ML20203N493

Westinghouse Setpoint Methodology for Protection Sys - Vogtle Station

ML20203N493
Person / Time
Site:	Vogtle
Issue date:	08/31/1986
From:	Moomau W, Tuley C WESTINGHOUSE ELECTRIC COMPANY, DIV OF CBS CORP.
To:
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ML19292F986	List: ML20203N488 ML20203N489 ML20203N493
References
WCAP-11270, NUDOCS 8610090156
Download: ML20203N493 (80)

Text

-

WESTINGHOUSE CLASS 3

~

WCAP 11270 4

,u e

WESTINGHOUSE SETPOINT METHODOLOGY FDR PROTECTION SYSTEMS

\\

V0GTLE STATION 1

i i

August, 1986 W. H. Mtxxnau i

C. R. Tuley i

i Westinghouse Electric Corporation i

Energy Systems l

P.O. Box 355 i

Pittsburgh, Pennsylvania 15230 i

Copyright by Westinghouse Electric..1984, @ All Rights Reserved 8610090156 860929 PDR ADOCK'05000424 A

PDR i 2

ii WESTINGHOUSE PROPRIETARY CLASS 2 i

Jo 1

FOREWORD l-4 f

This doctment contains material that is proprietary to the Westinghouse Electric Corporation. The proprietary infonnation has been marked by brackets. The

3 basis for marking the infonnation proprietary and the basis on which the l-infonna ion may be withheld frcan public disclosure is set forth in the affidavit 3

j of R. A. Wiesemann. Pursuant to the provisions of Section 2.790 of the l4 Conmission's regulations, this affidavit is attached to the application for l

1 withholding from public disclosure which accompanies this doctnent.

d t

~

4 i

This infonnation is for your internal use only and should not be released to any g

persons or organizations outside the Office of Nuclear Reactor Regulation and j

the ACRS without the prior approval of Westinghouse Electric Corporation.

}{

Should it become necessary to obtain such approval, please contact R. A.

},

Wiesernann, Manager, Licensing Programs, Westinghouse Electric Corporation, P.O.

, e

{

Box 355, Pittsburgh, Pennsylvania 15230.

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TABLE OF CONTENTS Section Title PaSe

1.0 INTRODUCTION

1-1 4

2.0 COMBINATION OF ERROR COMPONENTS 2-1 2.1 Methodology 2-1 2.2 Sensor Allowances 2-3 4

2.3 Rack Allowances 2-5 2.4 Process Allowances 2-6 2.5 Measurement and Test Equipment Accuracy 2-6 3.0 PROTECTION SYSTEMS SETPOINT METHODOLOGY 3-1 i

3.1 Margin Calculation 3-1 3.2 Definitions for Protection System 3-1 i

Setpoint Tolerances 3.3 Statistical Methodology Conclusion 3-6 4.0 TECHNICAL SPECIFICATION USAGE 4-1 4

4.1 Current Use 4 -1 4.2 Westinghouse Statistical Setpoint 4-2

]

Methodology for STS Setpoints l

4.2.1 Rack Allowance 4-2 i

4.2.2 Inclusion of 'As Measured" 4-3 Sensor Allowance j

4.2.3 Implementation of the 4-4 Westinghouse Setpoint Methodology 4.3 Conclusion 4-8 Appendix A SAMPLE V0GTLE SETPOINT TECHNICAL A-1

~

SPECIFICATIONS l

11 45550:10/073186 l

LIST OF TABLES Table Title Page l

3-1 Power Range, Neutron Flux-High and Low Setpoints 3-7 3-2 Power Range, Neutron Flux-High Positive Rate and 3-8 High Negative Rate 3-3 Intermediate Range, Neutron Flux 3-9 3-4 Source Range, Neutron Flux 3-10 3-5 Overtemperature AT 3-11 3-6 Overpower AT 3-13 i

j 3-7 Pressurizer Pressure - Low and High, Reactor Trips 3-15 3-8 Pressurizer Water Level - High 3-16 3-9 Loss of Flow 3-17 3-10 Steam Generator Water Level - Low-Low 3-18 3-11 Containment Pressure - High-1, High-2, and High-3 3-19 3-12 Pressurizer Pressure - Low, Safety Injection 3-20 3-13 Steamline Pressure - Low 3-21 3-14 Negative Steamline Pressure Rate - High 3-22

=

j 3-15 Steam Generator Water Level - High-High 3-23 3-16 RWST - Level - Automatic Switchover 3-24 3-17 Reactor Protection System / Engineered Safety Features 3-25 Actuation System Channel Error Allowances 3-18 Overtemperature AT Gain Calculations 3-26 3-19 Overpower AT Gain Calculations 3-28 i

3-20 Steam Generator Level Density Variations 3-29 3-21 AP Measurements Expressed in Flow Units 3-30 1

I iii 45550:10/073186

1 LIST OF TABLES (Continued) i Ig.h.].1 Title P.agt 4-1 Examples of Current STS Setpoints Philosophy 4-10 4-2 Examples of Westinghouse STS Rack Allowance 4-10 a

4-3 Westinghouse Protection System STS Set' point Inputs 4-13' i

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45550:10/073186

i LIST OF ILLUSTRATIONS Figure Title P_4.2.1 4-1 NUREG-0452 Rev. 4 Setpoint Error 4-11

~

Breakdown i

4-2 Westinghouse STS Setpoint Error 4-12 Breakdown 1

I

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45550:10/073186

1.0 INTRODUCTION

In March of 1977, the NRC requested several utilities with Westinghouse i

Nuclear Steam Supply Systems to reply to a series of questions concern-inq the methodology for determining instrument setpoints. A statistical i

methodology was developed in response to those questions with a corres-ponding defense of the technique used in determining the overall i

allowance for each setpoint.

4 The basic underlying assumption used is that several of the error com-l ponents and their parameter assumptions act independently, e.g., [

)+a,c This allows the use of a statistical summation of the various breakdown components instead of a strictly arithmetic sununation. 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 sumation, to form independent 3

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.

In nearly all cases, significant margin exists betwe2n th'e statistical summation and the total allowance.

Section 4.0 notes what the cu,rrent standardized Technical 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 pro-vided noting a recomended set of Technical Specifications using the plant specific data in the statistical approach.

i l

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4555Q:10/062786 1 -1 y

m..

2.0 COM8INATION OF ERROR COMPONENTS s

L 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 I

combined.

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

" square root of the sum of the squares" which has been utilized in other Westinghouse reports. This technique, or other statistical approaches of a I

similar nature, have been used in WCAP-10395II) and WCAP-8567I2).

j WCAP-8567 has been approved by the NRC Staff thus noting the acceptability of statistical techniques for the application requested.

In addition, ANSI, the American Nuclear Society, and the Instrument Society of America approve of the use of probabilistic techniques in determining safetr related I

setpoints(3)(4)

Thus it can be seen that the use of statistical approaches in analysis techniques is widespread.

i i

l (1) Grigsby, J. M., Spier E. M., Tuley, C. R., " Statistical Evaluation of LOCA Heat Source Uncertainty," WCAP-10395 (Proprietary), WCAP-10396

+

(Nor.-Proprietary), November,1983.

(2) Chelemer H., Boman, L. H., and Sharp, D. R., " Improved Thermal Design Procedure," WCAP-8567 (Proprietary), WCAP-8568 (Non-Proprietary), July, 1975.

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

(4) ISA Standard S67.04-1982, "Setpoints for Nuclear Safety-Related Instrumentation Used in Nuclear Power Plants."

9 a

45550:10/073186 2-1

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

2 CSA=EA+{(PMA)2+ PEA)2+(SCA+SMTE+SD)2+(STE)+(SPE)

+(RCA+RMTE+RCSA+RD)+(RTEf}1/2 (Eq. 2.1) where:

Channel Statistical Allowance CSA

=

l PMA Process Measurement Accuracy

=

Primary Element Accuracy PEA

=

Sensor Calibration Accuracy SCA

=

Sensor Measurement and Test Equipment Accuracy SMTE

=

Sensor Drif t SD

=

Sensor Temperature Ef fects STE

=

Sensor Pressure Effects SPE

=

Rack Calibration Accuracy RCA

=

Rack Comparator Setting Accuracy l

RCSA

=

Rack Measurement and Test Equipment Accuracy RMTE

=

Rack Drift RD

=

RTE Rack Temperature Effects

=

Environmental Allowance EA

=

1 As can be seen in Equation 2.1, drif t and calibration accuracy allowances are 1

interactive and thus not independent. The environmental allowance is not necessarily considered interactive with all other parameters, but as an i

additional degree of conservatism is added to the statistical sum.

It should I

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 1

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 probability with a high confidence level. With the exception of Process l

Measurement Accuracy, Rack Drift, and Sensor Drift, all uncertain 1 ties assumed l

l 45550:10/073186 2-2 i

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

2.2 SENSOR ALLOWANCES Five parameters are considered to be sensor allowances, SCA, SMTE SD, STE, and j

SPE (see Table 3-17).

Of these five parameters, two are considered to be statistically independent, STE and SPE, and three are considered interactive SD, SMTE and SCA. STE and SPE are considered to be independent due to the manner in which the instrumentation is checked, i.e., the instrumentation is calibrated and drif t determined under conditions in which pressure and temperature are assumed constant. An example of this would be as follows; assume a sensor is placed in some position in the containment during a refueling outage. After placement, an instrument technician calibrates the sensor. This calibration is performed at ambient pressure and temperature conditions. Some time later with the plant shutdown, an instrument technician checks for sensor drif t.

Using the same technique as for calibrating the sensor, the technician determines whether the sensor has drif ted. The conditions under which this determination is made are again at ambient pressure and temperature conditions. ThusthetemperatuEeandpressurehave no impact on the drif t determination and are, therefore, independent of the drif t allowance.

