Year
2004
Abstract
The Cerenkov viewing device (CVD) and Digital Cerenkov viewing device (DCVD) are used to verify spent fuel in storage ponds by imaging the Cerenkov glow generated by fission products in the fuel. A key verification characteristic is the distinctive highly collimated image produced by the spent fuel assembly. This high degree of light collimation is attributed to the vertical component of the Cerenkov light that is generated along the total length of the fuel assembly. Cerenkov light that is not vertical to the fuel assembly is absorbed by the dark oxidized surfaces of the fuel rods. The collimation effect has not been confirmed by theoretical calculations. Therefore, a modelling study was conducted to determine the axial contribution to the measured Cerenkov image. The results show that the entire length of the spent fuel assembly contributes to the measured Cerenkov image. The Cerenkov glow from deeper parts of the fuel assembly contributes most to the collimation effect.