Movable Element Position Sensing in Nuclear Reactors with Fiber Tracks
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing position measurement technologies for movable elements in nuclear reactors, such as control rods, face challenges in high-temperature, high-pressure, and corrosive environments, leading to reliability issues and complexity in manufacturing and maintenance.
Innovation Solution
A fiber optic position sensor system using probes and tracks resistant to primary reactor environments, employing reflecting and diffusing surfaces, with a three-level coding system to detect anomalies, and a mechanical system to maintain signal integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If induction measurement technology is used, then position measurement capability is provided, but the system requires numerous cables and temperature-resistant coils that are difficult to produce
Solution Approach 1:
The patent replaces the electromagnetic induction measurement system with an optical measurement system using fiber optic probes. The optical system eliminates the need for temperature-resistant coils and numerous cables, as the fiber optic probes can directly withstand high temperatures and transmit optical signals through the harsh reactor environment without requiring complex cable management.
Solution Approach 2:
The patent changes the measurement parameter from electromagnetic induction to optical reflection/diffusion. By using optical signals instead of electromagnetic induction, the system achieves position measurement capability while eliminating the need for complex temperature-resistant components and cable assemblies.
2Device complexity
If reed relay measurement is used, then the number of wires is reduced, but permanent magnets and reed relays become ineffective at high temperatures (290°C-350°C)
Solution Approach 1:
The patent changes the measurement principle from magnetic field interaction (reed relays) to optical interaction (fiber optic probes). The optical system remains effective at high temperatures because optical fibers and their protective coatings can withstand thermal conditions up to 350°C, unlike permanent magnets and reed relays which fail in this temperature range.
Solution Approach 2:
The patent uses composite material structures for the fiber optic probes, combining temperature-resistant materials (such as ceramic or specialized polymers) with optical fibers. This composite approach allows the probe to maintain both mechanical integrity and optical functionality in the high-temperature reactor environment.
3Measurement precision
If conventional fiber optic sensors are used, then position measurement is possible, but they are not suitable for corrosion and pressure conditions within the reactor vessel
Solution Approach 1:
The patent employs a protective coating or sheath around the fiber optic probe that acts as a barrier against corrosion and pressure. This flexible protective layer allows the probe to withstand the harsh chemical and mechanical environment of the reactor vessel while maintaining the optical transmission properties needed for position measurement.
Solution Approach 2:
The patent uses composite material construction for the fiber optic probe assembly, combining corrosion-resistant materials (such as stainless steel or ceramic coatings) with the optical fiber core. This composite structure provides both mechanical protection against pressure and corrosion while maintaining optical functionality.
4Ease of manufacture
If a simple position sensor is used, then manufacturing is simplified, but fault detection capability is insufficient for safety-critical nuclear applications
Solution Approach 1:
The patent incorporates feedback mechanisms where the optical system not only measures position but also monitors the integrity of the measurement signal. By analyzing the characteristics of the reflected or diffused optical signal, the system can detect faults such as probe misalignment, target obstruction, or signal degradation, providing feedback on system health without adding complex hardware.
Solution Approach 2:
The measurement system performs self-diagnosis by monitoring its own operational parameters. The optical fiber probe simultaneously serves as both the measurement tool and the diagnostic sensor, detecting its own status and potential failures through changes in optical signal characteristics, eliminating the need for separate complex monitoring systems.
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
Provides precise and reliable position measurement of movable elements in nuclear reactors, with improved fault detection and reduced complexity, suitable for harsh reactor conditions.
Implementation Method 1
Reception of the kN optical signals by N tracks resistant to a primary medium, each track receiving k optical signals, said tracks being made up of reflecting surfaces and diffusing surfaces
Implementation Method 2
tracks being made up of reflecting surfaces and diffusing surfaces
Implementation Method 3
Emission of kN optical signals, k and N being natural integers greater than or equal to 1, by kN optical fibers called emitters included in N probes resistant to a primary medium
Data Source
Figure 1~3
Figure 4~6
Figure 7~8
AI summary
The invention relates to a method (300) for measuring the position of a translationally movable element (111) of a nuclear reactor, comprising the following steps: - Emission (301) of kN optical signals (210), k and N being natural integers greater than or equal to 1, by kN optical fibers called emitters (215) included in N probes resistant to a primary medium; - Reception (302) of the kN optical signals by N tracks (22) resistant to a primary medium, each track receiving k optical signals, said tracks consisting of reflecting surfaces (222) and diffusing surfaces (221); - Reception (303) by mN optical fibers called receivers (214), m being a natural integer greater than or equal to k, included in the N probes (21) of the kN optical signals reflected (2221) or diffused (2211) by the N tracks (22); - Conversion (304) of the kN optical signals received by the mN receiving optical fibers (214) into binary code.