| PRESSURE INSTRUMENT ISOLATION VALVE FOUND IN INCORRECT OPEN POSITION|
"On October 10, 2019, at approximately 1830 MDT, a responsible individual at Louisiana Energy Services LLC, dba URENCO USA, was informed that on June 5, 2018, at approximately 1600 MDT, pressure instrument isolation valve, 1001-471-1A12, was found open when it should have been shut to maintain the pressure boundary of autoclave 1LS1. The autoclave is used to homogenize UF6 and obtain samples. The autoclave pressure boundary forms IROFS10 [Item Relied on for Safety].
"Prior to the event, on May 31, 2018, annual maintenance was performed on the autoclave as required by the IROFS10 surveillance requirements. Subsequently, a homogenization and UF6 sampling was performed June 1st through June 5th on a 30B cylinder of UF6. During preparations for a subsequent homogenization cycle, valve 1001-471-1A12 was found open. The valve should have remained closed from the previous homogenization. There was not an initiating event (no release of UF6) and no initiation of an accident sequence. The valve has been shut and the IROFS boundary has been restored. The plant is in a safe configuration.
"This event has been identified in UUSA's corrective action program as EV 133619 and a causal investigation is planned."