ML15113A095
| ML15113A095 | |
| Person / Time | |
|---|---|
| Site: | Oconee  |
| Issue date: | 04/30/1984 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML15113A094 | List: |
| References | |
| NUDOCS 8405160185 | |
| Download: ML15113A095 (3) | |
Text
oRE &I UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D. C. 20555 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION SUPPORTING AMENDMENT NO. 128 TO FACILITY OPERATING LICENSE NO. DPR-38 AMENDMENT NO.
128TO FACILITY OPERATING LICENSE NO.
DPR-47 AMENDMENT NO. 125TO FACILITY OPERATING LICENSE NO.
DPR-55 DUKE POWER COMPANY OCONEE NUCLEAR STATION. UNITS NOS. 1, 2, AND 3 DOCKETS NOS. 50-269, 50-270 AND 50-287 1.0 Introduction By letter dated February 13, 1984, Duke Power Company (the licensee) proposed changes to the Technical Specifications (TSs) of Facility Operating Licenses Nos.
DPR-38, DPR-47, and DPR-55 for the Oconee Nuclear Station, Units Nos. 1, 2 and 3. These amendments would consist of changes to the Station's common TSs.
The present TSs require the emergency condenser circulating water (ECCW) system to be operable all the time. For maintenance to be performed, the system would have to be declared inoperable, and all three Oconee units would have to shutdown. The licensee has proposed changes to the TSs to allow for continued operation of the Oconee units for a limited period of time (seven days) if the ECCW system becomes or is declared inoperable.
The ECCW system is a unique design feature at Oconee that allows for continued condenser circulating water flow by gravity following a loss of all station power except station batteries. This feature allows closed loop recir culation of condensate which might normally be vented to the atmosphere through the main steam relief valves as at other nuclear plants.
2.0 Discussion The main feedwater system and the turbine bypass system are normally used for decay heat removal and cooldown above 250*F. In the event the main feedwater system is inoperable, the emergency feedwater system assures the capability to remove decay heat and cooldown the reactor coolant system to the operating conditions for switch over to decay heat removal by the Decay Heat Removal system.
Normally, decay heat is removed by steam relief through the turbine bypass system to the condenser. Condenser cooling water flow is provided by a siphon effect from Lake Keowee through the condenser for final heat rejection to the Keowee Hydro Plant tailrace. The condenser cooling water (CCW) system provides for cooling of the condensers during normal and emergency operation of the plant. The CC! system also has an emercency discharge line to the Keowee Hydro tailrace.
This discharge line is connected to all three condensers of each Oconee unit and is called the Emergency Condenser Cooling Water (ECCW) system. This feature allows lake water to flow through the condenser tubes due to gravitational 8405160185 840430 PDR ADOCK 05000269 P
-2 forces only, in the absence of forced flow. Thus, the ECCW system allows continued use of the condenser for heat removal following the unlikely event.of'a complete loss of offsite and onsite power..
The ECCW system is normally closed by a power-to-close valve. To perform maintenance on the valve, the system would have to be declared inoperable and all three Oconee units would have to shutdown per TSs, since the valve is on discharge pipe common to all three unit condensers.
As stated earlier, the ECCW will maintain a source of coolant flow to the condenser in the unlikely event in which all station power except station batteries is lost. Even if the CCW or the ECCW systems cannot provide coolant flow to the condensers, then steam produced in the steam generators will be relieved to the atmosphere through the main steam relief valves.
3.0 Evaluation The ECCW provides for continued circulating water flow following a loss of all AC power at the plant and is utilized in conjunction with the turbine driven AFW pumps to remove decay heat from the plant without venting to the atmosphere. The ECCW consists of a single train which takes flow from the lake and by gravity provides cooling for the condenser. Maintenance therefore is a problem. With the ECCW inoperative, the three Oconee units could utilize the turbine driven AFW pumps to remove decay heat from the plant by venting steam from the steam generators through the main steam relief valves. The condensate storage tank, upper surge tank and the condenser hotwell contain an eleven hour supply of feedwater for the steam generators, which is well beyond the two hour duration of the loss of AC power required by Standard Review Plan (SRP) 10.4.9.
The requested inoperative period for the ECCW, seven days, appears to be a reasonable period to allow maintenance of the system. We, therefore, find the proposed TS changes acceptable.
4.0 Environmental Consideration We have determined that the amendments do not authorize a change in effluent types or total amounts nor an increase in power level and will not result in any significant environmental impact. Having made this determination, we have further concluded that the amendments involve an action which is insignificant from the standpoint of environmental impact, and pursuant to 10 CFR §51.5(d)(4), that an environmental impact statement, or negative declaration and environmental impact appraisal need not be prepared in connection with the issuance of these amendments.
-3 5.0 Conclusion We have concluded, based on the considerations discussed above, that: (1) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner, and (2) such activities will be conducted in compliance with the Commission's regulations and the issuance of these amendments will not be inimical to the common defense and security or to the health and safety of the public.
Dated:
April 30, 1984 Principal Contributor:
P. Hearn