ML20092D414
| ML20092D414 | |
| Person / Time | |
|---|---|
| Site: | McGuire  |
| Issue date: | 02/07/1992 |
| From: | Mcmeekin T DUKE POWER CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| NUDOCS 9202140028 | |
| Download: ML20092D414 (4) | |
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' February 7, 1992 Document Control Desk U.S. Nuclear Regulatory CLmmission Washington, D.C.
-2055b
Subject:
McGuire Nuclear Station, Unit 1 Docket Nos' 50-365, Dear' Sir on-s.aary 6,
1992, an approximate 2 gpd primary to secondary leakage was i
detected in Steam. Generator (S/0)
D" of McGuire Unit 1.
The leakage rate
. increased to :pproximately 8 gl.d by January 13, 1992 and to apprcximately 235 gpd 2
on January 16, 1992. At this time, a ducision was made to shut the unit down to identify and. repair-the s/G t ee leakage.
A pressure test of S, G D" judicated leakage f rom tubes 36-30 and 47-46.
Tube
' 30 was determined.o be an inaderpate bonding of the kinetically welded sleeve
>=
4'
, which had been installed durir.J the previvus outage. This tube has been plugged, g
-Examination' of. tube 47-45 icntif1.ed an approxi:nate one inch long indication G.
- apprytimately five inchse Lboo ttu.; 20th tube support plate. The attached action
~.
plar was developed to re-evalusta araminations performed during the 1EOC7 outage, which was' completed in Doctanber 1S*1, and examine other tubes an all four Unit
- 17 steam generators.
?his action plan was discussed with representatives from F'C/ONRR and NRC/Regivn I?, on February 3,1992. The following actions are also planned:c a)l
. Duke Power coup *3y will share the results of the steam generator
- inspection effortw and our conclusions with the NRC staff prior to-restart of Unit-1.
c b
b)-
Representhtivets - f rom Duke Powe;' and appecpriate contractors will meet with the NRC Staf f at the NRC's-Rockville, Maryland offices within approximately thres months to share the technical details of chose inspectione and results of an analysis performed pursuant to draft Regulatory Guide: 1.121.
c)-
Tube 47-46 will be pulled during the 1EOC8 refuelino outage for.
I laboratory examination.
e d)
Technical Specification 3.4.6.2(c) primary to secondary leakage for
?
1 Unit = 1 will be-administrativo1y limited during the temainder of Q
Cycle 8 to.50 gpd with Mode 3 reached within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />.
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Further details of this event will be documented-in a Licennee Event
- ).
Report.
LVery truly yours j[
o ac T.'C. McHeekin i
ROS/mgc.
9202140028 920207 I
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(bR February 7, 1992
? age 2 xc Mr. S.D. Ebneter Administrator, Region II U.S. Nuclear Regulatory Commission 101 Marietta St.,
NW, Suite 2900 Atlanta, Ga.-
30323.
Mr.-Tim Reed U.S. Nuclear Regulatory Commissior Office of Nuclear Reactor Regular $on Washington, D.C.
20555 Mr. P. K Van Coorn NRC Resident 7.nspector McGuire Nuclear Station
..-. -.~... - _ -.. -._ - - - -
g-McGuire -Nuclear Station January 19 92. Tube.. Leak on ' 1D Steam Generator Recovery Action Plan A re-evaluation of the 1991 RFO MRPC data on tubo 47-46 indicates that the defect which leaked was incorrectly classified as a manufacturer's burnish mark. (MBM).
As such, an action plan was developed to remove tubes from service with similar MBM indications.
On Tuesday,'1/28/92, additional information was obtained which caused a significant r9 vision to the original plan.
Review of the bobbin coil data -taken ~during this outage on tube 4 6 identified several indications between the 14th and 15th TSP's.
MRPC of these indications showed them to be similar to the leak defect.
The largest of these defects was sized at 60% through wall (TW) with MRPC.
Review of (.ata taken during the 1991 RFC indicated that this indication was present but was'not identified for special inspection or plugging due to it's very small amplitude.
To address this concern, the following action plan will be implemented:
1.
Develop revised conservative criteria for analyzing bobbin coil.
This criteria is such that all indications with cha ract e ri s tics similar to those of the 60% TW indication on tube 47-46 will be identified for further analysis.
2.
Train and qualify by test all analysts on the new criteria.
3.
Review all 1991 RFO bobbin coil data using the new criteria.
~
Because the above criteria is conservative, many indications will be called which are not actual defects, To prevent over plugging, the f bilowing methodology will be used to further screen the indications identified in the above process.
1.
Reanalyze a21 "D" steam -generator 1991 bobbin coil data first.
2.
All indications that..are -identified from the bobbin coil data in "D"
steam generator will be 100% eddy carrent tested using a motorized rotating pancake coil (MRPC).
".his data, coupled with
.the existing bobbin coil data, will be analyzed by recognized technicaA experts within Duke Power Compat y and/or the industry.
This detailed analysis will be used to validate one of the following processes that will be used to determine the tubes which must be removed from service:
A.
MRPC test all indications called f rom the bobbin coil reanalysis that can not be resolved by detailed expert review.
This could result in 100% MRPC test of these indications.
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_ _ =.. _ _ _ _ _
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N' Recovery Action Plan l' age 2
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B. A historical review of past bobbin coil data will be performed to identify any-indications that are changing over time.
Suspect indications from this process will either be plugged or MRPC tested to detqrmine if the tube can remain in service or needs to be plugged.
3.
Process A or B,.or a combination of the two, will be utilized to analyze the-remaining three Unit 1 steam generators to effectively remove all suspect tubes from servico, 1
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