ML20077D820
| ML20077D820 | |
| Person / Time | |
|---|---|
| Site: | Beaver Valley |
| Issue date: | 05/31/1991 |
| From: | Noonan T DUQUESNE LIGHT CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| ND3MNO:3138, NUDOCS 9106050213 | |
| Download: ML20077D820 (3) | |
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Shippengport PA 4 077 0004 l-May 31, 1991 ND3MNO:3138 il f
Beaver Valley Power Station, Unit No.1 Docket No. 50-334,. License No. DPR-64 Special Report United States Nuclear Regulatory Commission Document Control Desk Washington, DC 20555 Gentlemen:
l In accordance with Appendix A,
Beaver Valley Technical Specifications 4.4.5.5.a and 4.4.5.5.c,
" Steam Generators,". the following Special Report is submitted.
This report is required to document the results of.the Inservice Inspection of the steam generator tubes, performed during the Eighth Refueling Outage.
On May 16, 1991, the inservice inspection of the tubing in steam generators RC-E-1A (S/G A), RC-E-1B (S/G B), and RC-E-1C (S/G C). Was completod.
The number of tubes inspected is documented below.
During the, first sample inspection of 3223; tubes in the A steam generator, using bobbin coil eddy current examinations, 65 tubes were-identified as defective (showing greater than 40 percent-through-wall indications).-
These results: fall into the C-3 Category of Technical-Specification 4.4.5.5.c, which. requires reporting to the Nuclear Regulatory Commission prior.to_ plant restart, and inspection of 100 percent of the tubes _in_ the other two steam generators.
Rotating-pancake coil examinations ='of all tube locations-which.had produced-distorted signals.were' conducted.
Hot leg sections of two tubes were removed from the A steam generator and sent for_ laboratory analysis.
Prior to
- removal, theseL tubes.were: examined;with a 3-coil rotating pancake 1 probe :in which the_ coils _are orthogonally' oriented to assist in distinguishing -between axial-and circumferential indications.
An ultrasonic examination was also performed..These tubes were-sent for laboratory analysis to Econfirm the mode of_ degradation-and to
~ correlate the data to the eddy-current and ultrasonic examinations.
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DR._ADOCK 0500 4
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May.31, 1991
'ND3MNO:3138 l
Page 2 j
Ninety-seven percent of the pluggable indications found were identified at the hot leg support plate intersections.
It is suspected that the defect mechanism for these tube degradations is outside diameter intergranular attack / stress corrosion cracking.
All i
defective tubes have been plugged and Beaver Valley will continue j
with boric acid addition to the secondary plant water.
Secondary i
side boric acid addition is intended to cause the tube-to-support j
plate crevices to become less basic and thereby reduce the propensity j
for intergranular attack.
1 In addition to the eddy-current inspection and plugging activities, plug-in-a-plug retainers were conservatively installed in 4
all Westinghousu Inconel 600 plugs that did not have plug retainers i
previously installed.
Plug retainers had been installed last refueling outage in Westinghouse plugs, manufactured from heat 3962, which were considered to be susceptible to primary water stress corrosion cracking.
This refueling
- outage, plug retainers were installed in an additional 100 heat 2387 plugs, in both hot and cold leg locations.
All Westinghouse Inconel 600 plugs used in Beaver 4
Valley Unit 1 now have plug retainers installed.
a The following documents the number of tubes plugged this outage in each steam generator, the number of sentinel plugs (leak limiters on outlet) installed this
- outage, the number of tubes previously
- plugged, the number of sentinel plugs previously installed, and the i
total number of tubes plugged:
S/G A S/G B S/G C Tuben plugged this outage 342 221 197 (Sentinel plugs this outage)
(3)
(0)
(2) i Previously plugged 165 81 47 (Sentinel plugs previously installed)
(1)
(0)
(4)
Total tubes plugged 507 (15%)
302 (8.9%) 244 (7.2%)
l The NSSS Vendor (Westinghouse) is currently analyzing for.an increased plugging limit.
The current limit is 10 percent in any steam generator.
,/
T.
P.
Noonan General Manager Nuclear Operations JWM/sl Attachment
ND3MNO:3138
.. May 31, 1991 Page 3 1
cc: Mr. T. T. Martin, Regional Administrator United States Nuclear Regulatory Commission j
Region 1 475 Allendale Road j
King of Prussia, PA 19406 C.
- h. Rcteck, Ohio Edison l
/6 S. Main Street j
Akron, OH 44308 Mr.
A.
DeAgazio, BVPS Licensing Project Manager United States Nuclear Regulatory Commission J
Washington, DC 20555 a
J.
Beall, Nuclear Regulatory Commission, i
3' BVPS Senior Resident Inspector i
Larry Beck Cleveland Electric 6200 Oak Tree Blvd.
Independence, Ohio 44101 4
INPO Records Center j
Suite 1500 1100 Circle 75 Parkway Atlanta, GA 30339 G.
E. Muckle, Factory Mutual Engineering 680 Anderson Drive #BLD10 4
Pittsburgh, PA 15220-2773 l
e Mr. Richard Janati Department of Environmental Resources l
P.
O.
Box 2063 16th Floor, Fulton Building Harrisburg, PA 17120 Director, Safety Evaluation & Control Virginia Electric & Power Co.
P.O.
Box 26666 One James River Plaza Richmond, VA 23261 W. Hartley Virginia Power Company 5000 Dominion Blvd.
2SW Glenn Allen, VA 23060 l
J.'M.
Riddle NUS Operating Service Corporation Park West'II Cliff Mine Road i
Pittsburgh, PA 15275
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