05000424/LER-1997-001, :on 970109,thermal Overload Bypass Jumper Connection Rendered ECCS Valve Inoperable.Caused by Cognitive Personnel Error.Electricians Involved Counseled
| ML20134H523 | |
| Person / Time | |
|---|---|
| Site: | Vogtle  |
| Issue date: | 02/06/1997 |
| From: | Mccoy C, Sheibani M GEORGIA POWER CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| LCV-0969, LCV-969, LER-97-001, LER-97-1, NUDOCS 9702110341 | |
| Download: ML20134H523 (5) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(i) |
| 4241997001R00 - NRC Website | |
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Georgia Power Company 40 invern ss Center Parkway Post Othee Box 1295
' %rmingham. Alabama 35201 TelepMe 205 992-7122 m
GeorgiaIbwer [c P es dent. Nuclear February 6, 1997 Vogtle Project Docket Nos. 50-424 l
U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D. C. 20555 I adies and Gentlemen:
VOGTLE ELECTRIC GENERATING PLANT LICENSEE EVENT REPORT 1-97-01 TIIERMAL OVERLOAD BYPASS JUMPER CONNECTION RENDERS ECCS VALVE INOPERABLE In accordance with the requirements of 10 CFR 50.73, Georgia Power Company (GPC) hereby submits a Vogtle Electric Generating Plant licensee event report concerning an event which was discovered on January 9,1997.
Sincerely, OD111' l
C. K. McCoy CKM/NJS i
Enclosure: LER l-97-01 xc:
Georgia Power Comp.any Mr. J. B. Beasley, Jr.
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Mr. M. Sheibani
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1 U. S. Nuclear Regulatory Commission Mr. L. A. Reyes, Regional Administrator Mr. L. L. Wheeler, Licensing Project Manager, NRR Mr. C. R. Ogle, Senior Resident Inspector, Vogtle 9702110341 970206 PDR ADOCK C5000424 j
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NRc 76RM ses U.S. NUCLEAR REGULATORY COMMISSION APPROVED OMB NO. 31804104 p)
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- 1. AN ENT D T. W ON F ACluTY NAME (1)
DOCKET NUMBER (2) 8' An8 't Vogtle Electric Generating Plant - Unit 1 l5l0l0l0l4l2l4 1
OF 4
TITLE (4)
THERMAL OVERLOAD BYPASS JUMP iR CONNECTION RENDERS ECCS VALVE INOPERABLE EVENT DATE (5)
LER NUMBER (6)
REPORT DATE (7)
OTHER F ActuTIES INVOLVED (8)
MONTH DAY YEAR YEAR Hg%A q gg MON 1H DAY YEAR F ACILITY NAME DUCKET NUMBER (S) a olslololol l l f ACILITY NAME 011 Ol9 9l7 917 01011
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Ol0 0l 2 0l6 9l7 ol3lojojol l l OPERATING THIS REPORT IS SUBMITTED PUR$UANT TO THE REQUIREMENTS OF 10 CFR g' (Checli one or amr.) (11)
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X SO 7ha,@0) 60 7he)(2)(vm)
POWER 20 220*a)(1) 20 220*a)(3)0)
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LEVEL (10)
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Spec #ym Abstectbelow h>c Mi 20 220hajm(w) 60 36(c)(2) 60 The)Q(vu) or m AIRC Form 366A LICENSEE CONT ACT FOR THIS LER (12)
NAME
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Mehdi Sheibani, Nuclear Safety and Compliance
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Walkdowns performed by NRC resident inspectors found the thermal overload bypass jumper for valve IHV-8802A improperly connected. This valve is normally closed, but must be opened post-LOCA to initiate hot-leg recirculation. Technical Specification 3.8.4.2 requires the thermal overload protection to be bypassed for this valve. Within 3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br /> of this discovery on January 9,1997, the jumper was connected to the correct location.
An investigation found that the last time work had been performed affecting thisjumper was during the refueling outage in March 1996. Thejumper had been removed and subsequently reinstalled during valve testing at that time. Due to a lack of evidence to the contrary, it was determined that thejumper must have been incorrectly installed following this valve testing. Therefore, the cause of this event was cognitive personnel error on the part of the electricians involved. The electricians were counseled regarding attention to detail, proper installation oflifted leads, and the value of independent verification. Also, this event will be addressed for maintenance personnel in 1997 continuing training.
NRC eom, ans peo)
i NRc FORM sesA U.S. NUCLEAR REGULATORY COMMUSION (ses)
LICENSEE EVENT REPORT (LER)
TEXT CONTINUATION FACMTY NAME (1)
DOCKET NUMBER (2)
LER NUMBER (S)
PAGE p)
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% "wou Vogtle Electric Generating Plant - Unit 1 015l0l0l0l4l2l4 9l7
- - 0l0l1
- - 0l0 l2 oF l4 TE.X1 (# moso comos a required use
- - _: copes of NRC Form 306AA17)
A. REQUIREMENT FOR REPORT This report is required per 10 CFR 50.73 (a)(2)(i) because the unit operated in a condition prohibited by the Technical Specifications (TS) when a thermal overload circuit was not bypassed as required by TS 3.8.4.2. In addition, since the thermal overload circuit could have prevented valve IHV-8802A from fulfilling its safety function, the failure to bypass the circuit rendered the valve inoperable. Therefore, the Train A ECCS subsystem was inoperable for the time that the circuit was not bypassed, and the unit operated in a condition prohibited by TS 3.5.2.
