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Advanced Imaging Magazine

Updated: January 12th, 2011 09:49 AM CDT

Imaging Spent Nuclear Fuel in Difficult Underwater Environments

Channel Systems Inc.
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Channel Systems Inc. (Pinawa, Manitoba, Canada)

The Imaging Challenge

Collect extremely low-light, ultra violet images of spent nuclear fuel in a very difficult environment. The target is small and located underwater, 10 to 13 meters (32.8 to 42.6 feet) from the viewing location. Waves, water impurities and other light sources introduce additional challenges.

The Solution

Spent nuclear fuel stored in water ponds emits Cerenkov light (or Cerenkov radiation) that is used to verify the fuel for safeguard purposes. Cerenkov is electromagnetic radiation emitted when a charged particle (such as a proton) passes through an insulator at a speed greater than the speed of light in that medium. The characteristic blue glow of nuclear reactors is due to Cerenkov light. Several imaging components and software visualization features work together to solve this difficult imaging challenge and produce very good results. First, the challenge of imaging in very low, UV light was solved by using an Andor (Belfast, Northern Ireland) Ixon camera. The UV sensitivity and very low noise floor of this camera provided the ability to image the spent fuel. Secondly, we needed an objective lens that allowed us to image several types and sizes of fuel. Partnering with Resolve Optics (Chesham Bucks, United Kingdom), we developed a unique zoom lens (80 to 200 mm) that is optimized for 270 to 350 nm. A bandpass filter is implemented to reject light outside the range of interest. The software implements false color visualization to enhance the features of the fuel that the inspectors use to perform the safety verification.

The Tools Used

  • Andor Ixon DU-887E camera
  • Resolve Optics 80-200 mm UV zoom lens
  • Spectra Physics Corion CFS-1809-950 bandpass filter

The Difference it Made

This instrument provides a huge improvement in two areas: sensitivity and usability. The DCVD-E system is much more sensitive than other verification methods. It not only is capable of verifying fuel, but it also can detect partial defects as well. It is non-contact and non-intrusive and allows the inspector to set up in a few minutes. The system's speed of inspection matches the fastest existing system. Collaboration and comfort of the inspector is also drastically improved. A computer monitor displays the image for easy viewing and collaboration with other inspectors.



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