SD, SMTE and SCA are considered to be interactive for the same reason that STE and SPE are considered independent, i.e., due to the manner in which the instrumentation is checked.

Instrumentation calibration techniques use the same process as determining instrument drif t, that is, the end result of the two is the same. When calibrating a sensor, the sensor output is checked to determine if it is representing accurately the input.

The same is done for a determination of the sensor drif t.

Thus it is impossible to determine the differences between calibration errors and drif t when a sensor is checked the 4555Q:10/073186 2-3 l

second or any subsequent time. Based on this reasoning, SD and SCA have been added to form an independent group which is then factored into Equation 2.1.

^

An example of the impact of this treatment is; for Pressurizer. Water Level-High (sensor parameters only):

a.c SCA

=

SMTE =

SD

=

STE

=

SPE

=

1 i

using Equation 2.1 as written gives a total of;

{(50 + SMTE+SCA)2 + (STE)2 + (SPE)2} 1/2 i

l

[

] * *# = 1,66 percent Assuming no interactive effects for any of the parameters gives the following i

results:

I V2

{ (SCA)2 + (SMTE)2+ (50)2 + (STE)2 + (SPE)2 g (Eq.2.2) j 3+a.c l

= 1,32 percent Thus it can be seen that the approach represented by Equation 2.1 which accounts for interactive parameters results in a more conservative sumation of the allowances.

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45550:10/073;J6 2-4 l

2.3 RACK ALLOWANCES o

Five parameters, as noted by Table 3-17, are considered to be rack allowances.

RCA, RCSA, RMTE, RTE, and RD.

Four of these parameters are considered to be l

interactive (for much the same reason outlined for sensors in 2.2), RCA, RCSA, i

RMTE and RD. When calibrating or determining drif t in the racks for a specific-channel, the processes are performed at essentially constant temperature, i.e., ambient temperature. Because of this, the RTE parameter is considered to be independent of any factors for calibration or drif t.

However, the same cannot be said for the other rack parameters. As noted in 2.2, when calibrating or determining drif t for a channel, the same end result is desired, that is, at what point does the bistable change state. After initial calibration it is not possible to distinguish the difference between a calibration error, rack drif t or a comparator setting error. Based on this logic, these four 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.c RCA

=

RCSA

=

RMTE

=

RTE

=

RD

=

using Equation 2.1 the result is;

{ (RCA + RMTE+RCSA + RD)2 + (RTE)2 }

[

']+a.c = 1.82 percent l

l 4555Q:10/073186 2-5 l

l

i Assuming no interactive of fects for any of the parameters yields the following i

l less conservat ve resu ts; 1/2

{ (RCAf + (RMTE)2+ (RCSA) + (RO)2 + (RTE)2

}

(Eq. 2.3)

]+a,c=1.25 percent

{

t Thus the impact of the use of Equation 2.1 is even greater in the area of rack ef fects than for the sensor. Therefore, accounting for interactive effects in j

the statistical treatment of these allowances insures a conservative result.

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 effects, 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.

2.5 MEASUREMENT AND TEST E0VIPMENT ACCURACY Westinghouse was informed by Plant Vogtle personnel that the equipment used for calibration and functional testing of the transmitters and racks did not OI requirement of test equipment accuracy being 10%

meet the SAME standard

)

or less of the calibration accuracy (referenced in 3.2.6 a or 3.2.7.a.).

This l

then required the inclusion of the accuracy of this equipment in equations 2.1 and 3.1.

Based on information provided by the plant, these additional uncertainties were included in the calculations, as noted on the tables included in this report, with minor impact on the final results. On Table i

3-17, the values for SMTE and RMTE are identified as being included in the calibration accuracy (Note 10 on Table 3-17).

l~

" Process Measurement and Control Terminology."

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

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45550:10/073186 2-6 l

i 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 apprcich. The equation used to determine the margin, and thus the acceptability of the parameter values used, is:

j Margin = (TA)- ( EA+ ((PMA)+(PEA)+(SCA+SMTE+SD)2+(SPE)2+(STE)

+(RCA+RMTE+RCSA+RD)2+(RTE)2 } 1/2 )

(Eq. 3.1) where:

TA = Total Allowance, and all other parameters are as defined for Equation 2.1.

Tables 3-1 through 3-16 provide individual channel breakdown and channel statistical allowance calculations for all protection functions utilizing 7300 process rack equipment. Table 3-17 provides a summary of the pravious 16 4

tables and includes analysis and technical specification values, total allowance and margin.

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 Accuracy The tolerance band containing the highest expected value of the difference between (a) the desired trip point value of a process variable and (b) the i

45550:10/073186 3-1

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 environ-mental 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 1

Synonymous with trip accuracy, but used where the word " trip" does not 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 must fall within this tolerance band.

It includes channel accuracy, accuracy of readout devices, and rack environmental ef fects, but j

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 calibration of modules intermediate in a chain is allowed to compensate for errors in other modules of the chain.

Rack environnmental effects l

45550:10/073186 3-2

are not. included here to avoid duplication due to dual inputs, however, normal environmental effects on field mounted hardware is o

included, l

6.

Sensor Allowable Deviation The accuracy that can be expected in the field.

It includes drif t, temperature ef fects, field calibration and for the case of d/p transmitters, an allowance for the ef fect of static pressure vari-1 ations.

1 The tolerances are as follows:

i a.

Reference (calibration) accuracy - [

]**'C percent unless other data indicates more inaccuracy. This accuracy is the SAMA J

reference accuracy as defined in SAMA standard PMC-20-1-1973III.

b.

Temperature effect - [

]+a,c percent based on a nominal temperature coefficient of [

]+a,c percent /100"F and a maxi-mum assumed change of 50*F.

c.

Pressure effect - usually calibrated out because pressure is

)

constant.

If not constant, nominal [

]+a,c percent is used. Present data indicates a static pressure effect of approximately [

]+a c percent /1000 psi, d.

Orift - change in input-output relationship over a period of time at reference conditions (e.g., constant temperature -

[ ]+a,c percent of snan).

4 e.

Measurement and f est Lquipment (M&tE) - provides for the accuracy of the measurement and test equipment and is combined with the reference accuracy.

(1) Scientific Apparatus Manuf acturers Association, Standard PMC-20-1-1973,

" Process Measurement and Control Terminology."

F 45550:10/073186 3-3 l

e 7.

Rack Allowable Deviation The tolerances are as follows:

^

a.

Rack Calibration Accuracy

~ The accuracy that can be expected during a calibration at reference l

conditions. This accuracy is the SAMA reference accuracy as defined in SAMA standard PMC-20-1-1973III. This includes all modules in a rack and is a total of.[

]+8 C 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 be ignored. All rack modules individually must have a C

reference accuracy within [

] +'J percent.

b.

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

[

]**>C 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.

i c.

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

constant temperature) - 1 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 t

(1) Scientific Apparatus Manufactureres Association, Standard

~

PMC-20-1-1973, " Process Measurement and Control Technology".

l 45550:10/073186 3-4

can be set, within such practical constraints as time and effort expended in making the setting.

The tolerances are as follows:

(a) Fixed setpoint with a single input - [

]+abc percent accuracy. This assumes that comparator nonlinearities are compensated by the setpoint.

(b) Dual input - an additional [

]+abc percent must be added for comparator nonlinearities between two inputs. Total [

]+abc t

percent accuracy.

e.

Measurement and Test Equipment (M&TE) - provides for the accuracy of the measurement and test equipment and is combined with the rack calibration accuracy.

8.

Nominal Safety System Setting The desired setpoint for the variable.

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

9.

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

10. Allowance for 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.

45550:10/073186 3-5

I

12. Total Allowable Setpoint Deviation Same definition as 9, but the difference between 8 and 12 encom-passes 6 and 7 3.3 STATISTICAL METHODOLOGY CONCLUSION The Westinghouse setpoint methodology results in a value with a 95 per-cent probability with a high confidence level. With the exception of Process Measurement Accuracy, Rack Drif t and Sensor Drif t, all uncer-tainties assumed are the extremes of the ranges of the various parameters, i.e., are better than 2a values. Rack Drift and Sensor Drif t are assumed, bascJ on a survey of reported plant LERs, and with Process Measurement Accuracy are considered as conservative values.

f I

4555Q:10/073186 3-6

TABLE 3-1 POWER RANGE, NEUTRON FLUX - HIGH AND LOW SETPOINTS Pa rameter Allowance

• O Process Measurement Accuracy

+.ac

_: a. c

~

Primary Element Accuracy Sensor Calibration

+a,c

[

]

Measurement and Test Equipment Accuracy Sensor Pressure Effects Sensor Temperature Effects

+a,c

[

]

Sensor Drift

+a,c

[

]

Environmental Allowance Rack Calibration Rack Accuracy Measurement and Test Equipment Accuracy Comparator One input Rack Temperature Effects Rack Drift

• In percent span (120 percent Rated Thermal Power)

Channel Statistical Allowance =

+a c 45550:10/073186 3-7

TABLE 3-2 POWER RANGE, NEUTRON FLUX - HIGH POSITIVE RATE AND HIGH NEGATIVE RATE Parameter Allowance

• Prosess Measurement Accuracy

_ Fa, c

+a,c Primary Element Accuracy Sen.s_or Calibration

+

_ a,c Sensor Pressure Effects Sensor Temperature Effects

.+a,c Sensor Drift

_ a,c

+

Environmental Allowance Rack Calibration Rack Accuracy Measurement and Test Equipment Accuracy Comparator One input Rack Temperature Effects Rack Drift

• In percent span (120 percent Rated Thermal Power)

Channel Statistical Allowance =

+a,c 4555Q:10/073186 3-8 i

1

TABLE 3-3 INTERMEDIATE RANGE, NEUTRON FLUX Pa rameter Allowance

• Pro, cess Measurement Accuracy

+

_ a,c

_+a,c Primary Element Accuracy Sensor Calibration

+a,c

[

]

