05000301/LER-2015-005, Regarding Main Transformer Lockout and Associated Loss of Buses Results in System Actuation
| ML15350A068 | |
| Person / Time | |
|---|---|
| Site: | Point Beach  |
| Issue date: | 12/16/2015 |
| From: | Mccartney E Point Beach |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| NRC 2015-0070 LER 15-005-00 | |
| Download: ML15350A068 (3) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(iv)(A), System Actuation 10 CFR 50.73(a)(2)(i) 10 CFR 50.73(a)(2)(vii), Common Cause Inoperability 10 CFR 50.73(a)(2)(ii)(A), Seriously Degraded 10 CFR 50.73(a)(2)(viii)(A) 10 CFR 50.73(a)(2)(ii)(B), Unanalyzed Condition 10 CFR 50.73(a)(2)(viii)(B) 10 CFR 50.73(a)(2)(ix)(A) 10 CFR 50.73(a)(2)(x) 10 CFR 50.73(a)(2)(v)(A), Loss of Safety Function - Shutdown the Reactor 10 CFR 50.73(a)(2)(v)(B), Loss of Safety Function - Remove Residual Heat 10 CFR 50.73(a)(2)(i)(A), Completion of TS Shutdown 10 CFR 50.73(a)(2)(v), Loss of Safety Function 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications |
| 3012015005R00 - NRC Website | |
text
ENERGY December 16, 2015 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555 Point Beach Nuclear Plant, Unit 2 Docket 50-301 Renewed License Nos. DPR-27 Licensee Event Report 301/2015-005-00 POINT BEACH NRC 2015-0070 10 CFR 50.73 Main Transformer Lockout and Associated Loss of Buses Results in System Actuation Enclosed is Licensee Event Report (LER) 301/2015-005-00 for Point Beach Nuclear Plant, Unit 2. NextEra Energy Point Beach, LLC, is providing this LER to report a system actuation.
This letter contains no new regulatory commitments.
If you have any questions please contact Mr. Bryan Woyak, Licensing Manager, at 920/755-7599.
Very truly yours, NextEra Energy Point Beach, LLC Eric McCartney Site Vice President Enclosure cc:
Administrator, Region Ill, USNRC Project Manager, Point Beach Nuclear Plant, USNRC Resident Inspector, Point Beach Nuclear Plant, USNRC PSCW NextEra Energy Point Beach, LLC, 6610 Nuclear Road, Two Rivers, WI 54241 Description of the Event:
APPROVED BY OMB: NO. 3150-0104 EXPIRES: 01/31/2017 Estimatsd, the NRC may not conduct or sponsor, and a person is not required to respond to, the information collection.
- 6. LERNUMER YEAR I SEQUENTIAL I NUMBER REV NO.
2015 -
005 00
- 3. PAGE 2
OF 2
At 0348 on October 29, 2015 while in MODE 3 during the Unit 2 refueling outage a main transformer lockout was generated when a short circuit was created while performing a tagout clearance activity. The main transformer lockout resulted in a loss of non-vital 4KV buses and a loss of all non-safeguards power. The loss of the two non-vital 4KV buses resulted in actuation of the Steam and Motor Driven Auxiliary Feedwater Pumps.
Unit 1 was at full power and none of the Unit 1 systems were affected by this event.
This 60-day licensee event report is being submitted in accordance with the requirements of 10 CFR 50.73(a)(2)(iv)(A),
System Actuation.
Cause of the Event
The System Actuation event occurred as a result of inadvertent contact of a metallic tagout clearance tool between two adjacent knife switches. Further investigation revealed that previous procedural guidance that could have prevented this event had been inappropriately removed from the procedure after an equipment modification. Also contributing to the event was that the procedure details for controlling knife switches and the knowledge of knife switch configuration was less than adequate.
Analysis of the Event
During investigation into the cause of this event, the root cause evaluation team identified that a procedure guiding operations of transformers and electrical equipment was revised based on a station modification. The procedure revision removed guidance for tag out clearance activities for knife switches. The clearance and tagging procedure also did not provide sufficient guidance for installing tagout clearances on knife switches. The team also identified a collective knowledge gap amongst personnel with respect to where power was located on these knife switches.
