ML20205N449

Nonproprietary Westinghouse Setpoint Methodology for Protection Sys,Millstone Nuclear Power Station Unit 3. W/ Revised Cover Page.Two Oversize Figures Encl

ML20205N449
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Site:	Millstone
Issue date:	11/30/1985
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ML20205N429	List: B11830, Forwards Proprietary WCAP-10991 & Nonproprietary WCAP-10992, Westinghouse Setpoint Methodology for Protection Sys, Millstone Nuclear Power Station Unit 3. Proprietary Rept Withheld ML20205N425 ML20205N449
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WCAP-10992-ERR, NUDOCS 8605020140
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- -

(WESTINGHOUSE PROPRIETARY CLASS 3)

WCAP-10992 WESTINGHOUSE SETPOINT METHODOLOGY FOR PROTECTION SYSTEMS MILLSTONE NUCLEAR POWER STATION UNIT 3 November,1985 C. R. Tuley

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WESTINGHOUSE ELECTRIC CORPORATION Nuclear Energy Systems P. O. Box 355 Pittsburgh, PA 15230 8605020140 DR 860415 ADOCK 05000423 PDR 51890:10/091785 I

(WESTINGHOUSE PROPRIETARY CLASS 3)

WESTINGHOUSE SETPOINT METHODOLOGY FOR PROTECTION SYSTEMS MILLSTONE NUCLEAR POWER STATION UNIT 3 September,1985 C. R. Tuley This document contains information proprietary to Westinghouse Electric Corporation; it is submitted in confidence and is to be used solely for the purpose for which it is furnished and returned upon request. This document and such information is not to be reproduced, transmitted, disclosed or used otherwise in whole or in part without authorization of Westinghouse Electric Corporation, Nuclear Energy Systems.

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WESTINGHOUSE ELECTRIC CORPORATION Nuclear Energy Systems P. O. Box 355 Pittsburgh, PA 15230 Copyright By Westinghouse Electric, 198h All Rights Reserved 51890:10/091785

(WESTINGHOUSE PROPRIETARY CLA33 5)

TABLE OF CONTENTS Page Section Title 1-1

1.0 INTRODUCTION

2-1 2.0 COMBINATION OF ERROR COMPONENTS 2.1 Methodology 2-1 2.2 Sensor Allowances 2-3 Rack Allowances 2-4 2.3 2.4 Process Allowances 2-6 3-1 3.0 PROTECTION SYSTEMS SETPOINT METHODOLOGY Margin Calculation 3-1 3.1 Definitions for Protection System 3-1 3.2 Setpoint Tolerances Statistical Methodology Conclusion 3-6 3.3 3.4 Rosemount Transmitter Calculations 3-6 4-1 4.0 TECHNICAL SPECIFICATION USAGE 4 -1 Current Use

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4.1 Westinghouse Statistical Setpoint 4 -1 4.2 Methodology for STS Setpoints 4.2.1 Rack Allowance 4-2 4.2.2 Inclusion of "As Measured" 4-3 Sensor Allowance Implementation of the 4 -4 4.2.3 Westinghouse Setpoint Methodology 4-6 4.3 Conclusion A-1 Appendix A SAMPLE MILLSTONE SETPOINT TECHNICAL SPECIFICATIONS II 51890:10/091785 L.

r (WESTINGHOUSE PROPRIETARY CLASS 3)

LIST OF TABLES Title Page Table Power Range, Neutron Flux-High and Low Setpoints 3-7 3-1 Power Range, Neutron Flux-High Positive Rate and 3-8 3-2 High Negative Rate Internediate Range, Neutron Flux 3-9 3-3 Source Range, Neutron Flux 3-10 3-4 Overtemperature AT 3-11 3-5 Overpower AT 3-14 3-6 Pressurizer Pressure - Low and High Reactor Trips 3-16 3-7 Pressurizer Water Level - High 3-18 3-8 Loss of Flow 3-20 3-9 Steam Generator Water Level - Low-Low 3-21 3-10 3-11 Containment Pressure - High, High-High, and High-High-High 3-23 Pressurizer Pressure - Low, Safety Injection 3-24 3-12 Steamline Pressure - Low 3-26 3-13 Negative Steamline Pressure Rate - High 3-27 3-14 Steam Generator Water Level - High-High 3-28 3-15 Reactor Protection System / Engineered Safcty Features 3-30 3-16 Actuation System Channel Error Allowances Overtemperature AT Gain Calculations 3-31 3-17 Overpower AT Gain Calculations 3-34 3-18 Steam Generator Level Density Variations 3-36 3-19 AP Measurements Expressed in Flow Unit; 3-39 3-20 RCP Shaft Underspeed 3-40 3-21 Examples of Current STS Setpoints Philosophy 4-9 4-1 Examples of Westinghouse STS Rack Allowance 4-9 4-2 Westinghouse Protection System STS Setpoint Inputs 4-12 4-3 l

l 111 51890:10/091785

i (WESTINGHOUSE PROPRIETARY CLASS 3) l LIST OF ILLUSTRATIONS Title Pige Fiaure NUREG-0452 Rev. 4 Setpoint Error 4-10 4-1 Breakdown Westinghouse STS Setpoint Error 4-11 4-2 Breakdown IV 51890:1D/091785

(WESTINGHOUSE PROPRIETARY CLASS 3)

1.0 INTRODUCTION

In March of 1977, the NRC requested several utilities with Westinghouse Nuclear Steam Supply Systems to reply to a series of questions concerning the methodology for determining instrument setpoints. A statistical methodology was developed in response to those questions with a corresponding defense of the technique used in determining the overall allowance for each setpoint.

The basic underlying assumption used is that several of the error components and their parameter assumptions act independently, e.g., [

]****. This allows the use of a statistical summation of the various breakdown components instead of a strictly arithmetic summation. A direct benefit of the use of this technique is increased margin in the total allowance. For those parameter assumptions known to be interactive, the technique uses the normal, conservative approach, arithmetic summation, to form independent quantities, e.g., [

]***". An explanation of the overall approach is provided in Section 2.0.

Section 3.0 provides a description, or definition, of each of the various components in the setpoint parameter breakdown, thus insuring a clear understanding of the breakdown. Also provided is a detailed example of each setpoint margin calculation demonstrating the technique and noting how each parameter value is derived. For those protection functions using both Ver.itrak and Rosemount transmitters, data is provided for both cases. In nearly all cases, significant margin exists between the statistical summation and the total allowance.

Section 4.0 notes what the current (read NRC) Tcchnical Specifications use for setpoints and an explanation of the impact of the statistical approach on them. Detailed examples of how to determine the Technical Specification setpoint values are also provided. An Appendix is provided noting a recommended set of Technical Specifications using the plant specific data in the statistical approach. For those protection functions using both Veritrak and Rosemount transmitters, only the most limiting case is provided, i

1 5189Q:1D/091785 1-1

(WESTINGHOUSE PROPRIETARY CLASS 3) 2.0 COMBINATION OF ERROR COMPONENTS 2.1 METHODOLOGY The methodology used to combine the error components for a channel is basically the appropriate statistical combination of those groups of components which are statistically independent, i.e., not interactive. Those errors which are not independent are placed arithmetically into groups. The groups themselves are independent effects which can then be systematically combined.

The methodology used for this combination is not new. Basically it is the

[ ]+ which has been utilized in other Westinghouse reports. This technique, or other statistical approaches of a similar nature, have been used in WCAP-10395 and WCAP-8567( '. It should be noted that WCAP-8567 has been approved by the NRC Staff thus noting the acceptability of statistical techniques for the application requested. It should also be recognized that ANSI, the American Nuclear Society, and the Instrument Society of America approve of the use of probabilistic techniques in determining safety-related setpoints(3)(4) Thus it can be seen that the use of statistical approaches in analysis techniques is becoming more and more widespread.

The relationship between the error components and the total statistical error allowance for a channel is,

_+ a ,c {

(Eq .2.1 )

l

' 1 l

I (1) Grigsby, J. M., Spier. E. M., Tuley, C. R., ' Statistical Evaluation of  !

I LOCA Heat Source Uncertainty," WCAP-10395 (Proprietary) WCAP-10396 i (Non-Proprietary). November,1983.

" Improved Thermal Design (2) Chelemer H., Boman, L. H., and Sharp, D. R.,

Procedure," WCAP-8567 (Proprietary), WCAP-8568 (Non-Proprietary), July, 1975.

(3) ANSI /ANS Standard 58.4-1979, " Criteria for Technical Specifications for l Nuclear Power Stations."

l (4) ISA Standard 567.04,1982, "Setpoints for Nuclear Saf ety-Related Instrumentation used in Nuclear Power Plants.'

51890:1D/091785 2-1 1

l 1

(WESTINGHOUSE PROPRIETARY CLASS 3)

)

I where:

CSA = Channel Statistical Allowance l 1

PMA = Process Measurement Accuracy PEA = Primary Element Accuracy SCA = Sensor Calibration Accuracy 50 = Sensor Drift STE = Sensor Temperature Effects SPE = Sensor Pressure Effects RCA = Rack Calibration Accuracy RCSA = Rack Comparator Setting Accuracy RD = Rack Drift RTE = Rack Temperature Effects EA = Environmental Allowance As can be seen in Equation 2.1, ( ]****

allowances are interactive and thus not independent. The (

)*" is not necessarily considered interactive with all other parameters, but as an additional degree of conservatism is added to the statistical sum. It should be noted that for this document it was assumed that the accuracy effect on a channel due to cable degradation in an accident environment will be less than 0.1 percent of span. This impact has been considered negligible and is not factored into the analysis. An error due to this cause found to be in excess of 0.1 percent of span must be directly added as an environmental error.

