L-2010-299, License Amendment Request for Extended Power Uprate, Attachment 12; WCAP-17070-NP, Revision 0, Westinghouse Setpoint Methodology for Protection Systems
ML103560188 | |
Person / Time | |
---|---|
Site: | Turkey Point ![]() |
Issue date: | 08/31/2010 |
From: | Drudy M, King Z, Reagan J, Spaulding D Westinghouse |
To: | Office of Nuclear Reactor Regulation |
References | |
L-2010-113, L-2010-299 WCAP-17070-NP, Rev 0 | |
Download: ML103560188 (58) | |
Text
Turkey Point Units 3 and 4 L-2010-113 Docket Nos. 50-250 and 50-251 Turkey Point Units 3 and 4 LICENSE AMENDMENT REQUEST FOR EXTENDED POWER UPRATE ATTACHMENT 12 WCAP-17070-NP, Revision 0, Westinghouse Setpoint Methodology for Protection Systems for Turkey Point Units 3 and 4 Power Uprate to 2644 MWt-Core Power August 2010 This coversheet plus 57 pages
WESTINGHOUSE NON-PROPRIETARY CLASS 3 Westinghouse Non-Proprietary Class 3 WCAP-17070-NP August 2010 Revision 0 Westinghouse Setpoint Methodology for Protection Systems Turkey Point Units 3 & 4 (Power Uprate to 2644 MWt - Core Power)
Westinghouse Electric Company LLC P.O. Box 355 Pittsburgh, PA 15230-0355
© 2010 Westinghouse Electric Company LLC All Rights Reserved
WESTINGHOUSE NON-PROPRIETARY CLASS 3 WCAP-17070-NP Revision 0 Westinghouse Setpoint Methodology for Protection Systems Turkey Point Units 3 & 4 (Power Uprate to 2644 MWt - Core Power)
D. R. Spaulding Setpoints and Uncertainty Analysis M. P. Drudy Setpoints and Uncertainty Analysis Z. C. King Setpoints and Uncertainty Analysis J. R. Reagan*
Setpoints and Uncertainty Analysis August 2010 Reviewer: T. P. Williams*
Setpoints and Uncertainty Analysis Approved: D. C. Olinski*, Acting Manager Setpoints and Uncertainty Analysis
- Electronically Approved Records Are Authenticated in the Electronic Document Management System Westinghouse Electric Company LLC P.O. Box 355 Pittsburgh, PA 15230-0355
© 2010 Westinghouse Electric Company LLC All Rights Reserved
TABLE OF CONTENTS LIST OF TABLES ................................................................................................................................. ii
1.0 INTRODUCTION
.................................................................................................................................. 1 1.1 References I Standards ............................................................................................................. 2 2.0 COMBINATION OF UNCERTAINTY COMPONENTS .................................................................. 3 2.1 Methodology ............................................................................................................................. 3 2.2 Sensor Allowances ................................................................................................................... 5 2.3 Rack Allowances ...................................................................................................................... 6 2.4 Process Allowances .................................................................................................................. 7 2.5 References I Standards ............................................................................................................. 8 3.0 PROTECTION SYSTEM SETPOINT METHODOLOGY ................................................................. 9 3.1 Instrument Channel Uncertainty Calculations ......................................................................... 9 3.2 Definitions for Protection System Setpoint Tolerances .......................................................... 9 3.3 References I Standards ........................................................................................................... 17 4.0 APPLICATION OF THE SETPOINT METHODOLOGY ............................................................... 50 4.1 Uncertainty Calculation Basic Assumptions I Premises ....................................................... 50 4.2 Process Rack Operability Determination Program and Criteria ........................................... 51 4.3 Application to the Plant Technical Specifications ................................................................. 52 4.4 References I Standards ........................................................................................................... 54 WCAP-17070-NP August 2010 Revision 0
LIST OF TABLES Table 3-1 Power Range Neutron Flux - High Setpoint.. ............................................................................. 18 Table 3-2 Overtemperature klT ................................................................................................................... 20 Table 3-3 Overpower klT ............................................................................................................................24 Table 3-4 High Steam Line Flow - SI, Steam Line Isolation ...................................................................... 27 Table 3-5 Steam Flow / Feedwater Flow Mismatch ................................................................................... 30 Table 3-6 Steam Generator Water Level- Low, Low-Low ........................................................................ 33 Table 3-7 Steam Generator Water Level- High-High ................................................................................ 35 Table 3-8 Steamline Pressure - Low (SI) Outside Containment Steam Break .......................................... 37 Table 3-9 Steamline Pressure - Low (SI) Inside Containment Steam Break .............................................. 39 Table 3-10 Reactor Coolant Flow - Low .................................................................................................... 41 Table 3-11 Reactor Trip System / Engineered Safety Features Actuation System Channel Error Allowances .......................................................................................... 43 Table 3-12 Overtemperatue klT Calculations ............................................................................................ .45 Table 3-13 Overpower klT Calculations .................................................................................................... .47 Table 3-14 M Measurements Expressed in Flow Units .............................................................................. 48 WCAP-17070-NP August 2010 11 Revision 0
1.0 INTRODUCTION
This report has been prepared to document the instrument uncertainty calculations for the Reactor Trip System (RTS) and Engineered Safety Features Actuation System (ESFAS) trip functions identified on Table 3-11 of this report for Turkey Point Units 3 and 4 Nuclear Power Stations (FPLlFLA) for a power uprate to 2644 MWt.
This document is divided into four sections. Section 2.0 identifies the general algorithm used as a base to determine the overall instrument uncertainty for an RTSIESFAS trip function. This approach is defined in a Westinghouse paper presented at an Instrument Society of AmericalElectric Power Research Institute (ISA/EPRI) conference in June, 1992(1). This approach is consistent with American National Standards Institute (ANSI), ANSIIISA-67.04.01-2006(2). The basic uncertainty algorithm is the Square-Root-Sum-of-the-Squares (SRSS) of the applicable uncertainty terms, which is endorsed by the ISA standard. All appropriate and applicable uncertainties, as defined by a review of the plant baseline design input documentation, have been included in each RTS/ESFAS trip function uncertainty calculation. ISA-RP67.04.02-2000(3) was utilized as a general guideline, but each uncertainty and its treatment is based on Westinghouse methods which are consistent or conservative with respect to this document. The latest version of NRC Regulatory Guide 1.105 (Revision 3(4)) endorses the 1994 version ofISA S67.04, Part 1. Westinghouse has evaluated this NRC document and has determined that the RTS/ESFAS trip function uncertainty calculations contained in this report are consistent with the guidance contained in Revision 3(4). It is believed that the total channel uncertainty (Channel Statistical Allowance or CSA) represents a 95/95 value as requested in Regulatory Guide 1.105(4).
Section 3.0 of this report provides a list of the defined terms and associated acronyms used in the RTSIESFAS trip function uncertainty calculations. Appropriate references to industry standards have been provided where applicable. Included in this section are detailed descriptions of the uncertainty terms and values for each RTSIESFAS trip function uncertainty calculation performed by Westinghouse.
Provided on each table is the function specific uncertainty algorithm which notes the appropriate combination of instrument uncertainties to determine the CSA. A summary Table (3-11) is provided which includes a listing of the Safety Analysis Limit (SAL), the Nominal Trip Setpoint (NTS), the Total Allowance (the difference between the SAL and NTS, in % span), margin, and the Allowable Value (A V). In all cases, it was determined that positive margin exists between the SAL and the NTS after accounting for the channel instrument uncertainties.
Section 4.0 provides a description of the methodology utilized in the determination of Turkey Point Units 3 and 4 Technical Specifications with regards to an explanation of the relationship between a trip setpoint and the allowable value.
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1.1 References / Standards
- 1. Tuley, C. R., Williams, T. P., "The Significance of Verifying the SAMA PMC 20.1-1973 Defined Reference Accuracy for the Westinghouse Setpoint Methodology," Instrumentation, Controls and Automation in the Power Industry, Vol. 35, Proceedings of the Thirty-Fifth Power Instrumentation Symposium (2 nd Annual ISAIEPRI Joint Controls and Automation Conference),
Kansas City, Mo., June 1992, p. 497.
