ENS 55564
ENS Event | |
|---|---|
18:07 Nov 5, 2021 | |
| Title | Loss of High Radiation Audible Alarm |
| Event Description | 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.
On November 5th, 2021, Louisiana Energy Services, LLC, dba Urenco USA, submitted Event Notification55564 to the NRC Emergency Operations Center. This event notified the NRC of a 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> 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) |
| Where | |
|---|---|
| Louisiana Energy Services Eunice, New Mexico (NRC Region 2) | |
| License number: | SNM-2010 |
| Reporting | |
| 10 CFR 70.50(b)(2) | |
| Time - Person (Reporting Time:+-0.02 h-8.333333e-4 days <br />-1.190476e-4 weeks <br />-2.7396e-5 months <br />) | |
| Opened: | Blake Bixenman 18:06 Nov 5, 2021 |
| NRC Officer: | Michael Bloodgood |
| Last Updated: | Jan 7, 2022 |
| 55564 - NRC Website | |
Louisiana Energy Services with 10 CFR 70.50(b)(2) | |
WEEKMONTHYEARENS 565502023-06-01T08:39:0001 June 2023 08:39:00
[Table view]10 CFR 70.50(b)(2) Partial Loss of Criticality Accident Alarm System ENS 555642021-11-05T18:07:0005 November 2021 18:07:00 10 CFR 70.50(b)(2) Loss of High Radiation Audible Alarm ENS 554802021-07-20T20:01:00020 July 2021 20:01:00 10 CFR 70.50(b)(2) CAAS Alarm Not Clearly Audible ENS 536042018-09-15T06:00:00015 September 2018 06:00:00 Information Only, 10 CFR 70.50(b)(2) Preplanned Outage of a Required Safety Monitoring System ENS 530462017-09-07T06:00:0007 September 2017 06:00:00 10 CFR 70.50(b)(2) Wrong Irofs Procedure Followed Prior to Filling Cylinder ENS 515932015-12-07T23:00:0007 December 2015 23:00:00 10 CFR 70.50(b)(2) Crane Item Relied Upon for Safety Never Installed 2023-06-01T08:39:00 | |