The Westinghouse setpoint methodology results in a value with a 95 percent With the exception of Process probability with a high confidence level.

Measurement Accuracy, Rack Drift, and Sensor Drift, all uncertainities assumed are the extremes of the ranges of the various parameters, i.e., are better than 2a values. Rack Drift and Sensor Drift are assumed, based on a survey of reported plant LERs, and with Process Measurement Accuracy are considered as conservative values.

2-2 5189Q:lD/091785

(EESTINGHOUSE PROPRIETARY CLASS 3) 2.2 SENSOR ALLOWANCES Four parameters are considered to be sensor allowances. SCA, SD, STE, and SPE (see Table 3-16). Of these four parameters, two are considered to be statistically independent. [ ]***#, and two are considered interactive [ ]***C . [ )" '" are considered to be independent due to the manner in which the instrumentation is checked, i.e.,

the instrumentatbn is [

' )***'. An example of ,

+a.c

[ ]***C are considered to b"e interactive for the same reason that

[ J+a c are considered independent, i.e., due to the manner in which the instrumentation is checked. [

i

]+a c . Based on

(

this reasoning, ( )** have been added to form an independent I

An example of the impact of group which is then factored into Equation 2.1.

this treatment is; for Pressurizer Water Level-High (Veritrak parameters r

only):

l 2-3 51890:10/091785

(WESTINGHOUSE PROPRIETARY CLASS 3)

. +a,b,c using Equation 2.1 as written gives a total of;

' . +a,c

= 1.66 percent Assuming no interactive effects for any cf the parameters gives the following results:

. +a C 1

(Eq. 2.2)

= 1.32 percent w

Thus it can be seen that the approach represented by Equation 2.1 which l

accounts for interactive parameters results in a more conservative summation l

l of the allowances.

2.3 RACK ALLOWANCES Four parameters, as noted by Table 3-16, are considered to be rack allowances, RCA, RC5A, RTE, and RD. Three of these parameters are considered to be interactive (for much the same reason outlined for sensors in 2.2), [

j+a,c ,

)+a,c 2-4

! 51890:10/091885 L

(WESTINGHOUSE PROPRIETARY CLASS 3)

[

J+. Based on this logic, these three factors have been added to form an independent group.

This group is then factored into Equation 2.1. The impact of this approach (formation of an independent group based on interactive components) is significant. For the same channel using the same approach outlined in Equations 2.1 and 2.2 the following results are reached:

+a,b,c using Equation 2.1 the result is;

- . + a,c

= 1.82 percent Assuming no interactive ef fects for any of the parameters yields the following less conservative results;

. +a.c (Eq. 2.3)

= 1.25 percent l Thus the impact of the use of Equation 2.1 is even greater in the area of rack effects than for the sensor. Theref ore, accounting f or interactive ef f ects in the statistical treatment of these allowances insures a conservative result.

51890:10/091885 2-5

(EESTINGHOUSE PROPRIETARY CLASS 3) 2.4 PROCESS ALLOWANCES Finally, the PMA and PEA parameters are considered to be independent of both sensor and rack parameters. PMA provides allowances for the non-instrument related ef fects, e.g., neutron flux, calorimetric power error assumptions, fluid density changes, and temperature stratification assumptions. PMA may consist of more than one independent error allowance. PEA accounts for errors due to metering devices, such as elbows and venturis. Thus, these parameters have been statistically factored into Equation 2.1.

i i

5189Q:10/091785 2-6

(WESTINGHOUSE PROPRIETARY CLASS 3) 3.0 PROTECTION SYSTEM SETPOINT METHODOLOGY 3.1 MARGIN CALCULATION As noted in Section One, Westinghouse utilizes a statistical summation of the various components of the channel breakdown. This approach is valid where no dependency is present. An arithmetic summation is required where an interaction between two parameters exists, Section Two provides a more detailed explanation of this approach. The equation used to determine the margin, and thus the acceptability of the parameter values used, is:

, .ac

+

(Eq. 3.1) where:

TA = Total Allowance (Safety Analysis Limit - Nominal Trip Setpoint), and all other parameters are as defined for Equation 2.1.

Tables 3-1 through 3-15 provide individual channel breakdown and channel statistical allowance calculations for all protection functions utilizing 7300 process rack equipment. Table 3-16 provides a summary of the previous 15 tables and includes analysis and technical specification values, total allowance and margin.

t 3.2 DEFINITIONS FOR PROTECTION SYSTEM SETPOINT TOLERANCES To insure a clear understanding of the channel breakdown used in this report, the following definitions are noted:

1. Trio Accu;;cy The tolerance band containing the highest expected value of the dif ference between (a) the desired trip point value of a process variable and (b) the 51890:1D/091785 3-1

(WESTINGHOUSE PROPRIETARY C!. ASS 3) actual value at which a comparator trips (and thus actuates some desired result). This is the tolerance band, in percent of span, within which the complete channel must perform its intended trip function. It includes comparator setting accuracy, channel accuracy (including the sensor) for each input, and environmental effects on the rack-mounted electronics. It comprises all instrumentation errors; however, it does not include process measurement accuracy.

2. Process Measurement Accuracy Includes plant variable measurement errors up to but not including the sensor. Examples are the effect of fluid stratification on temperature measurements and the effect of changing fluid density on level measurements.

3. Actuation Accuracy Synonymous with trip accuracy, but used where the word ' trip" does n-t apply.

4. Indication Accuracy The tolerance band containing the highest expected value of the difference between (a) the value of a process variable read on an indicator or recorder and (b) the actual value of that process variable. An indication It includes channel accuracy, must fall within this tolerance band.

accuracy of readout devices, and rack environmental effects, but not process measurement accuracy such as fluid stratification. It also assumes a controlled environment for the readout device. -

5. , Channel Accuracy ,

The accuracy of an analog channel which includes the accuracy of the primary element and/or transmitter and modules in the chain where 3-2 51890:10/091785

(WEST 1NGHOUSE PROPRIETARY CLASS 3) calibration of modules intermediate in a chain is allowed to compensate for errors in other modules of the chain. Rack environmental elfects are not included here to avoid duplication due to dual inputs, however, normal environmental offects on field mounted hardware is included.

6. Sensor Allowable Deviation The accuracy that can be expected in the field. It includes drift, temperature effects, field calibration and for the case of d/p transmitters, an allowance for the ef fect of static pressure variations.

The tolerances are as follows:

a. Reference (calibration) accuracy - [ ]*"' percent unless other data indicates more inaccuracy. This accuracy is the SAMA reference accuracy as defined in SAMA standard PMC 20.1-1973( }.

b. Temperature effect - [ ]*"' percent based on a nominal temperature cecificient of [ ]* percent /100*F and a maximum assumed change of 50*F.

c. Pressure effect - usually calibrated out because pressure is constant. If not constant, nominal [ ]* percent is used.

Present data indicates a static pressure effect of approximately

[ ]**' percent /1000 psi.

d. Drift - change in input-output relationship over a period of time at reference conditions (e.g., [ ]* -

[ ]**' of span).

20.1-1973, (1) Scientific Apparatus Manufacturers Association, Standard PMC

" Process Measurement and Control Terminology."

3-3 5189Q:10/091985

(WESTINGHOUSE PROPRIETARY CLASS 3)

7. Rack Allowable Deviation The tolerances are as follows:

a. Rack Calibration Accuracy The accuracy that can be expected during a calibration at reference conditions. This accuracy is the SAMA reference accuracy as defined in SAMA standard PMC 20.1-1973UI. This includes all modules in a rack and is a total of [ ]**' percent of span assuming the chain of modules is tuned to this accuracy. For simple loops where a power supply (not used as a converter) is the only rack module, this accuracy may L:. ignored. All rack modules individually must have a reference accuracy within [ ]* percent.

b. Rack Environmental Effects Includes effects of temperature, humidity, voltage and frequency An accuracy of changes of which temperature is the most significant.

[ ]**' percent is used which considers a nominal ambient temperature of 70*F with extremes to 40*F and 120*F for short periods of time.

c. Rack Drif t (instrument channel drif t) - change in input-output relationship over a period of time at reference conditions (e.g.,

[ ]## ) - t1 percent of span.

d. Comparator Settino Accuracy Assuming an exact electronic input, (note that the " channel accuracy" takes care of deviations from this ideal), the tolerance on the precision with which a comparator trip value (1) Scientific Apparatus Manufactureres Association, Standard PMC 20.1-1973, " Process Measurement and Control Technology".

3 -4 51890:10/091885

(WESTINGHOUSE PROPRIETARY CLASS 3) can be set, within such practical constraints as time and offcrt expended in making the setting.

The tolerances are as follows:

(a) Fixed setpoint with a single input - [ ]**' percent accuracy. This assumes that comparator nonlinearities are compensated by the setpoint.

(b) Dual input - an additional [ ]+a,b.c percent must be added for comparator nonlinearities between two inputs. Total

( ]+a,b,c percent accuracy.

Note: The following four definitions are currently used in the Standardized Technical Specifications (STS).

8. Nominal Safety System Settina 4

The desired setpoint for the variable. Initial calibration and subsequent 4

recalibrations should be made at the nominal safety system setting (" Trip Setpoint" in STS).

9. Limitina Safety System Setting A setting chosen to prevent exceeding a Safety Analysis Limit (" Allowable Yalues" in STS). Violation of this setting represents an STS violation.

10. Allowance f or Instrument channel Orif t The difference between (8) and (9) taken in the conservative direction.

' 11. Safety Analysis Limit The setpoint value assumed in safety analyses.

