ML18153A714

Proposed Tech Specs Establishing New Setpoint Limit for SG high-high Level & Provides More Restrictive Setting Limits for Certain Rps/Esfas Setpoints

ML18153A714
Person / Time
Site:	Surry
Issue date:	07/20/1995
From:	VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:
Shared Package
ML18153A713	List: ML18153A712 ML18153A714
References
NUDOCS 9507270070
Download: ML18153A714 (9)

Text

• TS 2.3-3 where 8 T O = Indicated 8 T at rated thermal power, °F T = Average coolant temperature, °F T' = Average coolant temperature measured at nominal conditions and rated power, °F K4 = A constant= 1.089 K5 = O for decreasing average temperature A constant, for increasing average temperature 0.02/°F K6 = 0 for T:s:;T'

= 0.001086 for T > T' f(81) as defined in (d) above,

't" = 10 seconds 3

(f) Low reactor coolant loop flow = ~ 90% of normal indicated loop flow as measured at elbow taps in each loop (g) Low reactor coolant pump motor frequency - ~ 57.5 Hz (h) Reactor coolant pump under voltage - ~ 70% of normal voltage

3. Other reactor trip settings (a) High pressurizer water level - ::;; 92% of span (b) Low-low steam generator water level - ~ 14.5% of narrow range instrument span (c) Low steam generator water level - ~ 15% of narrow range instrument span in coincidence with steam/feedwater mismatch flow - ::;; 1.0 x 106 lbs/hr (d) Turbine trip (e) Safety injection - Trip settings for Safety Injection are detailed in TS Section 3.7.

Amendment Nos.

9507270070 950720 PDR ADOCK 05000280 I '

P PDR

• TS 2.3-4 B. Protective instrumentation settings for reactor trip interlocks shall be as follows:

1. The reactor trip on low pressurizer pressure, high pressurizer level, turbine trip, and low reactor coolant flow for two or more loops shall be unblocked when power ~ 10% of rated power.

2. The single loop loss of flow reactor trip shall be unblocked when the power range nuclear flux~ 50% of rated power.

3. The power range high flux, low setpoint trip and the intermediate range high flux, high setpoint trip shall be unblocked when power

10% of rated power.

4. The source range high flux, high setpoint trip shall be unblocked when the intermediate range nuclear flux is ::;; 5 x 10-11 amperes.

The power range reactor trip low setpoint provides protection in the power range for a power excursion beginning from low power. This trip value was used in the safety analysis. ( 1) The Source Range High Flux Trip provides reactor core protection during shutdown (COLD SHUTDOWN, INTERMEDIATE SHUTDOWN, and HOT SHUTDOWN) when the reactor trip breakers are closed and reactor power is below the permissive P-6. The Source and Intermediate Range trips in addition to the Power Range trips provide core protection during Amendment Nos.

e

• TS 2.3-8 will prevent the minimum value of the DNBR from going below the applicable design as a result of the decrease in Reactor Coolant System flow associated with the loss of a single reactor coolant pump.

Although not necessary for core protection, other reactor trips provide additional protection. The steam/feedwater flow mismatch which is coincident with a low steam generator water level is designed for and provides protection from a sudden loss of the reactor's heat sink. Upon the actuation of the safety injection circuitry, the reactor is tripped to decrease the severity of the accident condition.

Upon turbine trip, at greater than 10% power, the reactor is tripped to reduce the severity of the ensuing transient.

References (1) FSAR Section 14.2.1 (2) FSAR Section 14.2 (3) FSAR Section 14.5 (4) FSAR Section 7 .2 (5) FSAR Section 3.2.2 (6) FSAR Section 14.2.9 (7) FSAR Section 7 .2 Amendment Nos.

-

• TS 3.7-6 reduces the consequences of a steam line break inside the containment by stopping the entry of feedwater.

Auxiliary Feedwater System Actuation The automatic initiation of auxiliary feedwater flow to the steam generators by instruments identified in Table 3.7-2 ensures that the Reactor Coolant System decay heat can be removed following loss of main feedwater flow. This is consistent with the requirements of the "TMl-2 Lessons Learned Task Force Status Report," NUREG-0578, item 2.1.7.b.

Setting Limits

1. The high containment pressure limit is set at about 10% of design containment pressure. Initiation of safety injection protects against loss of coolant(2) or steam line break(3) accidents as discussed in the safety analysis.

2. The high-high containment pressure limit is set at about 23% of design containment pressure. Initiation of containment spray and steam line isolation protects against large loss-of-coolant(2) or steam line break accidents(3) as discussed in the safety analysis.

3. The pressurizer low pressure setpoint for safety injection actuation is set substantially below system operating pressure limits. However, it is sufficiently high to protect against a loss-of-coolant accident as shown in the safety analysis. (2) The setting limit (in units of psig) is based on nominal atmospheric pressure.

4. The steam line high differential pressure limit is set well below the differential pressure expected in the event of a large steam line break accident as shown in the safety analysis. (3)

5. The high steam line flow differential pressure setpoint is constant at 40%

full flow between no load and 20% load and increasing linearly to 110%

of full flow at full load in order to protect against large steam line break accidents. The coincident low T avg setting limit for SIS and steam line isolation initiation is set below its HOT SHUTDOWN value. The coincident Amendment Nos.

