05000390/LER-2011-002, Regarding ERCW System Valve Misalignment
| ML111640467 | |
| Person / Time | |
|---|---|
| Site: | Watts Bar  |
| Issue date: | 06/10/2011 |
| From: | Grissette D Tennessee Valley Authority |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| LER 11-002-00 | |
| Download: ML111640467 (6) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications 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) 10 CFR 50.73(a)(2)(ii)(B), Unanalyzed Condition 10 CFR 50.73(a)(2)(iii) 10 CFR 50.73(a)(2)(ix) 10 CFR 50.73(a)(2)(iv)(A), System Actuation 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 |
| 3902011002R00 - NRC Website | |
text
Tennessee Valley Authority, Post Office Box 2000, Spring City, Tennessee 37381 June 10, 2011 10 CFR 50.73 ATTN:
Document Control Desk U.S. Nuclear Regulatory Commission Washington, D.C.
20555-0001 Watts Bar Nuclear Plant, Unit 1
Facility Operating License No. NPF-90 NRC Docket No. 50-390
Subject:
Licensee Event Report 390/2011-002, Essential Raw Cooling Water System Valve Misalignment This submittal provides Licensee Event Report (LER) 390/2011-002.
This LER documents an instance where Technical Specification (TS) Surveillance Requirement (SR) 3.7.8.1 for the Essential Raw Cooling Water (ERCW) System was not met which resulted in failure to meet TS Limiting Condition for Operation (LCO) 3.7.8.
The condition is reported as an LER in accordance with 10 CFR 50.73(a)(2)(i)(B).
There are no regulatory commitments in this letter.
Please direct any questions concerning this matter to Chris Riedl, WBN Site Licensing Manager, at (423) 365-1742.
Respectfully, D. E. Grissette Site Vice President Watts Bar Nuclear Plant Enclosure cc:
See Page 2
U.S. Nuclear Regulatory Commission Page 2 June 10, 2011 Enclosure cc (Enclosure):
NRC Regional Administrator - Region II NRC Senior Resident Inspector - Watts Bar Nuclear Plant
NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION (10-2010)
LICENSEE EVENT REPORT (LER)
(See reverse for required number of digits/characters for each block)
- 1. FACILITY NAME Watts Bar Nuclear Plant APPROVED BY OMB:
NO. 3150-0104 EXPIRES:
10/31/2013 Estimated burden per response to comply with this mandatory 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 ncorporated into the licensing process and fed back to industry. Send comments regarding burden estimate to the Records and FOIA/Privacy Service Branch (T-5 F52),
U.S.
Nuclear Regulatory Commission, Washington, DC 20555-0001, or by internet e-mail to infocollects@nrc.gov, and to the Desk Officer, Office of Information and Regulatory 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 OMB control number, the NRC may not conduct or
- sponsor, and a
person is not required to respond to, the information collection.
- 2. DOCKET NUMBER 05000390
- 3. PAGE 1
OF 4
- 4. TITLE ERCW System Valve Misalignment
- 5. EVENT DATE MONTH 06 DAY 22 YEAR 2009
- 9. OPERATING MODE 1
- 10. POWER LEVEL 100%
- 6. LER NUMBER YEAR 2011 SEQUENTIAL NUMBER 002 REV NO.
