ML19329A444
| ML19329A444 | |
| Person / Time | |
|---|---|
| Site: | Oconee  |
| Issue date: | 11/14/1975 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML19329A443 | List: |
| References | |
| NUDOCS 8001031010 | |
| Download: ML19329A444 (3) | |
Text
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SUPPLEMENT TO THE DRAFT SAFETY EVALUATION REPORT (CONTAINMENT SYSTEMS)_
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OCONEE_ NUCLEAR STATION UNITS, 1 2 and 3 l
DOCKET NO. 50-269,270,287 ECCS Containment Pressure Evaluation Appendix K to 10 CFR 50 of the Commission's regulations requires that the effect of operation of all the installed pressupe~r' educing systems and processes be included in.the ECCS evaluation.
For the evaluation it is conservative to minimize the containment pressure since this will increase the resistance to steam flow in the reactor coolant loops and reduce tb; reflood rate in the core. Following a loss-of-coolant accident, the pressure in the containment building will be increased by the addition of steam and water from the primary reactor system into the containment atmosphere. After initial blowdown, heat flow from the core, primary metal structures, and steam generators to the ECCS water, will produce additional steam.
This steam together with any ECCS water spilled from the primary system will flow through the postulated break into the containment.
This energy will be released to the containment during both the blow-down and later ECCS operation phases; i.e., reflood and post-reflood phases.
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Energy removal occurs within the containment by several means.
condensation on the, containment walls and internal structures serves j
as a passive energy heat sink.that becomes effective early in the blowdown transient. Subsequently, the operation of the containment heat removal systems such as containment sprays and fan coolers will remove a
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When the energy removal rate energy from the containment atmosphere.
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1 exceeds the rate of energy addition from the primary system, the contain-l ment pressure will decrease from its maximum value.
The ECCS containment pressure calculations for Oconee Nuclear Station were done generically by B&W for reactors of this type as described in BAW-10103 "ECCS Evaluation of B&W's 177-FA Lowered Loop 'NSS."
The NRC staff reviewed B&W's ECCS evaluation nodel and published a Status Report on October 15, 1974, which was amended November 13, 1974. We concluded I
that B&W's containment pressure model was acceptable for ECCS evaluation.
We required, however, that justification of the plant-dependent input parameters used in the analysis be submitted for our review of each plant.
Justification for the containment input data were submitted for Oconee Nuclear Station dated October 28, 1975. This justification includes comparison of the actual containment parameters for Oconee Nuclear Duke Power Company Station with those assumed by B&W in BAW-10103.
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has reevaluated the containment net-free volume, the passive heat sinks,
- and operation of the containment heat-removal systems with regard to This evaluation was.ba' sed on Ji conservatism for the ECCS analysis.
as-built design information. The containment heat removal systems were assumed to operate at their maximum capacities, and minimum operation values for the spray water and service water temperatures
.i The containment pressure analysis by B&W in BAw-10103 were assumed.
was demonstrated to be conservative for Oconee Nuclear Station.
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We have concluded that the plant-dependent information used for the ECCS containment pressure analysis for Oconee Nuclear Station is reasonably conservative and, therefore, the calculated containment pressures are in accordance with Appendix K to 10 CFR Part 50 of the Comnission's regulations.
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