ML19211C956
| ML19211C956 | |
| Person / Time | |
|---|---|
| Site: | Arkansas Nuclear  |
| Issue date: | 12/28/1979 |
| From: | Seyfrit K NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV) |
| To: | Cavanaugh W ARKANSAS POWER & LIGHT CO. |
| References | |
| NUDOCS 8001160052 | |
| Download: ML19211C956 (1) | |
Text
UNITED STATES
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NUCLEAR REGULATORY COMMISSION PDR:HQ
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-~ p Dece=ber 28, 1979 Docket Nos.
50-313 50-368 Arkansas Power and Light Co::rpany ATTN:
Mr. '41111am Cavanaugh III Vice ? resident of Generation and Construction P. O. Box 551 Little Rock, Arkansas 72203 Gentlemen:
This IE Infor=ation Notice is provided as an early notification of a possibly significant =atter.
It is expected that recipients vill review the information for possible applicability to their facilities.
No specific action or response is requested at this ti=e.
If NRC evaluations so indicate, further licensee actions =ay be requested or required.
If you have questions regarding this
=atter, please contact the Director of the appropriate NRC Regional Office.
Sincerely, 0
/i'I
/
Ok '
A' <-
-Karl V. Seyfric /
Director Inclosures:
1.
IE Infor ation Notice No. 79-37 2.
List of Recently Issued II Infor ation Notices cc:
,Ia=es ?. O'L nton, Plant Manager Arkansas Nuclear One
?. O. Box 608 Russellville, Arkansas 72801 1756 128 Ofa 8001260
UNITED STATES ISINS NO.:
6870 NUCLEAR REGULATORY COM:ilSSION Accession No.:
OFFICE OF INSPECTION AND ENFORCEMENT 7910250525 WASHINGTON, D.C.
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December 28, 1979 Sh AJ b
IE Information Notice No. 79-37 CRACKING IN LOW PRESSURE TURBINE DISCS Description of Circumstances:
An anonymous letter was received by the Director of the Office of Inspection and Enforcement, on November 17, 1979 which alleged possible violation of Part 10 CFR 50.55e and/or 10 CFR 21 Regulations concerning reportability of recently discovered stress corrosion cracking in Westinghouse 1800 rpm low pressure turbine discs.
Westingbouse had made a presentation on the turbine disc cracking to electric utility executives on October 30, 1979.
Telephone discussions between the NRC staff and Westinghouse's Turbine Division on November 20, 1979 established that cracking, attributed to stress corrosion phenomena, had ' Men found in the keyway areas of several LP turbine discs at operating plants and that inservice inspection techniques (i.e., in situ ultra-sonic examination) for crack detection have been developed and are being imple-mented in the field.
The Office of Inspection and Enforcement was also notified on November 20, 1979 that during the current overhaul of Commonwealth Edison's Zion Unit 1 LP turbine, ultrasonic examination revealed embedded cracks located on the inlet side on the disc bore area where no cracks h.d been previously observed.
Ultrasonic measurements indicate this disc bore cracking is of greater depth than the keyway cracks found to date.
According to Westinghouse, these bore cracks have been metallurgically examined and preliminary findings show them not to be typical of classical stress corrosion cracking observed in the keyways.
The probable cracking mechanism and impact on disc integrity is being further evaluated by Westinghouse.
A meeting was held on December 17, 1979 between the NRC staff, Westinghouse and utility representatives to discuss the disc cracking problem, repair alter-natives, turbine missile evaluation, inspection techniques and plant inspection priorities.
In response to the staffs' request, Westinghouse provided the staff an updated report on December 21, 1979 regarding the current field inspection program that included a list of nuclear power plants already inspected, recom-mended inspection schedules and pertinent information related to LP turbines where cracks have been observed.
Inspections to date have identified turbine disc cracks at Surry Unit 2, Point Beach Unit 2, Palisades, Indian Point Unit 3 and Zion Unit 1.
All units except Point Beach Unit 2 will make repairs before the plants return to power.
Point Beach returned to power on December 23, 1979 with a small crack in the No. 2 disc of LP Turbine No. 2.
An analysis by Westinghouse indicated that the observed crack will not attain critical dimensions during 28 additional months of turbine operation.
The NRC staff is evaluating the turbine inspection results and analysis by Westinghouse.
i/bo 129
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IE Information Notice No. 79-37 December 28, 1979 Page 2 of 2 Westinghouse also notified the staff that extrapolation of information obtained from Indian Point Unit 3 inspection and analysis indicates that disc cracking could be significant at Indian Point Unit 2 and the turbines should be inspected sooner than the spring outage of 1980. The NRC staff is currently reviewing Consolidated Edison's plans for prompt evaluation of this potential problem at this unit. lists the PWR plants having Westinghouse 1500/1800 rpm turbines.
The AA category represents those turbines which appear to have the earliest need for inspection. With the exception of Yankee Rowe, Westinghouse has recommended to utilities that inspection of these machines be completed by the Spring 1980 outage period.
The Rowe unit is uninspectable by the present ultrasonic techniques due to its design.
