ML20050Z054
| ML20050Z054 | |
| Person / Time | |
|---|---|
| Site: | 05000000, Sequoyah |
| Issue date: | 03/09/1981 |
| From: | ORGANIZATION FOR ECONOMIC COOPERATION & DEVELOPMENT |
| To: | |
| Shared Package | |
| ML19240B432 | List: |
| References | |
| FOIA-81-380 NUDOCS 8204150201 | |
| Download: ML20050Z054 (2) | |
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MAR 9 1981 No IRS 27 RESTRICTED DIFFUSION RESTREINTE Date of Receipt 19th February 1981 Date de R6ception Name of nuclear power station Sequoyah 1 (US)
Nom de la centrale Date of incident Date de l' incident 11th February 1981 Type of reactor PWR*
Type de r6acteur Authorized electrical power 1148 lide net' l
Niveau de puissance 61ectrique autoriss October 1980*
First commercial operation Date de mise en service
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Inadvertant ooeration of containment scray and accumulation of water in containment at Seouoyah Nuclear Power Plant No. 1 NRC Preliminary notice (PNO-II-81-15) dated February 12, 1981 1.
At 8.40 p.m. on February 11 an auxiliary operator incorrectly opened a containment spray valve that resulted in 105,ooo gallons of water being sprayed into the contain-ment.
2.
The plant was in a cold shutdown condition at a reactor coolant system (RCS) pressure of 400 psig and a temperature of 180 degrees F.
Two reactor coolant pumps (RCP) were operating for coolant circulation and the residual heat removal (RHR) system was in service controlling decay heat.
The auxiliary operator was to verify that the containment spray valve from the RHR system was physically closed.
Due apparently to miscommunications, the spray valve was manually opened.
A loss of pressurizer level and pressure occurred.
The RCP's were secured and the RHR suction was transferred to take suction from the refueling water storage tank (RWST).
3.
Containment spray was secured when the spray valve was observed to be open at 9 17 p.m. after 105,000 gallons of wate from the RWST and reactor coolant system was sprayed into the containment.
The water remains in the containment, pending completion of transfer plans by the licensee.
The RCS level is estimated'to have remained in the upper levels of the steam generators, well above the top of the core.
4.
The reactor building was evacuated.
Twelve workers were in the containment at the time of spray initiation.
Eight workers required some decontamination.
All have been whole body counted and show no internal or external contamination.
The reactor building vent monitor showed a small radioactive release occurred that is less than 1 percent of the allowable limit.
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MAR 13 m,
tio. IRS 28.1 RESTRICTED DIIi USIOli 16STidIIJ1E Date of Receipt Date de R6ception 3rd March 1981 Ilame of nuclear power station FJRs (U.S. Westinghouse)
IIom de la centrale Cracking in Low Pressure Turbine Discs (generic i. : sue)
Date of incident Date de l' incident Type of reactor Type de r6acteur Authorized electrical power Iliveau de puissance 61ectrique autoris6 First commercial operation Date de mise en service l
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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 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 Nover.ber 17, 1979 which alleged possible violation of Part 10 CFR 50.55e and/or 10 CFR 21 Regulations concerning reportability of recently discoverec stress corrosion cracking in Vestinghouse 1800 rpm low pressure turbine discs.
Westinghouse 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 phencmena, 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 erved.
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 str2ss 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 inspectios 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 rHmensions during 28 additional months of turbine operation.
The NRC staff is evaluating the turbine inspection results and analysis by Westinghouse.
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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 reconnended to utilities that inspection 'of these machines be completed by the Spring 1980 outage period.
ultrasonic' techniques due to its design.The Rowe unit is uninspectable by the p 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 p.lants having other interfacing turbine designs shown in Enclosure 2.
Westinghouse may be necessary as new technical information be From the information available to the NRC staff at this time i.t ap bore areas)y be more generically widespread in turbine discs (e.g. pears that cracking ma
, keyways and 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.
L are currently undergoing review by the NRC staff.
will review the information applicable to their facilities.It is expected that recipients 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 c
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
W'isc. 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 Bailey Point 1
Rochester G&E Ginna 1
Northern States Prairie Island 1
Visc. P.S.
Kewaunee 1
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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 McGui.re 1
Duke Power McGuire 2
Duquesne'Lt.
Shippingport 1
Duquesne Lt.
Beaver Valley 1
Duquesne Lt.
Beaver Valley 2
Flordia Power Corpr Crystal River 1
Flordia Power & Lt.
St. Lucie 1
Flordia Power & Lt.
St. Lucie 2
l 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
1
- (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 i
SMUD.
Rancho Seco*
1 TVA Sequoya^h 1
TVA Sequoyah 2
TVA Watts Bar 1
TVA Watts,Bar 2
l VEPCO North Anna 1
VEPCO North Anna 2
VEPCO North Anna 3
VEPCO North Anna 4
VEPCO North Anna 2
WNPS WPPSS 1
WNPS WPPSS 3
WNPS WPPSS 4
WNPS 5
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UTIt'TY I
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 Trojan 1
Toledo Edison Davis Besse 1
Arkansas Power &
Light Arkansas Nuclear One 2
WPPSS Hanford 1
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