ML17053B319
| ML17053B319 | |
| Person / Time | |
|---|---|
| Site: | Nine Mile Point  |
| Issue date: | 12/31/1979 |
| From: | Grier B NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| To: | Rhode G NIAGARA MOHAWK POWER CORP. |
| References | |
| NUDOCS 8001140225 | |
| Download: ML17053B319 (16) | |
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Docket No.
50-410 UNITED STATES NUCLEAR REGULATORY COMMISSION REGION I 631 PARK AVENUE KING OF PRUSSIA, PENNSYLVANIA19406 DEC 3 g 197'iagara Mohawk Power Corporation ATTN:
Mr.
G.
K.
Rhode Vice President System Project Management 300 Erie Boulevard, West
- Syracuse, New York 13202 Gentlemen:
This Information Notice is provided as an early notification of a possibly significant matter.
It is expected that recipients will review the infor-mation for possible applicability to their facilities.
No specific action or response is requested at this time.
If NRC evaluations so indicate, further licensee actions may be requested or required.
If you have questions regarding this matter, please contact this office.
Sincerely, Bk'PPk ~
oyce H. Gr r Director Enclosures 1.
IE Information Notice No. 79-37 with attachments 2.
List of Recently Issued IE Information Notices CONTACT:
L.
E. Tripp (215-337-5282) cc w/encls:
Eugene B. Thomas, Jr.,
Esquire
ENCLOSURE 1 UNITED STATES NUCLEAR REGULATORY COMMISSION OFFICE OF INSPECTION AND ENFORCEMENT MASHINGTON, D. C.
20555 ISINS NO.:
6870 Accession No.:
7910250525 CRACKING IN LOM PRESSURE TURBINE DISCS Description of Circumstances:
IE Information Notice No. 79-37 Date:
December 31, 1979 Page 1 of 2 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 50.55(e) and/or 10 CFR 21 Regulations concerning reportability of recently discovered stress corrosion cracking in Mestinghouse 1800 rpm low pressure turbine discs.
Mestinghouse 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 been 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 had 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'equest, 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 Mestinghouse 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 Mestinghouse.
Enclosure 1
IE Information Notice No. 79-37 Date:
December 31, 1979 Page 2 of 2 Mestinghouse 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.
Attachment 1 lists the PMR plants having Westinghouse 1500/1800 rpm turbines.
The AA category represents those turbines which appear to have the earliest need for inspection.
Mith 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 Attachment 2.
Changes to the forementioned inspection schedules proposed by Mestinghouse 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 Mestinghouse 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 account.
Also, Westinghouse is currently re-evaluating their previously estimated 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 Mestinghouse 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.
Attachments:
As stated
0 Attachment 1 to IE Information Notice No. 79-37 Page 1 of 3 CATEGORY AA UTILITY
'lorida, P8L Consolidated ED.
PASNY Arkansas P8L VEPCO Carolina P8L So. Calif.
Ed.
Yankee A. P.
Wise.
Mich. Pwr.
Consumers Pwr.
Commonwealth Ed.
Commonwealth Ed.
Florida P8L Nebraska PPD Misc. Mich. Pwr.
Maine Yankee Rochester G8E Northern States Misc.
P.S.
STATION Turkey Point Indian Point Indian Point Russellville Surry Robinson San Onofre Rowe Point Beach Palisades Zion 1 Zion 2 Turkey Point Cooper Point Beach Bailey Point Ginna Prairie Island Kewaunee UNIT 3
2 3
1 1
2 1
1 1
1 2
4 1
2 1'1 1
1
Attachment 1 to IE Information Notice No. 79-37 Page 2 of 3 CATEGORY A UTILITY STATION UNIT Alabama Power Alabama Power Baltimore G8L Farley Farley Calvert Cliffs Carolina P8L Carolina P&L Carolina P&L
. Carolina P&L Harris Harris Harris Harris Cincinnati G&E Zimmer Commonwealth Ed.
