ML20091N376

Revised Proposed Tech Specs,Changing P-7 Setpoint from Pressure Equivalent to 10% Rated Thermal Power to 10% Full Load Turbine Impulse Chamber Pressure

ML20091N376
Person / Time
Site:	North Anna
Issue date:	06/04/1984
From:	VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:
Shared Package
ML20091N362	List: ML20091N359 ML20091N376
References
NUDOCS 8406120294
Download: ML20091N376 (5)

Text

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TABLE 3.3-1 (Continued)

REACTOR TRIP SYSTEM INTERLOCKS O ALLOWABLE g FUNCTION DESIGNATION CONDITION SETPOINT VALUES

-10 -10 Allows manual block of source P-6 1 of 2 Intermediate range 1 x 10 <3 x 10 range reactor trip g above setpoint (increasing p power level)

~ ~I -11 2 of 2 Intermediate range 5 x 10 >3 x 10 Defeats the block of source below setpoint (decreasing range reactor trip power level)

P-10 2 of 4 Power range above set- 10% <11% Allows manual block of power point'(increasing power range (low setpoint) and inter-level) mediate range reactor trips and intermediate range rod stop.

Blocks source range reactor w trip.

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u 3 of 4 Power range below 8% >7% Defeats the block of power range E setpoint (decreasing power (low setpoint) and intermediate level) range reactor trips and inter-mediate range rod stop.

Input to P-7 P-7 2 of 4 Power range above 10% <11% Allows reactor trip on: Low flow setpoint or reactor coolant pump breakers or open in more than one loop, Under-1 of 2 Turbine Impulse Pressure equi- <11% voltage (RCP busses), Under-chamber pressure above valent to 10% frequency (RCP busses), Turbine setpoint Rated Turbine Trip, Pressurizer low pressure, (Power level increasing) Power and Pressurizer high level.

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TABLE 3.3-1 (Continued)

REACTOR TRIP SYSTEM INTERLOCKS so g ALLOWABLE DESIGNATION CONDITION SETPOINT VALUES FUNCTION

-10 -10 P-6 1 of 2 Intermediate range 1 x 10 <3 x 10 Allows manual block of source g above setpoint (increasing range reactor trip p power level)

-1 -11 2 of 2 Intermediate range 5 x 10 >3 x 10 Defeats the block of source below setpoint (decreasing range reactor trip power level)

, P-10 2 of 4 Power range above set- 10% <11% Allows manual block of power point (increasing power range (low setpoint) and inter-

. level) nediate range reactor trips and intermediate range rod stop.

Blocks source range reactor trip.

g y 3 of 4 Power range below 8% >7% Defeats the block of power range m setpoint (decreasing power (low setpoint) and intermediate level) range reactor trips and inter-mediate range rod stop.

Input to P-7 P-7 2 of 4 Power range above 10% <11% Allows reactor trip on: Low IJsw setpoint or reactor coolant pump bresers or open in more than one loop, Under-1 of 2 Turbine Impulse Pressure equi- <11% voltage (RCP busses), Under-chamber pressure above valent to 10% frequency (RCP busses), Turbine setpoint Rated Turbine Trip, Pressurizer low pressure, (Power level increasing) Pcwer and Pressurizer high level.

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UPDATED DISCUSSION OF PROPOSED TECHNICAL SPECIFICATION CHANGES The purpose of the P-7 interlock is to allow an orderly reactor startup when plant primary conditions are off normal and the unit is coming out of a shutdown condition. For example, not all reactor coolant pumps may be running, pressurizer level and pressure will be outside normal operating ranges, and the turbine may not be latched and loaded. To prevent uncalled for reactor trips during these startup conditions, certain reactor trips (RCS low flow or RCP breakers open, pressurizer low pressure, pressurizer high level, RCP Bus undervoltage or underfrequency and turbine unlatched) are permitted to be blocked by P-7 provided power level is limited to 10%.

The determination of actual plant power level for the P-7 interlock is based on the P-10 interlock which serves as a direct measure of 10% rated thermal power (i.e. reactor power) and the P-13 interlock which, by design, is to be a measure of 10% rated turbine power. P-10 is sensed via the excore nuclear instrumentation system power range detectors, and P-13 is sensed via first stage impulse pressure in the high pressure turbine.

The existing Technical Specification for the P-13 input to the P-7 setpoint incorrectly relates to 10% rated reactor power.

The Turbine impulse pressure is not a constant value at 10% Rated Thermal Power since the turbine is not the only steam load. Use of auxiliary steam and/or steam dumps cause the turbine impulse pressure to vary for a given Rated Thermal Power. Therefore, Rated Thermal Power cannot be used as a measure of turbine power which is what P-13 is to reflect. The proposed change will allow the system to be operated as designed. This change is consistent with the Setpoint Study /PLS for North Anna.

Therefore, the probability of occurrence or the consequences of a malfunction of equipment important to safety and previously evaluated in the FSAR is not increased, the possibility of a different type of accident or malfunction than was previously evaluated in the FSAR has not been created and the margin of safety as described in the BASES section of any part of the Technical Specification is not reduced. This change is administrative in nature and fits example 1 of an amendment that is not likely to involve a significant hazards consideration as referenced in the April 6, 1983 Federal Register.