- 2. ANSIIISA-67.04.01-2006, "Setpoints for Nuclear Safety-Related Instrumentation," May 2006.
- 3. ISA-RP67.04.02-2000, "Methodologies for the Determination of Setpoints for Nuclear Safety-Related Instrumentation," January 2000.
- 4. Regulatory Guide 1.105, Revision 3, "Setpoints for Safety-Related Instrumentation," 1999.
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2.0 COMBINATION OF UNCERTAINTY COMPONENTS This section describes the Westinghouse setpoint methodology for the combination of the uncertainty components utilized for Turkey Point Units 3 and 4. The methodology used in the determination of the overall CSA, for the functions listed in Table 3-11 of this report, is in Section 2.1 below. All appropriate and applicable uncertainties, as defined by a review of Turkey Point Units 3 and 4 baseline design input documentation have been included in each RTS/ESFAS trip function CSA calculation.
2.1 Methodology The methodology used to combine the uncertainty components for a channel is an appropriate combination of those groups which are statistically and functionally independent. Those uncertainties which are not independent are conservatively treated by arithmetic summation and then systematicalIy combined with the independent terms.
The basic methodology used is the SRSS technique. This technique, or others of a similar nature, has been used in WCAP-l 0395 (I) and WCAP-8567 (2). WCAP-8567 is approved by the NRC noting acceptability of statistical techniques for the application requested. Also, various ANSI, American Nuclear Society (ANS), and ISA standards approve the use of probabilistic and statistical techniques in determining safety-related setpoints (3,4). The basic methodology used in this report is essentialIy the same as that identified in a Westinghouse paper presented at an ISAIEPRI conference in June, 1992(5).
Differences between the algorithm presented in this paper and the equations presented in Tables 3-1 through 3-10 are due to Turkey Point Units 3 and 4 specific characteristics in design and should not be construed as differences in approach.
The generalized relationship between the uncertainty components and the calculated uncertainty for a channel is noted in Eq. 2.1:
PMA 2 +PEA 2 +SRA 2 +(SMTE+SDY + (SMTE+ SCAY +
CSA = SPE 2 +STE 2 +(RMTE+RDY + (RMTE + RCAY + Eq.2.1 RTE2
+EA+Bias WCAP-17070-NP August 2010 3 Revision 0
- where, CSA Channel Statistical Allowance PMA Process Measurement Accuracy PEA Primary Element Accuracy SRA Sensor Reference Accuracy SCA Sensor Calibration Accuracy SMTE Sensor Measurement and Test Equipment Accuracy SPE Sensor Pressure Effects STE Sensor Temperature Effects SD Sensor Drift RCA Rack Calibration Accuracy RMTE Rack Measurement and Test Equipment Accuracy RTE Rack Temperature Effects RD Rack Drift EA Environmental Allowance BIAS One directional, known magnitude allowance Each of the above terms is defined in Section 3.2, Definitions for Protection System Setpoint Tolerances.
Eq. 2.1 is based on the following: 1) The sensor and rack measurement "nd test equipment uncertainties are treated as dependent parameters with their respective drift and calibration accuracy allowances. 2)
While the environmental allowances are not considered statistically dependent with all other parameters, the equipment qualification testing generally results in large magnitude, non-random terms that are conservatively treated as limits of error which are added to the statistical summation. Westinghouse generally considers a term to be a limit of error if the term is a bias with an unknown sign. The term is added to the SRSS in the direction of conservatism. 3) Bias terms are one directional with known magnitudes (which may result from several sources, e.g., drift or calibration data evaluations) and are also added to the statistical summation. 4) The calibration terms are treated in the same radical with the other terms based on the assumption that general trending, i.e., drift and calibration data are evaluated on a periodic and timely basis. This evaluation should confirm that the distribution function characteristics assumed as part of treatment of the terms are still applicable. 5) Turkey Point Units 3 and 4 will monitor the "as left" and "as found" data for the sensors and process racks. This process provides performance information that results in a net reduction of the CSA magnitude (over that which would be determined if data review was not performed). Consistent with the request of Regulatory Guide 1.105(6), the CSA value from Eq. 2.1 is believed to have been determined at a 95 % probability at a 95 % confidence level (95/95).
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2.2 Sensor Allowances Seven parameters are considered to be sensor allowances: SRA, SeA, SMTE, so, STE, SPE and EA.
Three of these parameters are considered to be independent, two-sided, unverified (by plant calibration or drift determination processes), vendor supplied terms (SRA, STE and SPE). Based on vendor supplied data, typically product data sheets and qualification reports, these parameters are treated as 95/95 values unless specified otherwise by the vendor. Three of the remaining parameters are considered dependent with at least one other term, are two-sided, and are the result of the plant calibration and drift determination process (SeA, SMTE and SO).
The EA term is associated with the sensor exposure to adverse environmental conditions (elevated temperature and radiation) due to mass and energy loss from a break in the primary or secondary side piping, or adverse effects due to seismic events. Where appropriate, e.g., steamline break, only the elevated temperature term may be used for this uncertainty. The EA term magnitudes are conservatively treated as limits of error.
SRA is the manufacturer's reference accuracy that is achievable by the device. This term is introduced to address repeatability and hysteresis effects when performing only a single pass calibration, i.e., one up and one down(5,7). 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 drift determined under conditions in which pressure and temperature are assumed constant. For example, assume a sensor is placed in some position in the containment during a refueling outage. After placement, an instrument technician calibrates the sensor at ambient pressure and temperature conditions. Some time later with the plant shutdown, an instrument technician checks for sensor drift using the same technique as was previously used for calibrating the sensor. The conditions under which this drift determination is made are again ambient pressure and temperature. The temperature and pressure should be essentially the same at both measurements. Thus, they should have no significant impact on the drift determination and are, therefore, independent of the drift allowance.
seA and SO are considered to be dependent with SMTE due to the manner in which the instrumentation is evaluated. A transmitter is calibrated by providing a known process input (measured with a high accuracy gauge) and evaluating the electrical output with a digital multimeter (DMM) or digital voltmeter (DVM). The gauge and DVM accuracies form the SMTE terms. The transmitter response is known, at best, to within the accuracy of the measured input and measured output. Thus the calibration accuracy (SeA) is functionally dependent with the measurement and test equipment (SMTE). Since the gauge and DVM are independent of each other (they operate on two different physical principles), the two SMTE terms may be combined by SRSS prior to addition with the seA term. Transmitter drift is determined using the same process used to perform a transmitter calibration.
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That is, a known process input (measured with a high accuracy gauge) is provided and the subsequent electrical output is measured with a DMM or DVM. In most cases the same measurement and test equipment is used for both calibration and drift determination. Thus the drift value (SD) is functionally dependent with the measurement and test equipment (SMTE) and is treated in the same manner as SMTE and SCA.
While the data is gathered in the same manner, SD is independent of SCA in that they are two different parameters. SCA is the difference between the "as left" value and the desired value. SD is the difference between the "as found" value of the current calibration and the "as left" value ofthe previous calibration.
It is assumed that a mechanistic cause and effect relationship between SCA and SD is not demonstrated and that any data evaluation will determine the distribution function characteristics for both SCA and SD and confirm that SD is random and independent of SCA.
2.3 Rack Allowances Four parameters are considered to be rack allowances: RCA, RMTE, RTE and RD. RRA is the manufacturer's reference accuracy that is achievable by the process rack instrument string. This term is introduced to address repeatability and hysteresis effects when performing only a single pass calibration, i.e., one up and one down(5). Review of a sample of Turkey Point Units 3 and 4 specific calibration procedures has concluded that the calibration tolerance identified in the procedures is sufficient to encompass "as left" deviation and the hysteresis and repeatability effects without an additional allowance. Thus this term has been included in the RCA term in the uncertainty calculations. RTE is considered to be an independent, two-sided, unverified (by plant calibration or drift determination processes), vendor supplied parameter. The process racks are located in an area with ambient temperature control, making consistency with the rack evaluation temperature easy to achieve. Based on Westinghouse Eagle process rack data and Hagan rack data, this parameter is treated as a 95/95 value.
