ML20127P455

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Proposed Tech Specs Revising TS Bases 3/4.3.1 & 3/4.3.2,to Incorporate Issuance of Amend 108,that Would Revise ESFs Response Times to Account for Sequential Stroking of Outlet Isolation Valves for RWST & VCT
ML20127P455
Person / Time
Site: Summer South Carolina Electric & Gas Company icon.png
Issue date: 01/29/1993
From:
SOUTH CAROLINA ELECTRIC & GAS CO.
To:
Shared Package
ML20127P436 List:
References
NUDOCS 9302010291
Download: ML20127P455 (3)
v • d • e


Text

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o INSTRUMENTATION BASES REACTOR TRIP AND ENGINEERED SMETY FEATURE ACTUATION SYSTEM INSTRUMENTATION (continued) specified in Table 3.3 4, in percent span, is the statistical summation of errors assumed in the analysis excluding those associated with the sensor and rack drift and the accuracy of their measurement. TA or Total Allowance is the difference, in percent span between the trip setpoint and the value used in the analysis for the actuation. R or Rack Error is the "as measured" deviation, in percent span, for the affected channel from the speelfied trip setpoint. S or Sensor Error is either the "as measured" deviation of the sensor from its calibration point or the value specified in Table 3.3 4, in percent span, from the analysis assumptions. Use of Equation 3.31 allows for a sensor drift factor, an increased rack drift factor, and provides a threshold value for REPORTABLE EVENTS.

The methodology to derive the trip setpoints is based upon combining all of the uncertainties in the channels. Inherent to the determination of the trip setpoints are the magnitudes of these channel uncertainties. Sensor and rack instrumentation utilized in these channels are expected to be capable of operating within the allowances of these uncertainty magnitudes. Rack drift in excess of the Allowable Value exhibits the behavior that the rack has not met its allowance.' Being that there is a small statistical chance that this will happen, an infrequent excessive drift is expected. Rack or sensor -

drin, in excess of the allowance that is more than occasional, may be indicative of more serious problems and should warrant further investigation.

The measurement of response time at the specified frequencies provides assurance that the reactor - .

trip and the engineered safety feature actuation associated with each channel is completM within the ,

time hmit assumed in the accident analyses. No credit was taken in the analyses for those channels with response times indicated as not appNable. Response time may be demonstrated by .any series of 1 sequential, overlapping or total channel test measurements provided that such tests demonstrate the total channel response time as defined. Sensor response time verification may be demonstrated by either 1) in place, onsite, or offsite test measurements or 2) utilizing replacement sensors with ceitided response times.

The Engineered Safety Features response times specified in Table 3.3-5 which include sequential operation of the RWST and VCT valves (Notes 2 and 3) are based on values assu. ied in the non-LOCA safety ana'yses. These analyses are for injection of borated water from the RWST. Injection of borated water is assumed not to occur until the VCT charging pump suction isolation valves are L closed following opening of the RWST charging pumps suction valves, When the sequential l operation of the RWST and VCT valves is not included in the response times (note 1) the values speelGed are based on the LOCA analyses. The LOCA analyses take credit for injection flow -

iegardless of the source. Veri 6 cation of the response times specified in table 3.3 5 will assure that the assumptions used for the LOCA and non-LOCA analyses with respect to the operation of the VCT j' and RWST valves are valid. l The Engineered Safety Features Actuation System senses selected plant parameters and determines whether or not predetermined limits are being exceeded, if they are, the signals are combined into logic matrices sensitive to combinations indicative of various accidents, events, and transients Once .

SUMMER - UNIT I B 3/4 3 la Amendment No.108' 9302010291 930129 '

PDR ADOCK 05000395 l P pon ,

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__ _ _ . , _ __ _ ._ _ . _ . 2.

a INSTRUMENTATION LMSES REACTOR PROTECTION SYSTEM AND ENGINEERED SAFETY FEATURE ACTUATION SYSTEM INSTRUMENTATION (continued) the required logic combination is completed, the system sends actuation signals to those engineered safety features components whose aggregate function best serves the requirements of the condition.