Westinghouse has recommended the remaining machines of the Category A plants be inspected as their service periods approach five years or in the event significant corrosion problems become evident during this time.
The NRC staff is currently reviewing the need for inspection of those PWR plants having other interfacing turbine designs shown in Enclosure 2.
Changes to the forementioned inspection schedules proposed by Westinghouse may be necessary as new technical information becomes available.
From the information available to the NRC staff at this time it appears that cracking may be more generically widespread in turbine discs (e.g., keyways and bore areas) than previously observed.
It is important to note that the UT inspections performed by Westinghouse thus far were essentially limited to the keyways (disc outlet) of selected discs whereas the Zion Unit 1 inspection results indicate that examination of the disc bore section must be taken into Also, Westinghouse is currently re-evaluating their previously estimated account.
turbine missile energies based on recent missile test results from model symmetric and non-symmetric missile impact tests.
Their preliminary findings, although subject to change, now indicate possible higher missile exit energies in some cases than previously expected.
This Information Notice is provided as an early notification of a possibly significant matter, the allegations and the generic safety implications of which are currently undergoing review by the NRC staff.
It is expected that recipients will review the information applicable to their facilities.
If NRC evaluations so indicate, further licensee actions may be requested or required.
Embedded cracking in keyways and disc bore areas have been observed only in Westinghouse LP turbines thus far.
However, the NRC staff believes that turbines of other manufacturers should be included in consideration of this problem.
No written response to this Information Notice is required.
If you have any questions regarding this matter, please contact the Director of the appropriate NRC Regional Office.
Enclosures:
As stated i756 130
CATEGORY AA UTILITY STATION UNIT Florida, P&L Turkey Point 3
Consolidated ED.
Indian Point 2
PASNY Indian Point 3
Arkansas P&L Russellville 1
VEPCO Surry 1
Carolina P&L Robinson 2
So. Calif. Ed.
San Onofre 1
Yankee A.P.
Rowe 1
Wisc. Mich. Pwr.
Point Beach I
Consumers Pwr.
Palisades 1
Commonwealth Ed.
Zion 1 1
Commonwealth Ed.
Zion 2 2
Florida P&L Turkey Point 4
Nebraska PPD Cooper 1
Wisc. Mich. Pwr.
Point Beach 2
Maine Yankee Bailey Point 1
Rochester G&E Ginna 1
Northern States Prairie Island 1
Wisc. P.S.
Kewaunee 1
17C' 171 1/JD iJi
. (Continued)
Page 2 of 3 CATEGORY A UTILITY STATION UNIT Alabama Power Farley 1
Alabama Power Farley 2
Baltimore G&L Calvert Cliffs 2
Carolina P&L Harris 1
Carolina P&L Harris 2
Carolina P&L Harris 3
Carolina P&L Harris 4
Cincinnati G&E Zimmer 1
Commonwealth Ed.
Byron 1
Commonwealth Ed.
Byron 2
Commonwealth Ed.
Braidwood 1
Commonwealth Ed.
Braidwood 2
Connecticut Yankee Haddam Neck 1
Duke Power McGuire 1
Duke Power McGuire 2
Duquesne Lt.
Shippingport 1
Duquesne Lt.
Beaver Valley 1
Duquesne Lt.
Beaver Valley 2
Flordia Power Corp.
Crystal River 3
Flordia Power & Lt.
St. Lucie 1
Flordia Power & Lt.
St. Lucie 2
Houston L&P So. Texas 1
Houston L&P So. Texas 2
Louisiana P&L Waterford 3
Metropolitan Ed.
Three Mile Island 2
Northern States Pwr.
Prairie Island 2
Pub. Service E&G Salem 1
Pub. Service E&G Salem 2
Pacific G&E Diablo Canyon 1
Pacific G&E Diablo Canyon 2
1756
!32
. (Continued)
Page 3 of 3 CATEGORY A UTILITY STATION UNIT P.S. Indiana Marble Hill 1
P.S. Indiana Marble Hill 2
Puget Sound P&L Skagit 1
SMUD.
Rancho Seco 1
TVA Sequoyah 1
TVA Sequoyah 2
TVA Watts Bar 1
TVA Watts Bar 2
VEPCO North Anna 1
VEPCO North Anna 2
VEPCO North Anna 3
VEPCO North Anna 4
VEPC0 North Anna 2
WPPSS Hanford 2
WPPSS WNPS 1
WPPSS WNPS 3
WPPSS WNPS 4
WPPSS WNPS 5
123 k-lC'30 tJ
UTILITY STATION UNIT Duke Power Co.
Oconee 1
Duke Power Co.
Oconee 2
Duke Power Co.
Oconee 3
OPPD Ft. Calhoun 1
Baltimore Electric
& Gas Calvert Cliffs 1
Metropolitan Edison Three Mile Island 1
Indiana & Michigan Electric D.C. Cook 1
Indiana & Michigan Electric D.C. Cook 2
Northeast Utilities Millstone 2
Portland General Electric Troj an 1
Toledo Edison Davis Besse 1
Arkansas Power &
Light Arkansas Nuclear One 2
WPPSS Hanford 1
1756 134