0
- 7. REPORT DATE MONTH 06 DAY 10 YEAR 2011
- 8. OTHER FACILITIES INVOLVED FACILITY NAME N/A FACILITY NAME N/A DOCKET NUMBER N/A DOCKET NUMBER N/A
- 11. THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR§:
(Check all that a
20.2201 (b)
20.2203(a)(3)(i)
50.73(a)(2)(i)(C)
50.73(a)(2)(vii)
20.2201 (d)
20.2203(a)(3)(ii)
50.73(a)(2)(ii)(A)
50.73(a)(2)(viii)
20.2203(a)(1)
20.2203(a)(4)
50.73(a)(2)(ii)(B)
50.73(a)(2)(viii)
20.2203(a)(2)(i)
50.36(c)(1)(i)(A)
50.73(a)(2)(iii)
50.73(a)(2)(ix)(>
20.2203(a)(2)(ii)
50.36(c)(1)(ii)(A)
50.73(a)(2)(iv)(A)
50.73(a)(2)(x)
20.2203(a)(2)(iii)
50.36(c)(2)
50.73(a)(2)(v)(A)
73.71 (a)(4)
20.2203(a)(2)(iv)
D 50.46(a)(3)(ii)
50.73(a)(2)(v)(B)
73.71 (a)(5)
20.2203(a)(2)(v)
50.73(a)(2)(i)(A)
50.73(a)(2)(v)(C)
OTHER
20.2203(a)(2)(vi)
B 50.73(a)(2)(i)(B)
50.73(a)(2)(v)(D)
Specify in Abstrac or in NRC Form ppiy)
(A)
(B)
- 0
- t below 66A
- 12. LICENSEE CONTACT FOR THIS LER FACILITY NAME Chris Riedl, Interim Site Licensing Manager TELEPHONE NUMBER (Include Area Code)
(423)365-1742CAUSE DYE SYSTEM COMPONENT MANU FACTURER REPORTABLE II
CAUSE
TO EPIX I
CAUSE
I
- 14. SUPPLEMENTAL REPORT EXPECTED IS (If yes, complete 15. EXPECTED SUBMISSION DATE)
ES NO SYSTEM COMPONENT
- 15. EXPECTED SUBMISSION DATE MANU FACTURER MONTH REPORTABLE TO EPIX DAY YEAR ABSTRACT (Limit to 1400 spaces, i.e., approximateiy 15 single-spaced typewritten lines)
While performing Surveillance Instruction 1-SI-67-1 on June 22, 2009, TVA discovered that both Primary Essential Raw Cooling Water (ERCW) Supply Valve (2-FCV-67-66) and Backup ERCW Supply Valve (2-FCV-67-68) to the 2A-A Emergency Diesel Generator heat exchangers were open.
Under normal operating conditions, 2-FCV-67-66 is open and 2-FCV-67-68 is closed.
With both supply valves open, the system was not properly aligned, and ERCW supply headers 1A and 2B were cross-connected.
This misalignment caused the ERCW system to be inoperable in accordance with Technical Specifications (TS) Limiting Condition for Operation (LCO) 3.7.8 and the system could not meet surveillance requirement (SR) 3.7.8.1, to verify valves are in the correct position.
With both ERCW trains inoperable, the plant entered LCO 3.0.3.
Valve 2-FCV-67-68 was closed immediately upon discovery, and the plant exited LCO 3.0.3.
Evaluation of the system alignment indicates that there was no loss of safety function, but because of the incorrect alignment, the ERCW system was inoperable for over nine hours, and Watts Bar failed to be in mode 3 within seven hours as required by LCO 3.0.3.
This event is reported as a condition prohibited by TS under 10 CFR 50.73(a)(2)(i)(B) because the plant was in LCO 3.0.3 for a period longer than allowed by TS.
NRC FORM 366 (10-2010)(10-2010)
LICENSEE EVENT REPORT (LER)
CONTINUATION SHEET U.S. NUCLEAR REGULATORY COMMISSION
- 1. FACILITY NAME
- 2. DOCKET
- 6. LER NUMBER
- 3. PAGE YEAR Watts Bar Nuclear Plant 05000390 2011 SEQUENTIAL NUMBER 002 REV No.
2 OF 4 I.
PLANT CONDITIONS
Watts Bar Unit 1 was in Mode 1
at 100% rated thermal power (RTP).
II.
DESCRIPTION OF EVENT
A.
Event On June 22, 2009 at 21:30 Eastern Daylight Saving Time (EDT) with Watts Bar Nuclear Plant, Unit 1 (WBN) in Mode 1, while performing Surveillance Instruction 1-SI-67-1 the Unit Operator discovered that both Primary Essential Raw Cooling Water (ERCW)
Supply Valve (2-FCV-67-66) and the Backup ERCW Supply Valve (2-FCV-67-68) [ENS Code Bl]1 to the 2A-A Emergency Diesel Generator (EDG) heat exchangers [ENS Code EK ] were open.