RCA and RD are considered to be two-sided terms dependent with RMTE. The functional dependence is due to the manner in which the process racks are evaluated. To calibrate or determine drift for the process rack portion of a channel, a known input (in the form of a voltage, current or resistance) is provided and the point at which the trip bistable changes state is measured. The input parameter is either measured by the use of a DMM or DVM (for a current or voltage signal) or is known to some degree of precision by use of precision equipment, e.g., a precision decade box for a resistance input. For simple channels, only a DMM or DVM is necessary to measure the input and the state change is noted by a light or similar device. For more complicated channels, multiple DVMs may be used or a DVM in conjunction with a decade box. The process rack response is known at best to within the accuracy ofthe measured input and indicated output. Thus the calibration accuracy (RCA) is functionally dependent with the measurement and test equipment (RMTE).
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In those instances where mUltiple pieces of measurement and test equipment are utilized, the uncertainties are combined via SRSS when appropriate.
The RCA term represents the total calibration uncertainty for the channels which are calibrated as a single string. Drift for the process racks is determined using the same process used to perform the rack calibration and in most cases utilizes the same measurement and test equipment. Thus the drift value (RD) is also functionally dependent with the measurement and test equipment (RMTE) and is treated in the same manner as RMTE and RCA.
While the data is gathered in the same manner, RD is independent of RCA in that they are different parameters. RCA is the difference between the "as left" value and the desired value. RD is the difference between the "as found" of the current calibration and the "as left" values of the previous calibration. The RD term represents the drift for all process rack modules in an instrument string, regardless of the channel complexity. For multiple instrument strings there may be multiple RD terms, e.g., Overtemperature i1T. It is assumed that a mechanistic cause and effect relationship between RCA and RD is not demonstrated and that any data evaluation will determine the distribution function characteristics for both RCA and RD and will confirm that RD is random and independent of RCA.
2.4 Process Allowances The PMA and PEA parameters are considered to be independent of both sensor and rack parameters.
The PMA terms provide allowances for the non-instrument related effects; e.g., neutron flux, calorimetric power uncertainty assumptions and fluid density changes. There may be more than one independent PMA uncertainty allowance for a channel if warranted. The PEA term typically accounts for uncertainties due to metering devices, such as elbows, venturis, and orifice plates. In this report, this type of uncertainty is limited in application by Westinghouse to RCS Flow (Cold Leg Elbow Taps), high steam flow, and steam flow / feedwater flow mismatch. In these applications, the PEA term has been determined to be independent of the sensors and process racks. It should be noted that treatment as an independent parameter does not preclude determination that a PMA or PEA term should be treated as a bias. Ifthat is determined appropriate, Eq. 2.1 would be modified such that the affected term would be treated by arithmetic summation with appropriate determination and application ofthe sign of the uncertainty.
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2.5 References / Standards
- 1. Grigsby, J. M., Spier, E. M., Tuley, C. R., "Statistical Evaluation of LOCA Heat Source Uncertainty," WCAP-10395 (Proprietary), WCAP-10396 (Non-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. ANSI/ISA-67.04.01-2006, "Setpoints for Nuclear Safety-Related Instrumentation," May 2006.
- 5. Tuley, C. R., Williams, T. P., "The Significance of Verifying the SAMA PMC 20.1-1973 Defined Reference Accuracy for the Westinghouse Setpoint Methodology," Instrumentation, Controls and Automation in the Power Industry, Vol. 35, Proceedings of the Thirty-Fifth Power nd Instrumentation Symposium (2 Annual ISAIEPRI Joint Controls and Automation Conference),
Kansas City, Mo., June 1992, p. 497.
- 6. Regulatory Guide 1. 105 Revision 3, "Setpoints for Safety Related Instrumentation," 1999.
- 7. ANSI/ISA-51.1-1979 (R1993), "Process Instrumentation Terminology," Reaffirmed May 26, 1995, p. 61.
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3.0 PROTECTION SYSTEM SETPOINT METHODOLOGY This section contains a list of defined terms used in the Turkey Point Units 3 and 4 RTS/ESF AS trip function uncertainty calculations. Also included in this section are detailed tables and a summary table of the uncertainty terms and values for each calculation that Westinghouse performed. It was determined that in all cases sufficient margin exists between the nominal trip setpoint and the safety analysis limit after accounting for uncertainties.
3.1 Instrument Channel Uncertainty Calculations Tables 3-1 through 3-10 provide individual component uncertainties and CSA calculations for the protection functions noted in Tables 2.2-1 and Table 3.3-3 of Turkey Point Units 3 and 4 Technical Specifications. Table 3-11 of this report provides a summary of the Reactor Trip System / Engineered Safety Features Actuation System Channel Uncertainty Allowances for Turkey Point Units 3 and 4. This table lists the Safety Analysis Limit, Nominal Trip Setpoint, and Allowable Value (in engineering units),
and Channel Statistical Allowance, Margin, Total Allowance and uncertainty terms (in % span).
Westinghouse reports the values in Tables 3-1 through 3-10 and Table 3-11 to one decimal place using the technique of rounding down values less than 0.05 % span and rounding up values greater than or equal to 0.05 % span. Parameters reported as "0.0" have been identified as having a value of s 0.04 %
span. Parameters reported as "0" or "---" in the tables are not applicable (i.e., have no value) for that channel.
3.2 Definitions for Protection System Setpoint Tolerances For the channel uncertainty values used in this report, the following definitions are provided in alphabetical order:
- As Found The condition in which a transmitter, process rack module, or process instrument loop is found after a period of operation. For example, after one cycle of operation, a Steam Generator Level transmitter's output at 50 % span was measured to be 12.05 rnA. This would be the "as found" condition.
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- As Left The condition in which a transmitter, process rack module, or process instrument loop is left after calibration or bistable trip setpoint verification. This condition is typically better than the calibration accuracy for that piece of equipment. For example, the calibration point for a Steam Generator Level transmitter at 50 % span is 12.0 +/- 0.04 rnA. A measured "as left" condition of 12.03 rnA would satisfy this calibration tolerance. In this instance, if the calibration was stopped at this point (i.e., no additional efforts were made to decrease the deviation) the "as left" error would be + 0.03 rnA or + 0.19 % span, assuming a 16 rnA (4 to 20 rnA) instrument span.
- Channel The sensing and process equipment, i.e., transmitter to bistable, for one input to the voting logic of a protection function. Westinghouse designs protection functions with voting logic made up of multiple channels, e.g. 2 out of 3 Steam Generator Level - Low-Low channels for one steam generator must have their bistables in the tripped condition for a Reactor Trip to be initiated.
- Channel Statistical Allowance (CSA)
The combination of the various channel uncertainties via SRSS and algebraic techniques. It includes instrument (sensor and process rack) uncertainties and non-instrument related effects (Process Measurement Accuracy), see Eq. 2.1. This parameter is compared with the Total Allowance for determination of instrument channel margin.
- Environmental Allowance (EA)
The change in a process signal (transmitter or process rack output) due to adverse environmental conditions from a limiting accident condition or seismic event. Typically this value is determined from a conservative set of enveloping conditions and may represent the following:
- Temperature effects on a transmitter
- Radiation effects on a transmitter
- Seismic effects on a transmitter
- Temperature effects on a level transmitter reference leg
- Temperature effects on signal cable insulation
- Seismic effects on process racks WCAP-17070-NP August 2010 10 Revision 0
- Margin The calculated difference (in % instrument span) between the Total Allowance (TA) and the CSA.
Margin = T A - CSA
- Nominal Trip Setpoint (NTS)
A bistable trip setpoint in plant procedures. This value is the nominal value to which the bistable is set, as accurately as reasonably achievable.
