UV-zoom lens to inspect spent nuclear fuel

May 4, 2007
MAY 4--Resolve Optics (Chesham, UK) has been selected by Channel Systems (Pinawa, Canada) to design and develop an ultraviolet-transmitting zoom lens for its DCVD.

MAY 4--Resolve Optics (Chesham, UK;www.resolveoptics.com) has been selected by Channel Systems (Pinawa, Canada) to design and develop a novel high-performance ultraviolet-transmitting zoom lens with a focal length of 80--200 mm for use in its Digital Cerenkov Viewing Device (DCVD). The DCVD is an imaging device for noninvasive verification of spent nuclear fuel.

Inspectors in the nuclear industry are responsible in part for the regulation of nuclear materials to ensure that they are not being diverted for clandestine purposes. Spent nuclear fuel emits a faint ultraviolet Cerenkov light when gamma rays from fuel assemblies interact with electrons in the cooling pond water. The DCVD is a highly effective instrument that captures the Cerenkov image of spent fuel for analysis and comparison. This instrument provides inspectors with an effective tool to differentiate irradiated fuel items from nonfuel items.

The UV-zoom lens was designed and wavelength-corrected to view a nuclear fuel assembly situated 13 m away from the lens and through 10 m of water. To meet the challenges of the application the UV-zoom lens was designed to optimally operate from 10°C to 55°C. Miniature motors allow accurate remote setting of both zoom and focus functions.

A filter slide was incorporated in the design that enables the lens to be switched between UV (270 to 350 nm) and visible (400 to 700 nm) without the need to refocus the lens. By using a telescopic focus the lens is able to image objects from 3 m to infinity. The lens achieves high image resolution with low distortion throughout the zoom range without refocusing (image tracking). Top-siding adjustment was provided on the lens so that the motor cables could be conveniently positioned. A unique lockable C-mount ensures the lens cannot come loose during operation.

Since 2002, Channel Systems (www.channelsystems.ca) has specialized in the design and development of instruments for a range of applications including hyperspectral imaging, nuclear fuel safeguard imaging, and infrared chemical imaging.

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