ML19322C107
| ML19322C107 | |
| Person / Time | |
|---|---|
| Site: | Oconee  |
| Issue date: | 10/29/1976 |
| From: | Long F NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| To: | Seyfrit K NRC OFFICE OF INSPECTION & ENFORCEMENT (IE) |
| Shared Package | |
| ML19322C104 | List: |
| References | |
| NUDOCS 7912300088 | |
| Download: ML19322C107 (3) | |
Text
CI8 UNITED STATES
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NUCLEAR, REGULATORY COfAf31SSi
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REGloN H 0.-
9Y 230 PEACHTREE STREET, N.W. SUITE 818 ATL ANTA, GEORGI A 30303 October 29, 1976
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K. V. Seyfrit, Reactor Technical Assistant Branch, Office of Inspection and Enforcement, Headquarters THRU:
N. C. Moseley, Director, Office of Inspection and Enforcement
,,@D W Region II DUKE POWER COVPANY, OCONEE 1, 2 & 3 (DNS 50-269, 50-270, 50-287) -
FLOODING OF TURBINE BUILDING - REQUEST FOR TRANSFER OF LEAD RESPONSIBILITY Oconee Reportable Occurrence, R0-287/76-18 (Enclosure 1) dated October 25, 1976, discusses flooding of the turbine building through the Unit-3 condenser on October 10, 1976. The incident occurred when electrical supply to the air controller on the six 78" condenser outlet valves, to Lake Keovee, was lost causing the air operated valves to attempt to open.
One of the six installed strong backs (pipes) on the valves failed and one of the 78" valves opened. Three manways were removed from the Unit-3 condenser for maintenance. The lake water back flowed through the open condenser manways into the turbine building.
(Enclosure 2) Units 1 and 2 were operating.
The above conditions existed for about 32 minutes, until electrical power was restored to the 78" valves and the open valve was closed.
Water accumulated to a depth of approximately 1 ft. above the turbine building basement floor and to within 5 in. of overflowing into the auxiliary building.
The turbine and auxiliary buildings are common to all 3 units.
Further flooding could have rendered all sources of water to the secondary side of all steam generators inoperable and the LPI and HPI pumps inoperable.
The possibility exists for an incident which would cause more severe flooding, from rupture of a pipe downstream from the 78" condenser outlet valves, in the turbine building, or failure of the valve housings. Another possibility is rupture of the condenser which could damage the outlet valves adjacent to the condenser.
A seismic event could cause such a failure.
The only possibility for stopping flow of Lake Kevvee water into the turbine building and ultimately into the auxiliary building, would be the installation of the large steel panels, "stop logs", into the two 96" condenser discharge pipes at Lake Keovee. This vould require the use of a crane to lift the "stop logs" and position each into runners and lover them into place.
Such an operation could take hours.
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2-It is recommended that consideration be given to installation of a gravity drain systen in the turbine building basement to remove enough water to prevent ficoding the turbine or auxiliary building unde.? ony conditions.
It is also recommended that consideration be given to installation cf bulk'nead doors between the turbine and e.uxiliary buildings.
Bulkhead docrs alone vould not prevent auxiliarf building flooding, however, since the vall between the turbine building snd auxiliary building may not withstand water pressure on one side.
It is requested that lead responsibility for evaluation and resolution of the flooding problem be transferred to NRR.
This subject has been discussed with the NRR project manager.
F. J. Long, Chief Reactor Operations and Nuclear Support Branch
Enclosures:
As stated cc:
G. Roy, 1E:HQ G. Gower, IE:HQ R. Leeis, IE:II l
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