ML19323G265
| ML19323G265 | |
| Person / Time | |
|---|---|
| Site: | Brunswick  |
| Issue date: | 05/16/1980 |
| From: | Ippolito T Office of Nuclear Reactor Regulation |
| To: | Jackie Jones CAROLINA POWER & LIGHT CO. |
| References | |
| NUDOCS 8006020060 | |
| Download: ML19323G265 (3) | |
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MAY 1 6 1900 Docket Nos. 50-325 50-324 Mr. J. A. Jones Executive Vice President Carolina Pcwer & Light Cocpany 336 Fayetteville Street Raleigh, Pforth Carolina 27602 Ocar Mr. Jones:
On December 28, 1979 the NRC Office of Inspection and Enforcement (IE) issued Information Notice No. 79-37 that discussed the discovery of cracks in the keyway and bore sections of discs in Westinghouse low-pressure turbines. A copy of this Information Notice with an errata sheet 1s enclosed. Subsequently, all licensee / users of low-pressure turbines manufactured by General Electric were invited to meet with the NRC staff and representatives of the vendor on January 9,1980 to discuss the probability of disc cracking in these turbines. A sumary of this meeting and the General Electric Cospany's presentation are also enclosed with this letter.
At the time of the January 9 meeting General Electric did not have any recent results of ultrasonic inspections of its Icw-pressure turbines.
Since that date full UT inspections have been performed on six retors at five nuclear power plants. Some indications in the keyway region have been reported in discs at three of these plants. General Electric personnel bel! eve that these indications were caused Dy water erosion rather than by stress corrosion.
The staff desires to learn more about the underlying reasons for the indications found and the probable rate of growth of these indications and their effects on turbine disc integrity.
For this purpose we request that you provide the infennation sought in to this letter and address its safety significance. Under the provistons of 10 CFR 50.54(f) your response is requested within 30 days of the receipt of this letter. A copy of this letter is being telecopied to you, along with Enclosure 3.
It is y understanding that additional UT inspections are to be perforced by General Electric in the near future. We enceurage this action as being the only certain means of determining the integrity of turbine discs. We also reconcend that if you have not already done so, that you develop a schedule for performing a full UT inspection of at least one of your low-pressure turbines during the next major cutage of your plant.
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...g NIC FORM 318 (9 76) NRCM 0240 DU.S. GOVERNMENT PRINTING OFFICE: 1979-289-369
Mr. J. A. Jones liAY I 6 G30 This request for deneric information was approved by GA0 under clearance nu::ter 3-180225 (579014); this clearance expires June 30, 1980.
Sincerely, original s8sned 4 T. A. Ippages Thomas A. Ippolito, Chief Operating Reactors Dranch #2 Division of Licensing
Enclosures:
1.
Information Sulletin 79-37 2.
Fecting Summary 3.
Information Requests cc w/o enclosures:
See next pace Distribution Docket ORB #2 Local PDR flRC PDR TIppolito SNorris Atty, OELD OI&E (3)
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. 5L. /80 NIC FO R M 318 (9-76) NRCM 0240 DU.S. GOVERNMENT PRINTING OFFICE: 1979 289 369
Mr. J. A. Jones May 16,*1980 cc:
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Richard E. Jones, Esquire Carolina Power & Light Company 336 Fayetteville Street Raleigh, North Carolina 27602 George F. Trowbridge, Esquire Shaw, Pittnan, Potts & Trowbridge 1800 M Street, N. W.
l Washington, D. C.
20036 John J. Burney, Jr., Esquire Burney, Burney, Sperry & Barefoot 110 North Fifth Avenue Wilmington, North Carolina 28401 Resident Inspector U. S. Nuclear Regulatory Commission P. O. Box 1D57 Southport, North Carolina 28461 Southport - Brunswick County Library 109 W. Mcore Street Southport, North Carolina 28461 Mr. Fred To111 son Plant Manager P. O. Box 458 Southport, North Carolina 28461
UNITED STATES ISINS NO.:
6870 NUCLEAR REGULATORY COMMISSION Accession No.:
OFFICE OF INSPECTION AND ENFORCEMENT 7910250525 WASHINGTON, D.C.
