ENS 52214
ENS Event | |
|---|---|
23:50 Aug 31, 2016 | |
| Title | Unanalyzed Condition with a Potential Tornado |
| Event Description | In Event Notification (EN) 52202 on August 25, 2016, Fermi 2 identified an unanalyzed condition related to the inoperability of Mechanical Draft Cooling Tower (MDCT) fans due to nonfunctionality of the associated brakes that occurred on April 6, 2016. The MDCT fan brake is required to prevent fan over speed from a design basis tornado. The MDCT fans are required to support the operability of the Ultimate Heat Sink (UHS) reservoir and associated Emergency Diesel Generators (EDGs). The EN noted that a past operability review was in progress to determine if declaring a MDCT fan inoperable due to a fan brake being nonfunctional resulted in additional instances of unanalyzed conditions within the: three years prior to August 25, 2016.
On August 31, 2016 at 1950 EDT, the past operability review identified five additional instances of unanalyzed conditions within the past three years. These five instances are being reported in one EN since they are related and were all discovered and reported within 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />. Although these instances are related to the one previously reported in EN 52202, they are being reported in a new EN due to the time elapsed since EN 52202. The MDCT fans and fan brakes are currently operable. 1) February 2016 - The Division 1 MDCT fan 'A' brake nitrogen bottle pressure was below the required limit from 0936 EST to 1344 EST on February 25, 2016. This nonfunctionality of the MDCT fan 'A' brake coincided with a High Pressure Coolant Injection (HPCI) system outage in Division 2. 2) March 2015 - The Division 1 MDCT fan 'A' brake nitrogen bottle pressure was below the required limit from 1000 EDT on March 23, 2015, until 1447 EDT on April 9, 2015. There is reasonable expectation that the nonfunctionality of the MDCT fan 'A' brake coincided with various Division 2 systems, structures, or components (SSCs) out of service during a forced outage. 3) February 2014 - The Division 2 MDCT fan 'B' brake nitrogen bottle pressure was below the required limit from 1118 EST to 1529 EST on February 20, 2014. There is reasonable expectation that the nonfunctionality of the MDCT fan 'B' brake coincided with various Division 1 SSCs out of service during a refueling outage. 4) February 2014 - The Division 1 MDCT fan 'A' brake nitrogen bottle pressure was below the required limit from 1747 EST on February 14, 2014, until 1514 EST on February 24, 2014. There is reasonable expectation that the nonfunctionality of the MDCT fan 'A' brake coincided with various Division 2 SSCs out of service during a refueling outage. 5) January 2014 - The Division 1 MDCT fan 'A' brake nitrogen bottle pressure was below the required limit from 0915 EST on January 24, 2014, until 1537 EST on January 31, 2014. This nonfunctionality of the MDCT fan 'A' brake coincided with approximately 30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br /> where various Division 2 safety-related SSCs were inoperable. The occurrences discussed above resulted in unanalyzed conditions because the plant configuration when equipment in one division was inoperable while a MCDT fan brake was nonfunctional in the opposite division would not support safe shutdown capability in the event of a tornado. This condition is reportable under 10 CFR 50.72(b)(3)(ii)(B), as an event or condition that results in an unanalyzed condition that significantly degrades plant safety. There was no adverse impact to public health and safety or to plant employees. The NRC Resident Inspector has been notified.
The licensee is RETRACTING item 1 only of the 5 events listed above: 1) February 2016 - The Division 1 MDCT fan 'A' brake nitrogen bottle pressure was below the required limit from 0936 EST to 1344 EST on February 25, 2016. This nonfunctionality of the MDCT fan 'A' brake coincided with a High Pressure Coolant Injection (HPCI) system outage in Division 2. Fermi 2 is retracting item 1 of the 8-hour event notification made on August 31, 2016, at 2332 EDT, (EN #52214). EN #52214 originally reported a non-functionality of the Division 1 MDCT fan 'A' brake on February 25, 2016, as an unanalyzed condition due to it coinciding with a Division 2 High Pressure Coolant Injection (HPCI) system outage. Subsequent engineering evaluation has determined that although the intermediate nitrogen bottle pressure was below its required limit, the pressure in the main nitrogen bottle was sufficient to ensure that the MDCT fan 'A' brake could have performed its intended function in the event of a tornado. Since the MDCT fan 'A' brake was determined to be functional, the MDCT fan 'A', the associated Division 1 UHS reservoir, and the Division 1 EDGs were all operable at that time. Therefore, no unanalyzed condition existed on February 25, 2016. The other four items [2-5] included in EN #52214 are not being retracted and are still considered unanalyzed conditions. The licensee notified the NRC Resident Inspector. Notified R3DO (Orth). |
| Where | |
|---|---|
Fermi  Michigan (NRC Region 3) | |
| Reporting | |
| 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition | |
| Time - Person (Reporting Time:+-0.3 h-0.0125 days <br />-0.00179 weeks <br />-4.1094e-4 months <br />) | |
| Opened: | Greg Miller 23:32 Aug 31, 2016 |
| NRC Officer: | Mark Abramovitz |
| Last Updated: | Oct 20, 2016 |
| 52214 - NRC Website | |
Unit 2 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (74 %) |
| After | Power Operation (74 %) |
WEEKMONTHYEARENS 552312021-05-03T13:30:0003 May 2021 13:30:00
[Table view]10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Unanalyzed Condition ENS 537122018-11-01T04:00:0001 November 2018 04:00:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition En Revision Imported Date 12/31/2018 ENS 536742018-10-19T04:00:00019 October 2018 04:00:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Low Pressure Core Injection Pumps Incapable of Automatic Startup ENS 527242017-05-02T21:00:0002 May 2017 21:00:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Unanalyzed Condition for Combustion Turbine Generator Configuration ENS 523422016-11-02T14:34:0002 November 2016 14:34:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Unanalyzed Condition for Control Rod Drop Accident at Low Power ENS 522142016-08-31T23:50:00031 August 2016 23:50:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Unanalyzed Condition with a Potential Tornado ENS 522022016-08-25T20:29:00025 August 2016 20:29:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Mechanical Draft Cooling Tower Declared Inoperable ENS 514402015-10-02T12:25:0002 October 2015 12:25:00 10 CFR 50.72(b)(3)(v)(A), Loss of Safety Function - Shutdown the Reactor, 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Loose Safety Relief Valve Discharge Flange Bolts ENS 422242005-12-23T03:25:00023 December 2005 03:25:00 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident, 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Eecw Temperature Control Valve Not Fully Open ENS 418472005-07-18T02:31:00018 July 2005 02:31:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Unanalyzed Condition of Maintenance Bus Tie Breakers ENS 418162005-06-30T23:31:00030 June 2005 23:31:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Unanalyzed Condition Related to the Standby Feedwater Pumps and Control Circuits ENS 417142005-05-18T22:50:00018 May 2005 22:50:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Identification of Design and Operating Procedure Deficiencies Related to Appendix R Events ENS 415512005-03-30T21:00:00030 March 2005 21:00:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Identification of Design and Operating Procedure Deficiencies 2021-05-03T13:30:00 | |