Measurement and Test Equipment Accuracy Sensor Pressure Effects Sensor Temperature Effects

+a,c

[

]

Sensor Drift

+a,c

[

]

Environmental Allowance Rack Calibration Rack Accuracy Measurement and Test Equipment Accuracy Comparator One input Rack Temperature Effects Rack Drift 5 percent of Rated Thermal Power In percent span (conservatively assumed to be 120 percent Rated Thermal Power)

Channel Statistical Allowance =

)~

- +a, c 4555Q:1D/073186 3-9

TABLE 3-4 SOURCE RANGE, NEUTRON FLUX Allowance

• Pa rameter Process Measurement Accuracy

_ -a, c i

+a,c Primary Element Accuracy Sensor Calibration

+a,c

[

]

Measurement and Test Equipment Accuracy Sensor Pressure Effects Sensor Temperature Effects

+a,c

[

-]

Sensor Orift

+a,c

[

]

Environmental Allowance Rack Calibration Rack Accuracy Measurement and Test Equipment Accuracy Comparator One input Rack Temperature Effects Rack Drift 3 x 104 cps In percent span (1 x 106 counts per second)

Channel Statistical Allowance =

+a,c l

i 45550:10/073186 3-10

TABLE 3-5 OVERTEMPERATURE AT Pa rameter Allowance

• Pro, cess Measurement Accuracy

+a,c

_ +a,c i

Primary Element Accuracy Sen_sor Calibration

,+a,c Measurement & Test Equipment

+a,c E

]

Sensor Pressure Effects Sensor Temperature Ef fects b

3

,c

+a Sensor Drif t

+a,c Environmental ~ Allowance 7300 Process Equipment Seismic Allowance AI- [(0.5% AI) (al gain)* + 0.87% AI ](100)/150 Pressure - (0.5% of pressure span)*

l Rack Calibration

+

_ a,c j

I Mea _surement and Test Equipment

_ +a,c

~

4555Q:lD/073186 3-11

TABLE 3-5 (Continued)

OVERTEMPERATURE AT Allowance

• Parameter a.C

_ +a,c

+

Total Rack Calibrtion Accuracy I

Comparator AT Tavg Rack Temperature Effects dack Drift AT T

avg See table 3-18 for gain calculations

• • In 5 AT span, AT - 89.l*F, Tavg - 100*F, Pressure 800 psi, Power - 150%

RTP, AI - +60% AI

+ Number of Hot Leg RTDs used

++ Number of Cold Leg RTDs used Channel Statistical Allowance =

+

_ a,c t

l 45550:10/073186 3-12

TABLE 3-6 OVERPOWER AT Pa rameter Allowance

• Process Measurement Accuracy

_ +a c

[

]+a c i

Primary Element Accuracy Sensor Calibration

[

]+a,c Sensor Pressure Effects Sensor Temperature Effects Sensor Drift

[

]+a,c Environmental Allowance Rack Calibration

+a c Mea _surement and Test Equipment. +a,c

. Tot.al Rack Calibration Accuracy

"+a.c Comparator l

AT Tavg I

t I

4555Q:1D/073186 3-13

TABLE 3-6 (Continued)

DVERPOWER AT Allowance

• Parameter

- +a c Channel Temperature Effects Rack Drift AT Tavg In % AT span AT = 89.1

'F, Tavg - 100*F, Power - 150% RTP

• • See table 3-19 for gain calculations

+ Number of Hot Leg RTDs used

++ Number of Cold Leg RTDs used

+a,c Channel Statistical Allowance =

l l

l l

45550:10/073186 3-14

1 TABLE 3-7 PRESSURIZER PRESSURE - LOW AND HIGH, REACTOR TRIPS i

Pa rameter Allowance

• _ta.c Process Measurement Accuracy Primary Element Accuracy Sensor Calibration Measurement and Test Equipment Accuracy Sensor Pressure Effects Sensor Temperature E.f fects Sensor Drift Environmental Allowance Rack Calibration Rack Accuracy Measurement and Test Equipment Accuracy Comparator One input l

Rack Temperature Effects Rack Drift In percent span (800 psi)

Channel Statistical Allowance =

+a,c i

45550:10/073186 3-15

TABLE 3-8 PRESSURIZER WATER LEVEL - HIGH Pa rameter Allowance *

+a,c Process Measurement Accuracy

[

)+a.c Primary Element Accuracy Sensor Calibration Measurement and Test Equipment Accuracy Sensor Pressure Effects Sensor Temperature Effects Sensor Drif t Environmental Allowance Rack Calibration Rack Accuracy Measurement and Test Equipment Accuracy Comparator One input i

Rack Temperature Effects j

Rack Drift In percent span (100 percent span)

Channel Statistical Allowance =

+

_ a,c 45550:10/073186 3-16

TABLE 3-9 LOSS OF FLOW Parameter Allowance

• t

_. a. c Process Measurement Accuracy [

]+a,c Primary Element Accuracy

[

]+a,c Sensor Calibration

[

]+a,c Sensor Pressure Effects

[

j+a,c Sensor Temperature Efficts

[

j+a,c Sensor Drif t [

]+a,c Environmental Allowance Rack Calibration Rack Accuracy [

]+a,c Measurement and Test Equipment Allowance [

j+a,c Comparator One input [

]+a,c Rack Temperature effects [

]+a,c Rack Drift 1.0 percent AP Span In percent flow span (120 percent Thermal Design Flow)

• • See Table 3-21 for explanation Channel Statistical Allowance =

_+a,c 455S0:10/080186 3-17

TABLE 3-10 STEAM GENERATOR WATER LEVEL - LOW-LOW Parameter Allowance *

+a.C Process Measurement Accuracy Density variations with load due to changes in recirculation **

Primary Element Accuracy Sensor Calibration Measurement and Test Equipment Accuracy Sensor Pressure Effects Sensor Temperature Effects Sensor Drif t En ironmental ljgwance Reference Leg Heatup

~

Rack Calibration Rack Accuracy Measurement and Test Equipment Accuracy Compa rator One input Rack Temperature Effects Rack Drift s'

/

/

In percent span (100 percent span)

• • See Table 3-20 for explanation Channel Statistical Allowance =

+

_ a,c 45550:10/080186 3-18

TABLE 3-11 CONTAINMENT PRESSURE - HIGH-1, HIGH-2, HIGH-3 Pa rameter Allowance *

+

_ a,c Process Measurement Accuracy Primary Element Accuracy Sensor Calibration Measurement and Test Equipment Accuracy Sensor Pressure Effects Sensor Temperature Effects Sensor Drift Environmental Allowance Rack Calibration Rack Accuracy Measurement and Test Equipment Accuracy Comparator One input Rack Temperature Effects Rack Drift In percent span (75 psig)

Channel Statistical Allowance =

+a c l

4555Q:10/080186 3-19

~ _ _ _ _. _

1 1

TABLE 3-12 PRESSURIZER PRESSURE LOW, SAFETY INJECTION 4

Pa rameter Allowance

• _fa,C Process Neasurement Accuracy Primary Element Accuracy Sensor Calibration Measurement and Test Equipment Accuracy Sensor Pressure Effects Sensor Temperature Effects Sensor Drift Environmental Allowance Rack Calibration Rack Accuracy Measurement and Test Equipment Accuracy Comparator One input Rack Temperature Effects Rack Drift In percent span (800 psi)

Channel Statistical Allowance =

-Fa, c l

[

4555Q:1D/080186 3-20

TABLE 3-13 STEAMLINE PRESSURE - LOW Pa rameter Allowance

• i fa.C Process Measurement Accuracy Primary Element Accuracy Sensor Calibration Measurement and Test Equipment Accuracy Sensor Pressure Effects j

Sensor Temperature Effects Sensor Drift Environmental Allowance Rack Calibration Rack Accuracy Measurement and Test Equipment Accuracy Comparator One input Rack Temperature Effects Rack Drift In percent span (1300 psig)

Channel Statistical Allowance =

~

-&a,c 4

a 45550:lD/080186 3-21

TABLE 3-14 NEGATIVE STEAMLINE PRESSURE RATE 'HIGH Parameter Allowance *

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

- +a,c Sensor Pressure Effects Sensor Temperature Effects

- +a.c 1

Sensor Drif t

- +a,c Environmental 1.ilowance Rack Calibration Rack Accuracy Measurement and Test Equipment Allowance Comparator One input Rack Temperature Effects i

Rack Drift 1

In percent span (1300 psig)

Channel Statistical Allowance =

+a,c

~

l l

l 45550:10/080186 3-22

+

~

r m

TABLE 3-15 e

STEAM GENERATOR WATER LEVEL - HIGH-HIGH Pa rameter Allowance

• Process Measurement Accuracy

+a,c Density Variations With Load Due to Changes in Recirculation **

Primary Element Accuracy Sensor Calibration Measurement and Test Equipment Allowances Sensor Pressure Effects Sensor Temperature Effects Sensor Drift Environmental Allowance Rack Calibration Rack Accuracy Measurement and Test Equipment Allowances Comparator One input Rack Temperature Effects Rack Drift In percent span (100 percent span)

• • See Table 3-20 for explanation Channel Statistical Allowance =

+a,c a

45550:10/080186 3-23

\\

TABLE 3-16 RWST LEVEL - LOW, AUTOMATIC SWITCHOVER Allowance

• Parameter

~

Process Measurement Accuracy Primary ~ Element Accuracy Sensor Calibration Measurement and Test Equipment Accuracy Sensor Pressure Effects Sensor Temperature Effects Sensor Drift Environmental Allowance Rack Calibration Rack Accuracy Measurement and Test Equipment Accuracy Comparator One Input Rack Temperature Effects Rack Drift i

i

• In percent span (100 percent span)

Channel Statistical Allowance =

+a,c

=

45550:10/080186 3-24

L NOTFS FOR I. ALL V ALUES IN PERCENT SPAN.

