B15947, Discusses Steam Generator Tube Plugging.Results of Tubes Plugged,Provided
| ML20128P590 | |
| Person / Time | |
|---|---|
| Site: | Millstone  |
| Issue date: | 10/16/1996 |
| From: | Brothers M NORTHEAST NUCLEAR ENERGY CO., NORTHEAST UTILITIES SERVICE CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| B15947, NUDOCS 9610180012 | |
| Download: ML20128P590 (3) | |
Text
i Northeast Maione omm. nope rerry u, waterroni, er
. Utilities System p,o 3,23 Waterfoni, CT 063850i28 l
(203) 447 1791 October 16,1996 Docket No. 50-423 B15947 Re: 10CFR 50.36 U.S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, DC 20555 Millstone Nuclear Power Station Unit 3 Steam Generator Tube Pluacina This special report is being submitted pursuant to the requirements of Plant Technical Specifications 4.4.5.5.a and 6.9.2. Plant Technical Specification 4.4.5.5.a requires that a special report be submitted to the Commission within 15 days of completion of an in-service inspection of the steam generator tubes. This is done to document the number of tubes plugged in each steam generator. Plant Technical Specification 6.9.2 addresses the issuance of the special report.
An eddy current inspection was conducted during the mid-cycle six (6) plant shutdown.
This exam was completed on October 1,1996. All inservice tubes in one steam generator (5622 tubes, or 25% (percent) of the total number of tubes in all steam generators) were inspected as identified on Table 1 (attached). The inspection was performed on steam generator "C". The eddy current testing identified flaws greater than or equal tu the plugging limit in two (2) tubes. Technical Specifications define the plugging limit as an imperfection depth greater than or equal to 40 percent of the nominal wall thickness. Both plugged tubes exhibited degradation attributed to anti-vibration bar wear. These tubes are identified on Table 2. They were removed from service on October 3,1996 using Framatome Technologies Inconel 690 mechanical plugs.
9610180012 961016 PDR ADOCK 05000423 G
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U.S. Nuctsar Regulatory Commission B1594,7\\Page 2 The complete results of the steam generator tube inspection will be submitted within twelve (12) months in accordance with Plant Technical Specification 4.4.5.5.b.
If you need additional information, please contact Mr. J.M.Peschel at (860) 437-5840.
Very truly yours, NORTHEAST NUCLEAR ENERGY COMPANY s
M.H. Brothehf Director - Millstone Unit No. 3 Attachment cc:
H. J.
Miller, Region I Administrator A. C. Ceme, Senior Resident inspector, Millstone Unit No. 3 V. L.
Rooney, NRC Project Manager, Millstone Unit No. 3 s
1 TABLE 1 MILLSTONE 3 S/G 'C' ECT
SUMMARY
Number of Tubes 5626 I
Number of Tubes Inspected 5622 Tubes with maximum flaw 240%
2 Tubes with flaws 220% but <40%
12 Tubes plugged as a result of this inspection 2 TAHLE2 LOCATION OF TUBES PLUGGED - MID CYCLE 6 OUTAGE Ep_w Column 36 61 40 48 Note: All tubes plugged on S/G 'C'.
i 1
TABLE 3 TOTAL TUBES PLUGGED TO DATE S/G A S/G B S/G C S/G D TOTAL Fabrication 1
2 2
0 5
Preservice 2
1 1
1 5
RFOl 1
0 0
1 2
RFO2 4
0 4
RFO3 0
5 5
RFO4 6
1 7
RFO5 1
10 11 Mid cycle 6 2
2 TOTAL 14 4
6 17 41 i
Note: "*" designates ECT not performed on S/G during a given outage.