ML20087B508
| ML20087B508 | |
| Person / Time | |
|---|---|
| Site: | Robinson  |
| Issue date: | 09/25/1971 |
| From: | Beattie G CAROLINA POWER & LIGHT CO. |
| To: | Jennifer Davis US ATOMIC ENERGY COMMISSION (AEC) |
| Shared Package | |
| ML20087B383 | List: |
| References | |
| NUDOCS 8403090117 | |
| Download: ML20087B508 (1) | |
Text
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1918A EDT.SEP 25 71 AA028 KA113 I 0F TELEPHONED TEr. con.,
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j D P R 23 ON FRIDAY SEPT 24fH 15 REACTOR TRIP BREAKER FAILED 3
10 RESP 000 TO A SIMULATE 0' TRIP' SIGNAL DURING THE PERFORMANCE;)
. F A R9UTINE TEST YOU WILL BE INFORNES OF THE C#NTINUING INVESTIGATION i-REPORTED T9 MR 9 KIRKPATRICK 9 24 71
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AT L A NT A, GE ORG I A o d3 October 1, 1971 J. G. Keppler, Chief, Reactor Testing and Operations Branch (19)(=G Division of Compliance, Headquarters CO INQUIRY REPORT NO. 50-261/71-17 CAROLINA POWER AND LIGHT COMPANY (H. B. ROBINSON NO. 2), LICENSE NO. DPR-23, i
DOCKET NO. 50-261, REACTOR TRIP RRFAKER FAILURE i
The attached Inquiry Report containing preliminary information on a reactor trip breaker failure is forwarded for action.
This is the third time in four months that one of these Westinghouse DP-50 reactor trip breakers has failed to open. Cn May 14,1971, a trip breaker failed to open due to a brcken linkage pin (C0 Report No. 71-7).
On August 19, 1971, a trip breaker failed to open due to linkage binding (C0 Inquiry Report No. 50-261/71-15).
The impr' per adjustment of undervoltage coil spring tension, which caused o
I the most' recent failure, may have also contributed to the second failure of August 19 In that the spring tensien is initially r.diusted by the manufacturer, I recc= mend our Technical Support Group r ok into the generic implication of these failures.
In an attempt to gain a better understanding as to the cause of these several failures at Robinson, Fr. Kirkpatrick and Mr. V. Burzi, Region I, are at Penn Center now talking with Fr. W. L. McKeitha, Manager, Reliability Centrol, Westinghouse Switch Gear Division. I vill inform you of any sig-nificant information obtained frcm this visit.
During our next site visit, which is scheduled for September 30 - October 1, we vill review CP&L's follevup on this matter. We vill be particularly interested in deter =ining why the CP&L preop testing program did not reveal these breaker deficiencies. We vill also discuss with CP&L the reliability of other breakers in safety-related systems.
The licensee's TWX informing Region II of the breaker failure is attached to the Inqui~ry 7.5portM.15~~ mat'ter vilrte'Tormally-reported ~to DRL within days.
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Enclosure:
h CO Inquiry Rpt. No.
50-26I/71-17, v/ attach.
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J. G. Keppler October 1, 1971 cc v/ encl:
A. Gia=busso, CO L. Kornblith, Jr., CO R. H. Engelken, CO J. G. Henderson, CO l
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U. S. ATOMIC ENERGY CO:CIISSION REGION II l
DIVISION OF COMPLIA' ICE l
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C0 Inquiry Report No. 50-261/71-17
Subject:
Carolina Power and Light Ccmpany Hartsville, South Carolina 1
License No.: DPR-23 Facility:
H. B. Robinson No. 2 Descriptive
Title:
Reactor Trip Breaker Fa,ilure Prepared By:
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'l ggg D. C. Kirkpdzrick, Eeactdr Inspector Date i
i On September 2L,1971, Mr. G. P. Beatty, Plant Superintendent, telephoned Mr. D. C. lKirkpatrick to report the failure of a reactor trip breaker to Pmetion.
On September 24, during routine testing prior to reactor startup, one of two redundant reactor trip breakers, Westinghcuse Model No. D3-50 failed i
to open following receipt of a reactor trip signal. The second breaker I
did function properly causing a reactor trip.
Mr. W. L. NcKeitha, Manager, Reliability Control, Westinghouse Switch Gear Division - Pittsburgh, was sent to the site to investigate the problem.
The manufacturer also sent a crew along with a breaker test van from their facility in Charlotte, North Carolina.
The malfunctioning breaker was mounted in the test equipment where it fa' led again on the first test trip. The problem was found to be an ' improper ad-justment o,f the undervoltage ec41. spring tension. The three other identical breakers, two of which are bypass breakers installed for testing purposes, were then removed from the reactor trip circuit and tested. Of the four breakers tlested, three were found to have improper spring tension, re-portedly set that way by the manufacturer prior to installation. The four breakers were adjusted properly and tested by decreasing the control volt-age steadily until the breaker tripped. All tripped at approximately 50 volts which is the proper level. This test was performed four times for each breaker with consistent results. Each breaker was then tripped twenty times by the usual method. No more failures were experienced.
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l CO Inquiry Rpt No. l 50-261/71-17 Mr. Beatty said that he had sent a telegram to the Region II office reporting the incident and that a report would be sent to DP1 within ten days. He said that the Plant Safety Co==ittee had reviewed the problem.
He said that six members of the Cc=pany Nuclear Safety Cc==ittee had been i
contacted by telephone and criefed on the prcblem. All had concurred in the decision to take the reactor back to pcwer.
Attachment:
M fm CP&L dtd 9/25/71 a
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