analysis device includes a separation device for separating gas from the first line carrying the liquid sample, which line has an outlet opening into the second line for gas separated from the liquid sample. The outlet opening fluidly connected to the second lines in such a manner that the gas separated from the liquid sample is suppliable as a gas sample to the second detector for measuring the radioactivity of fission products contained therein.