5189Q:10/091885 3-5

(WEST 8NGHOUSE PROPRIETARY CLASS 3)

12. Total Allowable Setooint Deviation Same definition as 9, but the dif ference between 8 and 12 encompasses [

),+a,c 3.3 STATISTICAL METHODOLOGY CONCtUSTON The Westinghouse setpoint methodology results in a value with a 95 percent probability with a high confidence level. With the exception of Process Measurement Accuracy, Rack Drift and Sensor Orift, all uncertainties assumed are the extremes of the ranges of the various parameters, i.e., are better than 2e values. Rack Orift and Sensor Drif t are assumed, based on a survey of reported plant LERs, and with Process Measurement Accuracy are considered as conservative values.

3.4 ROSEMOUNT TRANSMITTER CALCULATIONS In addition to the Veritrak transmitters supplied by Westinghouse, Northeast utilities Service Company has utilized Rosemount transmitters for many of the I protection functions. Westinghouse has determined the instrument uncertainties for SCA, SPE, STE, and SD based on Rosemount Product Data Sheets 2388 (1153 series 0), 2302 (1153 series 5), and 2514 (1154) which were supplied to Westinghouse via Stone and Webster Engineering Corporaton letters NES-35935 (7/19/84), NES-32874 (8/16/83), and NES-37613 (2/18/85). In addition, Westinghouse received explicit instructions concerning the determination of the Environmental Allowance for these transmitters, NES-36896 (11/19/84), NES-37085 (12/13/84), and NES-37613 (2/18/85). Westinghouse has calculated these values in accordance with these instructions.

t i

i 51890:10/091885 3-6 l

i

[

(WESTINGHOUSE PROPRIETARY CLASS 3)

T ABLE 3-1 POWER RANGE, NEUTRON FLUX - HIGH AND LOW SETPOINTS Allowance

• Parameter _ ,+a .c . . a+ ,c Pr,,

o cess Measurement Accuracy

_i 6

E Primary Element Accuracy

+a,c 1

Sensor Calibration l

Sensor Pressure Effects

+a,c Sensor Temperature Ef fects 1 l +a,c 1

Sensor Drift i

Environmental Allowance Rack Calibration Rack Accuracy Comparator One input Rack Temperature Effects

\

Rack Drift Tag No.'s - N41, N42, N43, N44

• In percent span (120 percent Rated Thermal Power)

_ +a ,C Channel Statistical Allowance =

L 3-7 51890:10/091885

(WESTINGHOUSE PROPRIETARY CLASS 3)

TA81E 3-2 POWER RANGE, NEUTRON FLUX - HIGH POSITIVE RATE AND HIGH NEGATIVE RA Allowance

• Parameter Process Measurement Accuracy ,ac

+

.. +a.C Primary Element Accuracy

,ac

+

Sensor Calibration Sensor Pressure Effects

_+ a,c Sensor Temperature Ef fects

,+ a,c Sensor Drift Environmental Allowance Rack Calibration Rack Accuracy Comparator One input Rack Temperature Effects Rack Drift - .

Tag No.'s - N41, N42, N43, N44 l

• In percent span (120 percent Rated Thermal Power)

Channel Statistical Allowance - _

W 3-8 51890:10/091885

(WESTINGHOUSE PROPRIETARY CLASS 3)

TABLE 3-3 INTERMEDIATE RANGE, NEUTRON FLUX Allowance

• Parameter

,+a.c Pro,c ess Measurement Accuracy

,+a,c Primary Element Accuracy

+a,c Sensor Calibration ]

[

Sensor Pressure Effects

+a,c Sensor Temperature Effects

]

[

+a,c Sensor Orift ]

[

Environmental Allowance Rack Calibration Rack Accuracy Comparator One input Rack Temperature Effects Rack Drif t 5 percent of Rated Thermal Power - .

Tag No.'s - N35, N36

• In percent span (conservatively assumed to be 120 percent Rated Thermal Powe Channel Statistical Allowance = .fa,e 3-9 51890:10/091885

(WESTINGHOUSE PROPRIETARY CLASS 3)

T ABLE 3-4 f

SOURCE RANGE, NEUTRON FLUX Allowance

• Parameter _

+a,c Process Measurement Accuracy +a,c Primary Element Accuracy

+a,c Sensor Calibration )

{

Sensor Pressure Effects

+a,c Sensor Temperature Effects 1

[

+a,c Sensor Orif t )

[

Environmental Allowance Rack Calibration Rack Accuracy Comparator One input Rack Temperature Effects Rack Drift . .i

' 3 x 104 cps Tag No,'s - N31, N32 6 counts per second)

• In percent span (1 x 10

+a,c Channel Statistical Allowance =

l l

f 6

l 3-10 51890:10/091985 L

(WESTINGHOUSE PROPRIETARY CLASS 3)

TABLE 3-Sa i r Pressure)

OVERIEMPERATURE AT (Veritrak Transmitter f or Allowance

• Pressur z Parameter . +a,c +a C Pr2 cess Measurement Accuracy W

_l L

Primary Element Accuracy

+g.c Sensor Calibration

_l 5

L Sensor Pressure Effects +a,c Sensor Temperature Effects

]

[ + 4,c Sen,sor Orift

.l L

)+a,c Environmental Allowance

[ , +a ,c Ra,kc Calibration N

Rack Accuracy AT channel Tava channel Preisure channel Al channel Total AT channel T channel _

Pe$surechannel Al channel 3-11

$1890:10/091885

(WESTINGHOUSE PROPRIETARY CLASS 3)

TABLE 3-Sa (Continued)

DVERTEMPERATURE AT Parameter Allowance

• Comparator - -

+a.c Two inputs Rack Temperature Effects Rack Drift AT channel Tavg channel - -

Tag No.'s - TE411A, TE4118, PT455, N41 TE421A, TE4218, PT456, N42

• In percent span (Ta v - 100'F, pressure - 800 psi, power - 150 percent Rated Thermal Power, AT - 00.3*F, AI - + 60 percent A1; 90.3*F span - 150 percent power)

• • See Table 3-17a for gain calculations Channel Statistical Allowance =

, +a.c 51890:10/091885 3-12

(BESTINGHOUSE PROPRIETARY CLASS 3)

TABLE 3-5b OVERIEMPERATURE AT (Rosemount Transmitter for Pressurizer Pressur All values are the same as Table 3-Sa except:

Allowance

• Parameter

_ +a,c Sensor Temperature Effects

[

)+a C Sensor Drift

[ pa,c - .

Tag No.'s - TE431 A, TE4318, PT457, N43 TE441 A, TE4418, PT458, N44 l

• In percent span (See Table 3-5b)

• • See Table 3-17a for gain calculations Channel Statistical Allowance = '

_+ a,c f ,

{

,5-I l

3-13

$189Q:10/091985

(WESTINGHOUSE PROPRIETARY CLASS 3)

TABLE 3-6 OVERPOWER AT Allowance

• Parameter

. Fa c Pricess Measurement Accuracy . - +a,C

~

Primary Element Accuracy

_+ a ,c Sensor Calibration Sensor Pressure Effects Sensor Temperature Effects Sensor Drift

[ 3+a c Environmental Allowance

.+a,c Raqk Calibration Rack Accuracy AT channel Tavg channel Total AT channel s T,yg channel Comparator Two inputs l

i Rack Temperature Effects Rack Drift AT channel T,yg channel - -

51890:1D/091785 3-14

(WESTINGHOUSE PROPRIETARY CLASS 3)

TABLE 3-6 (Continued)

DVERPOWER AT Tag No.'s - TE411A, TE411B TE421A, TE421B TE431 A, TE4318 TE441A, TE4418

• In percent span (Tav 100*F, pressure - 800 psi, power - 150 percent Rated Thermal Power,g A T - 90.3*F; 90.3*F span = 150 percent power)

• • See Table 3-18 for gain calculations Channel Statistical Allowance = _ +B ,C l

l 3-15 51890:10/091885

(WESTINGHOUSE PROPRIETARY CLASS 3)

TABLE 3-7a PRESSURIZER PRLSSURE - LOW AND HIGH, REACTOR TRIPS (With Veritrak Transmitter)

Parameter Allowance *

- +a.c Process Measurement Accuracy Primary Element Accuracy Sensor Calibration Sensor Pressure Effects Sensor Temperature Ef fects Sensor Drift Environmental Allowance Rack Calibration Rack Accuracy Comparator One input Rack Temperature Effects Rack Drift - -

Tag No.'s - PT455, PT456

• In percent span (800 psi)

Channel Statistical Allowance = +a,c l

i 5189Q:10/091885 3-16 I

l (WESTfNGHOUSE PROPRIETARY CLASS 3)

TABLE 3-7b PRESSURIZER PRESSURE - LOW AND HIGH, REACTOR TRIPS (With Rosemount Transmitter)

All values are the same as Table 3-7a except:

Allowance

• Parameter

. . +a .c Sensor Temperature Effects Sensor Drift . .

Tag No.'s - PT457, PT458

• In percent span (100 percent span)

Channel Statistical Allowance = +4,C 5189Q:lD/091885 3-17

(WESTINGHOUSE PROPRIETARY CLASS 3)

TABLE 3-8a PRESSURIZER WATER LEVEL - HIGH (With Veritrak Transmitter)

Allowance

• Parameter Process Measurement Accuracy _ _ac+

+a,c

[ ]

Primary Element Accuracy Sensor Calibration Sensor Pressure Effects ,

Sensor Temperature Effects Sensor Drift Environmental Allowance Rack Calibration Rack Accuracy Comparator One input Rack Temperature Effects Rack Drift

~ ~

Tag No.'s - LT459

• In percent span (100 percent span)

Channel Statiscical Allowance -

. +a,c i

51890:10/091885 3-18

(WESTINGHOUSE PROPRIETARY CLASS 3)

TABLE 3-8b PRESSURIZER WATER LEVEL - HIGH (With Rosemount Transmitter)

All values are the same as Table 3-8a except:

Allowance

• Parameter

, .ac

+

Sensor Pressure Effects Sensor Temperature Effects Sensor Drift . .

