Case Study 20

Verifying Spent Nuclear Fuel

Verifying Spent Nuclear FuelSpent nuclear fuel emits a faint ultraviolet Cerenkov light when gamma rays from fuel assemblies interact with electrons in the cooling pond water.  A global leader in nuclear safeguards technology approached Resolve Optics to design a wavelength corrected UV Zoom lens to enable its Digital Cerenkov Viewing Device (DCVD) to view a nuclear fuel assembly situated 13 metres away from the lens and through 10 metres of water.

The DCVD equipped with UV Zoom lens provides a highly-effective system that captures the Cerenkov image of spent fuel for analysis and comparison. This unique system provides inspectors with an effective tool for non-intrusive verification of spent nuclear fuel.

To meet the challenges of the application the UV Zoom lens is able to optimally operate from 10 to 55ºC.  Miniature motors allow accurate remote setting of both zoom and focus functions.  A filter slide was incorporated in the design enabling 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 3m to infinity.  The lens achieves high image resolution with low distortion throughout the zoom range without refocusing. A lockable C mount ensures the lens cannot come loose during operation.