- Normalization The process of establishing a relationship, or link, between a process parameter and an instrument channel. This is in contrast with a calibration process. A calibration process is performed with independent known values, i.e., a bistable is calibrated to change state when a specific voltage is reached. This voltage corresponds to a process parameter magnitude with the relationship established through the scaling process. A normalization process typically involves an indirect measurement, e.g., determination of Steam Flow via the ~P drop across a flow restrictor. The flow coefficient for this device, (effectively an orifice which has not been calibrated in a laboratory setting), is not known. Therefore a mass balance between Feedwater Flow and Steam Flow must be made. The mass Feedwater Flow is known through measurement via the ~P across the venturi, Feedwater Pressure and Feedwater Temperature. Presuming no mass losses prior to the measurement of the Steam Flow, the mass Steam Flow can be claimed to equal the mass Feedwater Flow. Measurement of the Steam Flow ~P and the Steam Pressure (to correct for density) can then be utilized to translate to a volumetric flow.
- Primary Element Accuracy (PEA)
Uncertainty due to the use of a metering device. In Westinghouse calculations, this parameter is limited to use on a venturi, orifice, elbow or potential transformer. Typically, this is a calculated or measured accuracy for the device.
- Process Loop (Instrument Process Loop)
The process equipment for a single channel of a protection function.
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- Process Measurement Accuracy (PMA)
Allowance for non-instrument related effects which have a direct bearing on the accuracy of an instrument channel's reading, e.g., temperature stratification in a large diameter pipe, fluid density in a pipe or vessel.
- Process Racks The analog modules downstream of the transmitter or sensing device, which condition a signal and act upon it prior to input to a voting logic system. For Hagan analog process systems, this includes all the equipment contained in the process equipment cabinets, e.g., conversion resistor, loop power supply, lead/lag, rate, lag functions, function generator, summator, control/protection isolator, and bistable. The go/no go signal generated by the bistable is the output of the last module in the analog process rack instrument loop and is the input to the voting logic.
- Rack Calibration Accuracy (RCA)
Rack calibration accuracy is defined as the two-sided calibration tolerance of the process racks.
It is assumed that the individual modules in a loop are calibrated to a particular tolerance and that the process loop as a string is verified to be calibrated to a specific tolerance. The tolerance is typically less than the arithmetic sum or SRSS of the individual module tolerances. This forces calibration of the process loop in such a manner as to exclude a systematic bias in the individual module calibrations, i.e., as left values for individual modules must be compensating in sign and magnitude when considered as an instrument string.
Review of a sample of Turkey Point Units 3 and 4 specific calibration procedures concluded that the calibration process and the identified RCA allowance is sufficient to encompass the as left deviation and the hysteresis and repeatability effects without an additional RRA allowance.
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- Rack Drift (RD)
The change in input-output relationship over a period of time at reference conditions, e.g., at constant temperature. For example, assume that a Water Level channel at SO % span (presuming a 1 to S V span) has an "as found" value of3.01 V for the current calibration and an "as left" value of2.99 V from the previous calculation. The magnitude of the drift would be {(3.01 -
2.99)(100/4) = + 0.5 % span} in the positive direction. For Turkey Point Units 3 and 4 plant specific surveillance procedures, Florida Power and Light will implement an additional requirement to compare the as found to the previous as left value to determine if drift allowance assumptions were exceeded since the last calibration activity.
- Rack Measurement & Test Equipment Accuracy (RMTE)
The accuracy of the test equipment (typically a transmitter simulator, voltage or current power supply, and DVM) used to calibrate a process loop in the racks. When the magnitude ofRMTE meets the requirements of SAMA Standard PMC 20.1-1973(9) or ANSIIlSA-Sl.1-1979 (RI993)(10) it is considered an integral part of RCA. Uncertainties due to M&TE that are 10 times more accurate than the device being calibrated are considered insignificant and are not included in the uncertainty calculations.
- Rack Reference Accuracy (RRA)
Rack Reference Accuracy is the reference accuracy, as defined by SAMA Standard PMC 20.1-1973(1) for a process loop string. It is defined as the reference accuracy or accuracy rating that is achievable by the instrument string as specified in the manufacturer's specification sheets.
Inherent in this definition is the verification of the following under a reference set of conditions;
- 1) conformity(2) or (6), 2) hysteresis(3) or (7) and 3) repeatability(4) or (8). An equivalent to the SAMA definition of reference accuracy is the ANSI/ISA-S 1.1-1979 (R1993)(5) term "accuracy rating,"
specifically as applied to Note 2 and Note 3.
Review of a sample of Turkey Point Units 3 and 4 specific calibration procedures and calibration assumptions concludes that the identified calibration allowance is sufficient to encompass the Rack Reference Accuracy without an additional allowance.
- Rack Temperature Effects (RTE)
Change in input-output relationship for the process rack module string due to a change in the ambient environmental conditions (temperature, humidity), and voltage and frequency from the reference calibration conditions. It has been determined that temperature is the most significant, with the other parameters being second order effects. For process instrumentation, a typical WCAP-17070-NP August 2010 13 Revision 0
value of[ ]a,e is used for analog channel temperature effects which allows for a +/- 50 of ambient temperature deviation.
- Range The upper and lower limits of the operating region for a device, e.g., for a Steamline Pressure transmitter, 0 to 1400 psig. This is not necessarily the calibrated span of the device, although lO quite often the two are close. For further information see ANSIIISA-51.1-1979 (RI993i ).
- Safety Analysis Limit (SAL)
The parameter value in the UFSAR safety analysis or other plant operating limit at which a reactor trip or actuation function is assumed to be initiated.
- Sensor Calibration Accuracy (SeA)
The calibration accuracy for a sensor or transmitter as defined by the plant calibration procedures. For transmitters, this accuracy is typically [ ]a,e. Utilizing Westinghouse recommendations for Resistance Thermal Detector (RTD) cross-calibration, this accuracy is typically [ t,e for the Hot and Cold Leg RTDs.
- Sensor Drift (SD)
The change in input-output relationship over a period of time at reference calibration conditions, e.g., at constant temperature. For example, assume a Water Level transmitter at 50 % level (presuming a 4 to 20 rnA span) has an "as found" value of 12.05 rnA from the current calibration and an "as left" value of 12.01 rnA from the previous calibration. The magnitude of the drift would be {(l2.05 - 12.01)(100/16) = + 0.25 % span} in the positive direction.
- Sensor Measurement & Test Equipment Accuracy (SMTE)
The accuracy of the test equipment (typically a high accuracy local readout gauge and DVM) used to calibrate a sensor or transmitter in the field or in a calibration laboratory. When the magnitUde ofSMTE meets the requirements of ANSIIISA-51.1-1979 (RI993PO) it is considered an integral part of SCA. Uncertainties due to M&TE that are 10 times more accurate than the device being calibrated are considered insignificant and are not included in the uncertainty calculations.
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- Sensor Pressure Effects (SPE)
The change in input-output relationship due to a change in the static head pressure from the calibration conditions or the accuracy to which a correction factor is introduced for the difference between calibration and operating conditions for a ilp transmitter.
- Sensor Reference Accuracy (SRA)
The reference accuracy that is achievable by the device as specified in the manufacturer's specification sheets. This term is introduced into the uncertainty calculation to address repeatability effects when performing only a single pass calibration, i.e., one up and one down, or repeatability and hysteresis when performing a single pass calibration in only one direction.
- Sensor Temperature Effects (STE)
The change in input-output relationship due to a change in the ambient environmental conditions (temperature, humidity), and voltage and frequency from the reference calibration conditions. It has been determined that temperature is the most significant, with the other parameters being second order effects. Note that the ambient temperature effects were evaluated using +/- 60 °P.
- Span The region for which a device is calibrated and verified to be operable, e.g., for a Steamline Pressure transmitter, 1400 psi.
- Square-Root-of-the-Sum-of-the-Squares (SRSS)
That is,
&=~(al +(b l +(c l as approved for use in setpoint calculations by ANSVISA-67.04.01-2006(1l).
- Total Allowance (TA)
The absolute value of the difference (in % instrument span) between the Safety Analysis Limit (SAL) and the Nominal Trip Setpoint (NTS).
