ML20134N026

Special Rept:On 961006,groundwater Alarm Was Received & Entered in TS Action Item List for Tracking.Field Survey of Surrounding Areas Was Performed to Verify That No Water Was Percolating to Surface That Would Indicate Pipe Leak

ML20134N026
Person / Time
Site:	McGuire
Issue date:	11/14/1996
From:	Mcmeekin T DUKE POWER CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
NUDOCS 9611260129
Download: ML20134N026 (5)

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Dukebru>cr Cony >any T C Mallum McGuire Nuclear Generation Department l' ice 1+aident 12700 Hagers ferry Road (MGOIL')

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.I Hunterstille, NC230WDIO (W1)87.54800 (WI)S?54809 Fat

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f November 14, 1996 i

i j U.S. Nuclear Regulatory Connaission

! DocuOsnt Control Desk j Washington, D.C. 20555 ,

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Subject:

McGuire Nuclear Station, Unit 1 and 2 4

Docket No. 50-369 i Special Report Number 96-04

Problem Investigation Process No.

2-M96-2898 i

j ' Gentlemen:

k Attached is Special Report 96-04, concerning selected Licensee Comunitment 16.9-8. The groundwater level at well Mk. GWA-2, monitored t

by 2WELS5060, was in alarm for 7 days. This event is considered to be of no significance with respect to the. health and safety of the public.

Very truly yours, NM T.C. McNeeki,n JWP/bcb Attachment cca Mr. S.D. Ebneter INPO Records Center Administrator, Region II Suite 1500

'U.S. Nuclear Regulatory Commission 1100 Circle 75 Parkway

- 101 Marietta St., NW, Suite 2900 Atlanta, GA 30339 Atlanta, GA 30323 Mr. Victor Norses Mr. Scott Shaeffer U.S. Nuclear Regulatory Commission NRC Resident Inspector ,

Office of Nuclear Reactor Regulation McGuire Nuclear Station J Washington, D.C. 20555

,-annn 9611260129 961114 I gDR ADOCK 050003 9 hhj i

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-. . = . ~. .- . - . ..... - . - _ .

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, bxc B. L. Walsh (EC11C) 4 M. S. Kitlan (CNS)

, G. A. Copp (EC050) 1 J. I. Glenn (MG02ME)

P. R. Herran (MG01VP) i C. B. Davis (MG01CP)

J. E. Burchfield (ONS Reg Compliance) l G. H. Savage (EC06E)

G. B. Swindlehurst (EC11-0842)

C. M. Misenheimer (EC08I)

R. F. Cole (EC05N)

J. M. Frye (EC05N)

T. G. Becker (PB02L)

P. M. Abraham (EC08I)

R. B. White (MG01VP)

L. V. Wilkie (ONO3SR) 4 D. P. Kimball (CN058R)

K. L. Crane (MG01RC)

, R. N. Casler (EC05N)

! D. A. Harton (EC05N)

NSRB Support Staff (EC05N) i i

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,. Duke Power Company McGuire Nuclear Station 4

i System Engineering Group special Report This Special Report is being submitted as required by Selected Licensee Commitment (SLC) 16.9-8. Groundwater well l i

j. Mk. GNA-2 (a Reactor Building well monitored by 2WZLS5060) i was above the Alert level of 731' for 7 days.

j Report No.: 96-04 Date of Report: 11/14/96

{ Description of Incident 1

Unit Status: Both Units were in Mode 1 (Power Operation) at j 100% power at the time the Groundwater Alarm was received.

i The Groundwater Alarm (730'11"'") at this location was initially received on 10/06/96 and entered in the Technical i

l Specification Action Item List (TSAIL) for tracking, even i though it is a not a Technical Specification related well.  :

This alarm was checked by the IAE group and appeared to be This alarm subsequently cleared in less than 7 days.

valid.

l The alarm returned and was again entered in the TSAIL on {

! 10/11/96. The alarm cleared on 11/2/96 at 2230, ~22 days.