The procedural deficiencies along with the knowledge gap resulted in the loss of the two non-vital 4KV buses causing the Steam and Motor Driven Auxiliary Feedwater Pumps to automatically actuate. The Auxiliary Feedwater System functioned normally upon actuation.
Unit 1 plant systems were not affected by this condition.
Corrective Actions
The main transformer, associated non-vital busses, plant systems and resultant auxiliary feedwater system actuation were restored to the required lineup. The causes of the event are being addressed in the corrective action program.
Safety Significance
This event has been deemed to be of low safety significance given the mode of operation, equipment affected and the equipment available to maintain safe and stable plant conditions. There was no change in Probabilistic Risk Assessment (PRA) for Unit 1 or Unit 2. No radiological or industrial safety issues resulted directly from this event.
Similar Events
There have not been similar events of system actuation from similar causes that were reported in the last three years.
Component Failure Data
None
NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BYOMB: N0.3150-0104 EXPIRES: 01/31/2017 (02-2014)
.:j')r;J"1\\REa11l.,JO tJ" f~
r;
- 2.
\\..... / LICENSEE EVENT REPORT (LER)
(See Page 2 for required number of digits/characters for each block)
- 1. FACILITY NAME Point Beach Nuclear Plant Unit 2
- 4. TITLE
, the NRC may not conduct or sponsor, and a person is not required to respond to, the information collection.
- 6. LERNUMER YEAR I SEQUENTIAL I NUMBER REV NO.
2015 -
005 00
- 3. PAGE 2
OF 2
At 0348 on October 29, 2015 while in MODE 3 during the Unit 2 refueling outage a main transformer lockout was generated when a short circuit was created while performing a tagout clearance activity. The main transformer lockout resulted in a loss of non-vital 4KV buses and a loss of all non-safeguards power. The loss of the two non-vital 4KV buses resulted in actuation of the Steam and Motor Driven Auxiliary Feedwater Pumps.
Unit 1 was at full power and none of the Unit 1 systems were affected by this event.
This 60-day licensee event report is being submitted in accordance with the requirements of 10 CFR 50.73(a)(2)(iv)(A),
System Actuation.
Cause of the Event
The System Actuation event occurred as a result of inadvertent contact of a metallic tagout clearance tool between two adjacent knife switches. Further investigation revealed that previous procedural guidance that could have prevented this event had been inappropriately removed from the procedure after an equipment modification. Also contributing to the event was that the procedure details for controlling knife switches and the knowledge of knife switch configuration was less than adequate.
Analysis of the Event
During investigation into the cause of this event, the root cause evaluation team identified that a procedure guiding operations of transformers and electrical equipment was revised based on a station modification. The procedure revision removed guidance for tag out clearance activities for knife switches. The clearance and tagging procedure also did not provide sufficient guidance for installing tagout clearances on knife switches. The team also identified a collective knowledge gap amongst personnel with respect to where power was located on these knife switches.
The procedural deficiencies along with the knowledge gap resulted in the loss of the two non-vital 4KV buses causing the Steam and Motor Driven Auxiliary Feedwater Pumps to automatically actuate. The Auxiliary Feedwater System functioned normally upon actuation.
Unit 1 plant systems were not affected by this condition.
Corrective Actions
The main transformer, associated non-vital busses, plant systems and resultant auxiliary feedwater system actuation were restored to the required lineup. The causes of the event are being addressed in the corrective action program.
Safety Significance
This event has been deemed to be of low safety significance given the mode of operation, equipment affected and the equipment available to maintain safe and stable plant conditions. There was no change in Probabilistic Risk Assessment (PRA) for Unit 1 or Unit 2. No radiological or industrial safety issues resulted directly from this event.
Similar Events
There have not been similar events of system actuation from similar causes that were reported in the last three years.
Component Failure Data
None
NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BYOMB: N0.3150-0104 EXPIRES: 01/31/2017 (02-2014)
.:j')r;J"1\\REa11l.,JO tJ" f~
r;
- 2.
\\..... / LICENSEE EVENT REPORT (LER)
(See Page 2 for required number of digits/characters for each block)
- 1. FACILITY NAME Point Beach Nuclear Plant Unit 2
- 4. TITLE Estimated burden per response to comply with this mandatoJY collection request:
80 hours9.259259e-4 days <br />0.0222 hours <br />1.322751e-4 weeks <br />3.044e-5 months <br />.
