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On November 5th, 2021, (1207 MDT) it was identified that a portable Area Radiation Monitor (ARM), which was performing the 10 CFR 70.24 safety function of the Criticality Accident Alarm System (CAAS) to energize clearly audible alarm signals if accidental criticality occurs, had been removed from the area in error. On July 20th, 2021, during routine CAAS maintenance, UUSA (Urenco USA) staff identified an area in which a CAAS alarm was not clearly audible. UUSA arranged the ARM as a compensatory measure which achieves an equivalent 10 CFR 70.24 safety function in the affected area. UUSA reported this event to the NRC under Event Notification 55480 in accordance with 10 CFR 70.50(b)(2) in which equipment is disabled or fails to function as designed when required by regulation. Removal of this ARM resulted in an inability for radiation detectors to energize clearly audible alarm signals if accidental criticality occurs in the affected area. UUSA hereby reports this event in accordance with 10 CFR 70.50(b)(2), in which equipment is disabled or fails to function as designed when required by regulation (10 CFR 70.24). The licensee will notify the NRC Region 2 office.

• * * RETRACTION ON 1/7/22 AT 1552 EST FROM BLAKE BIXENMAN TO THOMAS KENDZIA * * *

On November 5th, 2021, Louisiana Energy Services, LLC, dba Urenco USA, submitted Event Notification (EN) 55564 to the NRC Emergency Operations Center. This event notified the NRC of a 24 hour reportable event where a portable Area Radiation Monitor (ARM) performing a 10 CFR 70.24 safety function of the Criticality Accident Alarm System (CAAS) was removed from service. UUSA reported this event in accordance with 10 CFR 70.50(b)(2), in which equipment is disabled or fails to function as designed when required by regulation (10 CFR 70.24). Following this event, UUSA staff revised the calculations defining the Immediate Evacuation Zone (IEZ). The location of the ARM was near the edge of the IEZ boundary and the original calculation was completed prior to construction of the facility. The calculation was reviewed to ensure the boundary was still adequate. UUSA determined the boundary remains adequate with the area in question no longer inside the IEZ. The affected location is now outside of the IEZ. The IEZ is an area where personnel could be subject to an excessive radiation dose in the event of a criticality, required by 10 CFR 70.24(b)(1). Therefore, CAAS equipment subject to the event described in EN 55564 was not required to prevent exposures to radiation and radioactive materials exceeding regulatory limits, or to mitigate the consequences of an accident and does not meet the criteria for a reportable event UUSA herby retracts EN 55564. Details related to the revised IEZ boundary determination can be found in UUSA document CALC-S-00150, Rev 1, Immediate Evacuation Zone Calculations at UUSA. The following additional information was obtained from the licensee in accordance with Headquarters Operations Officers Report Guidance: The licensee will notify the NRC Region 2 office. Notified the R2DO (Miller) and NMSS Events Notification (email)

EN Revision Text: UNANALYZED CONDITION RESULTING FROM INCORRECT IMPLEMENTATION OF ITEMS RELIED ON FOR SAFETY (IROFS) Appendix A to 10 CFR 70 (b)(1) An incorrect implementation of IROFS36c (Limit Cylinder Mover to Electric or Diesel with less than 280L (74 gallons) Fuel Load) has been identified as having occurred for feed deliveries into the Cylinder Receipt and Dispatch Building (CRDB). IROFS36c requires that UF6 transporters/movers inside CRDB truck bays utilize a tractor which has a limited fuel capacity of less than 74 gallons. This requires the Over the Road (OTR) tractor truck to disconnect the trailer in a designated staging area and a local tractor with a fuel tank capacity less than 74 gallons be utilized with the OTR trailers. Methods were used allowing an OTR truck trailer to access the CRDB with the OTR tractor and fuel tanks of the vehicle remaining outside. Activities involving OTR tractor trailers entering the CRDB truck bay in this manner have not been evaluated in the ISA. 10 CFR 70.50 (c)(iii) (A) There was not a material release, no radiological or chemical hazards were present. (B) No exposure occurred (C) A condition exists which resulted in the facility being in a state that was different from that analyzed in the Integrated Safety Analysis. The method for cylinder transport into the CRDB truck bay by an OTR tractor, in proximity to cylinders inside the CRDB, has not been specifically evaluated as the evaluated condition prohibited the use of vehicles with fuel capacities in excess of 74 gallons within the CRDB truck bay. The only piece of equipment which entered the CRDB was the OTR trailer; the tractor remained connected and outside the CRDB. (D) IROFS36c remains available and reliable to perform its safety function. The identified deficiency only affects OTR tractors that could potentially expose UF6 cylinders in the CRDB to fuel sources greater than 74 gallons. UUSA (Urenco USA) has issued a stop work to prevent the introduction of excessive fuel capable of causing a release of UF6 inventory in the area of concern should a fire occur. The capabilities of existing IROFS are sufficient to meet the performance requirements of 10 CFR 70.61. (iv) No external conditions affect this event. (v) A stop work was issued to prevent the access of OTR tractor trucks to the CRDB where proximity to UF6 cylinders could occur. (vi) An event did not occur at UUSA. UUSA remains in a safe and stable condition. (vii) Current and planned site status is normal. No emergencies have been or will be declared. (viii) No local, state, or federal agencies will be notified. (ix) No press releases will occur. Condition has been entered into the UUSA Corrective Action Program. Event Record 125051. The licensee will notify R2 (Lopez).

• * * RETRACTION ON 07/11/2018 AT 1534 EST FROM BLAKE BIXENMAN TO STEVEN VITTO * * *

EN53445, made June 5th, 2018, reported a condition in accordance with Appendix A to 10 CFR 70 (b)(1) in which the facility was in a state different from that analyzed in the Integrated Safety Analysis, and which resulted in failure to meet the performance requirements of 10 CFR 70.61. This report was prompted by an incorrect implementation of IROFS36c (Limit Cylinder Mover to Electric or Diesel with <280L Fuel Load) during feed deliveries into the Cylinder Receipt and Dispatch Building (CRDB). An Over the Road (OTR) tractor containing greater than the maximum allowable fuel load was permitted access the CRDB Truck Bay with the OTR truck trailer. At the time of the report, this method for cylinder transport into the CRDB Truck Bay by an Over the Road (OTR) tractor in proximity to cylinders inside the CRDB had not been evaluated. URENCO USA conservatively assumed a failure in the performance requirements of 10 CFR 70.61 at the time of the 24 hour report. Since the time of the initial report, URENCO USA has completed an assessment of safety significance for the events reported in EN53445. With detailed results documented in the UUSA corrective action program, Event Record EV125051, the following conclusion has been made: The fuel delivery events using the OTR truck into the CRDB can be categorized as events with low safety significance since they would not result in breached/ruptures of UF6 cylinders and no uranic material would be released in the event of a fire involving UF6 cylinders in the CRDB Truck Bay. This correlates with a low consequence event. Based on calculations shown in the 'Assessment of Safety Significance for Events Documented in EV125051', the conditions reported in EN53445 did not result in failure to meet the performance requirements of 10 CFR 70.61. Therefore, the condition reported in EN53445 did not exceed the criteria which would necessitate an event be reported to the NRC. URENCO USA hereby retracts Event Notification 53445. Notified R2DO(Rose), Fuels Group, and NMSS Events Notification email.