ML20071N059
| ML20071N059 | |
| Person / Time | |
|---|---|
| Site: | Oconee, 05000000 |
| Issue date: | 12/01/1982 |
| From: | Tucker H DUKE POWER CO. |
| To: | James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| Shared Package | |
| ML20071H243 | List: |
| References | |
| FOIA-83-123 NUDOCS 8306060076 | |
| Download: ML20071N059 (2) | |
Text
p EtC 0 / GQ' DUKE T'OWER Go>meer l
- ~
E 6ve -Mt P.0, stox 33189 4]p citAlti Orrr, N.c. 28042 MAL D.TL'CRER n u r >< os z (704) 373-4331 e,e c... e
..e w,
.-.......m December 1, 1982 C
Mr. James P. O'Reilly, Regional Administrator U. S. Nuclear Regulatory Commission Region II 101 Marietta Street, Suite 3100 Atlanta, Georgia 30303 Re: Oconee Nuclear Station Docket Nos. 50-269, -270, -287
% --~~ -
Dear Mr. O'Reilly:
As you are aware, a probabilistic risk assessment study is being done on oconee Unit 3.
The preliminary results of this study indicated that the turbine building flooding induced accident sequences are the most dominant sequences with respect to. degraded core accidents.
The study considered a rang'e of potential flooding rates, their impact on icportant plant equipment, and actions necessary to terminate at:d/or to 1*mit the consequences of the pos,telated ficod.
It has been found that the turbine building drain, tripping the CCW pumps and chsing the pump discharge valves, limiting the magnitude of possible backfloV from the condenser discharge through the condensate coolers after
~
ter'minating the flow from the CCW intake, and preventing flood water to enter the auxiliary building are important aspects of mitigating the postulated turbine bui3 ding flooding events..
Although part of the design basis for the Standby Shutdown Facility (SSF) is turbine building flooding, the system is not presently operational.
In light of this situation, and in an ef fort to reduce the impact of a major turbine
. building flood, interim actions were taken by Duke Power. The doors between the turbine and auxiliary building at the basement level were scaled shut.
All other penetrations up to six feet above the floor level were also scaled shut.
This will protect the!HP1 and LP1 pumps in the auxiliary building from all but the most severe, and least likely, floods.
The CCW crossover valves were closed such that only flow from any one unit would be available to feed a break. Also, osing manual isolation valves, ont condensate cooler on each unit was isolated to limit possible backflow.
These interim actions are providing an adequate Icvel of safety and protection and vill be reviewed and evaluated to determine if they (or other modifications) should be made permanent.
Very truly yours, fS/
ek
~Hal B. Tucker p *1 JCP/phP B306060076 830407 PDR FOIA A9 6 V
SHOLLYB3-123 PDR
- " ' ~ ~,.
Mr. James P.'O'Reilly, Regional Administrator
.-. December 2, 1982
-Page 2 cc: - Mr. Philip C. Wagner -
. Office of Nuclear Reactor Regulation',
U. S. Nuclear Regulatory Ccnunission Washington, D. C.,20555
'Nr. R,obert M. Bernero, Director Division of Risk Analysis
. Office of Nuclear Reactor Regulation
~
U.. S. Nuclear Regulatory Concnission.
Vashington, D. C. 20555 O
h 4
e t
e s.
- ge 4
e s
9 0
g e
4 4
g._
g a
4 4
g 4