10. INCLUDES ALLOWANCE FOR MEASUREMENT AND TEST EQUIPMENT UN3

2. AS NOTED IN TABLE 15.0.6-1 0F FSAR l l.c 3****

^

3. AS NO)fD IN IABLES 2 2-1 AND 3.3-4 0F 12.C 3****

PL ANT TECHNIC AL SPECIFIC ATIONS.

13.C 3'***

e...

e...

g4 L

J L

J r

5. NOT USED IN S AFETY ANALYSIS 15.c 3"

6. AS NOTED IN FIGURE 15.0.3-1 0F FSAR

16. INCORE/EXCORE f(el) COMPARISON AS NOTED IN

7. AS NOTED IN TABLE 2 2-1 NOTE 2 T ABLE 4.3-1 0F PL ANT TECHNICAL SPECIFICAll0NS OF PLANT TECHNICAL SPECIFICAil0NS 17.C 3****

8. AS NOTED IN TABLE 2 2-1 NOTE 4 0F PLANT TECHNICAL SPECIFICATIONS

9. NOT NOTED IN TABLE 15.0.6-1 0F FSAR BUT USED IN SAFETY ANALYSIS V

REACTOR PROTECTION SY@

ACTUAil0N SYSTEN V03 4-SENSOR

=

L 2_.

3 1

3

_A _.<

PROCESS PRIMARY CAtl8AAfton PRES $URE IEMPERATURE DRIFT C[

PR0fECTION CHANNEL NEASUREMENT ELEMENI ACCURACT EFfLCIS EFFECIS (Il AccuRACT ACCURAGY (1)

(Il (1)

(l)

(Il i

POWER R ANGE. Neuf ROM FLUM = HICH SETPOINI 2

POWER R ANGE. NEUTROM FLUX - LOW SEIP0lNT.

3 P0hER RANGE. NEufRON FLUM - HlCH POSlilVE RATE 4

POWER RANCE. NEUIRON FLUX - HICH NEGAilVE RAIE S JNIERMEDI AIE, RANCE.,NEUTR_0N NUN 4

SOURCE RANCE. NEUTRON FLUE T

OVERTEMPERATURE *T si CHANNEL (RdF RTO) 8 TAVG CMANNEL (RdF Rion s

10 PRESSURIZER PRESSURE CHANNEL 11 f(all CHANNEL 12 CVERP0wER at af CHANNEL (RdF RIOD q

13 j

14 TAVC CHANNEL (RdF RIO) is PRESSelrER PRgset_- LOL,,REAC{pR,,[ RIP (veritee6 No!U sel j

to Pu SSURlrER PRES $uRE - Hlon (ve,ei,e6 xailleen q

IT PRESSUR1rER WATER tEVEL - MicH (v..it,e6 xalH+el q

to LOSS Or Flow (Ve,i t e6 x.i t t.,9

,y le STEAn cENERATOR WATER LEVEL - Low-Low (H (verstee6 Xeetteel y

4 20 uN0ERv0LI Act - RCP (0.E. NCV Relegl

,y 21 UNDERFREQUENCT - PCP (l.i.E. Releyl

_j 9

,)

22 CONT AINMENT PMSSURE ltlGH -l_, (8, j ee,Ne s g ?97),,, _

23 PRESSURl!ER PRESSURE LOW - $1 (Ver s tren yes tteet 24 STEAM.lNE PRES $URE-tow tiebec. Versteen Xeettecel 2S CONT AINMENT PRESSURE HIGH-2 (Serie. Napiteel J

e 26 CONTAINMENI PRESSURE HIGH-3 (Beets. Nes tjert 21 NEGAnK STEAn PRESSURE RATE - H}G1,({g6 gg,Vggttre6 Neeltecel J

9 2s STEAn CENERATOR WAftR tEvEL HicH - HlcM (ve,lte.6 ze gi.,5

]

2e Rwn,pvEt - tow. Auf 0nATIC_SwliCH0vER (ve,it,e6 moitie,i

_q

>0 4

lisJts2s 24-AUG-06 L

FABLE 3-IPREV.

I PAGE 3-25 JRTAINTIES 18.c 3*'"

3...e ggg 20 d

AyEM*

c#

,BLE 3-IP gygNSNO 3N/ ENGINEERED SAFETY FEATURES CAfd pHANNEL ERROR ALLOWANCES hpCIW 1E STA110N P _ _.-

-. -. ----lieSIRur1ENT R ACK ll_

_-.. l]

13

.11

. Il -.

II.

R 1 _..__ 19 _. l l__

3lRONMENI AL Call 8RAll0N CONP AR ATOR IEr1PERATURE ORIFI S AFEf f STS SIS 10fAL CrAMkEL

'ttARGIN 3LOWAhCE ACCUNACT SEfitNG LFFECIS (1)

AN AL Y $ t S ALL OW A8t E IRIP ALLOWAMCC, SI AllSitCAL til til til ACCUHACT til Linil V AL UE SEfP0tNI til ALLOWAMCE (t )

(2)

(3)

(3) til 1

t.0 IIO3 RIP I:1_.33 RTP 1093 RTP 10 352 RTP 27.32 RTP 25% RTP 2

0.5 151 6.31 RIP 5 01 RIP 3

0.5 6 9% RTP (9) 6.3% RTP 5 01 RTP 4

4.2

($3 31.12 RTP 252 RIP 5

3.0 (5) 1.4E*05 CPS 1 0E*05 CPS 4

F l.0 7

9.0 8

f... tee. (6)

F..stee. (F) 2 5%.i ggy., h3.ti..

(1) 9 10

! II I

12 1.0

~i l

i3 re..ii.. (6i r..eti.. Een.2 42.J.ee..

t...ti..

tes 0.0 14 l 85

.0 is35..!

_ 1959,, !.__

.,Jo60_e.!n 1.0 2410 pe e g (2) 2395 pese

_ pe,5_ggsg_,

( 16

.0 (Si s3.st.,..

e2 _.g33,,,_

l ir 0.6 e r. 02 4....._

e s. 4% f..j e.___ __

30 4.....__.

I is i.0 Or.,...

ir.ex..,..

is.5.,:...

l is 2.0 e3e4 v0Lis s4et v0Lis 3600 votis j 20 22 57.0 HZ

_ 57.1 HZ SF.3 HZ l 21 I0,,5J ag!g(9) 4.4 f f!t _.-.

.. _3 5. g. ! g _

, j22 10 tT45 f *!g (9) 1960 pe! L, _,,,,

,,1870. tut _

f 23

=.

l.0 4t6 g3gt9L 570 e.J3 505 g3te

! 24 t.0_

16.8 ogig 15.4 eess 14.5 eels l 25 f.0 23.8 gy.!g__

22.4 seee

21. 5 _gy lg.,_,.

( 26 '

1.0 153 s-12 M s-100 ge L

' 27 t.0 8 M t y e._

19.92.f..

78.0% eso.

28 t.0 32.5% eje.

34.3 e19 34.02 es o.

• s

..--~g 30 8l,I 06Q b % -o

.M

1 i

TABLE 3-18 OVERTEMPERATURE AT GAIN CALCULATIONS i e The equation for Overtemperature AT is:

1 + t)S

)

Overtemperature AT (j

,T

3) ()

3) 5 2

,,3 1+T S 3

AT, { K) -KI 4}

(I + '6 I ~ ') ~ f1 (AI)}

2l+T S S

3 S

[

]+a,c K1 (max)

=

1.10 (Technical Specification Trip Setpoint)

K1 (nominal)

=

0.012/*F K2

=

l K3 0.00056/ psi

=

618.2*F Vessel TH

=

Vessel TC 558.8'F i

=

0.83% FP AI/% al Positive AI gain

=

l

+a.c AT span =

l Process Measurement Accuracy AT

+a,c PMA =

=

AI

+

_ a,c PMA1 =

=

=

PMA2 =

=

=

r 45550:10/080186 3-26 l

,9.-

w w

r=

TABLE 3-18 (Continued)

OVERTEMPERATURE AT GAIN CALCULATIONS Pressure Channel Uncertainties

.+a.c Pressure Gain =

=

+

_ a,c l

SCA

=

M&TE =

=

3 STE

=

=

E SD

=

M

~

Total Allowance

+

. a,c TA =

=

i I

I I

i 45550:10/080186 3-27

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

1+TS Overpower AT ()

j ) ( j,3

3) 5

,,23

,3 T S I

UI I

AT, { K4 - K,()

3) ()

l+T 5 2

+ '6S 6

,T 6

[

f K4 (max)

=

1.089 (Technical Specification Trip Setpoint)

K4 (nominal)

=

0.02 K

=

S 0.0013 K

=

6 Vessel T 618.2*F

=

H Vessel T 558.8'F

=

C

~

~

AT span,=

=

Process Measurement Accuracy AT

- +a,C PMA =

Total Allowance

.,+a c i

TA =

I J

9 a

45550:10/080186 3-28

.=

TABLE 3-20 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 calibra-tion 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 from plant to plant. These errors are only from density changes and do not reflect channel accuracies, trip accuracies or indi-cated accuracies which has been defined as a AP measurement only.II)

INDICATED LEVEL (50 Percent Power Calibration) 10 70' 100 0

+

percent percent percent percent

- +a,c Actual Level O Percent Power Actual Level 100 Percent Power

~

(1) Miller, R.

B., " Accuracy Analysis for Protection / Safeguards and Selected Control Channels" WCAP-8108 (Proprietary), March 1973.