20555 December 28, 1979 IE Information Notice No. 79-37 CRACXING 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.
West 4.n.ase had eade 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 obs e rved. 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 examihed and preliminary findings show thee not to be typical of classical stress corrosion cracking observed in the key-ays.
The probable cracking mechanism and impact on disc integrity is being further i
evaluated by Westinghouse.
I A meeting was held on Oe'cember 17, 1979 between the NRC staff, Westinghouse and utility representatives to discuss the disc cracking problem, repair alter-natives, turbine oissile 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 Surn 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 4
Westinghouse indicated that the observed crack will not attain critical dimensionsa during 28 additional months of turbine operation. The NRC staff is evaluating kgV the turbine inspection results and analysis by Westinghouse.
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CATEGORY AA UTILIT_Y STATION UNIT Florida, P&L Turkey Point 3
Consolidated ED.
Indian Point 2
PASNY Indian Point 3
i 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 1
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 Sailey Point 1
Rochestar G&E Ginna 1
Northern States Prairie Island 1
Wisc. P.S.
Kewaunee 1
N
- (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
VEPCO North Anna 2
WPPSS Hanford 2
WPPSS WNPS 1
WPPSS WNPS 3
WPPSS WNPS 4
WPPSS WNPS 5
i e
e e
9
1 UTILITY STATION UNIT Duke Power Co.
Oconee 1
Ouke Power Co.
Oconee 2
Duke Power Co.
Oconee 3
1 OPPD Ft. Calhoun 1
Baltimore Electric
& Gas Calvert Cliffs 1
Metropolitan Edison Three Mile Island 1
Indiana & Michigan Electric 0.C. Cook 1
Indiana & Michigan Electric D.C. Cook 2
Northeast Utilities Millstone 2
Portland General Electric Trojan 1
Toledo Edison Davis Besse 1
Arkansas Power &
Light Arkansas Nuclear One 2
WPPSS Hanford 1
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Errata Sheet For IE Information Notice No. 79-37 Page 1, paragraph 2 line 9: Change " inlet" to " outlet" Page 1, paragraph 3, lines 9 and 10: Change " Point Beach Unit 2" to
" Point Beach Unit 1" Page 1, paragraph 3 line 10: After Point Beach Unit 1 add an asterisk
("*") footnote and place a note at the bottom of the page as follows:
"* Wisconsin Electric Power Company orally notified the NRC project manager on Novaber 5 that turbine disc cracking had been observed at Point Beach Unit 1.", line 4: Change "Russellville" to "ANO", line 8: Change to read: " Yankee Atomic Electric, Yankee Rowe", lines 9 and 15: Change '" disc Mich Pwr" to "Wisc Elec Pwr", line 16: Change to read " Maine Yankee Atomic Pwr, Maine Yankee", page 3, line 13: Delete as redundant reference to North Anna 2 f ['
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UNITED STATES
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NUCLEAR REGULATORY COMMISSICN 5 ', '.
WASHINGTON. D. c. 20555 8 h
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g FE3XUfuY Z 12D MEMORANDUM FOR:
A. Schwencer, Chief Operating Reactors Branch #1, 00R FROM:
W. J. Ross, Project Manager Operating Reactors Branch #1, 00R
SUBJECT:
MEETING WITH GENERAL El.ECTRIC REl.ATED TO TURBINE DISC CRACXS At the staff's request, representatives of General Electric met with the staff and licensee / user of G.E. turbines on January 9,1980 te discuss the design of and operational experience of low pressure turbines. A list of attendees at the non-pmprietary and proprietary sessions is attached.
In the non-proprietary session General Electric's personnel discussed the following topics: (a) turbine wheel (disc) integrity; (b) minimizing wheel (discs) bursts. Copies of the slides used in this presentation are attached in Enclosure 3.
Turbine Wheel Integrity There has been no indication of cracks in the bore regions of G.E. Icw pressure turbine wheels. This experience includes the operation of 35 turbines at nuclear generating plans (22 BWRs-of which only three have actually been inspected) and 4000 wheels at 235 fossil units (percent of wheels inspected was not established at the meeting). A G.E. turbine has the following design enaracteristics:
(1) 14 wheels or discs per rotor with 38" or 43" active length buckets or blades.
(2) Rectangular axial keyway and cir'-imferential locking ring minimize rotation of wheels on tne turbine shaft (i.e.
minimize stress).
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