TA = I SAL - NTS I WCAP-17070-NP August 2010 15 Revision 0
Two examples of the calculation ofTA are:
- Power Range Neutron Flux - High SAL 115% RTP NTS -109% RTP TA I 6% RTPI = 6% RTP If the instrument span = 120% RTP, then
'T'A = (6% RTP) * (JOO%span) 1..t1 5.0 % span (120% RTP)
- Steamline Pressure - Low (SI)
SAL 566.3 psig NTS -614.0 psig TA -47.7psigl =47.7psig If the instrument span = 1400 psig, then
'T'A __ (47.7 psig) * (lOO%span) 1£1 3.4 % span (1400 psig)
WCAP-17070-NP August 2010 16 Revision 0
3.3 References / Standards
- 1. Scientific Apparatus Makers Association Standard PMC 20.1-1973, "Process Measurement &
Control Terminology," p. 4.
- 2. Ibid, p. 5.
- 3. Ibid, p. 19.
- 4. Ibid, p. 28.
- 5. ANSIIISA -5l.l-1979 (R 1993), "Process Instrumentation Terminology," Reaffirmed May 26, 1995, p. 12.
- 6. Ibid, p. 16.
- 7. Ibid, p. 36.
- 8. Ibid, p. 49.
- 9. Scientific Apparatus Makers Association Standard PMC 20.1-1973, "Process Measurement &
Control Terminology," p. 36.
- 10. ANSI/ISA-51.1-J979 (RI993), "Process Instrumentation Terminology," Reaffirmed May 26, 1995, p. 61.
II. ANSIIISA-67 .04.01-2006, "Setpoints for Nuclear Safety-Related Instrumentation," May 2006.
WCAP-17070-NP August 2010 17 Revision 0
Table 3-1 Power Range Neutron Flux - High Setpoint Parameter Allowance*
a,c Process Measurement Accuracy
[
[
Primary Element Accuracy (PEA)
Sensor Calibration Accuracy (SCA)
[ t,C Sensor Reference Accuracy (SRA)
[ t,C Sensor Measurement & Test Equipment Accuracy (SMTE)
Sensor Pressure Effects (SPE)
Sensor Temperature Effects (STE)
Sensor Drift (SD)
Rack Calibration Accuracy (RCA)
Rack Measurement & Test Equipment Accuracy (RMTE)
Rack Temperature Effect (RTE)
Rack Drift (RD)
- In percent span (120 % RTP)
WCAP-17070-NP August 2010 18 Revision 0
Table 3-1 (continued)
Power Range Neutron Flux - High Setpoint Channel Statistical Allowance =
2 PMA~ +PMA~ + PEA + (SMTE + SCA)2 + (SMTE+SD)2 +SPE 2 +STE +SRA +
2 2 (RMTE + RCA) 2 + (RMTE+ RD)2 +RTE2 a,c WCAP-17070-NP August 2010 19 Revision 0
Table 3-2 Overtemperature ~T Parameter Allowance*
Process Measurement Accuracy (PMA) a,e
[
[
[
[
[
[
Primary Element Accuracy (PEA)
Sensor Calibration Accuracy (SCA)
Sensor Reference Accuracy (SRA)
]a,e t,e Sensor Measurement & Test Equipment Accuracy (SMTE)
]a,e t,e Sensor Pressure Effects (SPE)
Sensor Temperature Effects (STE)
Sensor Drift (SD)
Bias
[
WCAP-17070-NP August 2010 20 Revision 0
Table 3-2 (continued)
Overtemperature ~T Parameter Allowance*
Rack Calibration Accuracy (RCA) a,c
[
[
Rack Measuring & Test Equipment Accuracy (RMTE)
[
Rack Temperature Effect (RTE)
[ t,C
]a,c
] a,c Rack Drift (RD)
]a,c
[
]a,c t,C
- In percent 11T span (Tavg - 75 of, Pressure - 1000 psi, 11T - 100 of = 159.4% RTP, 111 - 120% 111)
NH = # of hot leg RTDs = 2 Nc = # of cold leg RTDs = 1 WCAP-17070-NP August 2010 21 Revision 0
Table 3-2 (continued)
Overtemperature .L\T Channel Statistical Allowance =
2 2 2 PMA"'I1 +PMA"'12 + PMApWRCAL2 + PEA +
.-----------------------------------------,2 Y
(SCA"'T + SMTE"'T + (SD"'T + SMTE"'T + SRA"'T 2 Y f-'------'='-"-------=-"-----------'-'--------....::::..:.-'-------='---- +
NH
+
\ (SCA"'T +SMTE"'TY + (SD"'T +SMTE"'Tf +SRA",/
Nc .-
2 (SMTEp +SDpY +SRA/ +SPE p +STE/ + (SMTEp +SCApY +
2 2 ( )2 -,2
( RMTE"'T +RD"'T ) +RTE"'T + RMTE"'T + RCA"'T I-'------~----~------~--~----~----~~+
NH
+
\ (RMTE"'T +RD"'TY +RTE",/ + (RMTE"'T + RCA"'T)2 Nc (RMTEp + RDp f + (RMTEp + RCA p + RTE/ + Y 2x [(RMTE "'I + RD "'I Y+ (RMTE M + RCA M Y+ RTE "'I 2J+
(RMTE N1S +RDN1SY +RTENIS2 + (RMTE N1S + RCANlsY
+ PMAbll"'T + PMAbuTavg + BIASpressllre WCAP-17070-NP August 2010 22 Revision 0
Table 3-2 (continued)
Overtemperature AT a,c WCAP-17070-NP August 2010 23 Revision 0
Table 3-3 Overpower ,1T Parameter Allowance
- Process Measurement Accuracy (PMA) a,c
[
[
[
[
[
Primary Element Accuracy (PEA)
Sensor Calibration Accuracy (SCA)
[
Sensor Reference Accuracy (SRA)
[
Sensor Measuring & Test Equipment Accuracy (SMTE)
] a,c Sensor Pressure Effects (SPE)
Sensor Temperature Effects (STE)
Sensor Drift (SD)
[
Environmental Allowance (EA)
[
Rack Calibration Accuracy (RCA)
[
[
WCAP-17070-NP August 2010 24 Revision 0
Table 3-3 (continned)
Overpower LiT Parameter Allowance*
Rack Measuring & Test Equipment Accuracy (RMTE) a,c t,C Rack Temperature Effect (RTE)
[
Rack Drift (RD)
- In percent ~T span (Tavg - 75 of, ~T - 100 of = 159.4 % RTP)
NH = # of hot leg RTDs = 2 Nc = # of cold leg RTDs = 1 WCAP-17070-NP August 2010 25 Revision 0
Table 3-3 (continued)
Overpower AT Channel Statistical Allowance =
2 PMApWRCAL2 +PEA +
2 (SCALIT +SMTELITY + (SDLlT +SMTELITY +SRA LI/
I~--~------~~--~~~----~~------~+
NH
+
(SCALIT +SMTELITY + (SD LlT +SMTELITY +SRA LI/
Nc Y
2 (RMTELIT + RDLlT)2 + RTELI/ + (RMTELIT + RCA LIT
~----~----~~----~--~----~------~~+
NH (RMTELIT + RD LIT Y+ RTELI/ + (RMTELIT + RCA LIT Y NC
+ PMA buLlT + PMAbuTavg + EA a,c WCAP-17070-NP August 2010 26 Revision 0
Table 3-4 High Steam Line Flow - SI, Steam Line Isolation Parameter Allowance*
Process Measurement Accuracy (PMA) a,e
[
[
[
Primary Element Accuracy (PEA)
Steam Flovv [
Sensor Calibration Accuracy (SCA)
Steam Flovv [
Turbine Pressure [
Sensor Reference Accuracy (SRA)
Steam Flovv [
Turbine Pressure [
Sensor Measurement & Test Equipment Accuracy (SMTE)
Steam Flovv [ t,e Turbine Pressure [ t,e Sensor Pressure Effects (SPE)
Steam Flovv ]a,e Sensor Temperature Effects (STE)
Steam Flovv [ ]a,e Turbine Pressure [ t,e Sensor Drift (SO)
Steam Flovv t,e Turbine Pressure ]a,e Environmental Allovvances (EA)
Steam Flovv Turbine Pressure Bias Steam Flovv - static pressure correction [
WCAP-17070-NP August 2010 27 Revision 0
Table 3-4 (continued)
High Steam Line Flow - SI, Steam Line Isolation Parameter Allowance*
Rack Calibration Accuracy (RCA) a,c Stearn Flovv [
Turbine Pressure [
Rack Measurement & Test Equipment Accuracy (RMTE)
Stearn Flovv [ t,c Turbine Pressure [ t,C Rack Temperature Effect (RTE)
Stearn Flovv [
Rack Drift (RD)
Stearn Flovv Turbine Pressure
- In percent flow span (135.9 % Span). Values are converted to flow via Equation 3-14.8 where Fmax = 135.9 % and FN = 114
%; therefore, gain = (1/2)(135.9/1 14) = 0.60.
