ML19256B409
| ML19256B409 | |
| Person / Time | |
|---|---|
| Site: | Brunswick  |
| Issue date: | 05/02/1979 |
| From: | James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| To: | Jackie Jones CAROLINA POWER & LIGHT CO. |
| References | |
| NUDOCS 7906130154 | |
| Download: ML19256B409 (1) | |
Text
UNIT E D ST ATEG a asos,q'o NUCLEAR REGULATORY COMMISSION m
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101 M AR IETT A ST R E ET. N.W.
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ATLANTA. GEORGI A 30303
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MAY 1979 In Reply Refer To:
RIL:JP0 5d-325 N
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Carolina Power and Light Coupany Attn:
Mr. J. A. Jones, Executive Vice President and Chief Operating Officer 411 Fayetteville Street Raleigh, North Carolina 27602 Gentlemen:
The enclosed IE Circular No. 79-07, is forwarded to you for information.
No written response is required. Should you have any questions related to your understanding of this matter, please contact this office.
Sincerely, 3
James P. O'Reilly k Director
Enclosure:
IE Circular No. 79-07 i
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7906130/ 7 7 G?
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MAY 2 1979 7
Carolina Power and Light Company cc w/ enc 1:
A. C. Tollison, Jr.
Plant Manager Box 458 Southport, North Carolina 28461 t
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9 UNITED STATES NUCLEAR REGULATORY COMMISSION OFFICE OF INSPECTION AND EhTORCEMENT WASHINGTON, D.C.
20555 May 2, 1979 IE Circular No. 79-07 UNEXPECTED SPEED INCREASE OF REACTOR RECIRCULATION MG SET RESULT REACTOR POWER INCREASE Description of Circumstances:
On November 24, 1978, an unexpected rapid speed increase was experienced on the 'B' Reactor Recirculation MG set (RRMG) at the Cooper Nuclear Prior to the event, the RRMG set had been inadvertently tripped Station.
during the performance of routine maintenance.
Upon restart, the MG set would not respond to a speed increase signal.
Licensee personnel com-menced trouble shooting this problem in accordance with the instructions in the manufacturer's technical manual.
One step of these instructions suggested removing the fuse from the Bailey scoop tube actuator circuit (a blown fuse would de-energize the actuator and not permit the scoop tube to move). When the terininal panel cover was removed, licensee personnel noted two fuses instead of one as shown on the vendor drawings. When licensee personnel removed the second fuse to verify fuse integrity, a rapid speed increase of the MG set occurred. This increase was terminated by replacement of the fuse or tripping of the MG set by the control room operator (both actions took place almost simultaneously).
The input signal to the scoop tube actuator is received from the speed controller via a function generator.
This signal is a scoop tube posi-tion demand signal. As the actuator drives the scoop tube in or out of the fluid coupler, a position followup signal is generated to null the The input signal and stop scoop tube motion at the required position.
vendor's drawings of the scoop tube actuator circuit showed only one fuse in the circuit. The licensee contacted the vendor regarding the second fuse and was informed that this fuse had been added as a change in the initial circuit design to provide protection for certain elec-tronic components in this circuit. This additional fuse is located in the position followup circuit. Removal or loss of the fuse would result in a loss of the nulling signal and would cause the scoop tube to drive to the maximum speed position.
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