ML20198K049
| ML20198K049 | |
| Person / Time | |
|---|---|
| Site: | Harris  |
| Issue date: | 05/14/1986 |
| From: | Joseph Willis CAROLINA POWER & LIGHT CO. |
| To: | Grace J NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| References | |
| CON-NRC-447 219, HO-860293-(O), NUDOCS 8606030305 | |
| Download: ML20198K049 (4) | |
Text
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CP&L Carohng gwer,%ight Company a.) c.. -
j SHEARON HARRIS NUCLEAR PROJECT P. O. Box 165 New Hill, North Carolina 27562 MAY 141986 File Number:
SHF/10-13510 Letter Number: HO-860293 (0)
NRC-447 Dr. J. Nelson Grace United States Nuclear Regulatory Commission l
Region II i
101 Marietta Street, Northwest (Suite 2900)
Atlanta, Georgia 30323 CAROLINA POWER & LIGHT COMPANY SHEARON HARRIS NUCLEAR POWER PLANT 1986 - 900,000 KW - UNIT 1 EMERCENCY SERVICE WATER PUMP MATERIAL FAILURE, ITEM 219
Dear Dr. Grace:
Attached is a final report on the subject item, which was deemed i
reportable per the provisions of 10CFR50.55(e) on November 8, 1985. With this report Carolina Power and Light Company considers this matter closed.
If you have any questions concerning this matter, please do not hesitate to contact me.
Yours very truly, 6
L.WillisSyN W
1 ant General Manager Shearon Harris Nuclear Power Plant DLT/ime Attachment cc: Messrs. C. Maxwell (NRC - SHNPP)
J. M. Taylor (NRC) 8606030305 860514 PDR ADOCK 05000400 I
S PDR Tbl
l CAROLINA POWER & LIGHT COMPANY i
SHEARON HARRIS NUCLEAR POWER PLANT UNIT 1
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FINAL REPORT P
t EMERGENCY SERVICE WATER PUMP
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MATERIAL FAILURE ITEM 219 d
May 12, 1986 REPORTABLE UNDER 10CFR50.55 (e) r i
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l SUBJECT 10CFR50.55(e) Reportable Item, Shearon Harris Nuclear Power Plant Unit 1, Emergency Service Water Pump Material Failure.
ITEM Emergency Service Water Pumps lA and IB for SHNPP Unit 1.
SUPPLIED BY Hayward-Tyler, Inc.
NATURE OF DEFICIENCY:
Loss of pump discharge pressure and flow occurred during operation of the 1A ESW pump. Subsequent inspection revealed the pump shaft was sheared at the pump upper bearing. Bearing and shaft sleeve were destroyed. Inspection of IB ESW pump also has indicated deterioration.
DATE PROBLEM IDENTIFIED:
September 5, 1985 DATE PROBLEM REPORTED:
On November 8, 1985 CP&L (Mr. K. V. Hate) notified the NRC (Mr. P.
Frederickson) that the item was reportable under the provisions of 10CFR50.55(e).
SCOPE OF PROBLEM:
i Visual inspection and detailed metallurgical examination indicate the shaft failure of 1A pump was due to extreme overheating. The flow slots in the bearing were plugged due to the damage to the bearing.
No further conclusions could be drawn from the damaged parts.
Two general areas were investigated, these areas were (1) the design and installation of the pump bearing and (2) the seal and bearing water injection system required during ESW pump starting and operation.
With regard to the bearing design, the bearing to shaft sleeve design clearances are specified to be 0.008" to 0.012".
These clearances appear to be adequate based on similar vertical pump / bearing design.
However the clearances found during repair of the pump did not meet thesis values.
The be aring housing was found to be slightly " hour glass" shaped.
The deviation from the nominal diameter was noted to be 30 mits and caused interference fit between the bearing and shaft. The housing was honed and bearing clearances verified. This problem was not noted in previous pump installation records.
The Seal Bearing Lube System design and operation was also investigated. Due to a lack of permanent design for the Seal Water System, a temporary design was installed providing Seal Water. This temporary system was operated for over a year with no apparent deficiencies. A temporary system was in service when the pump failed.
After the A pump was repaired and proper bearing clearances verified on reassembly, testing was done to develop a correlation between injection supply pressure and flow to the seal.
The testing was representative of the temporary design. The flow rates obtained (5-8 gpm) were adequate to cool the bearing assuming proper bearing clearances. However, this data cannot be correlated with the situation that existed prior to the failure. In conclusion, it is impossible to determine if the failure was a direct result of either the bearing installation or the seal injection flow provided.
SAFETY IMPLICATIONS:
Loss of the ESW pumps would prevent heat removal from other safety systems.
REASON 'EFICIENCY IS REPORTABLE:
The failure required extensive repair to establish system adequacy.
CORRECTIVE ACTION:
i ESW pump 1A and IB was disassembled, components inspected and repaired and/or replaced as necessary.
PREVENTIVE MEASURES:
t The permanent seal / bearing water system has been redesigned to allow a higher pressure seal water supply. This seal water system is in operation. CP&L has disassembled both pumps for the second time during April 1986 and reinspected for evidence of shaft overheating or bearing failure due to heat. This inspection found bearing wear within tolerance and with no signs of shaft overheating.
FINAL REPORT Both pumps have been returned to service and are performing at design levels. Based on the satisfactory inspection and performance of these pumps, this item is considered closed.
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