WCAP-17070-NP August 2010 28 Revision 0
Table 3-4 (continued)
High Steam Line Flow - SI, Steam Line Isolation Channel Statistical Allowance =
2 PEA SF +
(SMTESF +SCASFY +SRAs/ + (SMTEsF +SDSFY + SPEs/ +STEs/ +
2 (RMTEsF + RCA SF Y + (RMTESF + RDSF Y + RTESF +
(SMTETP +SCATPY +SRA T/ + (SMTETP +SD TP )2 +SPE T/ + STET/ +
2 (RMTETP + RCA TP Y + (RMTETP + RDTP Y + RTETP
+ PMA ISF + PMA 2SF + PMA TP + BiasI + EA a,c WCAP-17070-NP August 2010 29 Revision 0
Table 3-5 Steam Flow / Feedwater Flow Mismatch Parameter Allowance*
Process Measurement Accuracy (PMA) a,c
[
[
[
Primary Element Accuracy (PEA)
Steam Flovv [
Feed Flovv Sensor Calibration Accuracy (SCA)
Steam Flovv [
Feed Flovv [
Steam Pressure [
Sensor Reference Accuracy (SRA)
Steam Flovv [
Feed Flovv [
Steam Pressure [
Sensor Measurement & Test Equipment Accuracy (SMTE)
Steam Flovv [ ]a,c Feed Flovv [ ]a,c Steam Pressure [ t,C Sensor Pressure Effects (SPE)
Steam Flovv [
Feed Flovv [
Sensor Temperature Effects (STE)
Steam Flovv [
Feed Flovv [
Steam Pressure [
Sensor Drift (SD)
Steam Flovv [
Feed Flovv [
Steam Pressure [
WCAP-17070-NP August 2010 30 Revision 0
Table 3-5 (continned)
Steam Flow / Feedwater Flow Mismatch Parameter Allowance*
a,c Environmental Allowances (EA)
Bias Steam Flow - static pressure correction (BiasI)
Feedwater Flow - static pressure correction (Bias2)
Rack Calibration Accuracy (RCA)
Steam Flow Feed Flow Rack Measurement & Test Equipment Accuracy (RMTE)
Steam Flow Feed Flow Rack Temperature Effect (RTE)
Feed Flow Rack Drift (RD)
Steam Flow Feed Flow
- In percent flow span (135.9 % Span). Values are converted to flow span via Equation 3-14.8 where Fmax = 135.9 %, FN (steam flow) = 100 %, and FN (feedwater flow) = 80 %; therefore, gain (steam flow) = (1/2)(135.9/100) = 0.68 and gain (feedwater flow) = (112)(135.9/80) = 0.85. The gain for steam pressure = 1.2 WCAP-17070-NP August 2010 31 Revision 0
Table 3-5 (continued)
Steam Flow / Feedwater Flow Mismatch Channel Statistical Allowance =
(SMTEsp +SCAspY + SRA Sp2 + (SMTEsp +SDspY +STEs/ +
PEAs/ + (SMTEsF +SCASFY +SRAs/ + (SMTEsF +SDSFY + SPEs/ +STEs/ +
(RMTEsF + RCA SF Y + (RMTEsF + RDSF Y +
PEA F/ + (SMTEFF + SCAFF Y + SRA F/ + (SMTE FF + SD FF Y + SPE F/ + STE F/ +
2 (RMTEFF + RCA FF )2 + (RMTEFF + RDFF Y + RTEFF
+ PMA ISF + PMA 2SF + PMA FF + BiasI + Bias 2 + EA a,c WCAP-17070-NP August 2010 32 Revision 0
Table 3-6 Steam Generator Water Level- Low, Low-Low Parameter Allowance*
Process Measurement Accuracy**
a,c a,c Primary Element Accuracy (PEA)
Sensor Calibration Accuracy (SCA)
Sensor Reference Accuracy (SRA)
Sensor Measurement & Test Equipment Accuracy (SMTE)
Sensor Pressure Effects (SPE)
Sensor Temperature Effects (STE)
Sensor Drift (SD)
Environmental Allowance** (EA)
Bias**
[
Rack Calibration Accuracy (RCA)
Rack Measurement & Test Equipment Accuracy (RMTE)
Rack Temperature Effect (RTE)
Rack Drift (RD)
- In percent span (l00 %)
- [ ]a,c WCAP-17070-NP August 20lO 33 Revision 0
Table 3-6 (continued)
Steam Generator Water Level- Low, Low-Low Channel Statistical Allowance =
PEA 2 + (SMTE + SCA) 2 + SRA 2 + SPE 2 + STE 2 + (SMTE + SD) 2 +
(RMTE + RCA) 2 + RTE 2 + (RMTE + RD) 2
+ BiasI + Bias 2 + EA + PMA pp + PMA RL + PMA FV + PMA sc + PMA MD a,c WCAP-17070-NP August 2010 34 Revision 0
Table 3-7 Steam Generator Water Level- High-High Parameter Allowance*
Process Measurement Accuracy** a,c a,c Primary Element Accuracy (PEA)
Sensor Calibration Accuracy (SCA)
Sensor Reference Accuracy (SRA)
Sensor Measurement & Test Equipment Accuracy (SMTE)
Sensor Pressure Effects (SPE)
Sensor Temperature Effects (STE)
Sensor Drift (SD)
Environmental Allowance** (EA)
Bias**
[
Rack Calibration Accuracy (RCA)
Rack Measurement & Test Equipment Accuracy (RMTE)
Rack Temperature Effect (RTE)
Rack Drift (RD)
- In percent span (100 %)
- [ ]a,c WCAP-17070-NP August 2010 35 Revision 0
Table 3-7 (continued)
Steam Generator Water Level- High-High Channel Statistical Allowance =
PEA 2 + (SMTE + SCA) 2 + SRA 2 + SPE 2 + STE 2 + (SMTE + SD) 2 +
(RMTE + RCA) 2 + RTE 2 + (RMTE + RD) 2
+ Bias] + Bias 5 + EA + PMA pp + PMA RL + PMA FV + PMA sc + PMA MD + PMA DL a,c Note: Negative sign (-) denotes direction (i.e. indicated lower than actual).
