[e1]
nirex
Technical Report
Part 3
[Inspection Cell – methods of inspectionlayout]
Prepared by
Mr. Sebastian Roberts
Mr. Tim Pegg
Mr. Sam Billing
Mr. Nick Petousis
Mr. Iain Hughes
Mr. Danny Thomas
Mr. Carl Young
Mr. Kevin Yong
Directed by
Dr. Phil Purnell
AIM
A well thought out layout will facilitate the most efficient and comprehensive inspection process possible. Visual inspection plays an important role in both the monitoring of the packages and also their inspection of packages. This report the looks into how visual inspection could be implemented in the iInspection cCell.various aspects of the Inspection Cell and puts forward an overall concept design.
INTRODUCTION
Visual inspection is one of the inspection methods being adopted in the Iinspection cCell, along with and also the waste monitoring in the storage vault. This report discusses the advantages and disadvantages of visual inspection and how it could be implemented into the Phased Geological Repository Centre (PGRC).
The Inspection Cell has been divided into component parts and each part examined, both in itself, but also its integration within the cell as a whole.
Visual inspection could be conducted in three ways
a) Entry/exit of package
naked eye with shielded windows approximately 1.2m thick
advantages
Reliable. Sophisticated electronic sensors rely on batteries and circuits. A small break down or malfunction in one of these two could cause malfunction of the whole sensor.
Doesn’t incur many operational costs and the maintenance fee is cheaper when compared to other forms of inspection.
only requires the maintenance of the shielded windows, such as cleaning and changing the oil film.
Completed on a ‘real-time’ basis. Unlike other inspection methods which requires time for computer processing or experiments to be finished, visual inspection provides an instant output to the viewer.
disadvantages
Visual inspection is often obstructed by blind spots(surely we must be able to view all over a package?)
arguably not reliable for it is subjective and difficult to compare results.
Shielded windows are also expensive and maintenance work is difficult to carry out.How do we know this? What’s the reference for this?
b)by mounting cameras on robotic crawlers that move within the ‘hot’ cell.
Advantages
disadvantages
some areas may inaccessiblity of crawlers.
c)‘endoscope’ – robotic arm that has a camera one the end.
Advantages
disadvantages
ADVANTAGE
Visual inspection is reliable. Sophisticated electronic sensors rely on batteries and circuits. A small break down or malfunction in one of these two could cause malfunction of the whole sensor.
Visual inspection doesn’t require much operational cost and maintenance cost is relatively cheaper compared to other forms of inspection.
Visual inspection only requires maintenance of shielded windows, such as cleaning and changing oil film.
Visual inspection could also be done in a ‘real-time’ basis. Instead of some inspection methods which require time for computer or experiments to be finished, visual inspection provides a direct output to the viewer. Hence, it could be done relatively quickly.
DISADVANTAGE
Visual inspection is somehow difficult to be implemented.
Visual inspection could only be conducted Visual inspection is often obstructed by blind spots or inaccessible of crawlers.
Visual inspection is arguably not reliable for it is subjective and difficult to compare results.
Often permissible crack widths are often difficult to be observed by the eye.
Shielded windows are also expensive and maintenance work is relatively difficult to
BEST PRACTICES
Visual inspection should be done with adequate lighting. Hence adequate lighting within the inspection cell should be made.
It is also advisablemay be necessary that robotic crawlers to be are equipped with lightings to allow assist visual inspection to be conducted easily.
CCTV cameras should also be radioactive resistant and be able to zoom, pan and tilt so all areas and angles of the package can be viewed. This is to increase flexibility of cameras.
Blind spots should be minimised through outlay of the inspection cell. Waste monitoring within the vault however should allow access for robotic crawlers.
It is best practice to Must be able to view and therefore monitor all inspection be able to view the processprocesses of inspecting packages and repackaging them via a shielded window to monitor . This could assure that all processes are carried out smoothly.
3D MAPPING
As each package enters the PGRC for the first time, it will be mapped en route to the storage vault. This will take place in the Inspection Cell of the target vault. This will provide a ‘reference map’ of the package.
After emplacement in the storage vault, each package will be taken to the Inspection Cell at regular intervals during the 300 year monitoring period to be mapped again. (e.g. approximately every 17 years if 1 package* from each vault is inspected each day).
Subsequent maps will be compared to the reference map to note changes to the envelope dimensions of a package over time.