Tag No.'s - LT460, LT461

• In percent span (100 percent span)

Channel Statistical Allowance -

_+ a,c 51890:10/091985 3-19

WA '

I (WESTINGHOUSE PROPRIETARY CLASS 3)

TA8LE 3-9a LOSS OF FLOW (With Rosemount Transmitter)

Allowance

• Parameter

+a,c Process Measurement Accuracy .

Primary Element Accuracy

)+a.c Sensor Calibration )+a,c

[

Sensor Pressure Effects )+a,c

[

Sensor Temperature Effects

)+a,c

[

Sensor Drift [ ]+a,c Environmental Allowance Rack Calibration

- Rack Accuracy [ ]+a,c Comparator One input [ ]+a,c Rack Temperature Effects [ ]+a,c Rack Drif t 1.0 percent Ap span -

Tag No.'s - FT414, FT415, FT416, FT424, FT425, FT426 FT434, FT435, FT436, FT444, FT445, FT446

• In percent span (120 percent Thermal Design Flow)

Percent Ap span converted to flow span via Eq. 3-20.8

+a,c

_ Channel Statistical Allowance -

3-20 51890:10/091885

(WESTINGHOUSE PROPRIETARY CLASS 3) 1 TABLE 3-10a STEAM GENERATOR WATER LEVEL - LOW-LOW (With Veritrak Transmitter)

Allowance

• Parameter Process Measurement Accuracy . _

+a,c Density variations with load due to changes in recirculation **

Primary Element Accuracy Sensor Calibration Sensor Pressure Effects Sensor Temperature Effects Sensor Drift Environmental Allowance Reference Leg Heatup Rack Calibration Rack Accuracy Comparator One input Rack Temperature Effects Rack Drift - _

Tag No.'s - LTSlT, LT518, LT519 LT527, LT528, LTS29 LT537, LT538, LT539 LT547, LT548, LT549

• In percent span (100 percent span)

• • See Table 3-22 for explanation Channel Statistical Allowance -

_+a,c 3-21 5189Q:10/091885

r (WESTINGHOUSE PROPRIETARY CLASS 3) i i TABLE 3-10h STEAM GENERATOR WATER LEVEL - LOW-LOW (WithRosemountTransmitter)

All values the same as Table 3-10a except:

Allowance

• Parameter . .

+a,c Sensor Pressure Effects Sensor Temperature Effects Sensor Drift Environmental Allowance Reference Leg Heatup 6 -

Tag No.'s - LT551, LT552, LT553, LT554

• In percent span (100 percent span)

Channel Statistical Allowance -

+a.c 3-22 51890:10/091885

(WESTINGHOUSE PROPRIETARY CLASS 3)

TABLE 3-11 CONT AINMENT PRESSURE - HIGH, HIGH-HIGH, HIGH-HIGH-HIGH Allowance

• Parameter

+a,c Process Measurement Accuracy Primary Element Accuracy Sensor Calibration Sensor Pressure Effects Sensor Temperature Ef fects Sensor Drift Environmental Allowance Rack Calibration Rack Accuracy Comparator One input Rack Temperature Effects

~

Rack Drift (0.6 psig) - _

Tag No.'s - PT934, PT935 PT936, PT937

• In percent span (60 psig)

Channel Statistical Allowance - _ +a ,c l

l 3-23 51890:1D/091885

(WESTINGHOUSE PROPRIETARY CLASS 3)

TABLE 3-12a PRESSURIZER PRESSURE - LOW, SAFETY INJECTION (With Veritrak Transmitter)

Allowance

• Parameter

. +a,c Process Measurement Accuracy Primary Element Accuracy Sensor Calibration Sensor Pressure Effects Sensor Temperature Effects Sensor Drift Environmental Allowance Rack Calibration Rack Accuracy Comparator One input Rack Temperature Effects Rack Drift _

Tag No.'s - PT455, PT456

• In percent span (800 psi)

Channel Statistical Allowance = +a,C i

~

3-24 l

51890:10/091885 i

r (WESTINGHOUSE PROPRIETARY CLASS 3)

TA8LE 3-12b PRESSURIZER PRESSURE - LOW, SAFETY INJECTION (With Rosemount Transmitter)

All values are the same as Table 3-12a except:

Allowance

• Parameter

. +a,c Sensor Temperature Effects Sensor Drift Environmental Allowance .

Tag No.'s - PT457 PT458

• In percent span (800 psi)

Channel Statistical Allowance =

. +a,c 51890:10/091885 3-25

(WESTINGHOUSE PROPRIETARY CLASS 3)

TABLE 3-13 STEAMLINE PRESSURE - LOW Allowance

• Parameter

+a c Process Measurement Accuracy Primary Element Accuracy Sensor Calibration Sensor Pressure Effects Sensor Temperature Effects Sensor Drift Environmental Allowance Rack Calibration Rack Accuracy Comparator One input Rack Temperature Effects Rack Drift Tag No.'s - PT514, PT515, PT516 PT524, PT525, PT526 PT534, PT535, PT536 PT544, PT545, PT546

• In percent span (1300 psig) l -

Channel Statistical Allowance - +a,c 1

~

l

[

l 51890:10/091885 3-26

(WESTINGHOUSE PROPRIETARY CLASS 3)

TABLE 3-14 NEGATIVE STEAMLINE PRESSURE RATE - HIGH Allowance

• Parameter .

+a,c Process Measurement Accuracy Primary Element Accuracy Sensor Calibration .ac+

Sensor Pressure Effects Sensor Temperature Effects .+a,c

.+a.c Sensor Drift Environmental Allowance Rack Calibration Rack Accuracy Comparator One input Rack Temperature Effects l

t l

Rack Drift . _.

Tag No.'s - PT514, PTS 15, PT516 PTS 24, PT525, PTS 26 PT534, PT535, PT536 PT544, PT545, PT546

• In percent span (1300 psig)

Channel Statistical Allowance = _+a.C I

l

\ .

3-27 51890:10/091885

(WESTINGHOUSE PROPRIETARY CLASS 3)

TABLE 3-15a STEAM GENERATOR WATER LEVEL - HIGH-HIGH (With Veritrak Transmitter)

Allowance

• Parameter Process Measurement Accuracy - - +a.c density variations with load due to changes in recirculation **

Primary Element Accuracy Sensor Calibration

- Sensor Pressure Effects Sensor Temperature Effects Sensor Drift Environmental Allowance Rack Calibration Rack Accuracy Comparator One input Rack Temperature Effects Rack Drift . -

Tag No. 's - LT517, LTS18, LT519 LT527, LT528, LT529 LT537, LT538, LT539 LT547, LT548, LT549

• In percent span (100 percent span)

• • See Table 3-19 for explanation Channel Statistical Allowance = _ +a,c 51890:1D/091885 3-28

(WESTINGHOUSE PROPRIETARY CLASS 3)

TA8LE 3-15b STEAM GENERATOR WATER LEVEL - HIGH-HIGH (With Rosemount Transmitter)

All values are the same as Table 3-15a except:

Allowance

• Parameter

. +a c

__ Sensor Pressure Effects Sensor Temperature Effects Sensor Orif t .

Tag No.'s - LT551, LT552, LT553, LT554

• In percent span (100 percent span)

[ Channel Statistical Allowance = . +a,c

[ ,

e .

l  :

I i

?

l t

l 1

I l

5189Q:10/091885 3-29 j

i s

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FTS 492-8989 l

l l l

1 (WESTINGHOUSE FRUPRIETARY CLASS 3) )

I l

l TA81.E 3-17a l

OVERTEMPERATURE AT GAIN CALCULATIONS (Veritrak Transmitter for Pressurizer Pressure)

The equation for Overtemperature AT is:

(1 + 1 S) f 3 3

)

Overtemperature AT '

) , ,p3) )

• '33)

. f1 + T 4)5 f 3 3 AT, 5

+

3( '} 1( }

K) - K2 (1 + 15) . (1 * '6s/

v As an example to show calculational methodology and conservatism for Millstone Unit 3;

= 1.08 TS trip setpoint K) (nominal)

K) (max)

=

[ ]+a,c K = 0.0131 2

K = 0.000603 3

vessel AT = 60.2*F positive f(AI) penalty function gain = 2.0 percent FP/ percent Al and all other parameters as defined in Note 1 of Table 2.2-1 of Appendix A.

+$ .c 51890:10/091785 3-30

(WESTINGHOUSE PROPRIETARY CLASS 3)

+a,c i

• Conservative assumption for temperature stratification error in the hot leg (2*F TH + 0*F TC )/2

• • 1.5 is AT instrument span, equivalent to 150 percent Rated Thermal Power.

51890:10/091785 3-31 L

1 (WESTINGHOUSE PROPRIETARY CLASS 3) v TABLE 3 '.7b I

OVERTEMPERATURE AT EAIN CALCULATIONS (Rosemount Transmitter for Pressurizer Pressure) i All values noted in Table 3-17a are the same except: >

. *a,c f

4 3-32

$1890:10/091785

r (WESTINGHOUSE PROPRIETARY CLASS 3)

TABLE 3-19 OVERPOWER AT GAIN CALCULATIONS The equation for Overpower AT is:

Il + T j) S ( ) )

I Overpower AT {)

( * '2 5) (1+T3j 5 AT, K -K '7 1 T-K 6 T 1 -T -f2 (b I k4

[1

( + 1 5 )l (6 7

1/ +1 ,

k * '6 / 1 For Millstone Unit 3:

K = 1.09 TS trip setpoint 4 (nominal)

= [ ]**'#

K4 (max)

K = 0.00129 6

vessel AT = 60.2*F

.+a.c l _

l l

3-33 51890:10/091885

(WESTINGHOUSE PROPRIETARY CLASS 3)

_ac +

• Conservative assumption for temperature stratification error in the hot leg (2*F TH + 0*F TC )/2.