WCAP-17070-NP August 2010 36 Revision 0
Table 3-8 Steam line Pressure - Low (SI)
Outside Containment Steam Break Parameter Allowance*
a,C Process Measurement Accuracy (PMA)
Primary Element Accuracy (PEA)
Sensor Calibration Accuracy (SCA)
Sensor Reference Accuracy (SRA)
Sensor Measurement & Test Equipment Accuracy (SMTE)
Sensor Pressure Effects (SPE)
Sensor Temperature Effects (STE)
Sensor Drift (SD)
Environmental Allowances (EA)
[ ] a,c Bias
[
[
Rack Calibration Accuracy (RCA)
Rack Measurement & Test Equipment Accuracy (RMTE)
Rack Temperature Effect (RTE)
Rack Drift (RD)
- In percent span (1400 psig)
WCAP-17070-NP August 2010 37 Revision 0
Table 3-8 (continued)
Steam line Pressure - Low (SI)
Outside Containment Steam Break Channel Statistical Allowance =
(RMTE+ RCAY +(RMTE+RDY +RTE2
+ EA + Bias] + Bias 2 a,c WCAP-17070-NP August 2010 38 Revision 0
Table 3-9 Steam line Pressure - Low (SI)
Inside Containment Steam Break Parameter Allowance*
a,c Process Measurement Accuracy (PMA)
Primary Element Accuracy (PEA)
Sensor Calibration Accuracy (SCA)
Sensor Reference Accuracy (SRA)
Sensor Measurement & Test Equipment Accuracy (SMTE)
Sensor Pressure Effects (SPE)
Sensor Temperature Effects (STE)
Sensor Drift (SD)
Environmental Allowances (EA)
[ ]~
Bias
[
[
Rack Calibration Accuracy (RCA)
Rack Measurement & Test Equipment Accuracy (RMTE)
Rack Temperature Effect (RTE)
Rack Drift (RO)
- In percent span (I400 psig)
WCAP-17070-NP August 2010 39 Revision 0
Table 3-9 (continued)
Steamline Pressure - Low (SI)
Inside Containment Steam Break Channel Statistical Allowance =
(RMTE+RCAY +(RMTE+RDY +RTE2
+ EA + Bias] + Bias 2 a,c WCAP-17070-NP August 2010 40 Revision 0
Table 3-10 Reactor Coolant Flow - Low Parameter Allowance*
Process Measurement Accuracy (PMA) a,C
[
[
Primary Element Accuracy (PEA)
[
Sensor Calibration Accuracy (SCA)
[ t,e Sensor Reference Accuracy (SRA)
[ ]~
Sensor Measurement & Test Equipment Accuracy (SMTE)
[ ]~
Sensor Pressure Effects (SPE)
[ ]~
Sensor Temperature Effects (STE)
[ ] a,c Sensor Drift (SO)
[ ]a,c Rack Calibration Accuracy (RCA)
[ ]~
Rack Measurement & Test Equipment Accuracy (RMTE)
[ ]~
Rack Temperature Effect (RTE)
[ r,c Rack Drift (RO)
[
- In % flow span (120 % Thermal Design Flow). Percent ilP span converted to flow span via Equation 3-14.8, with Fmax =
120 % and FN = 90 %, therefore, gain = (112) (120% /90%) = 0.67.
WCAP-17070-NP August 2010 41 Revision 0
Table 3-10 (continued)
Reactor Coolant Flow - Low Note the CSA equation for this function has been defined by FPL as:
Channel Statistical Allowance =
2 2 PMA j + PMA 2 +PEA 2 +
{~PEA2 +(SMTE+SCAY +(SMTE+SDY +STE 2 +SPE 2 +SRA2}2 +
2 2 2 (SMTE+SCAY +(SMTE+SDY +STE +SPE +SRA +
(RMTE+RCAY +(RMTE+RDY +RTE2 a,c WCAP-17070-NP August 2010 42 Revision 0
---- - ~~-
WESTINGHOUSE NON-PROPRIETARY CLASS 3 Page 43 Table 3-11 & Page 44 Reactor Trip System I Engineered Safety Features Actuation System Channel Error Allowances Turkey Point Units 3 & 4 (FPUFLA)
SENSOR INSTRUMENT RACK 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 MEASUREMENT MEASUREMENT PROCESS PRIMARY & TEST & TEST SAFETY CHANNEL PROTECTION CHANNEL MEASUREMENT ELEMENT CALIBRATION REFERENCE EQUIPMENT PRESSURE TEMPERATURE ENVIRONMENTAL CALIBRATION EQUIPMENT TEMPERATURE ANALYSIS ALLOWABLE TRIP TOTAL STATISTICAL ACCURACY ACCURACY ACCURACY ACCURACY ACCURACY EFFECTS EFFECTS DRIFT ALLOWANCE ACCURACY ACCURACY EFFECTS DRIFT LIMIT VALUE SETPOINT ALLOWANCE ALLOWANCE MARGIN (1) (1) (1) (1) (1) (1) (1) (1) (1) (1) (1) (1) (1) (2 or 3) (4) (4) (1) (1) (1)
- , -a,c - -"
1 POWER RANGE NEUTRON FLUX - HIGH SETPOINT 115%RTP 109.6% RTP 109%RTP 5.0 1 2 OVERTEMPERATURE LIT LlTCHANNEL 2 TAVG CHANNEL PRESSURIZER PRESSURE CHANNEL FUNCTION (11) FUNCTION (12) FUNCTION (12) 8.8.11T Span I(LlI) CHANNEL NISCHANNEL 3 OVERPOWER M LlT CHANNEL 3 I Tavg CHANNEL FUNCTION (11) FUNCTION (13) FUNCTION (13) 3.8.11T Span 4 HIGH STEAMLINE FLOW - SI, STEAM FLOW ~ 60% 1129% full 41.2%1 114.4% lull 40% 1114% full 14.7/11.0 4 STEAM LINE ISOLATION TURBINE PRESSURE steam flow steam flow steam flow flow span 5 STEAM FLOW 1FEEDWATER FLOW MISMATCH STEAM FLOW - 20.7% below rated 20% below rated -- 5 FEEDWATER FLOW steam flow steam flow STEAM PRESSURE 6 STEAM GENERATOR WATER LEVEL - LOW, LOW-LOW 4% span 15.5% span 16% span 12.0 6 7 STEAM GENERATOR WATER LEVEL - HIGH-HIGH 96.8% span (30) 80.5% span 80% span 16.8 7 8 STEAMLINE PRESSURE - LOW (SI) OUTSIDE 432.3 psig 607 psig 614 psig 13.0 8 CONTAINMENT STEAM BREAK 9 STEAMLINE PRESSURE - LOW (SI) INSIDE 566.3 psig 607 psig 614 psig 3.4 9 CONTAINMENT STEAM BREAK 10 REACTOR COOLANT FLOW - LOW '-- - 84.5% thermal 89.6% thermal 90% thermal 4.6 flow span I- - 10 design flow design flow design flow NOTES:
I. All values percent of span unless otherwise noted. 12. As noted in Table 2.2-1, Notes I and 2 of the Plant Technical Specifications. 24. [ I'" 34. [ I'"
- 2. As noted in Chapter 14 of the UFSAR. 13. As noted in Table 2.2-1, Notes 3 and 4 of the Plant Technical Specifications. 25. [ ]""
- 3. Not included in Chapter 14 of UFSAR but used in Safety Analysis. 14. [ I a,' 26. [ I'"
- 4. As noted in Tables 2.2-1 and 3.3-3 of the Plant Technical Specifications. 15. [ la" 27. [
- 5. [ I'" 16. [ I'" I'"
- 6. [ I a., 17. lncore/Excore f(M) comparison as noted in Table 4.3-1 of Plant Technical Specifications. 28. [ I a.,
- 7. [ I'" 18. [ la" 29. [
- 8. [ la" 19. [ I ~, I a.,
- 9. [ I'" 20. [ I a., 30. [ I'"
- 10. [ la" 21. [ J"" 31. [ I a.'
II. As noted in Figure 7.2-1 of the UFSAR. 22. [ la" 32. [ I'"
- 23. [ I'" I a.'
