Technical Review of the Characteristics of Spent Nuclear Fuel Scrap

Spent Nuclear Fuel scrap generated while washing the SNF in Hanford's K-Basins to prepare it for cold vacuum drying differed significantly from that envisioned during project design. Therefore, a technical review panel evaluated the new information about the physical characteristics of scrap generated during processing by characterizing it based on measured weights and digital photographic images. They examined images of the scrap and from them estimated the volume and hence the masses of inert material and of large fragments of spent fuel. The panel estimated the area of these particles directly from images and by fitting a lognormal distribution to the relative number particles in four size ranges and then obtaining the area-to-volume ratio from the distribution. The estimated area is 0.3 m2 for the mass of scrap that could be loaded into a container for drying, which compares to a value of 4.5 m2 assumed for safe operation of the baseline process. The small quantity of scrap genera ted is encouraging. However, the size and mass of the scrap depend both on processes degrading the fuel while in the basin and on processes catching the scrap during washing, the latter including essentially unintentional filtration as debris accumulates. Therefore, the panel concluded that the estimated surface area meets the criterion for loading scrap into an MCO for drying, but because it did not attempt to evaluate the criterion itself, it is not in a position to actually recommend loading the scrap. Further, this is not a sufficiently strong technical position from which to extrapolate the results from the examined scrap to all future scrap generated by the existing process