* In the reference case, 1 package = 4x 500L drums/ 1x3m3 box/ 1x3m3 drum
HOW 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.
ACCURACY
can detect change in envelope dimensions of the package to approximately 1mm[e2].
crack detection is possible in that small areas of the drum can be zoomed in on and mapped.(e.g. an area of 0.1x0.1m would detect changes in dimensions of 0.001mm)
What is the upper limit for the max allowable crack size before reworking is needed?
Figure 1 – Specifications of 3D Mapping system1
Figure 2 – Example of comparison of a subsequent map and a reference map.1
Yellow is zero deviation, while red corresponds to +1mm and blue corresponds to -1mm deviation.
Figure 3 – Schematic of 3D Mapping system1
THREE POSITIONS OF 3D MAPPING.
a)To map the sides of a package, the 3D mapping equipment will be located as in Figure 4. The package will be rotated such that four sides are mapped.
Figure 4 – 3D mapping of the sides of a package
b)To map the top of the package, the 3D mapping equipment will move to the top of the window.
Figure 5 – 3D mapping of the top of a package
c)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 6 – 3D mapping of the base of a package
i) Single crane
The crane in the storage vault will pass over the Transfer Tunnel and place the package into the ‘Docking Area’ (3). The package will be transferred to the ‘Outlet’ (4) during the Inspection Process. The Storage Vault Crane will then carry the inspected package back to the storage vault (6) or onto a transfer bogie (5) in the Transfer Tunnel, should the package need to be taken to the Overpacking Cell.
Figure 1 – Entry/exit of package using Option i) Single Crane
ii) Single + horizontal shift to Transfer Tunnel
Same as for Option i) except Storage Vault Crane can only take a package at the ‘Outlet’ (4) back to the Storage Vault. A secondary crane or conveyor belt would transport the package to the transfer bogie (5) should this be necessary.
Figure 2 – Entry/exit of package using Option ii) Single + horizontal shift
to Transfer Tunnel
iii) Single Crane to Transfer Tunnel
The Storage Vault Crane only takes the package to and from the transfer bogie, either (1) to (2) OR (5) to (6). Like Option ii) a secondary crane or conveyor belt would transfer the package between (4) and (5) but also between (2) and (3).
Figure 3 – Entry/exit of package using Option iii) Single to Transfer Tunnel
b) Docking Area
This area needs to accept stillages (containing four 500L drums), 3m3 boxes and 3m3 drums. Each package will have a T-lock which a crane would use to lift/carry it with. However, to remove a 500L drum from a stillage/carry it, the crane would also need a ‘3 point grab’, in addition to the T-lock feature.
c) Buffer Store
Packages would enter this area following entry to the Inspection Cell, should the Inspection or Reworking Areas be unavailable. This would occur when:
- inspection or reworking is currently taking place
- inspection shows that a package needs overpacking so it stay in the inspection area until the overpacking container arrives
d) Pending packages
This area houses stillages from which a 500L has been removed to be inspected. After inspection, any reworking, and assuming overpacking is not needed, the 500L drum will be returned to its original stillage. This stillage is then returned to the storage vault.
e) Windows/Viewing Areas
Inspectors would stand in the ‘cold’ Viewing Areas to carry out Direct Viewing of the packages through the oil filled shielded windows.
f) Reworking
Master/slave manipulators and other necessary equipment would be located in the Viewing Areas. This is so reworking can be carried out on a package, in a similar fashion to the reworking procedure currently used at Harwell.
h) Overpack store
This would house containers in which faulty packages would be overpacked. The advantage of such a store in the Inspection Cell would be that packages deemed ‘faulty’ after inspection, could be placed into their overpack container in the Inspection Cell. Their faulty state would now not be a problem during transport to the Overpacking Cell.
REFERENCES
[1] IST Imaging (unknown). “Thru-Wall Endoscope”. [Online]. Viewed 2007 February 26. Available:
[2] IST Imaging (unknown). “Radiation Tolerant Thru-Wall/Roof Viewing System”. [Online]. Viewed 2007 February 26. Available:
[13]Skothei,. Øystein.(March 2006). “Optical shape measurement with structured light”. [Online]. Viewed 2007 February 16. Available:
BIBLIOGRAPHY
Sintef (2005). “3D shape measurement”. [Online]. Viewed 2007 February 16.
Available:
[e1]
[e2]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.