05000424/LER-2002-001, Re Improperly Wired Interlock Affects ECCS Recirculation Valve
| ML021440212 | |
| Person / Time | |
|---|---|
| Site: | Vogtle  |
| Issue date: | 05/07/2002 |
| From: | Beasley J Southern Nuclear Operating Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| LCV-1622 LER-02-001-00 | |
| Download: ML021440212 (6) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(i) 10 CFR 50.73(a)(2)(viii) 10 CFR 50.73(a)(2)(ii) 10 CFR 50.73(a)(2)(x) 10 CFR 50.73(a)(2)(iii) 10 CFR 50.73(a)(2)(iv), System Actuation 10 CFR 50.73(a)(2)(v), Loss of Safety Function 10 CFR 50.73(a)(2)(vii), Common Cause Inoperability |
| 4242002001R00 - NRC Website | |
text
J. Barnie Beasley, Jr., P.E.
Vice President Southern Nuclear Operating Company, Inc.
40 Inverness Center Parkway Post Office Box 1295 Birmingham, Alabama 35201 Tel 205.992.7110 Fax 205.992.0403 SOUTHERNUI.
COMPANY Energy to Serve YourWorld" May 7, 2002 LCV-1 622 Docket No.: 50-424 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D. C. 20555 Ladies and Gentlemen:
VOGTLE ELECTRIC GENERATING PLANT LICENSEE EVENT REPORT 1-02-001 IMPROPERLY WIRED INTERLOCKS AFFECTS ECCS RECIRCULATION VALVE In accordance with the requirements of 10 CFR 50.73, Southern Nuclear Operating Company hereby submits a Vogtle Electric Generating Plant licensee event report for a condition that occurred on Unit 1 on March 12, 2002.
JBB/JPC Enclosure: LER 1-02-001 cc: Southern Nuclear Operating Company Mr. J. T. Gasser Mr. M. Sheibani SNC Document Management U. S. Nuclear Regulatory Commission Mr. L. A. Reyes, Regional Administrator Mr. F. Rinaldi, Vogtle Project Manager, NRR Mr. J. Zeiler, Senior Resident Inspector, VEGP VI '
NRC FORM 366 U.S.NUCLEAR REGULATORY COMMISSION APPROVED OMB NO. 3150-0104 EXPIRES: 06/30/2001 NR(
OR6 66USN1998RGUAOY O MISO
, the NRC may not conduct or sponsor, and a person is not required to respond to, the information collection.
FACILITY NAME (1)
DOCKET NUMBER (2)
PAGE (3)
Vogtle Electric Generating Plant - Unit 1 0 5 0 0 0 4 2 4 1 OF 5
TITLE (4)
IMPROPERLY WIRED INTERLOCK AFFECTS ECCS RECIRCULATION VALVE EVENT DATE (5)
LER NUMBER (6) l REPORT DATE (7)
OTHER FACILITIES INVOLVED (8)
MONTH lDAY I YEAR YEAR SEQUENTIAL REUtOtON DAY YEAR FACILITY NAME DOCKET NUMBER 0 5 0 0 0 FACILITY NAME 0 31212002200210 0 11 0 0 05072002 0 5 0 0 0 OPERATING THIS REPORTIS SUBMITTED PURSUANTTO THE REQUIREMENTS OF 10 CFR§: (Checkone ormore)
(11)
MODE (9) 5 20.2201(b) 20.2203(a)(2)(v) 50.73(a)(2)(i) 50.73(a)(2)(viii)
POWER 20.2203(a)(1) 20.2203(a)(3)(i) 50.73(a)(2)(ii) 50.73(a)(2)(x)
LEVEL (10) 0 20.2203(a)(2)(i) 20.2203(a)(3)(ii) 50.73(a)(2)(iii) 73.71 I
20.2203(a)(2)(ii) 20.2203(a)(4) 50.73(a)(2)(iv)
OTHER 20.2203(a)(2)(iii) 50.36(c)(1) 50.73(a)(2)(v)
Specify in Abstract below 20.2203(a)(2)(iv) 50.36(c)(2) 50.73(a)(2)(vii) l or in NRC Form 366A LICENSEE CONTACT FOR THIS LER (12)
NAME TELEPHONE NUMBER (include area code)
Mehdi Sheibani, Nuclear Safety and Compliance 17 ° 6 -
8 2 6 3 2 0 9 COMPLETE ONE LINE FOR EACH COMPONENT FAILURE DESCRIBED IN THIS REPORT (13)
CAUSE
SYSTEM COMPONENT MANUFACTURER REPORTABLE
CAUSE
SYSTEM COMPONENT MANUFACTURER REPORTABLE TO EPIXTO EPIX SUPPLEMENTAL REPORT EXPECTED (14) l EXPECTED IOMONTH YEAR SUBMISSION YES (If yes, complete EXPECTED SUBMISSION DATE) lX INO DATE (5)l ABSTRACT (Limit to 1400 spaces, i.e., approximately 15 single-space typewritten lines) P1b1 During the IRl0 refueling outage, two wiring errors were discovered that would have prevented the opening of 1HV-8804B during a loss of power to Train A. 1HV-8804B provides a path from the discharge of the Train B Residual Heat Removal Pump to the suction of the high head Centifugal Charging Pumps and the intermediate head Safety Injection Pumps. Although post-LOCA flow requirements continued to be met for design bases accidents, this condition represents operation of the unit in a condition prohibited by the Technical Specifications for post-LOCA ECCS recirculation operations.
