ML20235X163
| ML20235X163 | |
| Person / Time | |
|---|---|
| Site: | Comanche Peak  |
| Issue date: | 03/03/1989 |
| From: | William Cahill TEXAS UTILITIES ELECTRIC CO. (TU ELECTRIC) |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| TXX-89072, NUDOCS 8903130341 | |
| Download: ML20235X163 (2) | |
Text
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s Log # TXX-89072
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File # 10010 C
C 910.2 7UELECTRIC Ref. # 10CFR50.30(a)
W. J. Cahm March 3, 1989 Executive nce Prendent U. S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, D.C.
20555
SUBJECT:
COMANCHE PEAK STEAM ELECTRIC STATION (CPSES)
DOCKET NOS. 50-445 AND 50-446 TURBINE DISK INSPECTIONS
REFERENCE:
TV Electric Letter TXX-4512 dated July 15, 1985 Gentlemen:
The referenced letter requested that the current proposed license condition concerning turbine disk ultrasonic (UT) inspections be modified to require inspection of cach low pressure turbine disk once every 50,000 operating hours, based on previously docketed turbine vendor (UPC/Siemens) engineering reports.
The letter also provided a proposed turbine generator inspection schedule which was consistent with the turbine vendor inspection recommendations.
l In a subsequent visual inspection performed in October of 1987 of the Unit I low pressure turbines, rust was found on the last stage turbine rotor disks.
Although the rust was not extensive, an analysis of the rust revealed that a small amount of chlorides (0.15%) was present.
The rust areas were subsequently cleaned and the turbine was reassembled. The source of the chlorides was believed to be from the auxiliary electrode boiler used to supply scaling steam to'the turbine during prior hot functional testing.
For proper operation, the electrode boiler required a chemical treatment to elevate the boiler water conductivity. The chemical utilized was found to contain some chloride impurities.
For the forthcoming startup testing, sealing steam to the turbine is planned to be provided by a conventional fossil fired boiler which utilizes a chemical treatment which complies with the EPRI guidelines for chlorides (the same chemical treatment used in the steam generators). Therefore, chloride carry-over is not a concern.
TV Electric, in association with the turbine vendor, has conducted a technical analysis to determine what impact, if any, the presence of this rust has on the previously recommended low pressure turbine disk inspection schedule.
Upon completion of the analysis the turbine vendor recommended that there be no restrictions on the operation of the turbines for the first 25,000 ll po I
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TXX-89072 March 3, 1989 Page 2 of 2 operating hours.
Prior to exceeding 25,000 operating hours, both low pressure turbine rotors are to be inspected volumetrically.
If no indication of disk cracking is found during these inspections, the period between UT inspections can be increased to 50,000 operating hours.
The schedule submitted to the NRC in the referenced letter (which provides for volumetric inspection of the low pressure turbine rotors during the second and third refueling cycles respectively) is consistent with the turbine vendor recommendations and thus does not alter our request for licensing condition modification.
Sincerely, Y!
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William J. Cahill, Jr.
BSD/bsd attachment c - Mr. R. D. Martin, Region IV Resident Inspectors, CPSES (3)
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