As an example, the following actions may be initiated by the Engheered Safety Features Actuation -

System to mitigate the consequences of a steam line break or loss of coolant accident 1) safety in.lection pumps start and automatic valves position,2) reactor trip,3) feedwater isolation,4) startup of the emergency diesel generators,5) containment spray pumps start and automatic valves position,

6) containment isolation,7) steam line isolation, 8) turbine trip, 9) auxiliary feedwater pumps start and automatie valves position,10) containment cooling fans start and automatic valves position,11) essential service water pumps start and automatic valves position, and 12) control room isolation and ventilation systema start.

Several automatic logic funettons included in this rpecification are not necessary for Engineered Safety Feature System actuation but their functional capability at the specified setpoints enhances the overall reliability of the Engineered Safety Features functions. %ese automatic actuation systems are purge and exhaust isolation from high containment radioactivity, turbine trip and feedwater isolation from steam generator high-high water level, initiation of emergency feedwater on a trip of the main feedwater pumps, automatic transfer of the auctions of the emergency feedwater pumps to service water on low suction pressure, and automatic opening of the containment recirculation sump suction valves for the RilR and spray pumps on low-low refueling water storage tank level.

The service water response time includes: 1) the start of the service water pumps and,2) the service water pumps discharge valves (3116A,B,C-SW) stroking to the fully opened position. This condition of the valves assures that flow will become established through the component cooling water heat exchanger, diesel generator coolers, ilVAC chiller, and to the suction of the service water booster pumps when these coniponents are placed in-service. Prior to this time, the flow is rapidly approaching required flow and sufficient pressure is developed as valves finish their stroke.E Each of-the above-listed components will be starting to perform their accident mitigation function, either directly or indirectly depending upon the use of the component, and will be operational within the service water response time of 71.5/81.5 seconds F. Only the service water booster pumps have a direct impact on the accident analysis via the RBCUs' heat removal capability as discussed below.

iffotal time is 1.5 second instrument response after setpoint is reached, plus 10 seconds diesel generator start, plus 10 seconds to reach service water pump start and begin 3116-SW opening via -

Engineered Safety features Loading Sequencer, t . 60 seconds stroke time for 3116-SW. During this total time, the service water pumps start and the service water pump discharge valve begins to open at 11.5 seconds and the pump discharge valve is fully open at 71.5 seconds without a diesel generator start required and 21.5 seconds and 81.5 seconds including a diesel generator start.

- SUMMER - UNIT I B 3/4 3-lb - Amendment No.108

4 INSTRUh1ENTATION BASES REACTOR PROTECTION SYSTEf.1 AND !!NGINEERIID SAFETY FEATURE ACTUATJON SYSTEh1 INSTRU h1ENTHIDE (continued)

The RBCU response time includes: 1) the start of the RBCU fan and the service water booster pumps and,2) at! the service water valves which must be driven to the fully opened or fully closed position. This condition of the valves allows the flow to become fully established through the RDCU.:

Prior to this time, the flow is rapidly approaching required flow as the valves finish their stroke.

Although the RBCU would be removing heat throughout the Engineered Safety Features response time, the accident analysis does not assume heat removal capability from 0 to 71.5 seconds 'sbecause the industrial cooling water system is not completely isolated until 71.5 seconds. A linear ramp increase from 95% full heat removal capability to 100% full heat removal capability is assumed by the accident analysis to start at 71.5 seconds and end at 86.5 seconds F. Full heat _ removal capability is assumed at 86.5 seconds based on the position of the valve 3107 SW.

2/I'otal time is 1.5 second instrument response aller setpoint is reached, plus 10 second diesel start plus 60 seconds

  • for valves to isolate industrial cooling water system.

3rrotal time is 1.5 second instrument response after setpoint is reached, plus 10 second diesel-generator start plus 75 seconds to stroke valves 3107A,B-SW.

  • During this time period, the Engineered Safety Features Loading Sequenect starts _ the RBCU fans at 25 seconds and service water booster pumps at 30 seconds aller the valves begin to stroke.

L SUhth1ER - UNIT l- B 3/4 Flc - Amer.dment No.108 L

i _ Li

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