Flexible Nuclear Level Gauge Using Scintillating Fibers
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Solution Overview
Problem
Nuclear level sensing gauges face limitations due to light intensity losses in long lengths of scintillating crystals and fibers, leading to complex and costly solutions, and rigidity issues that restrict flexibility and maintenance in harsh environments.
Innovation Solution
The use of flexible scintillating fibers as light guides to transfer gamma-radiation scintillations to a common light sensor, eliminating the need for contact coupling and allowing the gauge to bend and conform to complex vessel shapes, while incorporating scintillating crystals or fibers within a protective housing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If scintillating crystals or fibers are used in long lengths, then the detection range is extended, but light intensity losses increase leading to reduced measurement precision
Solution Approach 1:
The scintillator is divided into multiple discrete crystal elements arranged in series along the detection path. Each crystal segment independently converts radiation to light signals, which are then optically coupled to a single photomultiplier tube. This segmentation maintains detection range while preserving light intensity through optimized segment-to-detector coupling.
Solution Approach 2:
Optical coupling media (such as optical grease or gel) are introduced as intermediaries between the scintillator crystal segments and the photomultiplier tube window. These coupling media maximize light transmission efficiency from the scintillator segments to the detector, reducing light intensity losses and maintaining measurement precision over extended detection ranges.
2Measurement precision
If scintillating crystals are used, then detection accuracy is maintained, but rigidity increases making the gauge difficult to install in complex vessel shapes
Solution Approach 1:
The rigid scintillator crystal is segmented into multiple smaller crystal elements that can be independently positioned and oriented. These segmented crystals are mounted on a flexible support structure, allowing the assembly to conform to curved or complex vessel geometries while maintaining detection accuracy through proper positioning of each crystal segment.
Solution Approach 2:
A flexible housing or support structure is introduced to hold the scintillator crystal segments. This flexible framework allows the gauge to bend and conform to complex vessel shapes while maintaining the precise alignment and optical coupling of the crystal segments to the photomultiplier tube, thus preserving detection accuracy.
3Loss of energy
If contact coupling between scintillators and light guides is used, then light transmission efficiency is maximized, but maintenance difficulty increases in harsh environments
Solution Approach 1:
The optical coupling is achieved through intermediary coupling media (optical grease or gel) applied at the interfaces between scintillator segments and the photomultiplier tube window. This intermediary layer maximizes light transmission efficiency while being easily reapplicable during maintenance, allowing quick restoration of optical coupling without complex realignment procedures in harsh environments.
Solution Approach 2:
The optical coupling system is designed to be self-maintainable through simple reapplication of coupling media. The scintillator segments and photomultiplier tube are positioned such that the optical interfaces are easily accessible, allowing field personnel to clean and reapply optical grease or gel without specialized tools or extensive disassembly, thus facilitating easy maintenance while preserving light transmission efficiency.
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
This approach extends the effective length of level detection, reduces costs and complexity, and enhances flexibility and maintainability by using flexible components that can accurately measure product levels in vessels with curved or complex shapes without requiring intimate contact between scintillators and light guides.
Implementation Method 1
A source of nuclear radiation is positioned on one side of the bin to be level sensed... The radiation exiting the source is in the shape of a wide, generally vertically dispersed beam, directed toward the interior of the bin. The product in the bin substantially absorbs the radiation that impinges upon it... the radiation reaching the detector creates scintillating light flashes in the detector.
Implementation Method 2
The use of flexible scintillating fibers as light guides to transfer gamma-radiation scintillations to a common light sensor... flexible scintillating fibers as light guides to transfer gamma-radiation scintillations to a common light sensor
Implementation Method 3
A photomultiplier tube (PMT), used as a light sensor, is coupled to an end of the crystal. The PMT detects photons of light emanating from the scintillating crystal, and produces a signal indicative of the amount of radiation impinging on the crystal
Data Source
AI summary
A nuclear level sensing gauge for measuring the level of product in a bin. The gauge includes a source of nuclear radiation positioned adjacent the product in the bin and a housing. A primary scintillator is provided in the housing, adjacent the product in the bin, and opposite the source of nuclear radiation. Nuclear radiation from the source passes through the bin and impinges upon the primary scintillator, generating scintillating light. A light guide conveys the scintillating light from the primary scintillator to light sensing circuitry. The light guide is coupled to the primary scintillator through an air gap. The light guide produces scintillating light flashes in response to absorption of the scintillating light from the primary scintillator. The light sensing circuitry collects the light flashes from the light guide to provide a representation of the level of radiation-absorbing product in the bin.