ML20090D476
| ML20090D476 | |
| Person / Time | |
|---|---|
| Site: | Nine Mile Point, 05000000 |
| Issue date: | 04/06/1973 |
| From: | Schneider R NIAGARA MOHAWK POWER CORP. |
| To: | Skovholt D US ATOMIC ENERGY COMMISSION (AEC) |
| Shared Package | |
| ML20090D471 | List: |
| References | |
| 2367, NUDOCS 8303010322 | |
| Download: ML20090D476 (4) | |
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Y e-NBAGARA MOHAWK POWER CORPORATION NIAGARA MOHAWK 300 ERIE BOULEVARD WEST G
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(h U.E7lM77 Mr. Donald J. Skovholt Assistant Director for Reactor Operations
' "q Division of Reactor Licensing
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United States Atomic Energy Cournission
~ ip Washington, D. C.
20545
Dear Mr. Skovholt:
Re: Provisional Operating License:
DPR-17 Docket No.: 50-220 The General Electric Company, designers of the nuclear-steam supply system at Nine Mile Point Nuclear Station Unit #1, has recommended that all baffles be removed from the suppression chamber and that " rams heads" be installed on the discharge piping from the electromatic relief valves.
The Analysis presented May 10, 1972, (Enclosure 1) addressed itself to the complete removal of all baffles and based the partial removal of baffling on that analysis. At that time only the baffles nearest the electromatic relief valve discharge piping were removed. By eliminating the nearest baffle to each of the vent discharges, calculational data available at that time indicated that, the local discharges should have much less effect on the remaining baffles as the force generated would diminish with distance.
In essence, a practical attempt was made to achieve an unbaffled torus by placing more distance between the vent discharge and the nearest baffle. However, test data recently compiled by General Electric indicates that the baffle loading on the remaining baffles would be higher than desired under the condition of sustained blowdown, from high aik power operation, of an electromatic relief valve and thus in the interest of main-2,h taining a high degree of safety have recommended total removal of all baffles.
{'thf The Safety Analysis presented May 10, 1972, (Enclosure 1) proved that an unbaffled torus would not reduce the existing safety margin because the half second pressure
[.. M blip is much less than the previously calculated maximum of 25 psig (the maximum unbaffled end point pressure) and well below the design pressure of 35 psig.
1b' The " rams heads" will provide better temperature distribution throughout the h3 entire suppression chamber.
In addition, it will eliminate any local hot spots which could be generated if an inadvertent sustained opening of an electromatic C
relief valve occurred at high power operations. Figures 1 & 2 depicts the arrangements of the " rams heads" and its supporting.
Therefore, it is our intent to remove all baffling from within the torus and install the " rams heads" on the electromatic relief valve discharge piping during the Spring 1973 refueling outage scheduled to begin April 13, 1973.
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8303010322 7212f2 d
PDR ADOCK 05000220
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Mr. Donald Skovholt April 6, 1973 U. S. Atomic Energy Commission i
Results of the May 10, 1972 analysis (Enclosure 1) and the proposed I
equipment changes have been reviewed by the On-Site and off-Site Safety Review Committees who concur that the changes are in the best interest of maintaining a high degree of safety.
Very truly yours,
. R. Schneider Vice-President Electric Operations RRS:em Enclosures i
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