DRAFT

TECHNICAL NOTE

Technical Report

[Inspection Cell – Visual Inspection and 3D Mapping]

Prepared by

Mr. Tim Pegg

Directed by

Dr. Phil Purnell

CONTENTS

1SUMMARY

2AIM

3INTRODUCTION

4VISUAL INSPECTION

4.1Direct Viewing

4.2Indirect Viewing – crawler-cam

4.3Indirect Viewing – fixed CCTV

4.4Indirect Viewing – Endoscope [1]

4.5Indirect Viewing – Master/Slave Manipulator held CCTV

53D MAPPING

5.1How it works

5.2Accuracy

5.3Positions of 3D mapping equipment

6DISCUSSION

7CONCLUSION

8BIBLIORGAPHY

9REFERENCES

357976 / 1

DRAFT

TECHNICAL NOTE

INSPECTION CELL – VISUAL INSPECTION AND 3D MAPPING

1SUMMARY

This technical note discusses Visual Inspection and 3D Mapping. Visual Inspection may be direct, that is, through a protective window, or indirect, using cameras. 3D Mapping is an optical technique for recording the envelope dimensions of a package.Each mapping of a package is stored on a database so that future mappings can be compared to previous mappings, thus highlighting any dimensional changes. It is proposed that two Visual Inspection methods are used, along with 3D mapping. The Visual Inspection would be direct, looking through an oil filled shielded window, and indirect, using an through-wall Endoscope with built in camera.

2AIM

To find methods that will create asmooth process of comprehensive, effective inspection and ensure the safe storage of the radioactive waste.A thorough procedure will allow faulty packages to be detected, and sent for reworking or overpacking where necessary.

3INTRODUCTION

A separate technical report, ‘Inspection Processes and Methods’, considers all the methods of inspection and discusses the preferred processes for an overall inspection routine. However, this report considers two of these methods in more detail – Visual Inspection and 3D Mapping. The advantages and disadvantages of each are discussedand a preferred method recommended.

4VISUAL INSPECTION

Visual inspection is one of the inspection methods proposed for use in the Inspection Cell. This section discusses the pros and cons of Visual Inspection and the means by which it could be implemented into the Inspection Cell.

Visual inspection could be conducted in any of following:

‘Direct Viewing’ - workers looking at packages through shielded windows

‘Indirect Viewing’ – crawler-cam – cameras mounted on robotic crawlers that move within the ‘hot’ cell

‘Indirect Viewing’ with fixed CCTV within the cell

‘Indirect Viewing’ with an Endoscope

‘Indirect Viewing’ with Master/slave Manipulator held CCTV[T1]

4.1Direct Viewing

Workers would view a package through an oil filled shielded window of thickness approximately 1.2m. needs to be referenced !!!!!!!!!!!

Advantages

  • Direct Viewing is carried out by humans so little maintenance is required.
  • Maintenance is straightforward – includes monthly inspection of oil reservoir levels and annual light transmissibility check.
  • Completed on a ‘real-time’ basis. Direct Viewing provides an instant output to the viewer.

Disadvantages

  • Accuracy may vary depending on the eyesight of the viewer
  • Yellow colour of the glass will impair viewing to some extent.
  • Impossible to compare results with previous ones. Experience of the viewer will mitigate this problem.

4.2Indirect Viewing – crawler-cam

Cameras are mounted on radio controlled robotic crawlers that move around the ‘hot’ cell, sending images to a remote monitor.

advantages

  • Cameras can zoom in on critical areas at any angle, enhancing the accuracy of the inspection.

disadvantages

  • Maintenance would need to be carried out remotely in the ‘hot’ area using Master/Slave Manipulators. If completed in a ‘cold’ area, the crawler-cam would need to be decontaminated beforehand.

I haven’t got a manufacturer of these things!!!

4.3Indirect Viewing – fixed CCTV

Cameras would be fixed at the base, mid-height, and above a package inspection area.

advantages

  • Cameras can zoom in on critical areas
  • Cheaper than Endoscopes.
  • Can have built in lights

disadvantages

  • Maintenance would need to be carried out remotely in the ‘hot’ area using Master/Slave Manipulators. If completed in a ‘cold’ area, the CCTV camera would need to be decontaminated beforehand.
  • Large size (could be upto 1m in length[e2]).

4.4Indirect Viewing – Endoscope [1]

The endoscope would pass through the Inspection Cell Wall from the ‘cold’ to ‘hot’ area.

advantages

  • Ability to pan, rotate 360° and ± 90° tilt in direction of viewing
  • Cameras can zoom in on critical areas
  • Dome acts as a seal against contamination from hot area so the control electronics, drive motors and camera are all accessible from the ‘cold’ side.
  • True colour representation. (No yellow tint as in 4.1 Direct Viewing)
  • Zoom 6x
  • Only extends into the hot area a short distance. (2-3cm)

disadvantages

  • Needs additional lighting
  • Twice the price of fixed CCTV.

Figure 1 - Rendering of Endoscope in the Inspection Cell1

Figure 2 – Schematic of Endoscope.1

4.5Indirect Viewing – Master/Slave Manipulator held CCTV

advantages

  • Ability to pan, rotate 360° and ± 90° tilt of direction of view
  • Cameras can zoom in on critical areas
  • Cameras can be held within a 2-3cm of package for very detailed viewing
  • Can have built in lights
  • Protective gaiters keep the camera from the ‘hot’ side

disadvantages

  • Needs additional lighting
  • Maintenance would need to be carried out remotely in the ‘hot’ area using Master/Slave Manipulators. If completed in a ‘cold’ area, the CCTV camera would need to be decontaminated beforehand.

