ML19256B407
| ML19256B407 | |
| Person / Time | |
|---|---|
| Site: | Hartsville  |
| Issue date: | 05/02/1979 |
| From: | James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| To: | Parris H TENNESSEE VALLEY AUTHORITY |
| References | |
| NUDOCS 7906130147 | |
| Download: ML19256B407 (1) | |
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UNITED STATES ps asoug#o,,
Y NUCLEAR REGULATORY COMMISSION R E GION il
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- 1979 In Reply Refer To
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50-25 ' 50 520' x 50-260
- 2 L' 50-296 50-553 cdAi8N.50-554 Q S0-519 y Tennessee Valley Authority Attn:
Mr.11. G. Parris Manager of Power 500A Chestnut Street Tower II Chattanooga, Tennessee 37401 Gentlemen:
The enclosed IE Circular No. 79-07, is forvarded to you for information.
No written response is required.
Should you have any questions related to your understanding of this inatter, please contact this office.
Sincerely, O
- ~
s James P. O'Reilly k Director
Enclosure:
IE Circular No. 79-07 7906130/971 9
EAY L'1979 T
Tennersee Valley Authority cc w/ encl:
J. G. Dewcase Plant Superintendent P. O. Box 2000 Decatur, Alabama 35602 D. E. McCloud, Project Engineer 400 Chestnut Street Tower II Chattanooga, Tennessee 37401 J. E. Gilleland Assistant Manager of Power 500C Chestnut Street Tower II Chattanooga, Tennessee 37401 R. T. Hathcote, Project Manager P. O. Box 2000 Hartsville, Tennessee 37074 J. F. Cox 400 Commerce Street W9D214 Knoxville, Tennessee 37902 J. E. Wills, P-ject Engineer 400 Chestne cet Tower II Chattanooga, 2ennessee 37401 W. P. Kelleghan, Project Manager P. O. Box 2000 Surgoinsville, Tennessee 37873 i
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v UNITED STATES NUCLEAR REGULATORY COMMISSION OFFICE OF INSPECTION AND ENFORCEMENT WASHINGTON, D.C.
20555 May 2, 1979 IE Circular No. 79-07 UNEXPECTED SPEED INCREASE OF REACTOR RECIRCULATION MG SET RESULTE REACTOR POWER INCREASE Description of Circumstances:
On November 24, 1978, an unexpected rapid speed incicase 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 terminal 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 motisn 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 Removal or loss of the fuse would result the position followup circuit.
in a loss of the nulling signal and would cause the scoop tube to drive to the maximum speed position.
DUPLICATE DOCUMENT Entire document previously entered into system under:
ANO 7 'l O 5 / 4 O i 4 2 No. of pages:
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