3-34 51890:10/091785

(WESTINGHOUSE PROPRIETARY CLASS 3) l TA8LE 3-19 STEAM GENERATOR LEVEL DENSITY VARIATIONS Because of density variations with load due to changes in recirculation, it is impossible without some form of compensation to have the same accuracy under all load conditions. In the past the recommended calibration has been at 50 percent power conditions. Approximate errors at 0 percent and 100 percent water level readings and also for nominal trip points of 10 percent and 70 percent level are listed below for a typical 50 percent power condition calibration. This is a general case and will change somewhat f rom plant to plant. These errors are only from density changes and do not reflect channel accuracies, trip accuracies or indicated accuracies which has been defined as a AP measurement only.III I INDICATED LEVEL (50 Percent Power Calibration) 0 10 70 100 percent percent percent percent

_+a,c (1) Miller, R. B., " Accuracy Analysis for Protection / Safeguards and Selected Control Channels", WCAP-8108 (Proprietary), March 1973.

1 51890:10/091785 3-35

(WESTINGHOUSE PROPRIETARY CLASS 3)

TABLE 3-20 AP MEASUREMENTS EXPRESSED IN FLOW UNITS The AP accuracy expressed as percent of span of the transmitter applies throughout the measured span, i.e., i 1.5 percent of 100 inches AP = 11.5 2

inches anywhere in the span. Because F = f(AP) the same cannot be said for flow accuracies. When it is more convenient to express the accuracy of a transmitter in flow terms, the following method is used:

. + a,c i

51890:10/091785 3-36

(WESTINGHOUSE PROPRIETARY CLASS 3) i Error in flow units is:

- +a,c t

Equation 3-20.8 is used to express errors in percent full span in this document.

51890:1D/091785 3-37

(WESTINGHOUSE PROPRIETARY CLASS 3) ,

TABLE 3-21 RCP SHAFT - LOW SPEED Allowance

• Parameter

. . +a.c Process Measurement Accuracy Primary Element Accuracy Sensor Calibration Sensor Pressure Effects Sensor Temperature Effects Sensor Drift Environmental Allowance Rack Calibration Rack Accuracy Comparator One input Rack Temperature Effects Rack Drift . ..

Tag No.'s - SE475, SE476, SE477, SE478

• In percent span (100% nominal rotation speed)

Channel Statistical Allowance -

_+a.c 51890:10/091885 3-38

(WESTINGHOUSE PROPRIETARY CLASS 3) 4.0 TECHNICAL SPECIFICATION USAGE _

4.1 CURRENT USE The Standardized Technical Specifications (STS) as used for Westinghouse type plant designs (see NUREG-0452, Revision 4) utilizes a two column format for the RPS and ESF system. This format recognizes that the setpoint channel breakdown, as presented in Figure 4-1, allows for a certain amount of rack drift. The intent of this format is to reduce the number of Licensee Event It appears that Reports (LERs) in the area of instrumentation setpoint drift.

However, the this approach has been successful in achieving its goal.

approach utilized is f airly simplistic [

l

)+a,c The use of the statistical summation technique described in Section 2 of this

[

report allows for a natural extension of the two column approach. )

l Also and allows for a more flexible approach in reporting LERs.

]**

of significant benefit to the plant is the incorporation of sensor drift parameters on an 18 month basis (or more of ten if necessary).

I I

4-1 51890:10/091785 }

(MESTINGHOUSE PROPRIETARV CLASS 3)

J J

J 4.2 WESTINGHOUSE STATISTICAL SETPOINT METHODOLOGY FOR STS SETPOINTS Recognizing that besides rack drif t the plant also experiences sensor drif t, a different approach to technical specificatjon setpoints, that is somewhat more sophisticated, is used today. This, methodology accounts for two additional factors seen in the plant during periodic surveillance, 1) interactive effects for both sensors and rack and, 2) sensor drif t ef f ects.

4.2.1 RACK ALLOWANCE When an The first item that will be covered is the interactive effects.

instrument technician looks for [ ]** he is seeing more than that. This interaction has been noted several times and is handled in Equations 2.1 and 3.1 [

]*". To provide a conservative " trigger value", the difference betseen the STS trip setpoint and The first is simply the the STS allowable value is determined by two swthods. '

].+

values used in the [

The second [

] as follows:

(Eq. 4.1)

[ ]+a c where

+a ,'c u

4-2 51890:1D/091985

(WESTfNGHOUSE PROPRlETARY CLAS5 3)

The smaller of the trigger values should be used for comparison with the 'as measured" [ ]" value. As long as the 'as measured" value If the 'as is smaller, the channel is well within the accuracy allowance.

measured" value exceeds the " trigger value", the actual numbers should be used in the calculation described in Section 4.2.3.

This means that all the instrument technician has to do during the 31 day periodic surveillance is determine the value of the bistable trip setpoint, verify that it is less than the STS Allowable Value, and does not have to account for any additional effects. The same approach is used for the sensor, i.e., the 'as measured" value is used when required. Tables 4-1 and 4-2 show the current STS setpoint philosophy (NUREG-0452, Revision 4) and the Westinghouse rack allowance (for use on 31 day surveillance only). A comparison of the two different Allowable Values will show the net gain of the Westinghouse version.

4.2.2 INCLUSION OF "AS MEASURED

• SENSOR ALLOWANCE If the approach used by Westinghouse was a straight arithmetic sum, sensor allowances for drif t would also be straight forward, i.e., a three column setpoint methodology. However, the use of the statistical sunnation requires a somewhat more complicated approach. This methodology; as demonstrated in Section 4.2.3 Implementation, can be used quite readily by any operator whose plant's setpoints are based on statistical sunnation. The methodology is based on the use of the following equation.

]+a,c (Eq. 4.2)

[

where:

R = the "as measured rack value" [ ]***'

S = the "as measured sensor value" [ ]

and all other parameters are as defined in Equation 4.1.

4-3 51890:10/091785

(WESTINGHOUSE PROPRIETARY CLASS 3)

Equation 4.2 can be reduced further, for use in the STS to:

(Eq. 4.3)

Z + R + 5 < TA where:

( ) +a.c Equation 4.3 would be used in two instances,1) when the "as measured" rack setpoint value exceeds the rack " trigger value" as defined by the STS Allowable Value, and, 2) when determining that the *as measured" sensor value is within acceptable values as utilized in the various Safety Analyses ar.d verified every 18 months.

4.2.3 IMPLEMENTATION OF THE WESTINGHOUSE SETPOINT METHODOLOGY Implementation of this methodology is reasonably straight forward, Appendix A prcvides a text and tables for use in the Millstone TS. An example of how the specification would be used for the Pressurizer Water Level - High reactor trip (with a Veritrak Transmitter) is as follows.

Every 31 days, as required by Table 4.3-1 of NUREG-0452. Revision 4, a functional test would be performed on the channels of this trip function.

During this test the bistable trip setpoint would be determined for each channel. If the 'as measured" bistable trip setpoint error was found to be less than or equal to that required by the Allowable Value, no action would be f necessary by the plant staf f. The Allowable Value is determined by Equation I

4.1 as follows:

l

_ + a,c 4 -4 5189Q:10/091785 f

I (WEST!NGHOUSE PROPRIETARY CLASS 3) l

+4 c l

i i

{

However, since only [

),+*** that value will be used as the " trigger value". The lowest of two values is used for the " trigger value"; [

),+a c Now assume that one bistable has " drifted" more than that allowed by the STS According to ACTION statement "A", the plant staff for3)daysurveillance.

must verify that Equation 2.2-1 is met. Going to Table 2.2-1, the following values are noted: Z = 2.18 and the Total Allowance (TA) = 8.0. Assume that the 'as measured" rack setpoint value is 4.5 percent high and the 'as measured" sensor value is 1.5 percent. Equation 2.2-1 looks like:

I + R + S 5 TA 2.18 + 4.5 + 1.5 5 8.0 8.2 > 8.0 As can be seen, 8.2 percent is not less than 8.0 percent thus, the plant staf f must follow ACTION statement '8" (declare channel inoperable and place in the

" tripped" condition). It should be noted that if the plant staff had not measured the sensor drif t, but instead used the value of S in Table 2.2-1 then the sum of Z + R + 5 would also be greater than 8.0 percent. In fact, almost 51890:10/091785 4-5

(WESTINGHOUSE PROPRIETARY CLASS 3) anytime the 'as measured" value for rack drif t is greater than T (the " trigger value"), use of S in Table 2.2-1 will result in the sum of Z + R + S being greater than TA and requiring the reporting of the case of the NRC.

If the sum of R + S was about 0.3 percent less, e.g., R = 4.1 percent, S = 1.3 percent thus, R + 5 = 5.4 percent, then the sum of Z + R + S would be less than 8 percent. Under this condition, the plant staff would recalibrate the instrumentation, as good engineering practice suggests, but the incident is not reportable, even though the " trigger value" is exceeded, because Equation 2.2-1 was satisfied.

In the determination of T for a function with multiple channel inputs there is

' a slight disagreement between Westinghouse proposed methodology and NRC approved methodology. Westinghouse believes that T should be either:

' +a,c (Eq. 4.4)

(Eq. 4.5) where the subscript 1 and 2 denote channels 1 and 2, and the value of T used is whichever is smaller.

The NRC in turn has approved a method of determining T for a multiple channel input function as follows, either:

, +a ,c (Eq. 4.6)

Again the value of T used is whichever is smaller. This method is described in appropriately circumspect terms in NUREG-0717 Supplement 4, dated August 1982.