With both supply valves open, the system was not properly aligned, and ERCW supply headers 1A and 2B were cross-connected, which caused both trains of ERCW to be inoperable.
Under normal operating conditions, 2-FCV-67-66 is open and 2-FCV-67-68 is closed.
Because 2-FCV-67-68 was not in the required position, SR 3.7.8.1, which requires verification that ERCW valves are in the correct position, could not be met.
Because this surveillance requirement could not be met, according to SR 3.0.1, WBN did not meet LCO 3.7.8.
Because both trains were inoperable, no LCO 3.7.8 actions applied, and LCO 3.0.3 applied, which required initiation of action within one hour and entry into MODE 3 within seven hours.
DatAWare, TVA's process data acquisition software reflected that the misalignment occurred at approximately 12:25 on June 22, indicating that from the time the valve was opened until it was closed more than nine hours had passed.
Because the duration of the condition exceeded LCO 3.0.3 action times, WBN was in a condition prohibited by TS.
The plant exited LCO 3.0.3 immediately after closing 2-FCV-67-68 at 21:37 on June 22. The event was documented in TVA's Corrective Action Program as Problem Evaluation Report (PER) 174704.
A reportability evaluation (RE) determined that no safety function was lost, because there was sufficient ERCW capacity to supply all safety related loads with both of these ERCW supply valves open.
TVA initially considered this item not to be reportable because the RE determined that even in its misaligned condition ERCW could perform its safety function and provide all necessary cooling water for both trains.
However, the NRC issued non-cited violation 05000390/2011008-001 as part of the WBN Problem Identification and Resolution (PI&R) Inspection in January of 2011.
The NRC PI&R inspection report stated that with ERCW header 1A and 2B cross connected, the system did not meet TS 3.7.8 requirements and was inoperable, noting that the RE failed to identify that operating for 9 hours1.041667e-4 days <br />0.0025 hours <br />1.488095e-5 weeks <br />3.4245e-6 months <br /> with the system inoperable exceeded LCO 3.0.3 action time and thus placed the unit in a condition prohibited by TS, which is a reportable event.
In a letter dated May 11, 2011, TVA agreed to provide this report within thirty days.
B.
Inoperable Structures, Components, or Systems that Contributed to the Event.
Misalignment of the ERCW system was due to inadvertent opening of 2-FCV-67-68 as a result of human error, which resulted in cross-tying ERCW supply headers 1A and 2B, and rendered ERCW inoperable.
No other structures, systems, or components contributed to the event.
C.
Dates and Approximate Times of Major Occurrences
Date 06/22/2009 06/22/2009 06/22/2009 Time (EST) 12:25 21:30 21:37 Event Drop in ERCW flow recorded in DatAWare Enter LCO 3.0.3 because both 2-FCV-67-66 and 2-FCV-67-68 were open which cross connected ERCW supply headers 1A and 2B.
Exit LCO 3.0.3, after closing 2-FCV-67-68.1 Energy Industry Identification System(10-2010)
LICENSEE EVENT REPORT (LER)
CONTINUATION SHEET U.S. NUCLEAR REGULATORY COMMISSION
- 1. FACILITY NAME
- 2. DOCKET
- 6. LER NUMBER
- 3. PAGE YEAR Watts Bar Nuclear Plant 05000390 2011 SEQUENTIAL NUMBER 002 REV No.
3 OF 4 II.
DESCRIPTION OF EVENT (continued):
D.
Other Systems or Secondary Functions Affected
No other system or secondary functions were affected by this event.
E.
Method of Discovery
Performance of Surveillance Instruction (SI) 1-SI-67-1, "ERCW Valves Serving Safety Equipment Position Verification."
F.
Operator Actions
After the Unit Operator was notified that flow control valve 2-FCV-67-68 was not closed, operators were dispatched to the 2A-A EDG room to verify valve position.
