ML18086A665

Forwards Southwest Research Inst Investigation of LP Turbine Disc Cracking,Salem Unit 1,Keyway Crack Size & Shape & Revised Westinghouse Info on Evaluation of Ultrasonic Test Disc Insp Findings

ML18086A665
Person / Time
Site:	Salem
Issue date:	06/05/1981
From:	Schneider F Public Service Enterprise Group
To:	Varga S Office of Nuclear Reactor Regulation
Shared Package
ML18086A666	List: ML18086A665 ML20004E466
References
NUDOCS 8106120227
Download: ML18086A665 (5)

Text

"

Frederick W. Schneider Public Service Electric and Gas Company 80 Park Plaza Newark, N.J. 07101 201/430-7373 Vice President Production June 5, 1981 Director Nuclear Reactor Division Nuclear Regulatory Commission Washington, D.C. 20555 Attn: Steven A. Varga Chief Operating Reactors Branch 1 Division of Licensing TURBINE DISC INSPECTION NO. 1 UNIT SALEM GENERATING STATION DOCKET NO. 50-272 Public Service Electric and Gas Company hereby submits, in the attachments to this letter, reports relative to the Westinghouse reevaluation of their UT turbine disc inspection findings. The new inspection data was included with the Westinghouse letter dated February 26, 1981 to Public Service. The analysis of the original inspection data was submitted to you with our letter dated November 19, 1980.

Attachment A is the revised Westinghouse report on their reevalu-ation of the UT disc inspection findings. Attachment B is the Southwest Research Institute report on the actual measurements of the cracks found in Keyways 1&2 of the removed Disc No. 2, Gov. End, No. 13 LP Turbine. Westinghouse has a copy of this report. Attachment C summarizes the Public Service analysis of the cracked discs using the revised Westinghouse data and the Southwest Research actual crack sizes.

The maximum crack growth rate of .0210 in./mo. was calculated using the largest measured crack size of 0.445 in. from the removed No. 2 Disc, Gov. End, No. 13 LP Turbine. This crack growth rate, when applied to the UT indicated crack size of 0.290 in. from Disc No. 2, Gov. End, No. 11 LP Turbine results in a reinspection time of 22.9 months. This is the minimum reinspection time for the No. 1 Unit Turbine. The next inspec-tion must be made sometime prior to 22.9 months from the October 1980 date of the initial inspection.

Director Nuclear Reactor Division 2 June 5, 1981 We have made a complete review of the basis of the Westinghouse reevaluation of the UT inspection data and concur with it.

Based on the reevaluation and the close correlation of the UT inspection data with the actual crack size measurement on the No. 2 Disc, Gov. End, No. 13 LP Turbine, we plan to reinspect sometime prior to 22.9 months from the October 1980 date of the initial inspection.

Sincerely, Attachments T6-l/l 2

.. ,\

~

f (.

ATTACHMENT C II REINSPECTION TIME FOR LP TURBINE DISCS - SALEM NUCLEAR GENERATING STATION - 112% OVERSPEED

• CRACK LENGTH CRACK GROWTH REINSPEC. TIME KEYWA'

..p. NO. KEYWAY NO. DISC :t'{O.

TEMP INCHES RATE MONTHS DA/DT Op IN/MO CRITICAL MEASURED x10-2 .

UT INDICATED ACTUAL 11 2 2 ,...... 2.62 .290 - 2.10 22.9 . ,9 I :z<

12 2 2 i:r.:i 2.89 .180 - 2.10 28.8 299 0 2.10 13.8 299 I 13 1 *2 2.06 .360 .445 13 2 *2 g: 2.06 .300 .283 2.10 17.9 299 0

(.!>

13 3 *2 2.06 .250 - 2.10 17.l 299 i

13 1 3 t=l 2.10 .200 - 1.23 32.1 238 z 238 13 2 3 i:r.:i 2.10 .190 - 1.23 32.5 13 3 3 ~

i:r.:i

(.!>

2.10 .150 - 1.23 34.2 238 NOTE: REVISED CALCULATIONS ARE BASED ON NEW DATA RECEIVED FROM WESTINGHOUSE WITH THEIR FEBRUARY 26, 1981 LETTER AND ACTUAL CRACK SIZES FROM SOUTHWEST RESEARCH

• REMOVED DURING FALL, 1980 OUTAGE v-1)>7 R. A. Demareski Revision 3 4-3-81

Power Generation . Steam Turbine Division Westinghouse

• Electric Corporation Group Lester Branch Box 9175

.Philade!Phia Pennsylvania 19113 February 26, 1981 Mr. R. D. Rippe Chief Mechanical Engineer Engineering Department .

Public Service Electric &Gas Company 80 Park Plaza Newark, NJ 07101

• Re: LP Disc Indications, Salem #1

Dear Mr. Rippe:

The purpose of this letter is to bring you up to date on our latest thinking as a result of a review of the LP disc inspection techniques and interpretations.

Due to what Westinghouse thought to be some discrepancies of infonnation (Salem data outside of the Westinghouse crack growth model and data obtained from Alabama Power Company, Farley #1), we undertook a program to re-evaluate the inspection results. Although the disc removed from the Salem unit has not yet gone thru lab crack depth verification, it is our opinion that the crack depth indications transmitted to you by our 10-17-81 .letter are not correct.

The attached sheet, Revision #1 dated 2-24-81, is what we believe to be more representative of your unit. It should be noted that it is the deeper indica-tions that have been over-estimated by a factor as large as 2.0. Based on our review, we have also recalculated the allowable service life and recommended time to*reinspection based on Westinghouse's interpretation of the NRC calcula- ..

tion technique with the overspeed trip setting of 103% of design speed. We~-

• would appreciate this infonnation being passed on to Mr. W. J. Ross of the NRC ~

staff for his infonnation and consideration. . .*

It must be recognized, of course, that the final proof of our accuracy will be the verification of the crack depth of the #2 disc presently at Southwest Research Institute.

Sincerely, I<.. e-C /f-t K. C. Conrad

/<(_

Project Manager

dfs Attachment cc: R. A. Demareski C. Barclay M. Huvane

i" PUBLIC SERVICE ELECTRIC &GAS t

[.

~

SALEM NO. 1 L*

'*I Condition of Unit as Inspected KEYWAY CRACKS c LP No. 1 LP No. 2 LP No. 3 Allow Reinspect Allow Reinspect Allow Reinspect Acr .Kevwav No. Service (Mths.) KeVI av No

• Service (Mths.) . Ke.vway No. Service (Mths.)

l 2 3 Life 1 2 3 Life l 2 3 Life CMths.) (Mths.) (Mths.)

Disc. No. 2

• Gov Crack Depth 2.62 .290" 48.4 24.2 Disc. No. 2

• Gov Crack Depth 2.89 .180" 60.8 30.4 i

Disc No. 2 'I Gov Crack Depth 2.06 .36* .30 .25 30.8 15.4 Disc No. 3 Gen Crack Depth 2.10 .20 .19*. .15* 64.2 32.1 NOTES: 1. Reinspection time and allowable service life are* c~mputed.*using the deepest crack observed (based on Westinghouse's interpretation of the NRC calculation technique [112% overspeed]).

1. 2 Discs .360 + .060 15,477 = .* 271 x 10- 4 1n./hr.

1. 3 Disc *.200 + .060

= .168 x 10*

4 .

1n./hr.

15,477

• These depths.were difficu1t*to determin~ f~om the photos. *REVISION #1 2-24-81