4-6 5189Q:10/091785

(WESTINGHOUSE PROPRIETARY CLASS 3)

An example demonstrating all of the above noted equations for Overpower AT is provided below:

_ +a c In this document Equations 4.5 and The value of T used is from Equation 4.5.

4.6, whichever results in the smaller value is used for multiple channel input Table functions to remain consistent with current NRC approved methodologies.

4-3 notes the values of TA, A, S, T, and Z for all protection f unctions and is utilized in the determination of the Allowable Values noted in Appendix A.

4-7 51890:10/091785

(WESTINGHOUSE PROPRIETARY CLASS 3)

Table 4.3-1 also requires that a calibration be performed every refueling (approximately 18 months). To satisfy this requirement, the plant staff would I determine the bistable trip setpoint (thus, determining the 'as measured" rack l

. value at that time) and the sensor "as measured" value. Taking these two "as measured" values and using Equation 2.2-1 again the plant staf f can determine that the tested channel is in fact within the Safety Analysis allowance.  ;

4.3 CONCLUSION

Using the above methodology, the plant gains added operational flexibility and yet remains within the allowances accounted for in the various accident analyses. In addition, the methodology allows for a sensor drif t factor and an increased rack drift factor. These two gains should significantly reduce the problems associated with channel drift and thus, decrease the number of LERs while allowing plant operation in a safe manner.

51890:10/091785 4-8

c.

(WESTINGHOUSE PROPRIETARY CLASS 3)

TABLE 4-1 EXAMPLES OF CURRENT STS SETPOINT PHILOSOPHY Power Range Pressurizer Neutron Flux - High Pressure - High*

Safety Analysis Limit 118 percent 2410 psig STS Allowable value 110 percent 2380 psig STS Trip Setpoint 109 percent 2370 psig TABLE 4-2 EXAMPLES OF WESTINGHOUSE STS RACK ALLOWANCE Power Range Pressurizer Neutron Flux - High Pressure - High*

Safety Analysis Limit 118 percent 2410 psig STS Allowable Value 111.2 percent 2384 psig (Trigger Value)

STS Trip Setpoint 109 percent 2370 psig

• With Veritrak Transmitter 51890:10/091785 4 -9

(WESTfNGHOUSE PROPRIETARY CLASS 3)

Safety Analysis Limit -

1

, Process Measurement Accuracy lJ l

), Primary Element Accuracy

- J J

l, Sensor Temperature Effects l, Sensor Pressure Effects

_ 1

)

, Sensor Calibration Accuracy 1

1 l, Sensor Drift a

ll, Environmental Allowance

, Rack Temperature Effects

' I la)RackComparatorSettingAccuracy l Rack Calibration Accuracy l

STS Allowable Value ll Rack Drift STS Trip Setpoint -

Actual Calibratio; 'etpoint Figure 4-1 WUREG-0452 Rev. 4 Setpoint Error Breakdown 51890:10/091785 4-10 ,

r-- .

(WEST 8NGH00SE PROPRIETARY CLASS 3)

Safety Analysis Limit -

Process Measurement Accuracy

_ a Primary Element Accuracy

)

l), Sensor Temperature Ef f ects

,l t

l, Sensor Pressure Effects

,l Sensor Calibration Accuracy

,1 1

, Sensor Drift 1

l, Environmental Allowance J

~

> Rack Temperature Effects STS Allowable Value -

l

) Rack Comparator Setting Accuracy J

Rack Calibration Accuracy

!, Rack Drift STS Trip Setpoint -

Figure 4-2 Westinghouse STS Setpoint Error Breakdown 51890:10/091785 4-11

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FTS 492 =S989 i

1

(WESTINGHOUSE PROPRIETARY CLASS 3)

APPENDIX A SAMPLE MILLSTONE SETPOINT TECHNICAL SPECIFICATIONS 51890:10/091785 A-1

(WESTINGHOUSE PROPRIETARY CLASS 3)

SAFETY LIMITS AND LIMITING SAFETY SYSTEM SETTINGS 2.2 LIMITING SAFETY SYSTEM SETTINGS REACTOR TRIP SYSTEM INSTRUMENTATION SETPOINTS 2.2.1 The Reactor Trip System Instrumentation and Interlock Setpoints shall be set consistent with the Trip Setpoint values shown in Table 2.2-1.

APPLICABILITY: As shown for each channel in Table 3.3-1.

ACTION:

a. With a Reactor Trip System Instrumentation or Interlock Setpoint less conservative than the value shown in the Trip Setpoint column but more conservative than the value shown in the Allowable Value column of Table 2.2-1, adjust the Setpoint consistent with the Trip Setpoint value.

b. With the Reactor Trip System Instrumentation or Interlock Setpoint less conservative than the value shown in the Allowable Values column of Table 2.2-1, either:

1. Adjust the Setpoint consistent with the Trip Setpoint value of Table 2.2-1 and determine within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> that Equation 2.2-1 was satisfied for the affected channel, or

2. Declare the channel inoperable and apply the applicable ACTION statement requirement of Specification 3.3.1 until the channel is restored to OPERABLE status with its Setpoint adjusted consistent with the Trip Setpoint value.

(Eq. 2.2-1) 2 + R + 51 TA 51890:10/091785 A-2

(WESTINGHOUSE PROPRIETARY CLASS 3)

Where:

I = The value f rom Column I of Table 2.2-1 for the af fected channel, R = The "as measured" value (in percent of span) of rack error for the affected channel, S = Either the "as measured" value (in percent of span) of the sensor error, or the value from Column 5 (Sensor Drift) of Table 2.2-1 for the affected channel, and TA = The value f rom Column TA (Total Allowance) of Table 2.2-1 for the affected channel, i

A-3 51890:10/091785

(WESTINGHOUSE PROPRIETARY CLASS 3)

TABLE 2.2-1 REACTOR TRIP SYSTEM INSTRUMENTATION TRIP SETPOINTS Total Allowance (TA) Z S Trip Setpoint Allowable Value Functional Unit N.A. N.A. N.A. N.A. N.A.

1. Manual Reactor Trip 7.5 4.56 0 $ 109 percent of RTP $ 111.1 percent of RTP

2. Power Range, Neutron Flux, High Setpoint 8.3 4.56 0 5 25 percent of RTP $ 27.1 percent of RTP Low Setpoint 1.6 0.50 0 5 5 percent of RTP with a 5 6.3 percent of RTP with

3. Power Range, Neutron Flux, a time constant 1 2 seconds High Positive Rate time constant 1 2 seconds 1.6 0.50 0 $ 5 percent of RTP with a 5 6.3 percent of RTP with a

4. Power Range, Neutron Flux, time constant 1 2 seconds High Negative Rate time constant 1 2 seconds 17.0 8.41 0 $ 25 percent of RTP 5 30.9 percent of RTP

5. Intermediate Range, Neutron Flux 17.0 10.01 0 $ 105 cps 5 1.4 x 105 cps

6. Source Range, Neutron Flux 8.3 5.90 1.1+1.1 See note 1 See note 2

7. Overtemperature AT (N loop) See note 2 (N-1 loop) 12.0 5.90 1.1+1.1 See note 1 4.8 1.43 0.11 See note 3 See note 4

8. Overpower AT 5.0 1.77 3.3 2 1885 psig 1 1875 psig

9. Pressurizer Pressure - Low 5.0 1.77 3.3 5 2370 psig 5 2380 psig

10. Pressurizer Pressure - High 8.0 5.13 2.7 5 89 percent of 5 90.7 percent of

11. Pressurizer Water Level-High instrument span instrument span 2.5 1.74 0.8 1 90 percent of loop 1 89.3 percent of loop

12. Loss of Flow design flow

• design flow

• l

• Loop design flow = 94,600 gpm (N loop operation), 99,600 gpm (N-1 loop operation)

(194n 10/091785

(WESTINGHOUSE PROPRIETARY CLASS 3)

TABLE 2.2-1 (Continued)

REACTOR TRIP SYSTEM INSTRUMENTATION TRIP SETPOINTS Total Allowance Functional Unit (TA) 2 S Tr1D SetDoint Allowable Value

13. Steam Generator Water 20.5 18.98 1.75 123.5 percent of narrow 1 22.6 percent of narrow Level - Low-Low range instrument span range instrument span

14. General Warning Alarm N.A. N.A. N.A. N.A. N.A.

15. RCP Shaft - Low Speed 3.8 0.5 0.0 97.8% nominal speed 94.6% nominal speed j

16. Turbine Trip

a. Low Fluid Oil Pressure N.A. N.A. N.A.

b. Turbine Stop Valve Closure N.A. N.A. N.A.

l 17. Safety Injection Input N.A. N.A. N.A. N.A. N.A.

from ESF l

l i

i i

t l

51890:1D/091785

(WESTINGHOUSE PROPRIETARY CLASS 3)

TABLE 2.2-1 (Continued)

REACTOR TRIP SYSTEM INSTRUMENTATION TRIP SETPOINTS Total Allowance Allowable Value (TA) S Trio Setpoint Functional Unit Z

19. Reactor Trip System Interlocks N.A. N.A. N.A. >l x 10-10 amps 16 x 10-11 amps

a. Intermediate Range Neutron Flux, P-6

b. Low Power Reactor Trips Block, P-7 i 1. P-10 input N.A. N.A. N.A. 110 percent of RTP $12.1 percent of RTP

2. P-13 input N.A. N.A. N.A. 510 percent turbine in- $12.1 percent turbine in-pulse pressure equivalent pulse pressure equivalent

c. Power Range Neutron N.A. N.A. N.A. 137.5 percent of RTP $39.6 percent of RTP Flux, P-8 (N loop operation)

d. Power Range Neutron N.A N.A N.4 137.5 percent of RTP $39.6 percent of RTP Flux, P-8 (N-1 loop operation?

e. Power Range Neutron N.A. N.A. N.A. 151 percent or RTP $53.1 percent of RTP Flux, P-9

f. Power Range Neutron N.A. N.A. N.A. 110 percent of RTP 27.9 percent of RTP Flux, P-10 N.A. N.A. N.A.

