Kr-85 Leak Detection in Nuclear Fuel Storage Containers
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Solution Overview
Problem
Existing leak detection methods for nuclear fuel elements are inadequate as they are performed before loading into containers, making them susceptible to damage during subsequent handling, and fail to detect leaks effectively due to undetectable gaseous isotopes after long storage.
Innovation Solution
A device equipped with Kr-85 detectors, a gas distribution box, and a pneumatic circuit to analyze gas from the container after loading, using scintillation detectors surrounded by a tungsten shield, with pressure, temperature, and flow sensors, and electronics for detecting Beta activity of Krypton-85.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If leak detection is performed before loading fuel elements into containers, then the detection process can be completed earlier, but the fuel elements remain susceptible to damage during subsequent handling and transfer operations
Solution Approach 1:
The patent applies preliminary action by performing leak detection before fuel elements are loaded into containers. The detection system is prepared and positioned in advance, and the inspection is conducted on fuel elements while they are still accessible in the spent fuel pool, ensuring that any leaks are identified before the elements undergo subsequent handling and transfer operations that could compromise their integrity
Solution Approach 2:
The patent implements feedback through a complete detection system that provides real-time information about the condition of fuel elements. The system includes sensors, signal processing electronics, and indication means that feed back the leak detection results to operators, enabling immediate identification and classification of elements with containment issues before they are moved to storage containers
2Device complexity
If conventional leak detection methods are used, then the inspection process is simpler, but they fail to detect leaks effectively due to undetectable gaseous isotopes after long storage periods
Solution Approach 1:
The patent replaces conventional mechanical or pressure-based leak detection methods with a nuclear physics-based detection system. Instead of using mechanical pressure tests or visual inspection, the system employs beta radiation detectors to sense the presence of Kr-85 gas that escapes from leaking fuel elements, providing highly sensitive detection capability that can identify even minimal leaks that would be undetectable by conventional means
Solution Approach 2:
The patent changes the detection parameter from mechanical pressure or visual appearance to beta radiation intensity. By measuring the beta radiation emitted by Kr-85 isotopes that escape from leaking fuel elements, the system transforms the detection approach to one that is sensitive to the actual physical phenomenon occurring in stored fuel elements - the radioactive decay and gas release - rather than relying on indirect mechanical indicators
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 leak detection of nuclear fuel elements within storage containers by detecting Krypton-85 outside the rods, ensuring containment integrity before final storage, avoiding damage during handling and overcoming the challenge of undetectable isotopes.
Implementation Method 1
The device is equipped with Kr-85 detectors, using scintillation detectors surrounded by a tungsten shield, with electronics for detecting Beta activity of Krypton-85
Implementation Method 2
using scintillation detectors surrounded by a tungsten shield
Implementation Method 3
a pneumatic circuit to bring gas from the fuel element storage container to the scintillation detectors
Implementation Method 4
the distribution box is provided with means for the condensation and extraction of moisture from the gas
Implementation Method 5
Detectors are surrounded by a sealed chamber and a shield made of tungsten or other heavy material
Data Source
Figure 1
Figure 2
AI summary
System for detecting leaks in nuclear fuel elements inside storage containers (1) comprising: at least two scintillation detectors (9); a gas distribution box (2) and a pneumatic circuit provided with a vacuum pump (4) adapted to bring said gas from the storage container (1) to the distribution box (2) and extract part of said gas from the box (2) and bring it to the detectors (9); electronics associated with the detectors (9) adapted to quantify the Beta activity of the Krypton-85 emitted by the gas.