Flow control valve 2-FCV-67-68 was found in the open position.
Valve was then closed in accordance with SI 1-SI-67-1.
G.
Safety System Responses Although flow control valve 2-FCV-67-68 was inadvertently open, which placed a greater load on ERCW train B, analysis showed that the required flow to the safety related equipment served by the ERCW system was not compromised.
This event did not require any safety system response.
III.
CAUSE OF EVENT
The most likely cause of this event was determined to be that painters in the area inadvertently contacted and actuated the local push buttons associated with flow control valve 2-FCV-67-68.
Workers recalled working near the push buttons but were not aware of contacting push buttons.
For this reason the instance was not immediately reported to Operations.
Apparent cause was failure of the workers to maintain proper awareness of their surroundings and take adequate precautions.
IV.
ANALYSIS OF THE EVENT
The local push buttons for 2-FCV-67-68 in the 2A-A Emergency Diesel Generator Room were inadvertently contacted which caused the flow control valve to open.
The control panel is located in a tight area that provides access to the backside of the EDG.
No protective cover was provided for the local push buttons to prevent inadvertent actuation.
When flow control valve 2-FCV-67-68 opened, it diverted additional ERCW flow to DG 2A-A heat exchangers which increased the load on ERCW Train B.
As discussed in Section V below, the additional load on ERCW Train B did not jeopardize plant safety.
V.
ASSESSMENT OF SAFETY CONSEQUENCES
The Reportability Evaluation (RE) concluded that the condition identified in PER 174704 would not have resulted in loss of design bases safety functions requiring ERCW support.
Both ERCW Trains A and B were capable of performing their design bases functions during the conditions that existed while flow control valve 2-FCV-67-68 was open.
The ERCW system would also have fulfilled its design bases functions if there had been a loss of Train A or Train B.
Consequently the WBN accident analysis would not have been adversely impacted by this condition.
NKG hUKM 366A (10-2010)
LICENSEE EVENT REPORT (LER)
CONTINUATION SHEET U.S. NUCLEAR REGULATORY COMMISSION
- 1. FACILITY NAME
- 2. DOCKET
- 6. LER NUMBER
- 3. PAGE YEAR Watts Bar Nuclear Plant 05000390 11 SEQUENTIAL NUMBER 002 REV No.
4 OF 4 VI.
CORRECTIVE ACTIONS
This event was documented within TVA's Corrective Action Program as PER 174704.
A.
Immediate Corrective Actions
1.
Entered LCO 3.0.3 2.
Closed flow control valve 2-FCV-67-68, which isolated the 2B ERCW supply header and returned ERCW system to its proper alignment.
3.
Exited LCO 3.0.3 after securing 2-FCV-67-68 in the closed position.
B.
Corrective Actions to Prevent Recurrence 1.
Briefed Modifications and Facilities organizations on this event, stressing maintaining awareness of surroundings and proper self-checking techniques.
2.
Installed protective devices for pushbutton switches to prevent inadvertent operation.
3.
Dynamic Learning Center training to emphasize attention to detail and more rigorous use of Human Error Prevention Tools, including use of the two-minute rule, to ensure a more in depth look at the work area, critical components, adjacent equipment, and if any local controls are present.
VII. ADDITIONAL INFORMATION
A.
Failed Components None B.
Previous LERs on Similar Events A search of LERs and PERs documenting misalignment of the ERCW at Watts Bar Unit 1 found no LERs, but one previous similar PER.
PER 123228 documented the identical misalignment for the 1A-A Emergency Diesel Generator, with the crosstie between 1A and 2B ERCW headers.
In both cases, analysis indicated safety function was not adversely impacted.
TVA identified the cause in both cases to be human error, but resolution of the failure to properly perform procedural steps in the first event was not applicable to prevent the inadvertent actuation that occurred during the June 22, 2009 event.
C.
Additional Information
None.
D.
Safety System Functional Failure This event did not involve a safety system functional failure as defined in NEI 99-02, Revision 5.
E.
Loss of Normal Heat Removal Consideration None.
VIII.COMMITMENTS None.