TABLE 3.7-4 ENGINEERED SAFETY FEATURE SYSTEM INITIATION LIMITS INSTRUMENT SETTING No. Functional Unit Channel Action Setting Limit 1 High Containment Pressure (High Containment a) Safety Injection ~ 19 psia Pressure Signal) b) Containment Vacuum Pump Trip c) High Press. Containment Isolation d) Safety Injection Containment Isolation e) F.W. Line Isolation 2 High-High Containment Pressure (High-High a) Containment Spray ~25 psia Containment Pressure Signals) b) Recirculation Spray c) Steam Line Isolation d) High-High Press. Containment Isolation 3 Pressurizer Low-Low Pressure a) Safety Injection ~ 1,760 psig b) Safety Injection Containment Isolation c) F.W. Line Isolation 4 High Differential Pressure Between a) Safety Injection ~ 150 psig Steam Line and the Steam Line Header b) Safety Injection Containment Isolation c) F.W. Line Isolation

i::,, ~ 40% (at zero load) of full 3 5 High Steam Flow in 2/3 Steam Lines a) Safety Injection steam flow CD c.. ~ 40% (at 20% load) of full 3

CD steam flow C"+ ~ 110% (at full load) of full 2 steam flow 0

Cll b) Steam Line Isolation c) Safety Injection Containment Isolation d) F.W. Line Isolation Coincident with Low Tavg or ~541°FTavg Low Steam Line Pressure ~ 500 psig steam line pressure -I V,

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N c.,,

TABLE 3.7-4 ENGINEERED SAFETY FEATURE SYSTEM INITIATION LIMITS INSTRUMENT SETTING No. Functional Unit Channel Action Setting Limit 6 AUXILIARY FEEDWATER

a. Steam Generator Water Level Low-Low Aux. Feedwater Initiation 2:'. 14.5% narrow range SIG Slowdown Isolation

b. RCP Undervoltage Aux. Feedwater Initiation 2:'. 70% nominal C.

d.

e.

Safety Injection Station Blackout Main Feedwater Pump Trip Aux. Feedwater Initiation Aux. Feedwater Initiation Aux. Feedwater Initiation All S.I. setpoints

~

N.A.

46.7% nominal **

7 LOSS OF POWER

a. 4.16 KV Emergency Bus Undervoltage Emergency Bus Separation and 75 {+/- 1.0)% volts with a (Loss of Voltage) Diesel start 2 (+5, -0.1) second time delay

b. 4.16 KV Emergency Bus Undervoltage Emergency Bus Separation and 90 (+/- 1)% volts with a (Degraded Voltage) Diesel start 60 (+/- 3.0) second time delay (Non CLS, Non SI)

> 7 (+/- .35) second time delay a (CLS or SI Conditions)

Cl)

Q.

a Cl) 8 NON-ESSENTIAL SERVICE WATER ISOLATION c-+-

a. Low Intake Canal Level Isolation of Service Water flow to 23 feet-6 inches

z non-essential loads 0

1/)

9 RECIRCULATION MODE TRANSFER

a. RWST Level-Low Initiation of Recirculation Mode 2:'. 18.93%

Transfer System ~19.43%

-I V'I 10 TURBINE TRIP AND FEEDWATER ISOLATION

a. Steam Generator Water Level High-High Turbine Trip ~ 80% narrow range

<.,.)

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Feedwater Isolation N C'\

ATTACHMENT 3 SIGNIFICANT HAZARDS CONSIDERATION DETERMINATION

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CFR 50.92 EVALUATION - BASIS FOR NO SIGNIFICANT HAZARDS DETERMINATION Virginia Electric and Power Company is proposing revisions to Sections 2.3, "Limiting Safety System Settings, Protective Instrumentation," and 3.7, "Instrumentation Systems." We have reviewed the proposed change against the criteria of 10 CFR 50.92 and have concluded that the change does not pose a significant safety hazards consideration as defined therein. Consistent with the examples of amendments not likely to involve a significant hazards consideration noted in the Federal Register (Vol. 50, No. 44) dated March 6, 1986, the proposed changes to 1) revise the units of the high-high containment pressure setpoint limit and 2) delete certain references to two-loop operation, since the plant is not licensed to operate in that manner, are purely administrative in nature and therefore are not a significant hazards consideration.

Likewise, the remaining proposed changes constitute additional restrictions not presently included in Technical Specifications and therefore are not a significant hazards consideration. Specifically, operation of Surry Power Station with the proposed change will not:

1. Involve a significant increase in either the probability of occurrence or consequences of any accident or equipment malfunction scenario which is important to safety and which has been previously evaluated in the Updated Safety Analysis Report (UFSAR). The effect of the proposed change is to ensure that actual plant setpoints remain conservative consistent with respect to accident analysis assumptions. The proposed change requires safety system actuation limits that are more conservative than those currently in Technical Specifications. The change does not invalidate currently implemented station setpoints or currently applicable accident analysis assumptions regarding these setpoints. Consequently, the results and conclusions of the current UFSAR accident analyses are not affected by these changes. The proposed Technical Specifications change revises setpoints used to mitigate accidents and therefore has no bearing on the probability of an accident. Further, the change ensures that the setpoints used to mitigate an accident bound the setpoints used in the accident analyses. Therefore, the probability of an accident or consequences of an accident is not adversely affected as a result of this change.

2. Create the possibility of a new or different type of accident than those previously evaluated in the UFSAR. Implementing the proposed Technical Specifications setpoint limits cannot create the possibility of an accident of a different type than was previously evaluated in the UFSAR. Since actual plant setpoints are not being affected, new accident precursors will not be introduced. Furthermore, spurious challenges to safety systems are also not expected to increase in frequency as a result of these changes since actual setpoints installed in the plant are not being changed. Consequently, no new accident precursors are created as a result of the new Technical Specifications setpoint limits.

3.,

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Involve a significant reduction in a margin of safety. Since the results of the existing UFSAR accident analyses remain bounding, safety margins are not impacted. The proposed Technical Specifications setpoint limits ensure plant setpoints remain conservative and consistent with design base accident analysis assumptions including appropriate instrument channel uncertainties due to harsh environmental conditions. Therefore, the margin of safety as defined in the Technical Specifications bases is unaffected.