20. Reactor Trip Breakers N.A. N.A.

21. Automatic Trip and Interlock N.A. N.A. N.A. N.A. N.A.

Logic

• Later 51890:10/091785

(WLSTINGHOUSE PROPRIETARY CLASS 3)

TABLE 2.2-1 (Continued)

REACTOR TRIP SYSTEM INSTRUMENTATION TRIP SETPOINTS NOTATION 1+t 35 j NOTE 1: OVERTEMPERATURE AT () , ,p3 ) () *'3 3

1+T 45 j T' +

3(P - P') - f)(AI))

i ATo (K - K2j Il + i S}

S (I * '63)

AT = Measured AT by RTD Manifold Instrumentation; Where:

I+t jS

= Lead-lag compensator on measured AT ,

3 , ,23

= 3 secs.

t 1 - Time constants utilized in the lead-lag controller for AT, t) = 8 secs.,12 j, 2

= Lag compensator on measured AT

) 3 T = Time constant utilized in the lag compensator for AT,13= 0 secs.

3

= Indicated AT at RATED THERMAL POWER; AT, K = 1.080 (N loop operation) ,

1.010 (N-1 loop operation) y K 0.01313 2

1+T 45

= The function generated by the lead-lag controller for T,yg dynamic compensation; 1+iS5 t ,1 = Time constants utilized in the lead-lag controller for T g, 14 = 33 secs., 15 " 4 '"' '

5 1 = Average temperature *f 1+1 6S 9 P "$ * " $"

• • 9

= 0 secs.

1 = Time constant utilized in the measured T,yg lag compensator, 16 6

5189Q:10/091785

(WESTINGHOUSE PROPRIETARY CLASS 3)

TABLE 2.2-1 (Continued)

REACTOR TRIP SYSTEM INSTRUMENTATION TRIP SETPOINTS NOTATION NOTE 1: (continued) at RATED THERMAL POWER)

T' =

$ 587.1*F (Nominal T avg K3

= 0.000603 P

= Pressurtu r pressure, psig P' = 2235 psig (Nominal RCS operating pressure); and S = Laplace transform operator, sec-I; and fj(AI) is a function of the indicated difference between top and bottom detectors of the power range nuclear ion chamber; with gains to be selected based on measured instrument response during plant startup tests such that:

for qt - 4b between -30 percent and +10 percent, 1f (AI) = 0 (where qt (1) and qb are percent RATED THERMAL POWER in the top and bottom halves of the core is total THERMAL POWER in percent of RATED THERMAL respectively, and qt + Ab POWER);

for each percent that the magnitude of (qt - Ab) exceeds -30 percent, the AT (ii) trip setpoint shall be automatically reduced by 3.6 percent of its value at RATED THERMAL POWER; and for each percent that the magnitude of (qt - 4b) exceeds +10 percent, the AT (iii)

Trip Setpoint shall be automatically reduced by 2.0 percent of its value at RATED THERMAL POWER.

NOTE 2:

The channel's maximum Trip Setpoint shall not exceed its computed trip point by more than 2.1 percent AT span (N loop operation), 4.1% AT span (N-1 loop operation).

l 51890:10/091785 i

(WESTINGHOUSE PROPRIETARY CLASS 3)

TABLE 2.2-1 (Continued)

REACTOR TRIP SYSTEM INSTRUMENTATION TRIP SETPOINTS NOTATION .

1+t S NOTE 3: OVERPOWER AT (, , ,j 3) (; +j 3)

T 3

2

'7 1 i AT, K4 -KS () , ,,5) (j + '65 6b +1 165 2 Where: AT

= As defined in Note 1, 1+Ti s = As defined in Note 1 j , ,23 t

j, 2 1 = As defined in Note 1 3,

= As defined in Note 1 3

1 = As deMned in Note 1 3

AT,

= As defined in Note i K = 1.09 4

K = 0.02/*F for increasing average temperature and 0 for decreasing average temperature 5

175

- The function generated by the rate-lag controller for T,,g dynamic compensation, 1+1 75 1 = Time constant utilized in the lead-lag controller for T,yg, t y = 10 secs.

7

= As defined in Note 1 3

1 = As defined in Note 1 6

---

. ... ,oc

(WESTINGHOUSE PROPRIETARY CLASS 3)

TABLE 2.2-1 (Continued)

REACTOR TRIP SYSTEM INSTRUMENTATION TRIP SETPOINTS NOTATION (Continued)

NOTE 3: (continued)

K6

=

0.00129/*F for T > T" and K6 = 0 for T 5 T' T = as defined in Note 1 T" = Indicated Tavg at RATED THERMAL POWER (calibration temperature for AT instrumentation, 5 587.l*F)

S = as defined in Note 1 f 2(81) = 0 for all AI NOTE 4: The channel's maximum Trip Setpoint shall not exceed its computed Trip Setpoint by more than 3.4 percent AT span.

CICQO in/n417AS

(WESTINGHOUSE PROPRIETARY CLASS 3) 2.2 LIMITING SAFETY SYSTEM SETTINGS BASES 2.2.1 REACTOR TRIP SYSTEM INSTRUMENTATION SETPOINTS The Reactor Trip Setpoint Limits specified in Table 2.2-1 are the nominal values at which the Reactor trips are set for each functional unit. The Trip Setpoints have been selected to ensure that the core and Reactor Coolant System are prevented from exceeding their Safety Limits during normal operation and design basis anticipated operational occurrences and to assist the Engineered Safety Features Actuation System in mitigating the consequences of accidents. The Setpoint for a Reactor Trip System or interlock function is considered to be adjusted consistent with the nominal value when the 'as measured" Setpoint is within the band allowed for calibration accuracy.

To accommodate the instrument drif t assumed to occur between operational tests and the accuracy to which Setpoints can be measured and calibrated, Allowable Values for the Reactor Trip Setpoints have been specified in Table 2.2-1.

Operation with Setpoints less conservative than the Trip Setpoint but within the Allowable Value is acceptable since an allowance has been made in the safety analysis to accommodate this error. An optional provision has been included for determining the OPERABILITY of a channel when its Trip Setpoint is found to exceed the Allowable Value. The methodology of this option utilizes the "as measured" deviation f rom the specified calibration point for rack and sensor components in conjunction with a statistical combination of the other uncertainties of the instrumentation to measure the process variable and the uncertainties in calibrating the instrumentation. In Equation 2.2-1, Z + R + 5 1 TA, the interactive effects of the errors in the rack and the I, as sensor, and the "as measured" values of the errors are considered.

specified in Teble 2.2-1, 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 Reactor Trip. R or Rack Error is the 'as measured" deviation, in percent span, for the affected channel from the specified Trip A-11 51890:10/091785

(BESTINGHOUSE PROPRIETARY CLASS 3)

Setpoint. S or Sensor Error is either the "as measured" deviation of the sensor from its calibration point or the value specified in Table 2.2-1, in percent span, from the analysis assumptions. Use of Equation 2.2-1 allows for a sensor drif t f actor, an increased rack drif t f actor, 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. Sensors and other instrumentaton 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 Rack of sensor drif t, will happen, an infrequent excessive drift is expected.

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

f i

l l

A-12 51290:10/091785 I- - - - - - ._ _ _ _ , __

(WESTINGHOUSE PROPRTETARY CLASS 3)

INSTRUMENTATION 3/4.3.2 ENGINEERED SAFETY FEATURFS ACTUATION SYSTEM INSTRUMENTATION LIMITING CONDITION FOR OPERATION 3.3.2 The Engineered Safety Features Actuation System (ESFAS) instrumentation channels and interlocks shown in Table 3.3-3 shall be OPERABLE with their Trip Setpoints set consistent with the values shown in the Trip Setpoint column of Table 3.3-4 and with RESPONSE TIMES as shown in Table 3.3-5.

APPLICABILITY: As shown in Table 3.3-3.

ACTION:

a. With an ESFAS Instrumentation or Interlock Trip Setpoint less conservative than the value shown in the Trip Setpoint column but more conservative than the value shown in the Allowable Value column of Table 3.3-4 adjust the Setpoint consistent with the Trip Setpoint value.

b. With an ESFAS Instrumentation or Interlock Trip Setpoint less conservative than the value shown in the Allowable Values column of Table 3.3-4, either:

1. Adjust the Setpoint consistent with the Trip Setpoint value of Table 3.3-4 and determine within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> that Equation 2.2-1 was satisfied for the af fected channel, or

2. Declare the channel inoperable and apply the applicable ACTION statement requirements of Table 3.3-3 until the channel is restored to OPERABLE status with its Setpoint adjusted consistent with the Trip Setpoint value.

Equation 2.2-1 Z + R + 5 5 TA 51890:10/091785 A-13

4 (WESTINGHOUSE PROPRIETARY CLASS 3) l Where:

I = The value f rom Column I of Table 3.3-4 f or the af fected channel, R = The "as measured" value (in percent span) or rack error for the affected channel, S = Either the "as measured" value (in percent span) of the sensor error, or the value from Column S (Sensor Drift) of Table 3.3-4 for the af fected channel, and TA = The value from Column TA (Total Allowance) of Table 3.3-4 for the affected channel.

c. With an ESFAS instrumentation channel or interlock inoperable, take the ACTION shown in Table 3.3-3.

