ML20085E961
| ML20085E961 | |
| Person / Time | |
|---|---|
| Site: | Browns Ferry  |
| Issue date: | 07/11/1975 |
| From: | Gilleland J TENNESSEE VALLEY AUTHORITY |
| To: | Knuth D NRC OFFICE OF INSPECTION & ENFORCEMENT (IE) |
| References | |
| 10CFR-050.55E, 10CFR-50.55E, NUDOCS 8308170175 | |
| Download: ML20085E961 (3) | |
Text
831 Power Building uTio,%c f
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. NNESSEE VALLEY AUTH TY e
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CHATTANOOGA, TENNESSEE 374o1
'/ra.t916 July 11, 1975 Mr. Donald F. Knuth, Director Office of Inspection and Enforcement U.S. Nuclear Regulatory Commission Washington, DC 20555 Deer Mr. Knuth:
BROWNS FERRY NUCLEAR PLANT UNIT 3 - REPORTABLE DEFICIENCY -
TURBINE ROOM SUPPLY AND EX11AUST FANS - LACK OF INTERLOCKS Initial report of the subject deficiency was made to NRC-IE, Region II, Inspector G. R. Klingler on June 12, 1975.
In compliance with paragraph 50.55(e) of 10 CFR Part 50, we eubmit the enclosed final report.
Very trulylyours, N
. E. Gilleland Assistant lianager of Power Enclosure CC (Enclosure):
Mr. Norman C. Moseley, Director Office of Inspection and Enforcement U.S. Nuclear Regulatory Commission Region II - Suite 818 230 Peachtree Street, NW.
Atlanta, Georgia 30303 0 IV B308170175 750711 N 2 (s PDR ADOCK 05000259 Q
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soscs An Equal Opportunity Employer
EriCLOSURE BR094..o FDIRY NUCLEAR PLANT UNIT 3 O TURBINE ROOM SUPPLY MiD EXHAUST FMIS LACK OF INTERLOCKS FINAL REPORT t
12,1975, an initial report was made by telephone to NRC Regicn II G. H. Klingler by T. W. Barkalow and R. D. Bradicy. The initial
..u made in compliance with 10CFR50 55(c).
This is the final report
., occurrence.
ton of Deficiency erforming preoperational test TVA-19, it was discovered that there interlocks between the supply and exhaust fans.
The lack of inter-exit that there was no control cystem to prevent a person frem
_ en more supply fans than exhaust fans.
It would thereby be possible
- nore supply than exhuast capacity thus pressurizing the turbine room.
? Deficiency
.: ol system for the turbine room supply and exhaust fans was i for tuuinal operaticn with no interlocks.
Since the Brevns Ferry acifies that the turbine building be maintained at a slight a pressure and that the c::haust air be monitored, an implicit
-ion in the design is that a reactor operator or vo'l cn wculd not r
more supply than exhaust capacity. However, without an inter-prevent such an occurrence, it is not possible to rule out ror in turning the supply and exhaust fans off and on.
)mlications
^dne room ventilation system is not safety-related.
However, federal
e,ns require that all effluents from nuclear power plants be monitored
'enctivity. Thus the air exhausted from the turbine room must be
~1.
If the turbine room were to be accidentally pressurized, some 14 be exhausted through unmonitored exits (doorways, stal:vays, cracks, Assuming that a radioactive source was present at the same time the
, pressurized, it would be possible for some radioactive material to med to the environ =ent without being monitored.
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In the highly unlikely occurrence of such an event, the majority of the relcase would be monitored since most of the air would be exhausted throu;;h the exhaust fans. Thus a large release would be det:cted and appropriate action initiated.
Description of Corrective Action Two Engineering Change Notices (ECN's) have been prepared to remedy this deficiency. These ECD's will interlock each turbine room supply fan, in fast speed mode, with two turbine roof exhaust fans (roof ventilators).
Th:y will also interlock each turbine room supply fan, in slow speed mode, with one turbine roof exhaust fan.
This interlock system will thus prevent someone from inadvertently pressurizing the turbine room.
Means Taken to Prevent a Recurrence Tto interlock system mentioned above will remove the design deficiency and thus will eliminate the potential of inadvertent pressurization of the
' turbine room.
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