System of mobile charged particle detectors and methods of spent nuclear fuel imaging

Patent metadata

Field	Value
Publication number	US-10872746-B2
Application number	US-201916674891-A
Country	US
Kind code	B2
Filing date	Nov 5, 2019
Priority date	Nov 2, 2018
Publication date	Dec 22, 2020
Grant date	Dec 22, 2020

Abstract

Systems, devices and methods for inspecting and imaging of contents of a volume is disclosed. One implementation of the disclosed systems, devices and methods includes an apparatus for inspecting and imaging of contents of a volume of interest which includes a first particle tracking unit of detectors to receive incoming charged particles that transit through an object and to measure position and direction of the charged particles that transit through the object while allowing the charged particles to pass through, and a second particle tracking unit of detectors installed relative to the first particle tracking unit of detectors and to the volume of interest containing the object of inspection so that it is positioned to receive the outgoing charged particles that transit through the first particle tracking unit and transit through the object of inspection and to measure a position and a direction of the outgoing charged particles. The apparatus also includes a processor that processes information from the first and second particle tracking units of detectors to yield an estimate of a spatial map of atomic number and a density of the object. The methods disclosed here include triggering algorithms for signal selection, positional calibration algorithms for locating particle tracking units in absolute three dimensional coordinate space, and three-dimensional tomographic image reconstruction algorithms combining the tracking information from multiple pairs of particle tracking units.

First claim

What is claimed is:

1. An apparatus for inspecting and imaging contents of a volume of interest comprising:
a first particle tracking unit of detectors located to receive incoming charged particles that further transit through an object of inspection contained in the volume of interest;
a second particle tracking unit of detectors located lower relative to the first particle tracking unit of detectors and on a side of the volume of interest opposite the first particle tracking unit of detectors, enabled to receive the charged particles that transit through the first particle tracking unit of detectors and transit through the object and to measure a position and a direction of each charged particle;
a mechanical support structure to keep both the first particle tracking unit of detectors and the second particle tracking unit of detectors in position wherein the first and second particle tracking units of detectors are enabled to receive the charged particles; and
a processor coupled to both the first particle tracking unit of detectors and the second particle tracking unit of detectors to process information from the first and second particle tracking units of detectors to yield an estimate of a spatial map of an atomic number and a density of the object,
wherein the mechanical support structure further comprises at least two mobile assemblies to provide mobility and support for the first and second particle tracking units of detectors, the mechanical support structure being structured to be in a generally vertical orientation to hold the at least two mobile assemblies at different vertical positions so that the first particle tracking unit of detectors is positioned higher than the second particle tracking unit of detectors, the mechanical support structure enabled to provide geometrical rigidity to the at least two mobile assemblies during the inspection.

2. The apparatus of claim 1 , further including at least one rigid metal bar interconnecting the at least two mobile assemblies to enhance a geometrical rigidity of the mechanical support structure.

3. The apparatus of claim 1 , wherein the at least two mobile assemblies are further arranged in a regular geometrical pattern around the object of inspection.

4. The apparatus of claim 1 , further including at least one portable canopy for weather protection of the at least two mobile assemblies.

5. The apparatus of claim 1 , wherein one of the two mobile assemblies is structured so that a mounting height of first particle tracking unit within the mobile assembly is mechanically adjustable.

6. The apparatus of claim 1 , wherein one of the two mobile assemblies is structured so that the mounting height of the second particle tracking sensitive unit within the mobile assembly is mechanically adjustable.

7. The apparatus of claim 1 , wherein the size of the gap between the first and second particle tracking units in the same mobile assembly is mechanically adjustable.

8. The apparatus of claim 1 , wherein the first and second particle tracking units further comprise drift tubes for detecting charged particles.

9. The apparatus of claim 1 , further including a coincidence trigger as a filter to separate signals from the charged particles from gamma-radiation induced signals.

10. A method of operating an inspection apparatus, the method comprising:
positioning an assembly of the first and second particle tracking sensitive units of detectors around the object of inspection to form a system of particle tracking sensitive units by using first and second mobile support structures to hold the first and second particle tracking sensitive units of detectors, respectively, to allow for adjustment of positions of the first and second particle tracking sensitive units of detectors;
receiving at a first particle tracking sensitive unit of detectors, incoming charged particles that further transit through an object of inspection and through a second particle tracking sensitive unit of detectors located lower relative to the first particle tracking detector and to a volume of interest containing the object of inspection;
measuring a position and a direction of each of the charged particles that transit through the object and the first and second particle tracking sensitive units;
collecting the position and the direction of a plurality of charged particles;
processing the position and the direction of the plurality of charged particles as numerical data based on electrical signals generated in the first and second particle tracking sensitive unit of detectors;
determining points of interaction of each charged particle with the first and second particle tracking sensitive unit of detectors;
approximating an incoming trajectory of each charged particle with a straight line based on the determined points of interaction of each charged particle with the first particle tracking sensitive units;
approximating an outgoing trajectory of each charged particle with a straight line based on the determined points of interaction of each charged particle with the second particle tracking sensitive unit of detectors; and
reconstructing a spatial map of material properties based on densities and radiation lengths of the object in the volume of interest and based on the collection of incoming and outgoing particle trajectories.

11. The method of claim 10 , wherein the number of assemblies in the system is chosen based on a size of the object of inspection.

12. The method of claim 10 , wherein a mounting height of the first and second particle tracking sensitive unit of detectors is chosen based on a model of incoming cosmic ray muon flux and a position of the volume of interest relative to the first and second particle sensitive tracking units.

13. The method of claim 10 , further including a geometry calibration based on collected measurements of incoming and outgoing trajectories of the plurality of charged particles.

14. The method of claim 10 , wherein the first and second particle tracking sensitive unit of detectors comprise a plurality of drift tubes and performing an iterative calibration of time-to-radius response function for each drift tube of the plurality of drift tubes.

15. The method of claim 10 , further including filtering out signals not belonging to the measured charged particles.

16. The method of claim 15 , wherein the charge particles are further identified within each assembly based on two indicators of the measured charged particles.

17. The method of claim 16 , wherein a first indicator is further based on a timing coincidence of the measured charged particles within a coincidence window.

18. The method of claim 17 , wherein the coincidence window size can be further set independently for each assembly.

19. The method of claim 18 , wherein the coincidence window size is further optimized based on a timing property of the first and second particle tracking sensitive unit of detectors and an ambient radiation field at a position of the first and second particle tracking sensitive unit of detectors.

20. The method of claim 16 , wherein a second indicator is further based on positions of the first and second particle tracking sensitive units.

21. The method of claim 20 , wherein the second indicator is further optimized based on a position of a selected drift tube within the assembly and relative a position of the assembly relative to the object of inspection.

Assignees

• Decision Sciences Int Corp

Inventors

• Borozdin Konstantin

Classifications

• G01N23/04

  and forming images of the material · CPC title

• G01N2223/626

  radioactive material · CPC title

• H01J37/244 Primary

  Detectors; Associated components or circuits therefor · CPC title

• G01T1/167

  Measuring radioactive content of objects, e.g. contamination (whole body counters G01T1/163) · CPC title

• H01J2237/24455

  Transmitted particle detectors · CPC title