Price?????

53D MAPPING

After entering the PGRC for the first time, a package will be ‘mapped’ in an Inspection Cell, before being emplaced in the associated Storage Vault. This will provide a ‘reference map’ of the package. When the package returns to the Inspection Cell for any reason, subsequent maps will be taken and compared to the reference map to note changes in the envelope dimensions of the package.

5.1How it works

A 2D pattern of light stripes is projected onto the object. The light stripes will reflect off the object and reach the camera lens at different angles due to the non-flat surface of the object. The pattern is imaged by means of a camera which is placed at an angle relative to the light projector.

5.2Accuracy

3D mapping can detect changes in envelope dimensions to approximately 1mm[e3]. Crack detection is possible in that small areas of the drum can be zoomed in on and mapped. For example, an area of 0.1x0.1m would detect changes in dimensions of 0.001mm). [2[e4]]

Figure 3 – Specifications of 3D Mapping system [3]

Figure 4 – Example of comparison of a subsequent map and a reference map. [3]

Yellow is zero deviation from the ‘reference map’, while red corresponds to +1mm and blue corresponds to a -1mm change.

Figure 5 - Schematic of 3D Mapping system [2]

5.3Positions of 3D mapping equipment

To inspect the entire package envelope, the 3D mapping equipment will either be moved to different heights or three sets of equipment will be setup – at the base, middle and top of the shielded window. The following figures assume that the mapping equipment can be moved.

To map the sides of a package, the 3D mapping equipment will be located as in Figure 6. The package will be rotated such that all sides are mapped[e5].

Figure 6 – 3D mapping the sides of a package

To map the top of the package, the 3D mapping equipment will move to the top of the window.

Figure 7 – 3D mapping the top of a package

To map the base of the package, the 3D mapping equipment will move to the base of the window and the package will be lifted.

Figure 8 – 3D mapping of the base of a package

6DISCUSSION

Despite disadvantages of direct viewing such as the reliance on the experience of the viewer and yellow tint of the oil filled glass, it is felt that direct Visual Inspection should be included as a method of inspection. This is the closest inspection method to actual physical inspection. Furthermore, it is considered that any independent inspectors visiting the PGRC would much prefer to actually see the waste packages for themselves. And finally, maintenance is minimal.

It is unclear at this stage whether suitable cameras are already available to be used in a crawler-cam. Having a mobile camera seems only to add complexity, when a fixed CCTV camera option is available, and many suitable models already on the market. [4]Nevertheless, using cameras in the ‘hot’ area of the Inspection Cell would mean a more complicated method of maintenance and they can be upto 1m in length. Although more expensive and with the added requirement of external lighting., the Endoscope option would provide detailed inspection with no maintenance issues as the camera and other moving parts would always be connected to the ‘cold’ side. It would also not take up space in the Inspection Area and thus the package could be located closer to the shielded window.

A camera held by the Master/Slave manipulators seems a very reasonable option, as the camera would have a light built in and manipulators could move it to any location and angle around a package. The camera could be surrounded by protective ‘gaiters’. However, it is not known whether this technique has been tried before.

The 3D Mapping takes only seconds to complete. As a package is mapped on entry to the PGRC and also during subsequent inspections, 3D mapping provides a robust comparison of a package’s envelope dimensions over time and thus indicating any pressure changes inside a container.

7CONCLUSION

The minimal maintenance and the very fact that a viewer can physically see a package, will mean direct Visual Inspection should be a part of the inspection process. Saving space in the ‘hot’ area, its ease of maintenance and proven track record are reasons to also put forward the Endoscope indirect Visual Inspection method. 3D Mapping would provide a quick, detailed examination, giving quantitative records that can track any changes in a package’s dimensions over time.

8BIBLIORGAPHY

Sintef (2005). “3D shape measurement”. [Online]. Viewed 2007 February 16.Available:

9REFERENCES

[1]IST Corp. (unknown) ONLINE “Radiation Tolerant Thru-Wall/Roof Viewing System”. [Online]. Last viewed 2007 March 11. Available:

[2]Personal correspondence with Øystein Skotheim. Sintef. (March 2007).

[3]Skotheim,. Øystein. (March 2007). “Optical shape measurement with structured light”. [Online]. Viewed 2007 February 16. Available:

[4]IST Corp. (unknown) ONLINE “Inspection: High Radiation Tolerant Cameras”. [Online]. Last viewed 2007 March 11. Available:

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[T1]Also check out Endoscope at Fortrum Finland and Nexia Solutions. Don’t think they use endoscopes for checking waste packages but may know a man who does. …

[e2]Picture may be black and white – most cameras seem to be black and white. I don’t know why.

[e3]Drum is 1200mm x 800mm. Accuracy is 1/1000 between x,y points

So drum is approx 1m high so a thousandth of a 1m is 1mm.

[e4]would these cracks still be too big – ask Mark

[e5]What to do with the 500L drum which is circular i.e. doesn’t have four sides?!!!!