05000327/LER-2018-002, Exceeded Breach Margin Renders Both Trains of the Auxiliary Building Gas Treatment System Inoperable
| ML19022A040 | |
| Person / Time | |
|---|---|
| Site: | Sequoyah  |
| Issue date: | 01/22/2019 |
| From: | Anthony Williams Tennessee Valley Authority |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| LER 2018-002-00 | |
| Download: ML19022A040 (7) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(v), Loss of Safety Function |
| 3272018002R00 - NRC Website | |
text
Tennessee Valley Authority, Sequoyah Nuclear Plant, P.O. Box 2000, Soddy Daisy, Tennessee 37384 January 22, 2019 10 CFR 50.73 ATTN: Document Control Desk U.S. Nuclear Regulatory Commission Washington, D.C. 20555-0001 Sequoyah Nuclear Plant, Units 1 and 2 Renewed FacilityOperating License Nos. DPR-77 and DPR-79 NRC Docket Nos. 50-327 and 50-328
Subject:
Licensee Event Report 50-327and 50-328/2018-002-00, Exceeded Breach Margin Renders Both Trains of the Auxiliary Building Gas Treatment System Inoperable The enclosed licensee event report provides details concerning a breached door associated with the auxiliary building secondary containment enclosure boundary that resulted in both trains of the Auxiliary Building Gas Treatment System being declared inoperable. This report is being submitted in accordance with 10 CFR 50.73(a)(2)(v), as an event or condition that could have prevented the fulfillment of a safety function of structures or systems that are needed to:
(C) controlthe release of radioactive material and (D) mitigatethe consequences of an accident.
There are no regulatory commitments contained inthis letter. Should you have any questions concerning this submittal, please contact Mr. Jonathan Johnson, Site Licensing Manager, at (423)843-8129.
Anthony L. Williams Site Vice President Sequoyah Nuclear Plant Enclosure: Licensee Event Report 50-327 and 50-328/2018-002-00 cc:
NRC Regional Administrator - Region II NRC Senior Resident Inspector-Sequoyah Nuclear Plant printed on recycled paper
NRC FORM 366 (04-2018)
U.S. NUCLEAR REGULATORY COMMISSION LICENSEE EVENT REPORT (LER)
(See Page 2 for required number ofdigits/characters for each block)
(See NUREG-1022, R.3 for instruction and guidance for completing this form http://www.nrc.Qov/readina-rrn/dcc-collections/nureQS/staff/sr1022/r3/)
APPROVED BY OMB: NO. 3150-0104 EXPIRES: 03/31/2020
, the NRC may not conduct or sponsor, and a personis notrequired to respondto,the information collection.
- 1. Facility Name Sequoyah Nuclear Plant Unit 1
- 2. Docket Number 05000327
- 3. Page 1 OF6
- 4. Title Exceeded Breach Margin Renders Both Trains of the Auxiliary Building Gas Treatment System Inoperable
- 5. Event Date ft I PPM..mW t
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- 6. LER Number
- 7. Report Date
- 8. Other Facilities Involved Month Day Year 11 24 2018 Year 2018 Sequential Number
- - 002 Rev No.
- 00 Month Day Year 01 22 2019 Facility Name Sequoyah Nuclear Plant Unit 2 FacilityName N/A Docket Number 05000328 Docket Number 05000 9.OperatingMode 1
20.2201(b)
Month N/A Day N/A Year N/A
I.
Plant Operating Conditions Before the Event
At the time ofthe event, Sequoyah Nuclear Plant (SON) Unit 1was in Mode 1at 100 percent rated thermal power. Unit 2was in Mode 5due to arefueling outage.
II.
Description of Event
A.
Event Summary
On November 24, 2018, at 0930 eastern standard time (EST), Maintenance Services personnel were removing surplus ice as part of ice condenser maintenance activities in connection with the Unit 2refueling outage. This required abreach of auxiliary building [EMS: NF] secondary containment enclosure (ABSCE) boundary Door [EMS: DR] A118 to allow ahose to be routed from avacuum truck outside to an ice bin inside the Unit 2Additional Equipment Buildinq A nrfoftn STILT ff?".and ^o^" U8ed by 0ther work 9rouPs-Performing different activities, prior to the event Maintenance Services personnel were aware ofthe open breach permit but were not aware of the compensatory measures required for the breach permit The ABSCE breaching permit required personnel to be stationed in the main control room MCR) in communication with personnel responsible for closing Door A118 within 3minutes At 1420 it was discovered that there were no personnel stationed in the MCR to perform this'function.'