Commonwealth Ed.
Commonwealth Ed.
Commonwealth Ed.
Byron Byron Br ai dwood Braidwood 12' Connecticut Yankee Haddam Neck Duke Power Duke Power McGuire McGuire Duquesne Lt.
.Duquesne Lt.
Duquesne Lt.
Florida Power Corp.
Florida Power & Lt.
Florida Power & Lt.
Shippingport Beaver Valley Beaver Valley Crystal River St.
Lucie St.
Lucie 3
Houston L&P
.Houston L8P Louisiana P&L Metropolitan Ed.
Northern States Pwr.
Pub.
Service E&G Pub.
Service E&G So.
Texas So.
Texas Materford Three Mile Island Prairie Island Salem Salem Pacific G&E
. Pacific G&E Diablo Canyon Diablo Canyon
Attachment 1 to IE Information Notice No. 79-37 Page 3 of 3 CATEGORY A UTILITY P.S.
Indiana P.S.
Indiana Puget Sound P8L SMUD.
TVA TVA TVA TVA VEPCO VEPCO VEPCO VEPCO VEPCO MPPSS MPPSS MPPSS MPPSS MPPSS STATION Marble Hill Marble Hill Skagit Rancho Seco Sequoyah Sequoyah Watts Bar Matts Bar North Anna North Anna North Anna North Anna North Anna Hanford MNPS MNPS MNPS MNPS UNIT 1
2 3
2
Attachment 2 to Information Notice No'. 79-37 UTILITY STATION UNIT Duke Power Co.
Duke Power Co.
Duke Power Co.
OPPD Baltimore Electric 8
Gas Metropolitan Edison Indiana 8 Michigan Electric Indiana 8 Michigan Electric Northeast Utilities Portland General Electric Toledo Edison Arkansas Power 8
Light MPPSS Oconee Oconee Oconee Ft.
Calhoun Calvert Cliffs Three Mile Island D.C.
Cook D.C.
Cook Millstone Trojan Davis Besse Arkansas Nuclear One Hanford
I
ENCLOSURE 2 IE Information Notice No. 79-37 Date:
December 31, 1979 Page 1 of 1 RECENTLY ISSUED IE INFORMATION NOTICES Information Notice No.
79"12A 79-27 79-28 Subject Attempted Damage to New Fuel Assemblies Steam Generator Tube Ruptures at Two PMR Facilities Overloading of Structural Elements Due to Pipe Support Loads Date Issued 11/9/79 11/16/79 11/16/79 Issued to All Fuel Facilities, Research Reactors and Power Reactors with an Operating License (OL) or Construction Permit
'(CP)
All Power Reactor Faci-lities with an OL or CP All Power Reactor Faci-lities with an OL or CP 79"29 Loss of Nonsafety Related ll/19/79 Reactor Coolant System In-strumentati,on During Operation All Power Reactor Faci-lities with an OL or CP 79"30 79"31 79-32 79"33 Reporting of Defects and Noncompliances, 10 CFR Part 21 Use of Incorrect Amplified
Response
Spectra (ARS)
Separation of Electrical Cables for HPCI and ADS Improper Closure of Primary Containment Access Hatches.
12/6/79 12/13/79 12/21/79 12/21/79 Al1 Power Reactor Faci-lities with an OL or CP All Power Reactor Faci-lities with an OL or CP All Power Reactor Faci-lities with an OL or CP All Power Reactor Faci-lities with an OL or CP 79"34 I
Inadequate Design of Safety-12/31/79 Related Heat Exchangers All Power Reactor Faci-lities with an OL or CP 79"35 79-36 Control of Maintenance and Essential Equipment Computer Code Defect in Stress Analysis of Piping Elbow 12/31/79 12/31/79 All Power Reactor Faci-lities with an OL or CP All Power Reactor Faci-lities with an OL or CP
If
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