B. UNIT STATUS AT TIME OF EVENT At the time of the discovery of this event on January 9,1997, Unit I was operating in Mode 1 (power operation) at 100 percent of rated thermal power. Other than that described herein, there was no inoperable equipment that contributed to the occurrence of this event.
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C. DESCRIPTION OF EVENT
On January 8,1997, NRC resident inspectors performed a walkdown of selected motor control center (MCC) cubicles. This walkdown included checking the termination points of the orange thermal overload bypassjumpers. On January 9,1997, an inspector began matching the as-found termination points for the thermal overload bypassjumpers with design drawings. Personnel observed that the MCC for the Train A safety injection (SI) pump discharge header valve, lHV-8802A, had a thermal overload bypassjumper connected to terminal 14 instead of terminal 15, as shown on the drawing. The inspector and the system engineer again went to the cubicle, verified the as-found configuration and notified the control room. This valve is normally closed, but it must be capable of opening following a LOCA to initiate hot-leg recirculation. Since the thermal overload circuit, which is required to be bypassed per TS 3.8.4.2, could prevent the valve from fulfilling its safety function, valve IHV-8802A was rendered inoperable by this condition. A limiting condition for operation (LCO) was entered at 1429 EST to remove the valve from service per the requirements of TS 3.8.4.2 and TS 3.5.2. The bypassjumper was re-installed to terminal 15, the LCO was exited at 1655 EST, and lHV-8802A was returned to service.
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groRm ma u.s.wucLEAR REGULATORY coMMISSicN LICENSEE EVENT REPORT (LER)
TEXT CONTINUATION F ACLITY NAME (1)
DOCKET NUMBER (2)
LER NUMBER (S)
PAGE p)
^" n ** *!","*' 9W "=
Vogtle Electric Generating Plant - Unit 1 015l0l0l0l4l2l4 9l7 0l0l1
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D. CAUSE OF EVENT
An investigation found that the last time work had been performed in the cubicle was during the refueling outage in March 1996. The jumper had been removed and subsequently reinstalled during valve testing at that time. Due to a lack of evidence to the contrary, it was determined that the jumper must have been incorrectly installed to terminal 14 instead of terminal 15 in March 1996.
The cause of this event was cognitive personnel error on the part of the Georgia Power Company electricians involved. There were no unusual characteristics of the work location that contributed to the occurrence of this error.
E. ANALYSIS OF EVENT
Valve IHV-8802A is normally closed to support safety injection to the reactor coolant system cold legs immediately following an accident. Some time into the accident, it would be necessary to open this valve to establish hot-leg recirculation. Therefore, this condition would not have affected the initial phase of accident mitigation. Later in the accident, had a thermal overload condition existed, lHV-8802A may not have opened when required to initiate the hot leg recirculation phase of ECCS cooling. So, a single failure consisting of a loss of Train B emergency power in conjunction with a condition resulting in a thermal overload of IHV-8802A could prevent initiation of hot-leg recirculation via the safety injection pumps (valves 1HV-8802A or B).
Hot-leg recirculation is intended to address the concern of boron precipitation during post-LOCA cooling following an RCS cold leg break. If the boron were to precipitate on the fuel cladding surface, it could result in additional thermal resistance to heat removal, and the boron could block cooling passages needed to maintain long-term core cooling. As a result, operating three and four loop pressurized water reactor:: of the Westinghouse design have in place emergency operating procedures to realign the ECCS to the RCS hot legs. However, in WCAP-14486, "ECCS Hot Leg Recirculation Elimination for Westinghouse 3 and 4 Loop Design NSSS," Westinghouse has demonstrated analytically that there is enough flow through the gap between the core barrel and the reactor vessel at the hot leg nozzles so that realignment of the ECCS for hot-leg recirculation is not necessary. This gap provides a flowpath directly from the upper plenum into the reactor vessel down comer, permitting highly borated water to be recirculated back to the containment sump via the break which is located downstream of the down comer. The forward flushing of the core through this gap is adequate to limit boron precipitation, thereby eliminating the need for hot-leg recirculation and assuring that the reactor core would remain subcritical.
g,*oam Nu U.S. NUCLEAR REGULATORY COMMLSION LICENSEE EVENT REPORT (LER)
TEXT CONTINUATION F ACILITY MME (1)
DOCKET NUMBER (2)
LER NUM9ER {G)
PAGE (3) ve^a 4 uoup 5 ag Vogtle Electric Generating Plant - Unit 1 0l5l0l010l4l2l4 9l7 0l0l1
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Finally, no event requiring a safety injection has occurred since this condition was instituted following the March 1996 refueling outage. Based on these considerations, t:. t has been no
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adverse affect on plant safety or en the health and safety of the public as a resuh of this event.
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F. CORRECTIVE ACTION
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- 1) The electricians involved were counseled regarding attention to detail, proper installation oflified leads, and the value ofindependent verification.
- 2) In response to this event, the other TS related valves in both Unit I and Unit 2 were checked to ensure their thermal overload bypass jumpers were properly installed.
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- 3) Other electricians have been advised of this event and the potential consequences ofimproperly
]
connectedjumpers.
- 4) This event will be addressed in the next segment of maintenance department personnel's 1997 continuing training, to be completed by April 25,1997.
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G. ADDITIONALINFORMATION l
- 1) Failed Components:
None i
- 2) Previous Similar Events:
None
- 3) Energy Industry Identification System Code:
Safety Injection System - BQ 4