4555Q:10/080186 3-29

TABLE 3-21 AP MEASUREMENTS EXPRESSED IN FLOW UNITS The AP accuracy expressed as percent of span of the transmitter applies throughout the measured span, i.e.,

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:

2 F = AP where N = nominal flow N

2f 3F = BAP y y y

BAP thus BF N " 2F N'

~

• N Error at a point (not in percent) is:

aF" BAP" BAPN Eq. 3-21.2

=

=

p 2AP" N

2FN and AP" F"2 where max = maximum flow Eq. 3-21.3

=

3p 2

max Fmx and the transmitter AP error is:

3AP" x 100 = percent error (full scale AP)

Eq. 3-21.4 3p max 0F AP (percent error (FS AP))

p 2

N max 100 percent error (FS AP) (Fmax)

F 2

2x100 N

2AP max [F N

N

)

Fmax Eq. 3-21.5 4555Q:10/080186 3-30

Error in flow units is:

2 F

Dercent error (FS AP) max)

Eq. 3-21.6 0FN=FN 2x100 F

N Error in percent nominal flow is:

2 OF F

N Dercent error (FS AH

( max)

Eq. 3-21.7 x 100

=

N N

Error in percent full span is:

2 3F" FN (percent error (FS AP))

F x 100 x 100

=

p F

x 2 x 100 F

max max N

Dercent error (FS AH ( max )

Eq. 3-21.8

~

N Equation 3-21.8 is used to express errors in percent full span in this document.

I 45550:10/080186 3-31

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 drif t.

The intent of this format is to reduce the number of Licensee Event Reports (LERs) in the area of instrumenta-tien setpoint drif t.

It appears that this approach has been successful in achieving its goal. However, the approach utilized is fairly sim-plistic and does not recognize how setpoint calibrations and verifica-tions are performed in the plant.

In fact, this two column approach forces the plant to take a double penalty in the area of calibration error. As noted in Figure 4-1, the plant must allow for calibration error below the STS Trip Setpoint, in addition to the allowance assumed in the various accident analyses, if f ull utilization of the rack drif t is wanted. This is due, as noted in 2.2, to the fact that calibration error cannot. be distinguished f rom rack drif t af ter an initial calibra-

' tion. Thus, the plant is lef t with two choices; 1) to assume a rack drift value less than that allowed for in the analyses (actual RD =

assumed RD-RCA) or, 2) penalize the operation of the plant (by increas-I ing the possibility of a spurious trip) by lowering the nominal trip 1

i setpoint into the operating margin.

The use of the statistical summation technique described in Section 2 of this report allows for a natural extension of the two column approach.

This extension recognizes the calibration / verification techniques used in the plants and allows for a more flexible approach in reporting LERs. Also of significant benefit to the plant is the incorporation of sensor drif t parameters on an 18 month basis (or more of ten if necessary).

4 45550:1D/080186, 4-1

~

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 specification 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 effects.

4.2.1 RACK ALLOWANCE The first item that will be covered is the interactive ef fects. When an instrument technician looks for rack drif t he is seeing more than that.

This intecaction has been noted several times and is handled in Equations 2.1 and 3.1 (the arithmetic summation of rack drif t, rack comparator setting accuracy, rack measurement and test equipment accuracy, and rack calibration accuracy for rack effects and sensor drif t, sensor measurement and test equipment accuracy, and sensor calibration accuracy for sensor ef fects). To provide a conservative

" trigger value", the difference between the STS trip setpoint and the STS allowable value is determined by two methods. The first is simply the values used in the statistical calculation, T =(RD + RMTE + RCA +

j RCSA). The second extracts these values from the calculations and compares the remaining numbers statistically against the total allowance as follows:

[

l

[

]+a c (Eq. 4.1) where:

Rack trigger value T

=

2 (PMA) + (PEA) + (SPE)2 + (STE) + (RTE)2 A

=

45550:10/080186 4-2 e

S = (SCA + SMTE + SD)

EA, TA and all other parameters are as defined for Equations 2.1 and 3.1.

The smaller of the trigger valuet should be used for comparison with the "as measured" (RD + RCA + RMTE + RCSA) value. As long as the "as mea-sured" value is sma'ller, the channel is well within the accuracy allowance.

If the "as 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 ef fects. The same approach is i

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 summation requires a somewhat more complicated approach. This method-ology; as demonstrated in Section 4.2.3, Implementation, can be used quite readily by any operator whose plant's setpoints are based.on sta-tistical summation. The methodology is based on the use of the follow-ing equation.

45550:10/080186 4-3

A + R + S + EA 5 TA.

(Eq. 4.2) where:

the "as measured rack value" (RD + RCA + RMTE + RCSA)

R

=

the "as measured sensor value" (SD + SCA + SMTE)

S

=

and all other parameters are as defined in Ecuation 4.1.

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

Z + R + S S TA (Eq. 4.3) where:

1/2

~

Z = {A}

+ EA 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 and verified every 18 months.

l 4.2.3 IMPLEMENTATION OF THE WESTINGHOUSE SETPOINT METHODOLOGY Implementation of this methodology is reasonably straight forward, Appendix A provides a text and tables for use in the Technical Specifications. An example of how the specification would be used for the Pressurizer Water Level - High reactor trip is as follows.

Every 31 days, as required by Table 4.3-1 of NUREG-0452, Revision 4, a f

functional test would be performed on the channels of this trip func-tion. During this test the bistable trip setpoint would be determined 4555Q:lD/080186 4-4 l

I

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 necessary by the plant staff. The Allowable Value is determined by Equation 4.1 as follows:

1/2 T = TA - ({(A) + (S)2}

+ EA) where:

TA 5 percent (an assumed value)

=

+a,C A

=

(S)

=

EA

=

T

=

=

=

=

However, since only 1.8 percent i's assumed for T in the various analy-ses, that value will be used as the " trigger value".

The lowest of two values is used for the " trigger value"; either the value for T assumed in the analyses or the value calculated by Equation 4.1.

45550:10/080186 4-5

-p..

d Now assume that one bistable has "drif ted" more than that allowed by the STS for 31 day surveillance.

According to ACTION statement "A", the plant staff 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) = 5.0.

Assume that the "as measured" rack setpoint value is 2.25 percent low and the "as measured" sensor value is 1.5 percent. Equation 2.2-1 looks like:

I Z + R + S $ TA 2.18.+ 2.25 + 1.5 5 5.0 5.9 5 5.0 As can be seen, 5.9 percent is not less than 5.0 percent thus, the plant staf f must follow ACTION statement "B" (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 + S would also be greater than 5.0 i

percent.

In fact, almost anytime the "as measured" value for rack drift

^

is greater than T (the " trigger value"), use of S in Table 2.2-1 will result in the sum of I + R + S being greater than TA and requiring the reporting of the case to the NRC.

1 If the sum of R + S was about one percent less, e.g., R = 2.0 percent, S = 0.75 percent thus, R + 5 = 2.75 percent, then the sum of I + R + S would be less than 5 percent. Under this condition, the plant staff l

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.

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

there is a slight disagreement between Westinghouse proposed methodology f

and NRC approved methodology. Westinghouse believes that T should be either:

i i

45550:10/080186 4-6

T12 = (RCA) + RMTE)+ RCSA) + RD)) + (RCA2 + RMTE + RCSA2 + RD )

(Eq. 4.4) 2 2

22 = TA -({A + (S))2 + (S ) )

+ EA)

(Eq. 4.5)

T 2

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:

T = {(RCA) + RMTE)+ RCSA) + RD))2 + (RCA2+ "

2+ " A2+ D) 3 2

or (Eq. 4.6)

Equation 4.5 as described above.

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

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

_+a,c TA

=

A

=

(S))2 (S )

2 RCA) + RMTEj + RCSA) + RD)

- a,c

=

RCA2 + RMTE2 + RCSA2+RD2

+a,c EA

=

i i

45550:10/080186 4-7

l Using Equation 4.4;

+

_ a,c T

12 Using Equation 4.5;

+a,c 22 Using Equation 4.6;

+a,c T

3

~

The value of T used is from Equation 4.5.

In this document Equations 4.5 and 4.6, whichever results in the smaller value is used for multiple channel input functions to remain consistent with current NRC approved methodologies. Table 4-3 notes the values of TA, A, S, T, and Z for all protection functions and is utilized in the determination of the Allowable Values noted in Appendix A.

l Table 4.3-1 also requires that a calibration be performed every refuel-ing (approximately 18 months). To satisfy this requirement, the plant staff would determine the bistable trip setpoint (thus, determining the "as measured" rack 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 staff 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 flexibil-ity and yet remains within the allowances accounted for in the various 4555Q:10/080186 4-8

accident analyses.

In addition, the methodology allows for a sensor drif t factor and an increased rack drif t factor. These two gains should significantly reduce the problems associated with channel drift and j

thus, decrease the number of LERs while allowing plant operation in a safe manner.

