ML18085A311
| ML18085A311 | |
| Person / Time | |
|---|---|
| Site: | Salem  |
| Issue date: | 12/01/1980 |
| From: | Schneider F Public Service Enterprise Group |
| To: | Varga S Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 8012020570 | |
| Download: ML18085A311 (5) | |
Text
,
0 PS~G*
Public Service Electric and Gas Company 80 Park Place Newark, N.J. 07101 Phone 201/430-7000 Director, Nuclear Reactor Division Nuclear Regulatory Commission Washington, DC 20555 ATTN:
Steven A. Varga, Chief Operating Reactors Branch 1 Division of Licensing
Dear Mr. Varga:
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 UT Turbine Disc Inspection of No. 1 Unit, Salem Nuclear Generating Station, conducted between September 29 and October 11, 1980.
Attachment A is the Westinghouse report on their inspection findings.
Attachments B and C summarize the Public Service analysis of those discs found to have developed cracks in the keyvvay areas.
Attachment B includes the critical crack sizes from the revised Westinghouse disc data sheets.
We intend to submit the revised data on the 32 discs that were clear of indications in a separate transmittal.
The actual crack size, as measured is increased by 60 mils in order to compensate for the radial aim method of inspection that Westinghouse employed for the inspection.
This crack size was subtracted from one half of the critical crack size in order to determine the allowable crack growth.
For crack growth rate, the largest measured crack size for each disc was divided by the operating hours (15,477) of the unit.
/Joo/
5 1/1 95-0942
Steven The allowable crack growth (the difference between half the critical crack size and the measured crack size) was divided by the crack growth rate to determine the remaining life prediction (months) which in turn was divided in half to arrive at the reinspection time.
The next turbine disc inspection will take place during the scheduled September~ 1981 outage.
Approximately 10 months of operating time is projected between the end of this year's outage and the start of the 1981 outage.
Attachment B shows a reinspection time of 4.2 months for Disc 2 of No. 13 LP rotor.
This disc has been removed and replaced with a collar and two pressure baffle plates supplied by Westinghouse.
Disc 2 of No. 11 LP rotor requires reinspection in 10.2 months.
In order to increase the reinspection time of Disc 2 of No. 11 LP rotor, the overspeed trip setting has been changed to 103% from the current 110%.
Attachment C shows that the larger critical crack sizes at the reduced maximum expected overspeed of 112% results in a calculated reinspection time for Disc 2 of No. 11 LP rotor of 12.4 months.
The removed disc segments will be sent to a third party laboratory for failure analysis.
The results will be provided for your review.
Westinghouse has expressed interest in this analysis.
We intend to share all data and conclusions with Westinghouse and any other utility requesting this information.
Very truly yours,
-f?)d~
F. W. Schneider Vice President -
Production RAD:nj PQ3 1/2-B
Acr isc. No. 2 ov Crack Depth 2.62 i sc. No. 2 ov Crack Depth 2.89 isc No. 2 ov Crack Depth 2.06
,isc No. 3
'en Crack Depth 2.10
-------------------o-;---__,---------------------
KeY'J av No.
l 2
3
.480 11 ATTACHMENT A PUBLIC SERVICE ELECTRIC &"GAS
. SALEM NO. l Condition of Unit as Inspected KEYWAY CRACKS LP No. l LP No. 2 Allow Reinspect Allow Reinspect Service (Mths.)
. Keywav No.
Service (Mths.)
Ke_vway No.
Life l
2 3
Life l
2 3
(Mths.)
(Mths.)
24.8 l 2o4
.360 11 33.0 16.5
.580.600.250
.* 200 *.400.240 LP No. 3 Allow Reinspect Service (Mths.)
Life (Mths.)
11.9 5.94 27.2 13.6- ~
NOTES:
- 1. Reinspection time and allowable servi~e life are computed using the deepest crack obse~ved (based on Westinghouse's interpretation of the NRC calculation technique [112% overspeed]).
- 2 Discs lf3 Di SC
.600 +.060 15,477
- .400 +.060 15,477
=.426 x lo-4 in./hr.
=.* 297 x io-4 in./hr.
ATIACHMENT B REINSPECTION TIME FOR LP TURBINE DISCS -
SALEM NUCLEAR GENERATING STATION - 120% OVERS:'.'EED LP NO.
11 12 13 13 13 13 13 13 KEY'WAY NO.
DISC NO.
CRACK LENGTH CRACK GROWTH REINSPECT ION TIME KEYWAY INC ms RATE MONTHS TEMP.
DA/DT 0
CRITICAL MEASURED IN/MO F
2 2
2.35 0.480 3.113 x 10-2 10.2 299 Q
z x 10-2 2
2 rLI 2.59 0.360 3.113 14.1 299
~
1 2
0 1.84 0.580 3.113 x 10-2 4.5 299 z
~
10-2 2
2 rLI 1.84 0.600 3.113 x 4.2 299 3
2 0
1.84 0.250 3.113 x 10-2 9.8 299
. I:!)
1 3
1.88 0.200 2.17 x 10 -2 15.7 238 0
fJ 10-2 2,
3 1.88 0~400 2.17 ~.
11.1 238 fJ I:!)
x 10-2 238-3 3
1.88 0.240 2.17 14.8 NOTE:
Critical crack length is based on existing overspeed of 120%.
DA/DT = (worst crack on given disc + 0~060) x 730 ~ 15,477 Data confirmed during conference calls with Westinghouse on October 15 and 16, 1980 R. A. Demareski Revision 1 10/16/80
ATTACHMENT C REINSPECTION TIME FOR LP TURBINE DISCS -
SALEM NUCLEAR GENERATING STATION -
11 12 13 13 13 13 13 13 KEYWAY NO.
DISC NO.
CRACK LENGTH CRACK GROWTH REINSPECT ION TIME KEYWA 2
2 1
2 3
1 2
3 INCHES RATE MONTHS DA/DT CRITICAL MEASURED IN/MO 2
p 2.62 0.480 3.113 x 10-2
'7 2
li::i 2.89 0.360 3.113 x 10~
2
.v 2
0 2.06 0.580 3.113 x l0_-2 z
p::;
10-2 2
li::i 2.06 0.600 3.113 x 2
0 2.06 0.250 3.113 x 10-2 t!:>
3 2.10 0.200 2.17 x 10-2 p
3 ffi 2.10 0.400 2.17 x~ 10 -2 ffi
-2 3
t!:>
2.10 0.240 2.17 X 10 I
NOTE:
Critical crack length is based on reduced overspeed of 112%
DA/DT = (worst crack on given disc + 0.060) x 730 ~ 15,477 12.4 16.5 6.3 6.0 11.6 18.2 13.6 17.3 TEMP Op 299 299 299 299 299 238 238 -
Data confinned during conference calls with Westinghouse on October 15 and 16, 1980 R. A. Demareski Revision 1 10/16/80 y