ML20207C170
| ML20207C170 | |
| Person / Time | |
|---|---|
| Site: | Harris  |
| Issue date: | 07/02/1986 |
| From: | Watson R CAROLINA POWER & LIGHT CO. |
| To: | Grace J NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| References | |
| CON-NRC-461, REF-PT21-86, REF-PT21-86-262-000 191, HO-8650080, PT21-86-262, PT21-86-262-000, NUDOCS 8607210184 | |
| Download: ML20207C170 (4) | |
Text
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CD&L Carolina Power & Light Company
'? 3 *. I SHEARON HARRIS NUCLEAR PROJECT P.O. BOX 165 New Hill, North Carolina 27562 JUL 2 1936 File Number:
SHF/10-13510 NRC-461 Letter Number:
HO-8650080 Dr. J. Nelson Grace United States Nuclear Regulatory Commission Region II 101 Marietta Street, Northwest (Suite 2900)
Atlanta, Georgia 30323 CAROLINA POWER & LIGHT COMPANY SHEARON HARRIS NUCLEAR POWER PLANT 1986-900,000 KW - Unit 1 7.5 KVA INVERTERS -
INSULATION BREAKDOWN, ITEM 191
Dear Dr. Grace:
Attached is a final report on the subject item, which was deemed reportable per the provisions of 10CFR50.55(e) and 10CFR, Part 21 on February 12, 1986. With this report, Carolina Power & Light Company considers this matter closed.
If you have any questions concerning this matter, please do not hesistate to contact me.
Yours very truly, R. A. Watson Vice President Harris Nuclear Project RAW /cge Attachment cc: Messrs. G. Maxwell (NRC-SHNPP)
J. M. Taylor (NRC) 8607210184 860702 PDR ADOCK 00000400 S
\\ I MEM/H0-8650080/ PACE 1/OS1 IE M
CAROLINA POWER & LIGHT COMPANY SHEARON HARRIS NIICLEAR POWER PLANT IJNIT 1 FINAL REPORT 7.5 KVA INVERTERS - INSIJLATION BREAKDOWN NCR 85-1420 ITEM 191 JIILY 1,1986 REPORTABLE IINDER 10CFR 50.55(e) AND 10CFR, PART 21 i
IBMD-MS86-OS4/ Item 191
SUBJECT:
Shearon Harris Nuclear Power Plant Unit Number 1, 10CFR 50.55(e) and 10CFR Part 21 reportable deficiency.
Insulation breakdown on General Electric transformers supplied with Westinghouse 7.5 KVA Inverters.
ITEM:
General Electric ferro-resonant transformers -
Westinghouse Part Number 3485C38 H08.
SUPPLIED BY:
Westinghouse Electric Corporation.
NATURE OF DEFICIENCY:
General Electric ferro-resonant transformers as supplied on Westinghouse 7.5 KVA Inverters have experienced failures on some units due to a shorting between the coil and core of one of two reactors i
connected to the secondary of the ferro-resonant i
transfo rmer. This failure has been attributed to vibration which resulted from insufficient securing of laminations making up the center leg of the G40 i
reactor core. Over a period of time the operation of l
I the transformer results in failure of coil insulation due to this vibration.
l i
DATE PROBLEM IDENTIFIED:
Westinghouse notified CP&L in October 1984 of this potential problem.
DATE PROBLEM REPORTED On October 29, 1984, Mr. N. J. Chiangi notified the NRC of a potentially reportable item under the provisions of 10CFR 50.55(e) and 10CFR, Part 21.
On February 12, 1986, Mr. N. J. Chiangi notified the NRC that this item was reportable per the provisions of 10CFR 50.55(e) and 10CFR, Part 21.
SCOPE OF PROBLEM:
This deficiency involves four NIS Inverters (Channels I, II, III, & IV) and two Auxiliary Transfer Panel Inverters (SA and SB), for a total of six inverters.
SAFETY IMPLICATION:
Failure of the ferro-resonant transformer results in a greatly reduced output which leads to a failure of the inverter output.
Loss of inverter output results in a loss of the safety function of the loads fed by the inverter.
IBHD-MS86-OS4/ Item 191
REASON DEFICIENCY IS REPORTABLE: Redundancy of safety systems will be compromised by a failure of one or more inverters. This could jeopardize the safety function of equipment powered from NIS Channels I, II, III, & IV, and the Auxiliary Transfer Panel.
CORRECTIVE ACTION:
In order to determine that the inverters supplied for the Harris Plant are adequate to perform their function, the six Harris inverters were subjected to a six month load test as recommended by Westinghouse.
This load test consists of connection of permanent loads and heaters as required to achieve a 20%
minimum load at all times on the inverters.
Completion of the load test is regarded as demonstration that the inverter is free from the defect in construction of the ferro-resonant transformer.
FINAL REPORT:
The six month load test of the Channel I, II, III, and IV inverters was successfully completed on August 15, 1985. The six-month load test for the SA and SB inverters supplying power to the Auxiliary Transfer Panels was successfully completed on March 30, 1986.
On September 6, 1985, the Channel IV Inverter ferro-resonant transformer shorted to ground. An investigation has determined that this failure was a failure of the laminations in the center leg of the G40 reactor core. The ferro-resonant transformer for the Channel IV Inverter has been replaced with a spare transformer. The Channel IV Inverter was subjected to a six-month load test which was successfully completed on June 30, 1986. This testing was necessitated by the transformer supplier's inability to guarantee that ferro-resonant transformers purchased as spare parts were not subject to the failures which resulted in the issuance of Westinghouse Technical Bulletin NSID-TB-84-11. General Electric is now manufacturing ferro-resonant transformers which are not subject to this failure. Any transformer replacements which are necessary in the future will be made using the ferro-resonant transformers which are free of these defects.
This is the final report for Item 191. No further correspondence is planned for this item.
IBMD-MS86-OS4/ Item 191
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