Reported lessons learned are incorporated into the licensing process and fed back to industJY.
Send comments regarding burden estimate to the FOIA, Privacy and Information Collections Branch (T-5 F53),
U.S.
Nuclear Regulatory Commission, Washington, DC 20555-0001, or by internet e-mail to lnfocollects.Resource@nrc.gov, and to the Desk Officer, Office of Information and RegulatoJY Affairs, NEOB-10202, (3150-0104), Office of Management and Budget, Washington, DC 20503. If a means used to impose an information collection does not display a currently valid OMS control number, the NRC may not conduct or sponsor, and a person is not required to respond to, the information collection.
- 2. DOCKET NUMBER
- 3. PAGE 05000301 1
OF 2
Main Transformer Lockout and Associated Loss of Buses Results in System Actuation
- 5. EVENT DATE
- 6. LER NUMBER
- 7. REPORT DATE
- 8. OTHER FACILITIES INVOLVED YEAR I SEQUENTIAL I Rev NUMBER NO.
MONTH YEAR FACILITY NAME uu""-t: 1 NUMBER NA NA MONTH DAY YEAR DAY FACILITY NAME DOCKET NUMBER 10 29 2015 2015 -
005 -
00 12 16 2015 NA NA
- 9. OPERATING MODE
- 11. THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR §: (Check all that apply)
D 20.2201 (b)
D 20.2203(a)(3)(i)
D 50.73(a)(2)(i)(C)
D 50.73(a)(2)(vii)
D 20.2201 (d)
D 20.2203(a)(3)(ii)
D 50.73(a)(2)(ii)(A)
D 50.73(a)(2)(viii)(A)
MODE3 D
D D
D 20.2203(a)(1) 20.2203(a)(4) 50.73(a)(2)(ii)(B) 50.73(a)(2)(viii)(B)
D 20.2203(a)(2)(i)
D 50.36(c)(1)(i)(A)
D
- 50. 73(a)(2)(iii)
D 50.73(a)(2)(ix)(A)
- 10. POWER LEVEL D 20.2203(a)(2)(ii)
D 50.36(c)(1 )(ii)(A)
IZl 50.73(a)(2)(iv)(A)
D 50.73(a)(2)(x)
D 20.2203(a)(2)(iii)
D 50.36(c)(2)
D 50.73(a)(2)(v)(A)
D 73.71 (a)(4)
D 20.2203(a)(2)(iv)
D 50.46(a)(3)(ii)
D 50.73(a)(2)(v)(B)
D 73.71 (a)(5) 0%
D D
D D
20.2203(a)(2)(v) 50.73(a)(2)(i)(A) 50.73(a)(2)(v)(C)
OTHER D 20.2203(a)(2)(vi)
D 50.73(a)(2)(i)(B)
D 50.73(a)(2)(v)(D)
~!'_e_::i2' in Abstract below or in 12. LICENSEE l.iUN IAI.i FOR THIS LER FACILITY NAME TFI FPHONF. NUMBER (Include Area Code)
Thomas P. Schneider, Senior Licensing Engineer 920-755-7797
- 13. r.nMPl.ETE ONE LINE FOR EACH = lENT I'll. II I I~ I=
u:n IN THS ru:r-u"-
CAUSE
SYSTEM COMPONENT MANU-REPORTABLE
CAUSE
SYSTEM FACTURER TO EPIX COMPONENT MANU-FACTURER REPORTABLE TO EPIX NA NA NA NA NA NA
- 14. SUPP,_EMENTAL ra:r-U"-1 EXPEGTED YES (If yes, complete 15. EXPECTED SUBMISSION DATE)
X NO ABSTRACT (Limit to 1400 spaces i.e, approximately 15
'J
- lines)
NA NA
- 15. EXPECTED SUBMISSSION DATE NA MONTH NA NA DAY YEAR NA NA On October 29, 2015, during Unit 2 refueling outage activities, a main transformer lockout was generated when a short circuit was created while performing a tagout clearance activity. The main transformer lockout resulted in a loss of non-vital 4KV buses, which resulted in actuation of the Steam and Motor Driven Auxiliary Feedwater Pumps.
Unit 1 was at full power and none of the Unit 1 systems were affected by this event.
This event is being reported pursuant to 10 CFR 50. 73(a)(2)(iv)(A), as a specified System Actuation.