4 1

l f

~

j 4555Q:10/080186 4-9 I

p.

l-TABLE 4-1 e

EXAMPLES OF CURRENT STS SETPOINT PHILOSOPHY Power Range Pressurizer Neutron Flux - High Pressure - High J

Safety Analysis Limit 118 percent

- 2410 psig STS Allowable Value 110 percent 2395 psig STS Trip Setpoint 109 percent 2385 psig TABLE 4-2 i

EXAMPLES OF WESTINGHOUSE STS RACK ALLOWANCE Power Range Pressurizer Neutron Flux - High Pressure - High i

l Safety Analysis Limit 118 percent 2410 psig STS Allowable Value 111'.2 percent 2396 psig (Trigger Value)

STS Trip Setpoint 109 percent 2385 psig 1

45550:1D/080186 4-10

-,.m-

.y

I Safety Analysis Limit s

l lProcess Measurement Accuracy l

l, Primary Element Accuracy Sensor Temperature Effects Sensor Pressure Effects i

l

Sensor Calibration Accuracy J

Sensor Measurement and Test Equipment Accuracy J

l' Sensor Drif t 1

o l Environmental Allowance j

J STS Allowable Value

'll Rack Temperature Effects l

l

Rack Comparator Setting Accuracy i

lJ

, Rack Calibration Accuracy JRack Measurement and Test Equipment hAccuracy 1

> Rack Drift l

STS Trip Setpoint l

l Actual Calibration Setpoint Figure 4-1 NUREG-0452 Rev. 4 Setpoint Error Breakdown l

45550:10/080186 4-11

Safety Analysis Limit

> Process Measurement Accuracy

~

> Primary Element Accuracy

, Sensor Temperature Ef fects

),SensorPressureEffects Sensor Calibration Accuracy

{SensorMeasurementandTestEquipment

) Accuracy h> Sensor Drift Environmental Allowance

)RackTemperatureEffects i

STS Allowable Value Rack Comparator Setting Accuracy

~

Rack Calibration Accuracy

{RackMeasurementandTestEquipment jAccuracy i

l STS Trip Setpoint l

Figure 4-2 Westinghouse STS Setpoint Error Breakdown 4555Q:10/080186 4-12

r l

[

VM L

c L

L

?

L o

WESTINGHOUSE PROTECT 10N V0GTLQ 1

l IABLE 4-3

-l l

PROTECTION CHANNEL TOTAL

)

l ALLOWANCE (9)

(9) 1 (T A)

(9)

(A)

(1)

-(S)

(2)

(I)

POWER RANCE. NEUIRON FLUX HICH SEfPOINI 7.5

_i***

0.0 t fQWER RANCE. NEUIRON FLU.t-LOW SEfP0lNT B.3 O.0 i

POWER RANGE. NEUIRON FLUX-HICH POSlflVE RATE 1.6 0.0 l

POWER RANCE. NEUIRON FLUX-HICH NEG AfivE RATE I.6 0.0 s

INTERME01 ATE RANCE. NEUfRON FLUX 17.0 0.0 6

SOURCE RANCE. NEUIRON FLUX 17.0 0.0 DVERfEMPERATURE af 6.6 1.95*0.50 i

DVERPOWER *Y 4.9 f.95 I

PRESSURIZER PRESSURE-LOW. REACIOR TRIP 3.1 f.67 i

PRESSURifER PRESSURE-HICH 3.1 1.67 PRESSURIZER WATER LEVEL *HICH B.0 1,67 l

LOSS OF FLOW 2.5 0.60 l-1 STE AM CENER Af 0R WATER LEVEL-LOW-LOW (F) 18.5 1.67 J

I UNDERVOLTACE - RCP 6.0 0.0 l

h l

i UNDERFREQUENCY - RCP 3.3 0.0 I

CONTAINNENT PRESSURE-HICH-l 3.1 f.67 P

PRESSURIZER PRESSURE LOW-S. I.

13.0 1.67 1

l l

SfEAftlNE PRESSURE - LOW 13.0 1.67 h

')

CONTAINMENT PRESSURE-HICH - 2 3.0 f.67

)

CONTAINNENT PRESSU9E-HICH - 3 3.1 f.67 I

JECAflVE STEAM PRESSURE RATE - HICH 3.0 0.0 2

STE AM CENER ATOR WATER LEVEL HICH - HICH 5,1 1.67 I

I'

)

RWSY LEVEL - LOW. Auf0MAftC SWifCHOVER 3.5 1.67 NOIESl J

(I)

A=

(PMA) e. (pg A3 s. (SPEI * * (ST El 8 + (RIE) 8 (71 E 3'J

(! *

(2) S* SCA+SNIE*SO (8) AS NOTED IN NOTE I 0F TABLE 2.2-1 0F IECHNI M l+

(3) is= RCA*RMTE*RCSA+RD OR la

• I A-(( A* (C)'l + /s +E A)

(9) ALL V ALUES IN PERCENT SPAN l

(10) AS N0 LED IN NOIE 3 0F TABLE 2.2*1 0F IECHNIC, OR is E (RC As *RMf Es +RCS Ai + RDe l * * (RC A + RMTE s *RCS As

• RDal ' )' /8 a

(4) Za (Al+/a e gA (5) TAiG-100'F aP - 800 PSI

• = 120 t RIP

• T - 89.I'F al - e601 al

]

(6) iAVG - 100'F aP - 800 PSI e - 120% RTP af - 89.I'F i

d e

u 1

e i

I l

l

^%

1 n -. _.. -

fla28s30 24-AUC-85 SYSTEM STS SEIPOINT INPUTS

. STATION INSTRUMENT STS TRIP STS ALLOWABLE MAXIMUM (9)

(9)

SPAN SETPOINT VALUE VALUE (3)

(Z)

(4)

(7) 1 92 4.56 I20% RIP 109% RIP 111.3% RTP

~

i f.e2 4.56 120% RIP 25% RTP 27.3% RTP 2

1 pf 0.50 I20% RTP 5.0% RTP 6.3% RTP 3

MA 0.50 120% RTP 5.0% RTP 6.3% RIP 4

3.12 8.41 120% RTP 25% RTP 3t.tX RTP 3.92 1 0.01 f.OE*06 CPS 1 0E*05 CPS

1. 4E*05 CPS 6

3d3_

3.37 (5)

FUNCil0N (8i FUNCTION (8) + 2.5% of SP AN 7

MI l.54 (61 FUNCfl0N (IL FUNCfl0N (10) + 2. 4% a f SP AN 8

1.31 0.71 800 PSI 1960 PSIC 1950 PSIC 9

f.31 0.71 800 PSI 2385 PSIC 2395 PSIC (0

1 32 2.18 100% SPAN 92% SPAN 93.9% SPAN ff Q 13 1.87 f20% DESIGN FLOW 90% FLOW 89.4% FLOW 12 0.75 17.tB 100% SPAN 18.5% SPAN

[7,8% SPAN 13 M,0 0.58 3600 VOLIS 9600 VOLfS 948I VOLfS 14 2.30 0.50 9.0 NZ 57.3 HZ 57.t HZ 15 M3 0.71 75 PSIC

3. 5 PSR_

4.4 PSIC 16 LII 10.71 800 PSI 1870 PSIC 1860 PSIC 17 1.19 ID.71 1300 PSI 585 PSIC 570 PSIC 18 Mi 0.71 75 PSIC 14.5 PSIC 15.4 PSIC (9

.L2.8 0.71 75 PSIC 21.5 PSIC 22.4 PSIC 20

_l.23.3

0. 5')

f300 PSI

-100 PSI

-t25 PS1 2f M1 2.ta 100% SPAN 78.0% SPAN 79.9% SPAN 22 23 M9 0.71 100% SPAN 36.0% SPAN 34.3% SPAN SPECIFICATIONS L SPECIFICAfl0NS.

W oo90;SGr o>

o g STM REV. I FOR INTERNAL PLANT USE ONLY g,ygD dso Mgilabic v" Card 4pertG50 m

APPENDIX A SAMPLE V0GTLE SETPOINT TECHNICAL SPECIFICATIONS l

45550:10/080186 A-1

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 consistent with the Trip Setpoint values shown in Table 2.2-1.

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

ACTION:

With a Reactor Trip System Instrumentation or Interlock Setpoint a.

less conservative than the value shown in the Trip Setpoint column but more conservatise 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, within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> either:

1.

Determine that Equation 2.2-1 was satisfied for the af fected channel and adjust the setpoint consistent with the Trip Setpoint value of Table 2.2-1, or 2.

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

EQUATION 2.2-1 Z + R + S < TA where:

The value for column Z of Table 2.2-1 for the af fected channel, Z

=

the "as measured" value (in percent span) of rack error for the R

=

affected channel, either the "as measured" value (in percent span) of the sensor S

=

error, or the value in column S (Sensor Error) of Table 2.2-1 for the affected channel, and the value from column TA (Total Allowance in % of span) of Table TA

=

2.2-1 for the af fected channel.

l 45550:10/070786 A-2 f

1

TABLE 2.2-1 REACTOR TRIP SYSTEM INSTRUMENTATION TRIP SETPOINTS TOTAL SENSOR ERROR FUNCTIONAL UNIT ALLOWANCE (TA)

Z S

TRIP SETPOINT ALLOWABLE VALUE 1.

Manual Reactor Trip N.A.

N.A.

N.A.

N.A.

N.A.

2.

Power Range, Neutron Flux a.

High Setpoint 7.5 4.56

-0

$109% of RTP*

$111.3% of RTP*

b.

Low Setpoint 8.3 4.56 0

$25% of RTP*

$27.3% of RTP*

3.

Power Range, Neutron Flux, 1.6 0.50 0

55% of RTP* with 56.3% of RTP* with High Positive Rate a time constant a time constant 12 seconds 12 seconds 4.

Power Range, Neutron Flux, 1.6 0.50 0

15% of RTP* with 16.3% of RTP* with t

High Negative Rate a time constant a time constant 22 seconds 22 seconds 5.

Intermediate Range, 17.0 8.41 0

$25% of RTP*

$31.1% of RTP*

Neutron Flux 6.

Source Range, Neutron Flux 17.0 10.01 0

$105 cps

$1.4 x 105 cps 7.

Overtemperature AT 6.6 3.37 1.95 + 0.50 See Note 1 See Note 2

.8.

Overpower AT 4.9 1.54 1.95 See Note 3 See Note 4 9.

