ML13331A888

Proposed Change 165 to Tech Specs,Requiring That Lower Pressurizer Level Trip Setpoint Be Maintained Until Mods to Mismatch Trip Completed

ML13331A888
Person / Time
Site:	San Onofre
Issue date:	08/21/1986
From:	SOUTHERN CALIFORNIA EDISON CO.
To:
Shared Package
ML13331A887	List: ML13331A886 ML13331A888
References
TAC-44652, TAC-62164, NUDOCS 8608250045
Download: ML13331A888 (17)

Text

ENCLOSURE 2 Proposed Change No. 165 Technical Specifications San Onofre Nuclear Generating Station Unit 1 PRELIMINARY

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2.1 REACTOR CORE -

Lin

)ng Combination of Power, Pres#

, and Temperature APPLICABILITY: Applies to reactor power, system pressure, coolant temperature, and flow during operation of the plant.

OBJECTIVE:

To maintain the integrity of the reactor coolant system and to prevent the release of excessive amounts of fission product activity to the coolant.

SPECIFICATION: Safety Limits (1) The reactor coolant system pressure shall not exceed 2735 psig with fuel assemblies in the reactor.

(2) The combination of reactor power and coolant temperature shall not exceed the locus of points established for the RCS pressure in Figure 2.1.1.

If the actual power and temperature is above the locus of points for the appropriate RCS pressure, the safety limit is exceeded.

MAXIMUM SAFETY SYSTEM SETTINGS The maximum safety system trip settings shall be as stated in Table 2.1 TABLE 2.1 Three Reactor Coolant Pumps Operating

• 1. Pressurizer

< 20.8 ft. above bottom of High Level pressurizer when steam/feedflow mismatch trip is not credited, or

< 27.3 ft. above bottom of pressurizer when steam/feedflow mismatch trip is credited

2. Pressurizer

< 2220 psig Pressure:

High

• • 3.

Nuclear Overpower

< 109% of indicated full power

• • • 4. Variable Low Pressure

> 26.15 (0.894 AT+T avg.) -

14341

• • • 5.

Coolant Flow

> 85% of indicated full loop flow Credit can be taken for the steam/feedflow mismatch trip when this system is modified such that a single failure will not prevent the system from performing its safety function.

The nuclear overpower trip is based upon a symmetrical power distribution. If an asymmetric power distribution greater than 10%

should occur, the nuclear overpower trip on all channels shall be reduced one percent for each percent above 10%.

May be bypassed at power levels below 10% of full power.

Maximum Safety System Settings

1.

Pressurizer High Level and High Pressure In the event of loss of load, the temperature and pressure of the Reactor Coolant System would increase since there would be a large and rapid reduction in the heat extracted from the Reactor Coolant System through the steam generators. The maximum settings of the pressurizer high level trip and the pressurizer high pressure trip are established to maintain the DNB ratio above 1.30 and to prevent the loss of the cushioning effect of the steam volume in the pressurizer (resulting in a solid hydraulic system) during a loss-of-load transient. (3) (4)

In the event that steam/feedflow mismatch trip cannot be credited due to single failure considerations, the pressurizer high level trip is provided. In order to meet acceptance criteria for the Loss of Main Feedwater and Feedline Break transients, the pressurizer high level trip must be set at 20.8 ft. (50%) or less.

2.

Variable Low Pressure, Loss of Flow, and Nuclear Overpower Trips These settings are established to accommodate the most severe transients upon which the design is based, e.g., loss of coolant flow, rod withdrawal at power, inadvertent boron dilution and large load increase without exceeding the safety limits. The settings have been derived in consideration of instrument errors and response times of all necessary equipment. Thus, these settings should prevent the release of any significant quantities of fission products to the coolant as a result of transients. (3) (4) (5)

In order to prevent significant fuel damage in the event of increased peaking factors due to an asymmetric power distribution in the core, the nuclear overpower trip setting on all channels is reduced by one percent for each percent that the asymmetry in power distribution exceeds 10%. This provision should maintain the DNB ratio above a value of 1.30 throughout design transients mentioned above.

The response of the plant to a reduction in coolant flow while the reactor is at substantial power is a corresponding increase in reactor coolant temperature. If the increase in temperature is large enough, DNB could occur, following loss of flow.