A review of work orders has found that these mis-wirings likely occurred during maintenance performed in 1991 and/or 1996. However, because of the time lapses involved, the root cause of these human performance errors cannot be conclusively determined. The appropriate procedure will be revised to require electricians to utilize the elementary drawing and wiring diagrams to verify wiring terminations prior to lifting leads on safety-related motor operated valves scheduled for maintenance.
NRC Form 366 (6-1998)
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.1 A-l-lV r n-au OI flLU.b.NUtLrAIN A -UULM I %JE_
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(6-1998)
LICENSEE EVENT REPORT (LER)
TEXT CONTINUATION FACILITY NAME (1)
DOCKET NUMBER (2)
LER NUMBER (6)
PAGE (3)
YEAR SEQUENTIAL RIN NUMBER NUMBER Vogtle Electric Generating Plant - UnitI 05000424 2 00 2 0 0 1 0 0 TEXT (If more space is required, use additional copies of NRC Form 366A)(17)
A. REQUIREMENT FOR REPORT This event is reportable per 10 CFR 50.73 (a)(2)(i) because the unit operated in a condition prohibited by the Technical Specifications when a valve in the suction path to the intermediate head safety injection (SI) pumps and the high head centrifugal charging pumps (CCPs) was inoperable.
B. UNIT STATUS AT TIME OF EVENTS At the time of the discovery of these events on March 7, 2002, and April 1, 2002, Unit 1 was in a refueling outage in Mode 5 (Cold Shutdown) and in Mode 6 (Refueling), respectively. Other than that described herein, there was no inoperable equipment that contributed to the occurrence of this event.
C. DESCRIPTION OF EVENT
During the 1 R10 refueling outage, some electricians adopted the practice of utilizing elementary drawing and wiring diagrams to verify wiring terminations prior to lifting leads on motor operated valves scheduled for maintenance. As a result, two wiring errors were discovered that would have prevented the opening of IHV-8804B during a loss of power to Train A. This valve provides a suction path from the discharge of the Train B Residual Heat Removal (RHR) pump to the suction of the high head CCPs and intermediate head SI pumps, during post-LOCA ECCS recirculation operations.
On March 7, 2002, maintenance was being performed on the Unit 1 common SI miniflow isolation motor operated valve, 1HV-8813. It was discovered that interlock wiring with a second SI motor operated valve, IHV-8804B, was not terminated in accordance with plant drawings. The wiring error was promptly corrected.
Following the March 7, 2002, discovery of the interlock mis-wiring, additional interlock testing was performed. On April 1, 2002, during testing of the Unit 1 high head CCP miniflow isolation motor operated valve, lHV-8509B, it was found that interlock wiring with IHV-8804B was also not terminated in accordance with plant drawings. Again, the wiring error was promptly corrected.
1-11AWfD' pfhIRRAIQC~lrMU.0.NUkALr S3 Sm.x UUL^ E W.
(6-1998)
LICENSEE EVENT REPORT (LER)
TEXT CONTINUATION LER NUMBER (6)
I PAGE (3)
FACILITY NAME (1)
Vogtle Electric Generating Plant - Unit 1 TEXT (If more space is required, use additional copies of NRC Form 366A)(17)
NUMBER l-NUMBER [2
0 0 2 -lo 0 1 l-00 3 OF 5
The Plant Vogtle intermediate head SI pumps and the high head CCPs have mini-flow paths from their pump discharge piping to the Refueling Water Storage Tank. If a single failure of Train A power occurs during a design bases accident, the following would be expected to occur:
- 1) The two SI pumps have a common miniflow isolation motor operated valve, IHV-8813, that is Train B powered. This miniflow path is isolated prior to transitioning from the Emergency Core Cooling Injection Mode to the Recirculation Mode of operation. A properly wired interlock allows the opening of lHV-8804B during switchover from Injection Mode to the Recirculation Mode after the SI pump miniflow path has been isolated by closing IFHV-8813.