Pressurizer Pressure-Low 3.1 0.71 1.67 11960 psig 11950 psig

10. Pressurizer Pressure-High 3.1 0.71 1.67 52385 psig

$2395 psig

11. Pressurizer Water Level-High 8.0 2.18 1.67 592% of instru-193.9% of instru-ment span ment span l

12. Reactor Coolant Flow - Low 2.5 1.87 0.60 190% of loop 289.4% of loop design flow **

design **

• = RATED THERMAL POWER 00 Loop design flow = 95,700 gpm A-3

TABLE 2.2-1 (Crntinued) l l

REACTOR TRIP SYSTEN INSTRUNENTATION TRIP SETPOINTS TOTAL SENSOR ERROR FUNCTIONAL UNIT ALLOWANCE (TA)

Z_

S TRIP SETPOINT ALLOWABLE VALUE

13. Steam Generator Water 18.5 17.18 1.67 218.5% of narrow 217.8% of narrow Level Low-Low range instrument range instrument span span

14. Undervoltage - Reactor 6.0 0.58 0

29600 Volts AC 2 9481 Volts AC Coolant Pumps

15. Underfrequency - Reactor 3.3 0.50 0

2 57.3Hz 2 57.1 Hz Coolant Pumps i

16. Turbine Trip a.

Low Fluid Oil Pressure N.A.

N.A.

N.A.

b.

Turbine Stop Valve N.A.

N.A.

N.A.

Closure-

_17. Safety Injection Input N.A.

N.A.

N.A.

N.A.

N.A.

from ESF i

i 45550:1D/070786 A -4

i.

l TABLE 2.2-1 (Continued)

REACTOR TRIP SYSTEN INSTRUMENTATION TRIP SETPOINTS TOTAL FUNCTIONAL UNIT ALLOWANCE (TA1 Z_

S TRIP SETPOINT ALLOWA8LE VALUE

18. Reactor Trip System Interlocks 4

l a.

Intermediate Range N.A.

N.A.

N.A.

El x 10-10 amps 26 x 10-11 amps Neutron Flux, P-6 a

b.

Low Power Reactor Trips i

Block, P-7 j

1.

P-10 input N.A.

N.A.

N.A.

510% of RTP*

$12.3% of RTP*

2.

P-13 input N.A.

N.A.

N.A.

510% turbine

$12.1% of turbine

]

impulse pressure impulse pressure I

equivalent equivalent t

Power Range Neutron N.A.

N.A.

N.A.

548% of RTP*

$50.3% of RTP*

j c.

Flux, P-8 j

d.

Power Range Neutron N.A.

N.A.

N.A.

550% of RTP*

$52.3% of RTP*

1 Flux, P-9 l

j e.

Power Range Neutron N.A.

N.A.

N.A.

210% of RTP*

17.7% of RTP*

l Flux, P-10 f.

Turbine Impulse Chamber N.A.

N.A.

N.A.

510% of RTP*

$12.1% of RTP* Turbine i

Pressure, P-13 Turbine Impulse Impulse Pressure Pressure Equivalent Equivalent

19. Reactor Trip Breakers N.A.

N.A.

N.A.

N.A.

N.A.

20. Automatic Trip and Interlock N.A.

N.A.~

N.A.

N.A.

N.A.

Logic

• RTP = RATED THERMAL POWER i

45550:1D/070786 A-5

TA8LE 2.2-1 (Crntinred)

REACTOR TRIP SYSTEM INSTRUNENTATION TRIP SETPOINTS NOTATION 4

NOTE 1: OVERTEMPERATURE AT 1+t S 1+t S I

AT Y~

I~b I

• '2SI I * '35 2

+

1 1

3 j

6 Measured %T by RTD Manifold Instrumentation; Where:

AT

=

1 1+t S j

lead-lag compensator on measured AT;

=

j,,23 Time constants utilized in lead-lag controller for AT, ti, 18s, ti, 12

.=

12 13s; I

)

Lag compensator on measured AT;

=

),

3 13 Time constants utilized in the lag compensator for AT, t3 1 0 s;

=

Indicated AT at RATED THERMAL POWER; ATo

=

1.10; Ki

=

K2 2

0.012/*F; 1+T 5 4

The function generated by the lead-lag compensator for T avg dynamic compensation;

=

1+t S5 14, tS Time constants utilized in lead-lag compensator for Tavg. T4 1 28 s,

=

15145; Average temperature. *F; T

=

1+1 3 Lag compensator on measured T,yg; 6

45550:10/080186 A-6

TABLE 2.2-1 (Continued)

REACTOR TRIP SYSTEM INSTRUMENTATION TRIP SETPOINTS NOTATION (Continued)

NOTE 1: (Continued) 16 Time constant utilized in the measured Tavg lag compensator. T6 5 0 s-

=

T' 5

588.5*F (Nominal Tavg at RATED THERMAL POWER);

K3 s

0.00056/ psig Pressurizer Pressure, psig; P

=

2235 psig (Nominal RCS operating pressure) and P'

=

Laplace transfom variable, 5-I; S

=

and fj(AI) is a function of the indicated difference between top and bottom detectors of the power-range a

nuclear ion chambers; with gains to be selected based on measured instrument response during plant startup tests such that:

between -AS%and +6.5% f ( AI) = 0, where qt and qb are percen't RATED THERMAL (1)

For qt - 4b i

POWER in the top and bottom halves of the core respectively, and qt + Ab is total THERMAL POWER in percent of RATED THERMAL POWER; (ii)

For each percent that the magnitude of qt - Ab exceeds -335%, the AT Trip Setpoint shall be automatically reduced by 1.27% of its value at RATED THERMAL POWER; and I

(iii)

For each percent that the magnitude of qt - Ab exceeds +6.% the AT Trip Setpoint shall be automatically reduced by 0.83% of its value at RATED THERMAL POWER.

NOTE 2: The channel's maximum Trip Setpoint shall not exceed its computed Trip Setpoint by more than 2.6%.

45550:1D/080186 A-7

- - = _.

TABLE 2.2-1 (Cent 1FuTd)

REACTOR TRIP SYSTEM INSTRUMENTATION TRIP SETPOINTS NOTATION (Continued) l NOTE 3: OVERPOWER AT 3

I+*3 1 )

('7

)

1 U(1+1 I

1

)

At ((j + '1 ) (

I I

Il + 1 5) 6 5

2 o

4 5 1+15 3I I + '35 7

6 6

2 Measured AT by RTD Manifold Instrumentation; Where:

AT

=

1+t S j

Lead-lag compensator on measured AT;

=

j,,23 Time constants utilized in lead-lag compensator for AT, 11 2 8 s., 12 5 3 5; ti, 12 I

Lag compensator on measured AT;

=

j,,33 Time constant utilized in the lag compensator for AT. T3 $ 0 s;

)

13

=

1 Indicated AT at RATED THERMAL POWER; ATo

=

f 1.08g; K4 K5 2

0.02/*F for increasing average temperature and20 for decreasing average temperature; i

'73 The function generated by the rate-lag compensator for T,yg dynamic compensation;

=

3,,3 l

17 Time constants utilized in rate-lag compensator for Tavg. T7 210 s;

=

1 1+1 3 Lag compensator on measured T,yg; 6

Time constant utilized in the measured Tavg lag compensator. 16 s O s; i

t6

=

45550:10/080186 A-8 l

TABLE 2.2-1 (Continued)

REACTOR TRIP SYSTEM INSTRUMENTATION TRIP SETPOINTS NOTATION (Continued)

NOTE 3: (Continued)

K6 2

0.0013/*F for T > T* and K 6 2 0 for T $ T",

T Average Temperature. *F;

=

T" Indicated T at RATED THERMAL POWER (Calibration temperature for AT

=

avg instrumentation, 5 588.S*F),

Laplace transform variable s -l; and S

=

f (a!)

0 for all AI 2

=

NOTE 4: The channel's maximum Trip Setpoint shall not exceed its computed Trip Setpoint by more than 3.6% of AT span.

45550:10/070786 A -9

f 4

2.2 LIMITING SAFETY SYSTEM SETTINGS BASES 2.2.1 REACTOR TRIP SYSTEM INSTRUMENTATION SETPOINTS i

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 I

unit. The Trip Setpoints have been selected to ensure that the reactor 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 l

to be adjusted consistent with the nominal value when the "as measured" setpoint is within the band allowed for calibration accuracy.

i j

To accomodate 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 l

measured" deviation from the specified calibration point for rack and i

sensor components in conjunction with a statistical combination of the other uncertainties in calibrating the instrumentation. In Equation l

2.2-1, Z + R + S 1 TA, the interactive effects of the errors in the rack j

and the sensor, and the "as measured" values of the errors are considered.

Z, as specified in Table 2.2-1, in percent span, is the i

statistical summation of errors assumed in the analysis excluding those associated with the sensor and rack drift and the accuracy of their i

45550:10/070786 A-10 i

7_

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 f' rom the specified trip setpoint. S or Sensor Drift 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 factor, an increased rack drif t factor, and provides a threshold value for REPORTABLE EVENT.

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 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 drif t is expected. Rack or sensor drif t, in excess of the allowance that is more than occasional, may be indicative of more serious problems and should warrant further investigation.

45550:10/070786 A-ll

I

.l 3/4.3.2 ENGINEERED SAFETY FEATURE ACTUATION SYSTEM INSTRUMENTATION 1

LIMITING CONDITION FOR OPERATION 3.3.2 The Engineered Safety Feature 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 I

in the Trip Setpoint column of Table 3.3-4 and with RESPONSE TIMES as shown.in Table 3.3-5.

i i

APPLICABILITY: As shown in Table 3.3-3.

l ACTION:

i a.

With an ESFAS Instrumentation or Interlock Setpoint Trip less conservative than the value shown in the Trip Setpoint column but l

more conservative than the value shown in the Allowable Value column of Table 3.3-4 adjust the Setpoint consistent with the Trip Setpoint I

value.

b.

With an ESFAS Instrumentation or Interlock Trip Setpoint less J

conservative than the value shown in the Allowable Value column of Table 3.3-4, either:

4 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 affected channel, or j

2.

Declare the channel inoperable and apply the applicable ACTION l

statement requirements of Table 3.3.3 until the channel is i

restored to OPERABLE status with its Setpoint adjusted f

consistent with the Trip Setpoint value.

