Disc-Collimated In-Pipe Detector for Nuclear Holdup Assay
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Solution Overview
Problem
Current non-destructive assay methods for holdup deposits in nuclear piping are labor-intensive, prone to gamma attenuation, and require manual deployment, leading to high uncertainty and costs in decommissioning processes.
Innovation Solution
A robotic device with disc-collimated gamma detection and an untethered autonomous crawler that surveys process piping internally, using disc collimation to view radiation from a cylindrical segment of pipe wall and exclude upstream and downstream radiation, enabling accurate U-235 assay with high count rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If external assay methods are used to measure holdup deposits through pipe walls, then the measurement can be performed without internal access, but gamma attenuation by pipe walls results in high uncertainty and long counting times
Solution Approach 1:
The patent inverts the conventional external assay approach by deploying the detector internally within the pipe. This reversal eliminates the pipe wall attenuation problem entirely, as the detector now views the holdup deposit directly without intervening material. The collimated detector is positioned inside the pipe to view the deposit on the inner wall surface, achieving high-precision measurements with significantly reduced counting times compared to external methods.
2Ease of manufacture
If manual deployment of collimated and shielded detectors is used, then the assay can be performed with existing equipment, but the process is labor-intensive and difficult to automate
Solution Approach 1:
The patent merges the detector assembly with a robotic manipulator system, creating an integrated automated assay device. The collimated detector is mounted on a robotic arm that can be programmatically positioned and deployed within the pipe. This combination eliminates manual deployment operations and enables full automation of the assay process, while maintaining the technical performance of collimated detection.
3Measurement precision
If in-pipe detection is implemented to eliminate through-wall attenuation, then high count rates and accuracy are achieved, but the pipe must be accessed internally which requires cutting or access manifolds
Solution Approach 1:
The patent designs the robotic detector system to be universally deployable through standard pipe access points. The robotic manipulator can navigate through existing manways, inspection ports, or temporary openings without requiring permanent modifications to the pipe structure. This multi-functional approach allows the same system to serve various pipe configurations and access scenarios, achieving internal detection benefits while minimizing structural intervention.
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 method provides accurate, high-cadence, and cost-effective U-235 determination with reduced personnel exposure and time, suitable for various pipe diameters and isotopes, while minimizing attenuation and centering errors.
Implementation Method 1
a detector assembly 101 including a collimator 102 and a detector 110. The collimator 102 and detector 110 are disposed within a pedestal 112 such that the detector assembly 101 is centered on a centerline 120 of the pipe 10
Implementation Method 2
The collimator 102 views radiation only from a known length 105 of pipe 10, thereby excluding radiation from upstream and downstream segments of the pipe 10
Data Source
AI summary
Disclosed herein are a method, apparatus, and software for passive, non-destructive assay of holdup deposits in nuclear piping by in-pipe apparatus. A detector deployed within a pipe is collimated to observe radiation impinging radially inward from decay of deposits that lie on the pipe wall. A radiation detector is centered in the pipe and collimated by a pair of coaxial shielding discs disposed equidistant from the detector. This arrangement causes radiation from a truncated cylinder of pipe deposit within a field of regard to impinge on the detector, while precluding radiation emanating from pipe walls beyond the field of regard from reaching the detector. Hence, observations are unique to a known cylindrical length of pipe. The detector assembly is translated through pipes by an autonomous mobile robotic apparatus. Computer software controls the robotic apparatus, logs data, and post-processes to assay deposits.