The low flow signal is set high enough to actuate a trip in time to prevent excessively high temperatures and low enough to reflect that a loss of flow condition exists. Since coolant loop flow is either full on or full off, any loss of flow would mean a reduction of the initial flow (100%) to zero. (3) (6) 0007P

SCE STATION BLACKOUT ANALYSIS SCE STATION BLACKOUT

• NO STEAM/FEED MISMATCH RX TRIP PLOT17 RUN I

-J 1.4

.6 e

1.2 cr TCME (SEC) 03/15/86

SEE STATi;ON BLACKOUT ANALYSIS SCE STATION BLACKOUT *NO STEAM/FEED M!SMATCHi RX TRIP PLOT?

RUN 1

-1.4 c

.6 ae cjm 4..

C) 010 TIE (SC 08.28

SCE STATION BLACKOUT ANALYSIS SCE STATION BLACKOUT

• NO STEAMiFEED MISMATCH RX TRIP PLOTTZ RUN 1 1600.

c 1400.

1200.

1000.

a 800.

(r 3

600.

Li 400.

0.0 oo18 T

02 103 8

TIME (SEC0 08/15/86

SCE STATION BLACKOUT ANALYSIS SCE STATION BLACKOUT - NO STEAMIFEED MISMATCH RX TRIP PLOTZ?

RUN 1

2800.

L2600.

2400.

2000.

1800.

1600.

1400.

w 1200.

1000.

800.

loo10,102 105 104 TIME ISEC) 081 J"6

SCE STATION BLACKOUT ANALYSIS SCE STATION BLACKOUT *NO STEA?1/FEED MiISMATCH RX TRIP PLOT 3 RUN 1

L700.

C3a675.0 650.

S625.

5600.

C3D cr Li 5S

.a 4 7 S, rME (SEC )

08/15/86 L.

SCE STATION BLACKOUT ANALYSIS SCE STATION BLACKOUT I NO STEAM/FEED MISMATCH RX TRIP PLOT19 RUN 1

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0.

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SEE STATION BLACKOUT ANALYSIS SCE STATION BLACKOUT

• NO STEAMIFEED MISMATCH RX TRIP LOOP 1(0),LOOP Z(*),LOOP (S)

PLOT13 1600.

1400.

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or 4 00.

z200.

00 0

102 2 104 TIME

(,SEC)

-08

SCE FED jIap RUPTURi A'JALYS!S SCE FEEDBREAKI'S9 - NO STEAMI'FEED MISMATCHI RX TI PLOTI7

!:jNI z1.4 z

cr cm.6 0L.4 c

ui

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0.

TIMlE (SECI

SCE FEEDLINE RUPTURE ANALYSIS SEE FEEDBREAK/SB

• NO STEAM/FEED MISMATCH RX TRIP PLOT 2 RUN 1

1.4 C0 z 1.2 0

• 0

1.

Cc U

cc at

.J

1

.4

0.

(n gn L -.21g0 t,

102 15 0

4 TIME ISECI

SEE FEEDLINE RUPTURE ANALYSIS SCE FEEDBREAK/SB

• NO STEAM/FEED MISMATCH RX TRIP PLOT12 RUN 1

1600.

La.

1400.

1200.

' 1000.

C)

a800.

S600.

at 400.

at w 200.

of

0.

10 10, 102 10 504 TIME ISECI

.SCS FEEDLINE RUPTURE ANALYSIS SCE FEEDBREAK/SB

• NO STEAM/FEED MISMATCH RX TRIP PLOTZZ RUN 1

2800.

' 2600.

2400.

2200.

ti a 2000.

V)

U) 1800.

t 1600.

at 1400.

D 1200.

1000.

800.

1o0 101 g2 105 104 TIME ISECl

SCE FEEDLINE RUPTURE ANALYS!S SCE FEED9REAKI'S9 - NO STEAMI'FEED MISMATCH PX TR!P PLOT 3 RUN I

700.

La 67S.

-: 650.

.625.

c600.

-J 02 550.

cc

a. 4 7 S.

C0 0

loo 10,

~

1021014 TIME ISECI

SEE FEEDLINE RUPTURE A!1ALYS!S SEE FEEDBREAKIS9 a NO STEAMFEED MISMATC14 P.X TR;!P PLOT19 PUN I

.S0E-S

.4 0( S E.3SE-S cc cx z~.20E.S cc (n.10E.S

.50E-4 fTIME (SEC)

SEE FEEDLINc RUPTURE ANALYSIS SEE FEEDBPEAK,'Sg *NO S~TAM/FEED MISMATCH RX TRIP PLOT! 3 S1600.

1Y 400.

ol 1200.

cx 1000.

oi:

800.

0x ce-I z~

400.

Li 200.

0.

300 101 102 10 04 TIME (SEC)