ML19330B339
| ML19330B339 | |
| Person / Time | |
|---|---|
| Site: | Dresden  |
| Issue date: | 07/28/1980 |
| From: | Janecek R COMMONWEALTH EDISON CO. |
| To: | Crutchfield D Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 8007310432 | |
| Download: ML19330B339 (2) | |
Text
,
[ 'N Commonwealth Edison
[
) one First National P_laza, Chicago. Ittinois g
g Addrsss R: ply to: Post Office Box 767 a
\\
,e Chicago, Illinois 60690 July 28, 1980 Mr. Dennis M. Crutchfield, Chief Operating Reactors ' Branch 5 Division of Licensing U.S. Nuclear Regulatory Commission Washington, DC 20555
Subject:
Dresden Station Units 1 and 2 Response to Request for Information Concerning Turbine Disks NRC Docket No. 50-10 References (a):
D. M.
Crutchfield letter to D.
L.
Peoples dated June 11, 1980 (b):
R. F. Janecek letter to T. A.
Ippolito dated June 23, 1980
Dear Mr. Crutchfield:
Reference (a) requested information concerning turbine disk design and previous inspection results for Dresden Units 1 and 2.
Our response for Dresden Unit 2 was provided in Reference (b).
The Attachment to this letter contains our partial response for Dresden 1.
The information provided is that which was readily available in the response time requested.
Because of the current extenced outage of Dresden 1, the diversion of manpower from other ongoing projects to provide al] the requested information was not considered to be whrranted.
The remainir.g information will be provideo prior to startup of Dresden 1.
Please address any questions concerning this matter to this office.
One-(l) original and thirty-nine (39) copies of this transmittal are provided for your use.
Very truly yours, W
Robert F.
Janecek Nuclear Licensing Administrator Boiling Water Reactors SUBSCRIBED and SWORN to before mj thp d,?n/
, day of Apy 1980 Notary Public 800 7810 % 7 _
I Response To Request For Information Concerning Dresden Unit 1 Turbine Disc Inspection 1.
Turbine type The Unit 1 turbine it a General Electric non-reheat, tandem 1800 r'm unit with three elements; high pressure (HP),
compound.
p intermediate pressure (IP) and double-flow low pressure (LP) sections.
Steam' f rom the high pressure crbine exhausts to the intermediate pressure turbine.
From the e it exhausts through a large cross-over pipe equipped with the moisture extractor to the double flow low' pressure turbine.
The low pressure section exhausts to the condenser.
The high pressure element's discs (wheels) are an integral part of the rotor, having been machined out of a solid alloy steel f orging.
The intermediate and low pressure rotors have separate forged discs which are shrunk onto the shafts and keyed.
There are seven discs on the IP rotor and three discs on each end of the double-fw LP rotor.
2.
Operating Hours The turbine had operated 111,196 hours0.00227 days <br />0.0544 hours <br />3.240741e-4 weeks <br />7.4578e-5 months <br /> prior to its inspection.
3.
Disc Material The nominal chemistry of the turbine disc material is 1CrhMo.
4.
Inspection Results The results of the ultrasonic inspection of the wheel bore areas of the IP and LP rotors are summarized below.
No. of Indications Depth Length Rotor Wheel (Keyway Corners)
In.
In.
IP 22 1
< 0.030 1.5 LP 23T Z
0.060 & 0.090 1.5 LP 23G 1
0.030 1.5 The visual examination revealed water cutting on the face cf the hubs of the wheels in line witn the keyways.
Water cutting eminating fr'm the keyway of the first stage (Wneel #23) of the LP o
rotor was visable.
Fiber optics examination inside the first stage wheel keyway showed that the water cutting extended axially into the keyway in-line with the sonic indications picked up from the top of the hub.
Photographs of the water cutting discussed above were presented to the Staff at the March 20, 1980 meeting with the Nuclear Regulatory Commission to discuss the results of the Pilgrim
- 1 (Boston Edison) and Dresden #3 disc inspections.
Thus, all of the inspections to date indicate that the sonic indications observed on the Dresden #1 IP and LP rotors are due to water cutting.
No evidence of stress corrosion crackint was found, i
PKC:mnh 5435A j