ML19347D003

Revised Tech Specs Re Limiting Safety Sys Settings

ML19347D003
Person / Time
Site:	Farley
Issue date:	03/04/1981
From:	ALABAMA POWER CO.
To:
Shared Package
ML19347D001	List: ML19347D000 ML19347D002 ML19347D003
References
NUDOCS 8103100503
Download: ML19347D003 (2)

Text

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1 99 LIMITING SAFETY SYSTEM SETTINGS h$

BASES i

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Overpower aT

- The Overpower delta T reactor trip provides assurance of fuel integrity,

, e.g. , no melting, under all possible overpower conditions, limits the required range for Overtemperature delta.T protection, and provides a backup to the High Neutron Flux. trip. The setpoint includes corrections for axial power distribution, changes in density and heat capacity of water with temperature, and dynamic compensation for piping delays from the core to the loop tempera-ture detectors. No credit was taken for opertion of this trip in the accident .

analyses; however, its functional capability at the specified trip setting is

- required by this specification to enhance the overall reif ability of the Reactor Protection System. _

1 Pressurizer Pressure The Pressurizer.High and Low Pressure trips are provided to limit the pressure range in which reactor operation is permitted. The High Pressure trip is backed up by the pressurizer code safety valves for RCS overpressure protection, and is therefore set lower than the set pressure for these valves pr""~ (2485 psig). The Low Pressure trip provides protection by tripping the reactor in the event of a loss of reactor coolant pressure.

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Pressurizer Water Level The Pressurizer High Water Level trip ensures protection against Reactor  ;

Coolant System overpressurization by limiting the water level to a volume sufficient to retain a steam bubble and prevent water relief through the

-- pressurizer safety valves. -No credit was taken for operation of this trip in the accident analyses; however, its functional capability at the specified trip setting is required by this specification to enhance the overall reliability of the Reactor Protection System.

Loss of Flow The Loss of ~ Flow trips provide core protection to prevent DNB in the event of a loss of one or more reactor coolant pumps.

Above 10 percent'of RATED THERMAL POWER, an automatic reactor trip will

- occur if .the flow in any~ two loops drop below-90% of ncminal full loop flow.

- Above 36% (P-8) of RATED THERMAL POWER, automatic reactor trip will occur if the flow in_ any single loop drops below 90% of nominal full loop flow. This J

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FARLEY-UNIT 2. B 2-5~

- 810810 Ocpb

LIMITING SAFETY SYSTEM SETTINGS BASES

1. M latter trip will prevent the r inimum value of the DNBR from going below i==Cas during normal operational transients and anticipated transients when 2 loops are in operation and the Overtemperature delta T trip set print is adjusted to the value specified for all loops in operation. With the Overtemperature delta T trip set point adjusted to the value specified for 2 loop operation, the P-8 trip at 66% RATED THERMAL POWER will prevent the minimum value of the DNBR from going below =i=+~e during normal operational transients and anticipated transients with 2 loops inhoeration.

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Steam Generator Water Level The Steam Generator Water Level Low-Low trip provides core protection by preventing operation with the steam generator water level belcw the minimum volume required for adequate heat removal capacity. The specified setooint provides allowance that there will be sufficient water inventory in the steam generators at the time of trip to allow for starting delays of the auxiliary feedwater system.

Steam /Feedwater Flow Mismatch and Low Steam Generator Water Level ,

The Steam /Feedwater Flow Mismatch in coincidence with a Stean Generator W Low Nater Level trip is not used in the transient and accident analyses but is included in Table 2.2-1 to ensure the functional capability of tne specified trip settings and thereby enhance the overall reliability of the Reactor Protection System. This trip is redundant to the Steam Generator Water Level Low-Low trip. The Steam /Feedwater Flow Mismatch portion of tnis trip is activated when the steam flow exceeds the feedwater flow by greater than or equal to 1.55 x 108 lbs/ hour. The Steam Generator Low Water level portion of the trip is activated when the water level drops below 25 percent, as indicated by the narrow range instrument. These trip values include sufficient allowance in excess of normal operating values to preclude spurious trips but will initiate a reactor trip before the steam generators are dry. Therefore, the required capacity and starting time requirements of the auxiliary feedwater pumps are reduced and the resulting thermal transient on the Reactor Coolant System and steam generators is minimized.

Undervoltaae'and Underfrecuency - Reactor Coolant Pumo Busses The Undervoltage and Underfrequency Reactor Coolant Pump bus trips provide reactor core protection against DNB as a result of loss of voltage or under-frequency to more than one reactor coolant pump. The specified set points assure a reactor trip signal is generated before the low ficw trip set point

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FARLEY-UNIT 2 B 2-6