The open door created abreach ofthe ABSCE boundary that exceeded the allowed breach SSSin^iSf;^Unitiente,Ied Technical Specification (TS) Limiting Condition for SvsSabgt^rF.'.l \\/Pindltl°n I °r aIe,qUi,red train °fAuxiliary Buildin9 Gas Treatmen<
ProTyt? 7 11 DV/] n°Perable Wlth fuel stored In the spent fuel pool and Unit 1entered LCO 3.7.12, Condition Bfor two trains ofthe ABGTS inoperable due to an inoperable ABSCE Zamsmz s z??, \\ ?* \\or,4- *1435-tne d°°r was d°sed and °°th ^ && lco 3.7.12 Condition Eand Unit 1exited LCO 3.7.12, Condition B.
^^re0^^?^"1 notification <EN 53751>was made to the NRC in accordance with 10 CFR 50.72(b)(3)(v) as an event or condition that could have prevented fulfillment ofa materia?andTn?m'STh °f SySt6mS** *? needed t0: (C) COntro1 the release of radi°active material and (D) mitigate the consequences of an accident. This LER documents the reportable event under 10 CFR 50.73(a)(2)(v)(C) and 10 CFR 50.73(a)(2)(v)(D).
reportable 05000-327 YEAR 2018 SEQUENTIAL NUMBER
- - 002 B.
Status of structures, components, or systems that were inoperable at the start ofthe event and contributed to the event:
No inoperable structures, components, or systems contributed to this event.
REV NO.
- - 00Page 2 of 6(04-2018)
U.S. NUCLEAR REGULATORY COMMISSION LICENSEE EVENT REPORT(LER)
CONTINUATION SHEET APPROVED BY OMB: NO. 3150-0104 EXPIRES: 03/31/2020
, the NRC may not conduct or sponsor, and a person isnotrequired torespond to,theinformationcollection.
Sequoyah Nuclear Plant Unit 1 05000-327 YEAR 2018
- 3. LER NUMBER SEQUENTIAL NUMBER
- 002 REV NO.
- - 00 C.
Dates and approximate times of occurrences
Date/Time (EST) 11/24/18, 0930 11/24/18, 1420 11/24/18, 1435
Description
Door A118 was breached tosupport ice condenser maintenance activities.
Operators identified that Door A118 was breached. The identified breach exceeded theallowed ABSCE breach margin. Operators directed Door A118 to beclosed. Unit 1entered LCO 3.7.12, Condition Band both units entered LCO 3.7.12, Condition E.
Door A118 was verified closed. This restored the ABSCE boundary Unit 1exited LCO 3.7.12, Condition Band both units exited LCO 3 7 12 Condition E.
D.
Manufacturer and model number of each component that failed during the event
There was no component that failed during theevent.
E.
Other systemsorsecondary functions affected:
There were no other systems or secondary functions affected by this event.
F.
Method of discovery of each component or system failure or procedural error
Operators identified that Door A118 was open creating a breach of the ABSCE boundary that exceeded the allowed ABSCE breach margin.
G.
Failure mode, mechanism, and effect of each failed component:
There was no component that failed during the event.
H.
Operator actions
Both trains ofABGTS were declared inoperable due to the breach associated with Door A118 urenKlcSTr.rcon^E mar9in' """'**" LC° 37'12' C°ndi,i°n Band bo,h I.
Automatically and manually initiated safety system responses
There were no automatic or manually initiated safety system responses associated with this event.Page 3 of 6(04-2018) f/J U.S. NUCLEAR REGULATORY COMMISSION LICENSEE EVENT REPORT (LER)
CONTINUATION SHEET APPROVED BY OMB: NO. 3150-0104 EXPIRES: 03/31/2020
, the NRC may not conduct or sponsor, and a person isnotrequired torespond to, theinformationcollection.
aLERNUMBER Sequoyah Nuclear Plant Unit 1 05000-327 YEAR 2018 SEQUENTIAL NUMBER
- - 002 REV NO.
- - 00 III.
Cause of the Event
A.
Cause ofeach component or system failure or personnel error:
Following are the identified causes of the event:
There was afailure to cover the ABSCE breach permit and required compensatory measures in the pre-job brief.
- There was afailure to cover internal and external operating experience during the pre-job B.
There was acommunication gap within separate work groups that contributed to not identifying the ABSCE breach permit owner and the required compensatory measures.
Personnel involved were non-licensed, Maintenance Services contractors They were performing work associated with ice condenser maintenance activities in connection with a refueling outage. There were no schedule or situational pressures present.
IV.
