ML19305B013
| ML19305B013 | |
| Person / Time | |
|---|---|
| Site: | Summer  |
| Issue date: | 02/29/1980 |
| From: | James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| To: | Nichols T SOUTH CAROLINA ELECTRIC & GAS CO. |
| References | |
| NUDOCS 8003190034 | |
| Download: ML19305B013 (2) | |
Text
'o UNITED STATES g
8 NUCLEAR REGULATORY COMMISSION o
g
,e REGION 11 0,
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101 MARIETTA ST., N.W., SUITE 3100 e
ATLANTA, GEORGIA 30303 In Reply Refer To:
RII:JPO FEB 291+
Ihb South Carolina Electric and Gas Company Attn:
T. C. Nichols, Jr., Vice President Power Production and System Operations P. O. Box 764 Columbia, SC 29218 Gentlemen:
This Information Notice is provided as an early notification of a possible significant matter.
It is expected that recipients will review the informa-tion 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,
- -[
~
James'P. O'Rei Director
Enclosures:
1 1.
IE Information Notice No. 80-07 2.
List of Recently Issued IE Information Notices j
800319003 4 m
SSINS No.:
6870 Accession No.:
UNITED STATES 7912190675 NUCLEAR REGULATORY COMMISSION OFFICE OF INSPECTION AND ENFORCEMENT WASHINGTON, D.C.
20555 February 29, 1980 IE Information Notice No. 80-07 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.
s 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.
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