SURVEILLANCE REQUIREMENTS 4.3.2.1 Each ESFAS instrumentation channel and interlock and the automatic actuation logic and relays shall be demonstrated OPERABLE by the performance of the ESFAS Instrumentation Surveillance Requirements specified in Table 4.3-2.

A-14 L' J90:10/091785

(WESTINGHOUSE PROPRIETARY CLASS 3)

TABLE 3.3-4 ENGINEERED SAFETY FEATURE ACTUATION SYSTEM INSTRUMENTATION TRIP SETPOINTS

~

Total Allowance Sensar Drift (S) Trio Setooint Allowable Value Functional Unit (TA) Z

1. Safety Injection, Reactor Trip Feedwater Isolation Control Room Isolation, Start Diesel Generators, Containment Cooling Fans, and Essential Service Water N.A. N.A. N.A.

N.A. N.A.

a. Manual Initiation N.A. N.A. N.A.

N.A. N.A.

b. Automatic Actuation Logic and Actuation Relays 5 3.0 psig $ 3.8 psig

c. Containment Pressure - High 3.3 1.01 1.75 13.67 3.3 1 1877.3 psig 1 1870.2 psig

d. Pressurizer Pressure - Low 16.5 15.31 2.2 1 658.6 psig* 1 644.9 psiga

e. Steamline Pressure - Low 17.7 1

1 l

51890:10/091785

(WESTINGHOUSE PROPRIETARY CLASS 3)

TABLE 3.3-4 (Continued)

ENGINEERED SAFETY FEATURE ACTUATION SYSTEM INSTRUMENTATION TRIP SETPOINTS Total Allowance Sensor Functional Unit (TA) Z Drift (S) TriD SetDoint Allowable Value

2. Containment Spray 4

a. Manual Initiation N.A. N.A. N.A. N.A. N.A.

b. Automatic Actuation N.A. N.A. N.A. N.A. N.A. .

Logic and Actuation Relays

c. Containment Pressure - 3.3 1.01 1.75 5 8.0 psig 5 8.8 psig High-3

3. Containment Isolation

a. Phase "A" Isolation

1. Manual Initiation N.A. N.A. N.A. N.A. N.A.

2. Automatic Actuation N.A. N.A. N.A. N.A. N.A.

Logic and Actuation Relays

3. Safety Injection See Item 1 above for all Safety functions and requirements.

8. Phase "B" Isolation

1. Manual Initiation N.A. N.A. N.A. N.A. N.A.

2. Automatic Actuation N.A. N.A. N.A. N.A. N.A.

Logic and Actuation Relays

3. Containment Pressure - 3.3 1.01 1.75 5 8.0 psig 5 8.8 psig High-3 51890:10/091785

(WESTINGHOUSE PROPRIETARY CLASS 3)

TABLE 3.3-4 (Continued)

ENGINEERED SAFETY FEATURE ACTUATION SYSTEN INSTRONENTATION TRIP SETPOINTS Total Allowance Sensor Functional Unit (TA) _1_ Drift (S) Trio Setpoint Allowable Value

3. Containment Isolation (continued)

c. Containment Purge Isolation

1. Manual Initiation N.A. N.A. N.A. N.A. N.A.

2. Automatic Actuation N.A. N.A. N.A. N.A. N.A.

Logic and Actuation Relays

3. Containment Isolation See Item 3.a. above for all Containment Isolation Phase "A" functions and Phase "A" requirements.

4. Steam Line Isolation

a. Nanual Initiation N.A. N.A. N.A. N.A. N.A.

b. Automatic Actuation N.A. N.A. N.A. N.A. N.A.

Logic and Actuation Relays

c. Containment Pressure - 3.3 1.01 1.75 5 3.0 psig 5 3.8 psig High-2

d. Steamline Pressure - Low 17.7 15.31 2.2 2 658.6 psig* 1 644.9 psig*

e. Negative Steam Pressure- 5.0 0.50 0.0 1 -100 osi 1 -122.7 psi Negative Rate - High with a time constant with a time constant of 50 secs. of 50 secs.

51890:10/091785

7

-_----------q (WESTINGHOUSE PROPRIETARY CLASS 3)

TA8LE 3.3-4 (Cor*inued) 1 FNGINEERED SAFETY FEATURE ACTUATION SYSTEM INSTRUMENTATION TRIP,SETPOINTS ,

1 ,

Total '

Allowance Sensor Functional Unit (TA) Z Drift (S) Tr1D SetDoint Allowable Value

5. Turbine Trip and Feedwater l Isolation s

a. Automatic Actuation N.A. N.A. N.A. N.A. N.A.

l Logic Actuation '

Relays

b. Steam Generator Water 3.7 2.33 1.75 1 82.0 percent of 5 82.8 percent of Level--High-High narrow range instrument narrow range instrument span span

6. Auxiliary Feedwater

a. Manual Initiation N.A. N.A. N.A. N.A. N.A.

b. Automatic Actuation N.A. N.A. N.A. N.A. N.A.

Logic and Actuation Relays

c. Steam Generator Water Level--Low-Low

1. Start Motor- 20.5 18.98 1.75 123.5 percent of narrcw 122.6 percent of narrow Driven Pumps range instrument span range instrument span

2. Start Turbine- 20.5 18.98 1.75 1 23.5 percent of narrow 1 22.6 percent of narrow Driven Pump range instrument span range instrument span

d. Safety Injection See Item 1 above for all Safety Injection Functions and requirements Start Motor-Driven Pumps 51890:10/091785

(WESTINGHOUSE PROPRIETARY CLASS 3)

TABLE 3.3-4 (Continued)

ENGINEERED SAFETY FEATURE ACTUATION SYSTEM INSTRUMENTATION TRIP SETPOINTS Total Allowance Sensor (TA) Z_ Drift (S) Trio Setpoint Allowable Value Functional Unit

6. Auxiliary Feedwater (continued)

N.A. N.A. N.A. N.A. N.A.

e. Station Blackout Start Turbine-Driven Pump N.A. N.A. N.A. N.A. N.A.

f. Trip Main Feedwater Pumps-Start Motor-Driven Pumps and Turbine-Driven Pump

7. Automatic Switchover lo Containment Sump N.A. N.A. N.A. N.A.

a. Automatic Actuation N.A.

Logic and Actuation Relays

b. RWST Level--Low-Low Coincident with Safety Injection See Item 1 above for Safety Injection functions and requirements.

8. Loss of Power ,

a. 4.16 kV Undervoltage

-Loss of Voltage

b. 4.16 kV Undervoltage

-Grid Degraded Voltage

9. Engineered Safety Feature Actaution Systen, Interlocks N.A. N.A. $ 1985 psig $ 1995 psig

a. Pressurizer Pressure, P-il N.A.

N.A. N.A. N.A. N.A. N.A.

b. Reactor Trip, P-4

(WESTINGHOUSE PROPRIETARY CLASS 3)

TABLE 3.3-4 (Continued)

TABLE NOTATION

• Time constants utilized in the lead-lag controller for Steam Pressure-Low are 1 < 5 seconds.

3. >_ 50 seconds and2 1

• • To be provided by plant.

i A-20 5189Q:1D/091885

' 2

(WESTINGHOUSE PROPRIETARY CLASS 3) 3.4.3 INSTRUMENTATION BASES 3/4.3.1 and 3/4.3.2 REACTOR TRIP SYSTEM AND ENGINEERED SAFETY FEATURES ACTUATION SYSTEM INSTRUMENTATION The OPERABILITY of the Reactor Trip System and the Engineered Safety Features Actuation System instrumentation and interlocks ensures that: (1) the associated action and/or Reactor trip will be initiated when the parameter monitored by each channel or combination thereof reaches its setpoint, (2) the specified coincidence logic is maintained, (3) sufficient redundancy is maintained to pemit a channel to be out of service for testing or maintenance, and (4) sufficient system functional capability is available from diverse parameters.

The OPERABILITY of these systems is required to provide the overall reliability, redundancy, and diversity assumed available in the facility design for the protection and mitigation of accident and transient conditions. The integrated operation of each of these systems is consistent with the assumptions used in the safety analyses. The Surveillance Requirements specified for these systems ensure that the overall system functional capability is maintained comparable to the original design standards. The periodic surveillance tests performed at the minimum frequencies are sufficient to demonstrate this capability.

The Engineered Safety Features Actuation System Instrumentation Trip Setpoints specified in Table 3.3-4 are the nominal values at which the bistables are set for each functional unit. A Setpoint is considered to be adjusted consistent with the nominal value when the "as measured" Setpoint is within the band allowed for calibration accuracy.

To accommodate the instrument drif t assumed to occur between operational tests and the accuracy to which setpoints can be measured and calibrated, Allowable A-21 5189Q:10/091785

(WESTINGHOUSE PROPRIETARY CLASS 3)

Values for the Setpoints have been specified in Table 3.3-4. Operation with Setpoints less conservative than the Trip Setpoint but within the Allowable Value is acceptable since an allowance has been made in the safety analysis to

' ommodate this error. An optional provision has been included for

'stermining the OPERABILITY of a channel when its Trip Setpoint is found to exceed the Allowable Value. The methodology of this option utilizes the "as measured" deviation from the specified calibration point for rack and sensor components in conjunction with a statistical combination of the other uncertainties of the instrumentation to measure the process variable and the uncertainties in calibrating the instrumentation. In Equation 3.3.-1, Z + R + S S TA, the interactive effects of the errors in the rack and the sensor, and the "as measured" values of the errors are considered. Z, as 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 dif ference, 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 af fected channel f rom the specified 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.

The methodology to derive the Trip Setpoints is based upon combining all of the uncertanties 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 drif t 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 drif t, in excess of the allowance that is more than occasional, may be jadicative of more serious problems and should warrant further investigation.

I 1

l 51890:1D/091785 A-22 m