Analysis of the Event
h^n,?TS filte? ai;bome/adioa<*ve particulates from the area ofthe fuel pool following afuel to hfnnlrS. f " *?? C°°lant aCCident (L0CA)- ln Mode 1*2-3' or 4-th* ABGTS is required to be operable to provide fission product removal associated with Emergency Core Cooling System leaks due to aLOCA and leakage from containment and annulus. The analysis ofthe fuel haE from S ZT" *?^ ABSCE "°Undary iS Capable of bein9 established^ ensure the releases
^^^Zr^X^AB^9S are consistent with the dosec"e>>
rnnlfJ*? SIandby SySte!?that COnsists of*"0 independent and redundant trains. Each train SXn fn'T ?Pref"ter' ahi9h effidency particulate airfilter. an activated charcoal adsorber section for removal of gaseous activity, and afan. The system initiates filtered ventilation of the ZZ aUHdlnh9 f0H0rg reCeiPJ °fahigh radiation sj9nal from the fuel handling aea radSn P^Arnn? ^'f^ s:gnalfrom the train-specific Auxiliary Building exhaust vent monitor, a 2XSffiTLKT Sl9nal fr°m ^reaCt0r' "ahi9h t6mperatUre Signal from thePage 4 of 6(04-2018)
U.S. NUCLEAR REGULATORY COMMISSION LICENSEE EVENT REPORT (LER)
CONTINUATION SHEET APPROVED BY OMB: NO. 3150-0104 EXPIRES: 03/31/2020
, the NRC may not conduct or sponsor, and a person isnotrequired torespond to, theinformationcollection.
- 3. LER NUMBER Sequoyah Nuclear Plant Unit 1 05000-327 YEAR 2018 SEQUENTIAL NUMBER
- - 002 REV NO.
- - 00 The breached door exceeded the allowed ABSCE breach margin rendering the ABSCE inoperable This configuration could have prevented the ABGTS from maintaining a pressure greater than or equal to -0.25 inches water gauge with respect to atmospheric pressure during the post accident mode of operation.
V.
AssessmentofSafety Consequences There were no actual safety consequences as aresult of this event. Engineering evaluation 7?JS^n*?13 ?elay associated with closin9 Door A118 would not have resulted in exceeding 10 CFR 100 dose limits. Accordingly, the risk associated with this event is considered to be small.
A.
Availability of systems or components that could have performed the same function as the componentsand systems that failed during the event:
There were no components or systems that failed during the event.
B.
For events that occurred when the reactor was shut down, availability of systems or components needed to shutdown the reactor and maintain safe shutdown conditions remove residual heat, control the release of radioactive material, or mitigate the consequences of an accident:
The ABGTS is credited for mitigating the consequences of an accident and controlling the release of radioactive material. Unit 2was in arefueling outage while the ABGTS was inoperable.
C.
For failure that rendered atrain of asafety system inoperable, an estimate of the elapsed time from discovery ofthe failure until the train was returned to service:
LhcwLaHPfed tlmeM0rT! djscovery of both trains ofABGTS being inoperable until both trains were restored tooperable status was approximately 15minutes.
VI.
Corrective Actions
cS^S^SuS!,he Tennessee Valley Au,hori,y Corredlve Action Pr09ram under A.
Immediate Corrective Actions
Briefings were conducted with maintenance services personnel to provide review and understanding of required compensatory actions for ABSCE breach permits.Page 5 of 6(04-2018)
U.S. NUCLEAR REGULATORY COMMISSION LICENSEE EVENT REPORT (LER)
CONTINUATION SHEET w
APPROVED BY OMB: NO. 3150-0104 EXPIRES: 03/31/2020
, the NRC may not conduct or sponsor, and a person isnotrequired torespond to,theinformationcollection.
- 3. LER NUMBER Sequoyah Nuclear Plant Unit 1 B.
Corrective Actions to Prevent Recurrence or to reduce probability of similar events occurrina in the future:
Corrective actions include revising the associated work order to add a hold point to ensure the ABSCE permit is reviewed, understood, and adhered to prior to and during breach. The hold point now requires a supervisor's signature to proceed in the work order.
VII.
Previous Similar Events at the Same Site
Areview of SQN LERs identified an event in which a penetration affecting the ABSCE was breached without required compensatory measures. LER 327 and 328/2017-001 associated with the event, identified the cause to be aless than adequate single barrier breaching procedure exits at SQN. Acontributing cause was an inconsistent approach to entry into the barrier breaching process. Corrective actions included revising the breaching procedure to address all possible breaches and include a matrix for doors and their associated impacts, and addressinq potential knowledge deficiencies.
VIM. Additional Information There is no additional information.
IX.
Commitments
There are no commitments.05000-327 YEAR 2018 SEQUENTIAL NUMBER
- - 002 REV NO.
- - 00 Page 6 of 6