ENS 53223
ENS Event | |
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18:25 Feb 20, 2018 | |
Title | All Three Auxiliary Feedwater Pumps Inoperable Due to Helb Door Being Open |
Event Description | At 1225 CST, all three Auxiliary Feedwater [AFW] pumps were declared inoperable at the Callaway Plant upon discovery that a door (DSK13311) credited for protection of equipment from the effects of a high-energy line break (HELB) hazard had come partially open due to vibration harmonics from the running turbine-driven Auxiliary Feedwater pump (TDAFP). Immediate investigation identified that play in the mechanism that holds the door closed had rendered it susceptible to movement from the vibration harmonics.
The affected HELB door specifically protects safety-related instruments that provide a swap-over signal upon detection of a low suction pressure condition for the AFW pumps and thereby automatically effect a suction transfer for the AFW pumps from the condensate storage tank (normal/standby source) to the Essential Service Water (ESW) system (credited safety-related source). All of the AFW pump suction transfer instrument channels were declared inoperable. Per Technical Specifications (TS) 3.3.2, 'Engineered Safety Feature Actuation System (ESFAS) Instrumentation,' the applicable Condition(s) and Required Action(s) for inoperable AFW pump suction transfer instrumentation only addresses a single channel being inoperable. Thus, the condition of having all three instrument channels inoperable required entry into TS Limiting Condition for Operation (LCO) 3.0.3. At the same time, however, with the automatic suction transfer capability rendered inoperable, all three AFW pumps, i.e., the TDAFP and the 'A' and 'B' motor-driven AFW pumps, were declared inoperable. Although LCO 3.0.3 was applicable, entry into the Required Actions of LCO 3.0.3 was suspended per the Note attached to Required Action E.1 of TS 3.7.5, 'Auxiliary Feedwater (AFW) System,' which states, 'LCO 3.0.3 and all other LCO Required Actions requiring MODE changes are suspended until one AFW train is restored to OPERABLE status.' At 1336 CST, Operations took actions to prevent the TDAFP from running, so the remaining [AFW Pumps] could be returned to Operable status. Operations then declared the affected instrumentation and the 'A' and 'B' motor-driven AFW pumps Operable. This allowed LCO 3.0.3 and Conditions A, B, D, and E under TS 3.7.5 to be exited. With only the TDAFP inoperable, TS 3.7.5 Condition C and its Required Actions remain in effect. Due to the degraded HELB door rendering all three AFW pumps inoperable, the unidentified condition is being reported as an unanalyzed condition that significantly degraded plant safety [per 10 CFR 50.72(b)(3)(ii)(B)] as well as a condition that could have prevented the fulfillment of the safety functions of structures or systems that are needed to shut down the reactor and maintain it in a safe shutdown condition, remove residual heat, and mitigate the consequences of an accident [per 10 CFR 50.72(b)(3)(v)(A), (B), and (D), respectively]. The NRC Senior Resident Inspector has been notified.
Event Notification (EN) # 53223, made on 2/20/2018, is being retracted because new information has been obtained that negates the original basis for reporting the unanalyzed condition. Specifically, an evaluation of the HELB that is postulated to occur in the TDAFP room has determined that without crediting door DSK13311 for protection, the affected safety-related instruments would not be exposed to environmental conditions beyond their analyzed capability. This resulted in a conclusion that the unanalyzed condition of door DSK13311 being open did not prevent the affected safety-related instruments or their supported AFW pumps from performing their required safety functions to shut down the reactor and maintain it in a safe shutdown condition, remove residual heat, and/or mitigate the consequences of an accident, nor did it significantly degrade plant safety. Consequently, the condition did not meet the criteria for an 8-hour notification per 10 CFR 50.72(b)(3)(ii)(B) and 10 CFR 50.72(b)(3)(v)(A), (B), or (D). The licensee notified the NRC Resident Inspector. Notified R4DO (Drake). |
Where | |
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Callaway Missouri (NRC Region 4) | |
Reporting | |
10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition 10 CFR 50.72(b)(3)(v)(A), Loss of Safety Function - Shutdown the Reactor 10 CFR 50.72(b)(3)(v)(B), Loss of Safety Function - Remove Residual Heat 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident | |
Time - Person (Reporting Time:+0.35 h0.0146 days <br />0.00208 weeks <br />4.7943e-4 months <br />) | |
Opened: | Bryan Parker 18:46 Feb 20, 2018 |
NRC Officer: | Donald Norwood |
Last Updated: | Apr 4, 2018 |
53223 - NRC Website | |
Unit 1 | |
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Reactor critical | Critical |
Scram | No |
Before | Power Operation (100 %) |
After | Power Operation (100 %) |
Callaway with 10 CFR 50.72(b)(3)(v)(A), Loss of Safety Function - Shutdown the Reactor, 10 CFR 50.72(b)(3)(v)(B), Loss of Safety Function - Remove Residual Heat, 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 | |
WEEKMONTHYEARENS 548062020-07-30T13:15:00030 July 2020 13:15:00
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Mitigate the Consequences of an Accident Discovery of a Condition That Could Have Prevented Fulfillment of a Safety Function ENS 532232018-02-20T18:25:00020 February 2018 18:25:00 10 CFR 50.72(b)(3)(v)(A), Loss of Safety Function - Shutdown the Reactor, 10 CFR 50.72(b)(3)(v)(B), Loss of Safety Function - Remove Residual Heat, 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 All Three Auxiliary Feedwater Pumps Inoperable Due to Helb Door Being Open ENS 529052017-08-15T16:46:00015 August 2017 16:46:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Discovery of Non-Conforming Conditions During Tornado Hazards Analysis ENS 526072017-03-13T18:58:00013 March 2017 18:58:00 10 CFR 50.72(b)(3)(v)(A), Loss of Safety Function - Shutdown the Reactor, 10 CFR 50.72(b)(3)(v)(B), Loss of Safety Function - Remove Residual Heat, 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 Discovery of Non-Conforming Conditions During Tornado Hazards Analysis ENS 518742016-04-20T19:05:00020 April 2016 19:05:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Unanalyzed Condition Due to Essential Service Water Pressure Transient ENS 506252014-11-19T01:00:00019 November 2014 01:00:00 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - 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Mitigate the Consequences of an Accident, 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Unanalyzed Condition Identified for Inoperable Rwst Level ENS 466932011-03-24T04:54:00024 March 2011 04:54:00 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 Pressure Transmitters Needed for Auxiliary Feedwater Suction Path Not Analyzed for Potential High Energy Line Break ENS 465972011-02-07T15:18:0007 February 2011 15:18:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition High Energy Line Break Analysis for Aux Steam to the Auxiliary Building ENS 457472010-03-05T19:25:0005 March 2010 19:25:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Unanalyzed Condition - Steam Supply Valve Credited as Closed in Fsar Analysis Is Normally Open During Operations ENS 455712009-12-15T20:30:00015 December 2009 20:30:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Helb Configuration Calculations Not Consistent with Previous Helb Analysis ENS 432402007-03-14T19:35:00014 March 2007 19:35:00 10 CFR 50.72(b)(3)(v)(A), Loss of Safety Function - Shutdown the Reactor, 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident Two Out of Three Auxiliary Feedwater Pumps Out of Service ENS 424542006-03-30T22:50:00030 March 2006 22:50:00 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident Inadequate Operator Response Time for Component Cooling Water System Realignment During a Large Break Loca ENS 422572006-01-13T14:30:00013 January 2006 14:30:00 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident, 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material Pressurizer Porv Stroke Times Exceed Analysis Assumptions ENS 422422006-01-04T19:45:0004 January 2006 19:45:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Unanalyzed Condition Related to Emergency Diesel Fuel Oil Tank Vortex Formation ENS 418772005-07-28T02:25:00028 July 2005 02:25:00 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident Two Trains of Control Room Emergency Ventilation Systems (Crevs) Inoperable and Not Restored within 24 Hours ENS 413262005-01-12T19:30:00012 January 2005 19:30:00 Other Unspec Reqmnt, 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition 24 Hour Condition of License Report Regarding Halon System Actuator Port Connection Error ENS 403732003-12-03T18:30:0003 December 2003 18:30:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Emergency Procedure Deficiency Causes Unanalyzed Condition 2020-07-30T13:15:00 | |