- 2) Similarly, CCP Train A has a miniflow isolation motor operated valve, IHV-8509B, that is Train B powered. This miniflow path is isolated prior to transitioning from the Emergency Core Cooling Injection Mode to the Recirculation Mode of operation. A properly wired interlock allows the opening of IHV-8804B during switchover from Injection Mode to the Recirculation Mode after the CCP's miniflow path has been isolated by closing IHV-8509B.
Valve IHV-8804B provides a suction path from the discharge of the Train B Residual Heat Removal (RHR) pump to the suction of the CCPs and SI pumps. Valve 1HV-8804B must be open to provide water to the suction of the CCPs and SI pumps if the Train A RHR pump is unavailable.
However, these wiring errors would have prevented lHV-8804B from being opened.
On March 12, 2002, at 0830 EST, following completion of an engineering evaluation of the March 7, 2002, discovery, it was determined that this condition may represent an unanalyzed condition that significantly degrades plant safety and was reportable per 10 CFR 50.72 (b)(3)(ii)(B). The NRC Operations Center was notified at 1450 EST. Further evaluation by the design engineer determined that the condition did not represent a significant degradation to plant safety and a retraction notice was submitted to the NRC Operations Center on April 24, 2002, at 1047 EDT.
D. CAUSE OF EVENT
A review of work orders has found that these mis-wirings likely occurred during maintenance performed in 1991 and/or 1996. In the case of the SI miniflow isolation motor operated valve, cramped conditions may have contributed to the mis-wiring. However, because of the time lapses involved, the root cause of these human performance errors by licensee employees cannot be conclusively determined.
NRC Formn 366A (6-119B)
1 l
M1=I it ATnoV IfnMUIRQAld_..
(6-1 998)
LICENSEE EVENT REPORT (LER)
TEXT CONTINUATION FACILITY NAME (1)
DOCKET NUMBER (2)
LER NUMBER (6)
PAGE (3)
YEAR SEQUENTIAL REVISION 01NUMBER NUMBER Vogtle Electric Generating Plant - Unit 1 0 5000424 2 00 2 -
0 0 1 2 0 0 4 OF 5
TEXT (If more space is required, use additional copies of NRC Form 366A)(17)
E. ANALYSIS OF EVENT
The reported condition exists only when a power failure of Train A occurs. In the case of a large break LOCA, all but one of the post-LOCA minimum flow requirements are met with only residual heat removal (RHR) system flow available. This unmet requirement can be considered acceptable by crediting natural circulation flow patterns in the core. In the case of a small break LOCA, no interruption in ECCS flow would have occurred. Therefore, there was no adverse affect on plant safety or on the health and safety of the public as a result of this event.
F. CORRECTIVE ACTIONS
- 1) Other Unit 1 ECCS motor-operated valve interlocks were verified to operate properly.
Additional wiring discrepancies that did not affect component operability were found and corrected.
- 2) Prior to the Unit 2 Fall 2002 Refueling Outage, procedure 20429-C, "Short Term Documentation Of Temporary Jumpers And Lifted Wires," will be revised to require electricians to utilize elementary drawing and wiring diagrams to verify wiring terminations prior to lifting leads on safety-related motor operated valves scheduled for maintenance.
- 3) Prior to the Unit 2 Fall 2002 Refueling Outage, appropriate procedures will be revised to require functional testing of interlocks following maintenance which affects that function.
- 4) Prior to the Unit 2 Fall 2002 Refueling Outage, this lifted lead event will be added to operating experience training for electricians.
- 5) During the Unit 2 Fall 2002 Refueling Outage, the corresponding interlock wiring in Unit 2 will be verified to be functionally correct.
G. ADDITIONAL INFORMATION
- 1) Failed Components:
NoneU.b.NSUCLrAK~ E.
ULA I UMT 4LAlUNIVII00'.Jr (6-1998)
LICENSEE EVENT REPORT (LER)
TEXT CONTINUATION FACILITY NAME (1)
DOCKET NUMBER (2)
LER NUMBER (6)
YEAR SEQUENTIAL REVI Vogtle Electric Generating Plant - Unit 1 05000424 200 2 - 0 0 1 0
TEXT (If more space is required, use additional copies of NRC Form 366A)(17)
- 2) Previous Similar Events:
None
- 3) Energy Industry Identification System Code:
Safety Injection System - BQ Chemical Volume and Control System (including Centrifugal Charging Pumps) - CB Residual Heat Removal System - BP