ML20113H580
| ML20113H580 | |
| Person / Time | |
|---|---|
| Site: | McGuire  |
| Issue date: | 07/29/1992 |
| From: | Mcmeekin T DUKE POWER CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| NUDOCS 9208050055 | |
| Download: ML20113H580 (5) | |
Text
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Duke huwr Company T C Al vittis
,AlcGuare kirar Generurwn ikpartment ih e fyrsodent I?iOOliners irrn Road @fGoIA)
(7046i54WI Iluntmn!k, NC280iS 8915 (704)hT5 4 W f a DUKEPOWER July 29, 1992 1
U.
S.
Nuclear Regulatory Commission Attention: Document Control Desk Washington, D. C.
20555
Subject:
McGuiro Nuclear Station, Unit 1 Docket Nos. 50-369 Gamma Plug Sual Wold Failurc Main Foodwater (CF)
Dear Sir; On Juno 16, 1992, during the final reactor building inspections prior to unit i startup, leakage f rom trio inspection port. for the pipe to olbow wolds (CFIF712) was discovered.
Tnis inspection port (or gamma plug) is located on the foodwater supply to the 1B Steam Generator down strohm of' chock valvo ICF29.
The uni'c was in modo 3 (hot standby) with the CF system pressure and temperature approximately 1169 PSIG and 557 F respectively.
The leakago was charactorized as minor due to the size of the steam pluine (loss than-a 1 foot) and the slight amount of water spraying from the leakago location.
A 1-1/8 inch, noven thread por inch, non tapered solid plug is inserted into the inspection port (son attached drawing, MDS-EG-4).
The plug is then seal wolded to provido a leak tight joint.
Sinco the strength of the threaded joint is not a function of the seal wold, the seal weld is categorized as a rion-structural wold.
The soal weld providos a nealing surface and koops tho.non-tapered threaded plug from backing out.
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9'00050055 920729 s
1 PDR ADOCK 05000369 l
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U. S. Nucioar Regulatory Commission July 29,-1992 pago 2 J
On non-taporod throads, a seal wold or a seating surface must be provided.(ref. NC-3671.3).
However, the rules of i
ASME section III, subsection NC, covet " the strength and pressuro intogrity of items the failure of which would violato tho prossure rotaining boundary", (ref. NC-1100).
Failure of a seal wold can result in a small amount of leakage, but such failuro doos not result in a significant violation of the pressure boundary.
Failvro of a soal wold does not compromise the structural integrity of the joint.
Since the seal wolds aro non-structural (ref. ASME S6ction XI IWA-9000), Duke believes that temporary repairs such as peoning are acceptable.
Permanent repairs shall be mado at the next available refueling outago, in accordance with the ASME Codo.
I Engineering guidelines for the ovaluation of temporary repairs and wolds havo boon developed.
This guido11no
-providos appropriato instructions on the uso of temporary repairs for soal wolds, including specifying that at the next-available refueling outage the seal wold be repaired in accordance with ASME codo requirements.
This quidelino assures correct and consistent action in the
, solution of similar problems that may ariso in the future.
On June 17,-1992, members of my staff discussed tho CF gamma plug.soal wold failures with members of the NRC staff.
Wo discussed our intentions to stop the leak by peoning the seal wold aren'that had.the crack.
In addition, the monitoring of potential leakage from this plug until the next refueling outage was also discussed.
Any leakago from
-this location wjl1 be collected by_the Containment Building Floor.and Equipment Sump, which is monitored from the control room by an annunciator alarm.
When unusually frequent ar.aunciator alarm ratos occur,-a chemical sample of the sump' contents will be obtained to datormine if the loakage is from tho feedwater system (indicated by a unusually high levels of hydrazino).
Further, this plug will be visually inspected for loakago during any
-unscheduled unit shutdown or reactor trip.
Final repair'of1this; plug will be performod at the next refueling outago. JAt that' time the plug will be removed and the piping and plug will bo inspected for damage.
The repair per this inspection will be performed in accordance with tho'ASME code.
4. - _.
e U.
S.
Nuclear Regulatory Commission July 29, 1992 pago 3 For 10':
information, on June 17, 1992 the seal wold was po.
end the leak was stopped.
A pipo rupture interaction ance als with respect to the postulated catastrophic failuro of the inspection port plug was performed.
Based on a field survey of the area around the inspection port, no unacceptable targets worn identified.
In addition, a review of an existing analysis regarding terminal end brook interactions was performed and the same conclusion was reached within the analysis, that no unacceptable intoractions exist.
Finally, based on our observations of the leak und of the plug area, the overall integrity of the threads havo not boon compromised.
If you have any questions regarding this matter, please contact Pdul Guill at (704) 875-4002.
Very truly yours, NW Tod C.
McMeekin xc S. D. Ebneter Regional Administrator, Rogion II P.
K. Van Doorn Senior Resident Inspector, McGuire a
T.
A.
Rood, Project Manager ONRR
i 4
U. S.
Nucioar Regulatory Commission July, 1992 pago 4 bcct with attachment R. O.
Sharpo L. J.
Kunka K.
L. Crano P.
F. Guill W
11.- Taylor R. L. Morgan R. B. Travis T. D. Motos
-R.
E.
Itall R.
R. Weidler R. L. Gill,jr (NS)
II. A. Froobo (NS) [ File MC-801.01)
J. O. Barbour (NS)
File 801.01
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