ML19344D411
| ML19344D411 | |
| Person / Time | |
|---|---|
| Site: | Cooper  |
| Issue date: | 02/29/1980 |
| From: | Seyfrit K NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV) |
| To: | Pilant J NEBRASKA PUBLIC POWER DISTRICT |
| References | |
| NUDOCS 8003120321 | |
| Download: ML19344D411 (1) | |
Text
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[M* "%,,o CENTRAL FILES UNITED STATES g HQ
,g fi)e( 3 g NUCLEAR REGULATORY COMMISSION LPDR E y [I -- p REGION IV TIC S,
-1 611 RYAN PLAZA DRIVE, SUITE 1000 NSIC w
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ARLINGTON, TEXAS 76012
+....
February 29, 1980 States Docket No.
50-298 Nebraska Public Power District ATTN:
J. M. Pilant, Director Licensing & Quality Assurance Post Office Box 499 Columbus, Nebraska 68601 Gentlemen:
This IE Informacion Notice is provided as an early notificat. ion of a possibly significant matter.
It is expected that recipients will review the information for possible applicability to their facilities.
No specific action or response is requested at this time.
If further NRC evaluations so indicate, an IE Circular or Bulletin will be issued to recommend or request specific licensee actions.
If you have questions regarding this matter, please contact the Director of the appropriate NRC Regional Office.
Sincerely,
((
[b
%KarlV.Sehit Director
Enclosures:
1.
IE Information Notice i
No. 80-07 2.
List of Recently Issued IE Information Notices cc:
L. C. Lessor, Superintendent 4
Cooper Nuclear Station Post Office Box 98 Brownville, Nebraska 68321 8003120 %
SSINS No.:
6870 Accession No.:
UNITED STATES 7912190675 NUCLEAR REGULATORY COMMISSION OFFICE OF INSPECTION AND ENFORCEMENT WASHINGTON, D.C.
20555 IE Information Notice No. 80-07 Februa ry 29, 1980 Page 1 of 2 PUMP SHAFT FATIGUE CRACKING On October 9, 1979, the Tennessee Valley Authority (TVA) reported to NRC that low-stress high-cycle fatigue cracks had been found in two non-safety-related feedwater pumps at their Browns Ferry BWR facility. One pump had been operated for approximately 20,000 hours0 days <br />0 hours <br />0 weeks <br />0 months <br /> and the other for approximately 28,000 hours0 days <br />0 hours <br />0 weeks <br />0 months <br />.
TVA indicated that excessive vibration had been experienced prior to detection of the cracks by ultrasonic and visual inspection. TVA also reported that catastrophic failure had been experienced with a boiler feed pump at their Paradise fossil unit. The TVA failed pump shafts were of type 414 stainless steel. TVA plans to replace the shafts with a type 17-4ph stainless steel.
A number of centrifugal charging / safety injection pump shaft failures have been reported since 1977. The pumps of interest are the dual purpose centrifugal pumps which are utilized for a normal charging function and in the safeguard mode are aligned for high pressure borated coolant injection. These pumps were procured by Westinghouse from the Pacific Pump Division of Dresser Industries. The pump shaft material was supplied to Pacific Pump by the Carpenter Technology Corporation.
Westinghouse and Pacific Pump have been conducting an on-going investigative program since 1977 to resolve the shaft failure problem.
Results from the program suggested that the causes of the shaft failures could be related to shaft material deficiencies, design and/or abnormal operation of the centrifugal pumps.
Forty centrifugal charging / safety injection pump shafts fabricated from four heats of A276 type 414 stainless steel bar were air cooled and tempered at 1000 F.
The above stated heat treating practice resulted in shafts with low toughness (Charpy "V" notch energies - Longitudinal 6-10 ft-lbs, transverse 2-3 ft-lbs)
Corrective actions taken to reduce the incidence of charging pump / safety injection pump shaft failure have included:
1.
Replacement of the type 414 low toughness stainless steel material.
Replacement material for the charging pump shafts is type 414 stainless steel, oil quenched and tempered at 1150-1200 F.
Some of the air cooled shafts have been re-tempered at 1150 F.
2.
Design modifications to the shaft to reduce stress raisers. The modifica-tions included increasing the fillet radius in the split ring groove, increasing the thread root in the locknut section of the shaft and the use of formed cutting tools during fabrication.
IE Information Notice No. 80-07 February 29, lioC Page ? -f 4 3.
A review of the operating history of the dual purpose centrifugal pumps indicate abnormal operation to be.a potentially significant contributor to the early failure of the pump shafts. Abnormal operation includes any condition that results in partial or complete loss of fluid in the pump or continued operation under high vibration conditions caused by misalign-ment or other installation problems.
Westinghouse Nuclear Service Division's Technical Bulletins 77-9, 78-1 Rev. I and 79-6 provide guidance for monitoring of and limits for pump vibration as well as guidance for pump operation and maintenance.
f Ten additional Safety Injection Pumps manufactured by Pacific Pump were identified as having shafts with the same material and heat treatment as the failed charging / safety injection pump shafts.
These ten additional pumps are of a different design and provide for medimn pressure boron injection in the safeguard mode but do not function in normal operation.
Licensees are encouraged to review the materials utilized for and the design of shafts in safety-related pumps and non-safety-related pumps which could affect safety-related system performance.
Particular attention should be paid to abnormal operating conditions which could induce high stress in the pump shafts, susceptibility of materials to crack initiation and growth, and the presence of stress raisers.
This Information Notice is provided as an early notification of a possibly significant matter that is still under review by the NRC staff.
It is expected that recipients will review the information for possible applicabi-lity to their facility. No specific action or response is requested at this time.
If you have any questions regarding this matter, please contact the 4
Director of the appropriate NRC Regional Office.
l
IE Information Notice No. 80-07 Februa ry 29, 1980 LISTING OF RECENTLY ISSUED IE INFORMATION NOTICES Information Subject Date Issued To Notice No.
Issued 79-36 Computer Code Defect 12/31/79 All holders of power reactor Stress Analysis of Piping Operating Licenses (OLs)
Elbow and Construction Permits (cps) 79-37 Cracking in Low Pressure 12/28/79 All holders of power reactor Turbine Discs Operating Licenses (OLs) and Construction Permits (cps) 80-01 Fuel Handling Events 1/4/80 All holders of power reactor Operating Licenses (OLs) and Construction Permits (cps) 80-02 8X8R Water Rod Lower 1/25/80 All BWR Facilities End Plug Wear holder of power reactor Operating Licenses (OLs) or Construction Permits (cps) 80-03 Main Turbine Electro-1/31/80 All holders of power Hydraulic Control System reactor Operating Licenses (OLs) and Construction Permits (cps) 80-04 BWR Fuel Exposure in 2/4/80 All BWR's holding a Excess of Limits power reactor Operating License (OL) or Construction Permit (CP) 80-05 Chloride Contamination 2/8/80 All licensees of nuclear of Safety Related Piping power reactor facilities and Components and applicants and holders of nuclear power reactor Construction Permit (CP) 80-06 Notification of Significant 2/27/80 All holders of Reactor Events Operating Licenses (OLs) and to near term Operating Licenses (OL) applicants Enclosure L-a