I i

EQUATION 2.2-1 Z + R + 5 $ TA I

l l

l 45550:10/070786 A-12 l

where:

The value for Column 2 of Table 3.3-4 for the af fected channel, Z

=

The "as measured" value (in percent span) of rack error for the R

=

affected channel, Either the "as measured" value (in percent span) of the sensor S

=

error, or the value from Column S (Sensor Drif t) of Table 3.3-4 for the affected channel, and The value from Column TA (Total Allowance) of Table 3.3-4 for TA

=

the affected channel.

45550:10/070786 A-13

TABLE 3.3-4 ENGINEERED SAFETY FEATURES ACTUATION SYSTEN INSTRUNENTATION TRIP SETPOINTS TOTAL SENSOR TRIP FUNCTIONAL UNIT ALLOWANCE (TA)

Z DRIFT (S)

SETPOINT ALLOWABLE VALUE

1. Safety Injection (Reactor Trip, Feedwater Isolation, Component Cooling Water, Control Room Emergency Mode Actuation, Start Diesel Generators, Containment Cooling Fans, and Nuclear Service Cooling Water, Containment Isolation, Containment Ventilation Isolation, and Auxiliary Feedwater Motor-Driven Pumps) a.

Manual Initiation N.A.

N.A.

N.A.

N.A.

N.A.

b.

Automatic Acutation Logic and Actuation Relays N. A.,

N.A.

N.A.

N.A.

N.A.

c.

Containment Pressure -

High-1 3.1 0.71 1.67 5 3.5 psig 5 4.4 psig

'd.

Pressurizer Pressure -

Low 13.1 10.71 1.67 1 1870 psig 1 1860 psig e.

Steam Line Pressure -

Low 13.0 10.71 1.67 1 585 psig 1 570 psig 45550:10/070786 A-14

/

L.

TABLE 3.3-4 (Continued)

ENGINEERED SAFETY FEATURES ACTUATION SYSTEN INSTRUNENTATION TRIP SETPOINTS TOTAL SENSOR TRIP FUNCTIONAL UNIT ALLOWANCE (TA) 2-DRIFT (S)

SETPOINT ALLOWABLE VALUE 2.

Containment Spray a.

Nanual Initiation N.A.

N.A.

N.A.

N.A.

N.A.

b.

Automatic Acutatinn Logic and Actuation Relays N.A.

N.A.

N.A.

N.A.

N.A.

c.

Containment Pressure -

High-3 3.1 0.71 1.67 5 21.5 psig 5 22.4 psig 3.

Containment Isolation a.

Phase "A" Isolation

1) Nanual Initiation N.A.

N.A.

N.A.

N.A.

N.A.

2) Automatic Actuation Logic and Actuation Relays.

N.A.

N.A.

N.A.

N.A.

N.A.

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

45550:1D/070786 A-15

1.

TABLE 3.3-4 (Centinuid)

ENGINEERED SAFETY FEATURES ACTUATION SYSTEN INSTRUNENTATION TRIP SETPOINTS TOTAL SENSOR TRIP FUNCTIONAL UNIT ALLOWANCE (TA)

Z DRIFT (S)

SETPOINT ALLOWABLE VALUE 3.

Containment Isolation (continued) b Containment Ventilation Isolation

1) Manual Initiation N.A.

N.A.

N.A.

N.A.

N.A.

2) Automatic Actuation Logic and Actuation Relays N.A.

N.A.

N.A.

N.A.

N.A.

3)

Safety injection See Item 3.a. above for all Phase "A" Isolation Trip Setpoints and Allowable Values.

4.

Steam Line Isolation a.

Nanual Initiation N.A.

N.A.

N.A.

N.A.

N.A.

b.

Automatic Actuation Logic and Actuation Relays N.A.

H.A.

N.A.

N.A.

N.A.

c.

Containment Pressure-High-2 3.1 0.71 1.67 5 14.5 psig

$ 15.4 psig d.

Steam Line Pressure-Low 13.0 110.71 1.67 2 585 psig 2 570 psig e.

Steam Line Pressure-3.0 0.50 0

5 -100 5 -125 Negative Rate - High psi /s psig/s**

45550:10/070786 A-16

- -J

e TABLE 3.3-4 (Continued)

ENGINEERED SAFETY FEATURES ACTUATION SYSTEM INSTRUMENTA110N TRIP SETPOINTS TOTAL SENSOR TRIP FUNCTIONAL UNIT ALLOWANCE (TA)

Z DRIFT (S)

SETPOINT ALLOWABLE VALUE 5.

Turbine Trip and Feedwater Isolation a.

Automatic Actuation Logic and Actuation Relays N.A.

N.A.

N.A.

N.A.

N.A.

b.

Steam Generator Water Level--High-High (P-14) 5.1 2.18 1.67 5 78% of 5 79.9% of narrow range narrow range instrument instrument c.

Safety Injection See item 1. above for Safety Injection span span 6.

Auxiliary Feedwater Trip Setpoints and Allowable Values.

a.

Manual Initiation N.A.

N.A.

N.A.

N.A.

N.A.

b.

Automatic Actuation Logic and Actuation Relays N.A.

N.A.

N.A.

N.A.

N.A.

C.

Steam Generator Water Level--Low-Low

1) Start Notor-18.5 17.18 1.67 2 18.5% of 2 17.8% of Driven Pumps narrow range narrow range instrument instrument span span

2) Start Turbine 18.5 17.18 1.67 2 18.5% of 2 17.8% of Driven Pumps narrow range narrow range instrument instrument span span 45550:1D/070786 A-17

TABLE 3.3-4 (Centinued)

ENGINEERED SAFETY FEATURES ACTUATION SYSTEM INSTRUMENTATION TRIP SETPOINTS TOTAL SENSOR TRIP FUNCTIONAL UNIT ALLOWANCE (TA)

Z DRIFT (S)

SETPOINT ALLOWABLE VALUE 6.

Auxiliary Feedwater (continued) d.

Safety Injection-Start Motor-Driven Pumps See Item 1. above for all Safety Injection Trip Setpoints and Allowable Values.

e.

Loss of or degraded 4.16 kV ESF Bus Voltage

i. Start Motor-Driven Pumps N.A.

N.A.

N.A.

(by others)

(by others) ii. Turbine Driven Pump' N.A.

N.A.

N.A.

(by others)

(by others) f.

Trip Main Feedwater Pumps-Start Motor-Driven Pumps N.A.

N.A.

N.A.

N.A.

N.A.

7.

Semi-Automatic Switchover to Containment Emergency Sump a.

Automatic Actuation Logic and. Actuation Relays N.A.

N.A.

N.A.

N.A.

N.A.

b.

RWST Level--Low-Low 3.5 0.71 1.67 36% of 34.3% of Coincident with instrument span instrument span Safety Injection See Item 1. above for Safety Injection Trip Setpoints and Allowable Values.

A-18 a

MEUME 2

TABLE 3.3-4 (Continued)

ENGINEERED SAFETY FEATURES ACTUATION SYSTEM INSTRUNENTATION TRIP SETPOINTS TOTAL SENSOR TRIP FUNCTIONAL UNIT ALLOWANCE (TA) 1 DRIFT (S)

SETPOINT ALLOWABLE VALUE

8. Loss of Power to 4.16 kV ESF Bus

a. 4.16 kV ESF Bus N.A.

N.A.

N.A.

(by others)

(by others)

Undervoltage-Loss of Voltage

b. 4.16 kV ESF Bus N.A.

N.A.

N.A.

(by others)

(by others)

Undervoltage-Grid Degraded Voltage

9. Engineered Safety Features Actuation System Interlocks

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

N.A.

N.A.

$1970 psig

$1980 psig

b. Reactor Trip, P-4 N.A.

N.A.

N.A.

N.A.

N.A.

10. Control Room Ventilation Emergency-Mode Actuation

a. Manual Initiation N.A.

N.A.

N.A.

N.A.

N.A.

b. Automatic Actuation Logic and Actuation Relays N.A.

N.A.

N.A.

N.A.

N.A.

c. Safety Injection See Item 3.a. above for all Phase "A" Isolation Trip Setpoints and Allowable Values.

TABLE 3.3-4 (Continued) e TABLE NOTATION Time constants utilized in the lead-lag controller for Steam Pressure-Low are ti, 1 50 seconds and T2, t 5 seconds.

The time constant utilized in the rate-lag controller for Steam Pressure Rate-High is 50 seconds, i

I b

45550:10/070786 A-20 i

i 3/4.0 INSTRUMENTATION g

BASES C5 3/4.3.1 and 3/4.3.2 REACTOR TRIP AND ENGINEERED SAFETY FEATURE ACTUATION SYSTEM INSTRUMENTATION The OPERABILITY of the Reactor Protectio'n System and Engineered Safety Feature Actuation System Instrumentation and interlocks ensure that 1) the associated action and/or reactor trip w'ill be initiated when the parameter monitored by each channel or combination thereof reaches its setpoint, 2) the specified coincidence logic is maintained, 3) suf ficient redundancy is maintained to permit 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 accident 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 Feature 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 drift assumed to occur between operational tests and the accuracy to which setpoints can be measured and calibrated, Allowable Values for the setpoints have been specified in 45550:1D/070786 A-21

l 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 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 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 caligrati.79 the instrumentation.

In Equation 2.2-1, Z + R + S S TA, the interactive ef fects 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 drif t 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 affected channel from the specified trip setpoint. S or Sensor Drif t 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 2.2-1 allows for a sensor drift factor, an increased rack drif t factor, and provides a threshold value for REPORTABLE [YENT.

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 i

drift is expected. Rack or sensor drif t, in excess of the allowance that is more than occasional, may be indicative of more serious problems and should warrant further investigation.

45550:10/070786 A-22 i