SLC 16.9-8 prompts this report when groundwater level at j this location is above 731' for 7 days. For conservatism,

! we have assumed that if instrument is in alarm we are above l 731'. While the report documenting this investigation was i being prepared, the alara returned on 11/7/96. This was not j unexpected due to precipitation the previous week and the

level was already near the setpoint. Level Switch 2WZLS5060 i is still in alarm at the time this report is being i submitted. The alarm is for the same reasons, and  ;

corrective actions are the same; therefore, this report

} covers both events. ,

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i Well Mk. GWA-2 monitors groundwater.at the Unit 2 Reactor

, Building wall. The Reactor Buildings at McGuire have been l analyzed for groundwater hydrostatic loading up to grade l elevation (760'). Therefore, there is no concern with the

safety and health of-the public or the safety of the station. After the analysis confirmed the Reactor and Diesel

, Buildings at McGuire were capable of withstanding l

hydrostatic loads up to grade elevation, the monitoring wells associated with these structures were removed from the l McGuire Tech Specs. They were kept in the McGuire SLC's to i be used as a tool in identifying piping leaks or breaks in

! the yard and as an indication of a problem with the

underground drainage grid system.

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DPC/MNS

,,Special report No. 96-04

- Page 2 6

Corrective Action f Insmediate It was verified that no other groundwater monitoring i

instruments were in alarm.

! e A field survey of the surrounding areas was performed to j

verify there was no water percolating to the surface that would indicate a pipe leak / rupture.

l e An interview was conducted with the steam generator j

replacement teamunate overseeing construction regarding recent excavation work on the Unit 2 side of the site.

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Environmental Engineering was requested to support this evaluation. Their evaluation concludes that this is a natural groundwater phenomenon vs. a leak induced rise in groundwater level. They have seen rises in groundwater 4

at other sites on the Duke Power system recently. They i

also feel that the underground drainage grid is still

! functioning adequately due to the lack of alarms at other

} locations. In.particular, the adjacent Auxiliary j

Building well (Mk. GWB-2) that is monitored by instrument i

2WELS5070 has not alarmed. Groundwater levels at the i

site are driven by the level of Lake Norman and precipitation. Both have been above average for the last j few years. Based on SAR documents related to i construction at the McGuire site, the level at which this

}' alarm _(2WELS5060) ham.been received does not appear i abnormally high. The documents also indicate that l

j groundwater would drain toward the Reactor Building.

Recent construction projects associated with the Unit 2 side of the site may have contributed to soil changes

that have affected this well. These projects have also j altered the topography in this area, allowing more l precipitation to soak into the soil as opposed to j

draining to the yard drain system. All of these factors could affect the local groundwater level. However, they are not jeopardizing the safety of the station or the public, as evidenced by the lack of alarms at any of the Technical Specification wells.

Planned e

Continue to monitor well Mk. GWA-2. This well (monitored by 2hzLS5060) is located at the Unit 2 Reactor Building exterior wall. The Reactor Building has been qualified for hydrostatic pressures up to grade elevation (760').

The alarm was received at ~731' and is a float switch type instrument. We will monitor this well with direct reading instrumentation in order to obtain better data on '

water level fluctuations.

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DPC/MNS l ,Specialreport No. %-04

. Pige 3 Monitor the nearest Technical specification related well (Bot. GWB-2, monitored by 2WZLS5070) in order to verify that this phenomenon is localized in the area of well Mk.

l GWA-2 and does not raise concerns with the Auxiliary

Building groundwater levels. As mentioned previously, we have not received any alarms associated with the

Auxiliary Building. The Auxiliary Building. monitors are associated with Technical specification 3/4.7.13. Should ~

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any three of the five indicate above elevation 731', the plant would be required to lower the groundwater level to less than 731' within one hour or shutdown within the following six hours.

e After confirming that the rise in groundwater is j

localized to the area of Mk. GWA-2 and there is no

,* problem that could affect the Auxiliary Building, Duke i

Power may seek a change to the SLC to more closely reflect the expected seasonal high groundwater elevation l at this well site. This should eliminate a nuisance i

j-alarm in the control room. No requests for changes to any of the Auxiliary Building (Technical specification 3 related) setpoints are anticipated.

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