Entergy's Arkansas Nuclear One has reported potential degradation in fuel assemblies transferred into a dry cask.A sample of helium used during the final stage of cask loading at unit 1 indicated the presence of krypton-85, a fission product that suggests fuel assemblies might have cladding defects greater than hairline cracks or pinhole leaks, according to a report filed with the Nuclear Regulatory Commission. The plant had conducted the sampling as part of an investigation into the actuation of the control room emergency ventilation system on Friday. The gas studied was used in the forced helium dehydration process for one of the site's HI-STORM 100 casks. The fuel assemblies' integrity had been checked using in-mast sipping and/or ultrasonic testing following their last operating cycle. Nonetheless, the krypton's presence means the plant cannot confirm that all assemblies in the cask meet the technical specifications required by the dry storage system, according to the report. The plant notified its resident NRC inspector. Operation of the reactors was unaffected, and both units were running at full power as of Monday morning.
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welcome to the world of krypton.....been there done that