- 33. [
WCAP-17070-NP August 2010 Revision 0
Table 3-12 Overtemperature ~ T Calculations The equation for Overtemperature LlTis:
KJ (nominal) < 1.31 KJ (max) [ ] a,c o
K2 > O.023/ F K3 > O.00116/psi LlT 62.74 of smallest LlT allowance for uprate conditions LlI gain 2.37 %
PMA conversions:
a,c LlI (PMAL;l1)
M (PMAL;J2)
LlT (PMAbuL;T)
Tavg (PMAbuTavg)
- Power Cal. (PMApWR cAd a,c Pressure gain Pressure (SCAp)
Pressure (SRAp)
Pressure (SMTEp)
Pressure (STEp)
Pressure (SDp)
Pressure (RCAp)
Pressure (RMTEp)
Pressure (RTEp)
Pressure (RO p)
Pressure (BiasI)
WCAP-17070-NP August 2010 45 Revision 0
Table 3-12 (continued)
Overtemperature ~ T Calculatious a,C M conversion M(RCA M )
~I (RMTEill )
~I (RTEilI)
M(RDilI) a,c NIS conversion NIS (RCA NIs)
NIS (RMTE NIS)
NIS (RTE N1S )
NIS (RDNIs)
Total Allowance = [ ] a,c = 8.8 % ~T span
- Tavg bumdown allowance, T' - T ref mismatch, accounted for in safety analyses WCAP-17070-NP August 2010 46 Revision 0
Table 3-13 Overpower LlT Calculations The equation for Overpower LlTis:
~ (nominal) < 1.10
] a,c
~(max) [
Ks O.O/oF K6 > 0.00 16fOF for T > T" and K6 = 0 for T::::; T" LlT > 62.74 OF smallest LlT allowance for uprate conditions PMA conversions:
a,C Ll T (PMAbuL\T)
T avg (PMAbuTavg)
- Power Cal. (PMA pWR cAd
- = [
]
Total Allowance = [ ] a,c = 3.8 % LlT span
- Tavg burndown allowance, T' - T ref mismatch, accounted for in safety analyses WCAP-17070-NP August 2010 47 Revision 0
Table 3-14 AI> Measurements Expressed in Flow Units The ~P accuracy expressed as percent of span of the transmitter applies throughout the measured span, i.e., +/- 1.5 % of 100 inches ~P = +/- 1.5 inches anywhere in the span. Because F2 = f(L1P) 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:
where N = Nominal Flow thus Eq.3-14.l Error at a point (not in percent) is:
8FN 811PN 811PN
--- Eq.3-14.2 FN 2{FNl 211PN and I1PN {FNl Eq.3-14.3 I1p max {Fmaxl where max = maximum flow and the transmitter ~P error is:
811 PN (1001l--
'/ percent error in FuI1 Scale ~P (% E FS ~P) Eq.3-14.4 I1Pmax WCAP-17070-NP August 2010 48 Revision 0
Table 3-14 (continued)
""p Measurements Expressed in Flow Units Therefore, L'l [%& FS bY]
FS bY ] [Fmax ]2
[%&
8 FN P11lax 100
- - - ---=------= Eq.3-14.5 (2)(100) FN 2L'l P11lax [ F N ]2 Fmax Error in flow units is:
8 FN
=
FN
[%& FS bY ] [F11lax ]2 (2)(100) FN Eq.3-14.6 Error in percent nominal flow is:
8FN (100)=[%& FS bY ] [F11lax ]2 Eq.3-14.7 FN 2 FN Error in percent full span is:
8FN (100)=[ FN l[%& FS bY ] [F11lax -2 (100)
F11lax Fmax J (2)(100) FN Eq.3-14.8 Equation 3-14.8 is used to express errors in percent full span in this document.
WCAP-17070-NP August 2010 49 Revision 0
4.0 APPLICATION OF THE SET POINT METHODOLOGY 4.1 Uncertainty Calculation Basic Assumptions I Premises The equations noted in Sections 2 and 3 are based on several premises. These are:
- 1) The instrument technicians make reasonable attempts to achieve the NTS as an "as left" condition at the start of each process rack's surveillance interval.
- 2) The process rack drift will be evaluated (probability distribution function characteristics and drift magnitude) over multiple surveillance intervals.
- 3) The process rack calibration accuracy will be evaluated (probability distribution function characteristics and calibration magnitude) over multiple surveillance intervals.
- 4) The process racks, including the bistables, are verified/functionally tested in a string or loop process.
It should be noted for (1) above that it is not necessary for the instrument technician to recalibrate a device or channel if the "as left" condition is not exactly at the nominal condition but is within the plus or minus of nominal "as left" procedural tolerance. As noted above, the uncertainty calculations assume that the "as left" tolerance (conservative and non-conservative direction) is satisfied on a reasonable, statistical basis, not that the nominal condition is satisfied exactly. This evaluation assumes that the RCA and RD parameters values noted in Tables 3-1 through 3-10 are satisfied on at least a 95 %
probability 195 % confidence level basis. It is therefore necessary for the plant to periodically reverifY the continued validity of these assumptions. This prevents the institution of non-conservative biases due to a procedural basis without the plant staff's knowledge and appropriate treatment.
In summary, a process rack channel is considered to be "calibrated" when the two-sided "as left" calibration procedural tolerance is satisfied. An instrument technician may determine to recalibrate if near the extremes of the "as left" procedural tolerance, but it is not required. Recalibration is explicitly required any time the "as found" condition of the device or channel is outside of the "as left" procedural tolerance. A device or channel may not be left outside the "as left" tolerance without declaring the channel "inoperable" and appropriate action taken. Thus an "as left" tolerance may be considered as an outer limit for the purposes of calibration and instrument uncertainty calculations.
WCAP-17070-NP August2010 50 Revision 0
4.2 Process Rack Operability Determination Program and Criteria The parameter of most interest as a first pass operability criterion is relative drift ("as found" - "as left")
found to be within RD, where RD is the 95/95 drift value assumed for that channel. However, this would require the instrument technician to record both the "as left" and "as found" conditions and perform a calculation in the field. This field calculation requires having the "as left" value for that device at the time of drift determination and Turkey Point Units 3 and 4 have elected to have a plant specific requirement to determine if the drift allowance assumptions were exceeded since the last calibration activity.
An alternative for the process racks is the Westinghouse method for use of a fixed magnitude, two-sided "as found" tolerance about the NTS. It would be reasonable for this "as found" tolerance to be RMTE +
RD, where RD is the actual statistically determined 95/95 drift value and RMTE is defined in the Turkey Point Units 3 and 4 procedures. However, comparison of this value with the RCA tolerance utilized in the Westinghouse uncertainty calculations would yield a value where the "as found" tolerance is less than the RCA tolerance. This is due to RD being defined as a relative drift magnitude as opposed to an absolute drift magnitude and the process racks being very stable, i.e., no significant drift. Thus, it is not reasonable to use this criterion as an "as found" tolerance in an absolute sense, as it conflicts with the second criterion for operability determination, which is the ability of the equipment to be returned to within its calibration tolerance. That is, a channel could be found outside the absolute drift criterion, yet be inside the calibration criterion. Therefore, a more reasonable approach for the plant staff was determined. The "as found" criterion based on an absolute magnitude is the same as the RCA criterion, i.e., the allowed deviation from the NTS on an absolute indication basis is plus or minus the RCA tolerance. A process loop found inside the RCA tolerance on an indicated basis is considered to be operable. A channel found outside the RCA tolerance is evaluated and recalibrated. The channel must be returned to within the procedural "as left" tolerance, for the channel to be considered operable. This criterion is incorporated into plant, function specific calibration and drift procedures as the defined "as found" tolerance about the NTS. At a later date, once the "as found" data is compiled, the relative drift
("as found"- "as left") can be calculated and compared against the RD value. This comparison can then be utilized to ensure consistency with the assumptions of the uncertainty calculations documented in Tables 3-1 through 3-10. A channel found to exceed this criterion multiple times should trigger a more comprehensive evaluation ofthe operability of the channel.
It is believed that a Turkey Point Units 3 and 4 systematic program of drift and calibration review used for the process racks is acceptable as a set of first pass criteria. More elaborate evaluation and monitoring may be included, as necessary, ifthe drift is found to be excessive or the channel is found difficult to calibrate. Based on the above, it is believed that the total process rack program used at Turkey Point Units 3 and 4 will provide a more comprehensive evaluation of operability than a simple determination of an acceptable "as found."
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4.3 Application to the Plant Technical Specifications The drift operability criteria described for the process racks in Section 4.2 would be based on a statistical evaluation of the performance of the installed hardware. Thus this criterion would change if the M&TE is changed, or the procedures used in the surveillance process are changed significantly and particularly if the process rack modules themselves are changed. Therefore, the operability criteria are not expected to be static. In fact they are expected to change as the characteristics of the equipment change. This does not imply that the criteria can increase due to increasingly poor performance of the equipment over time.
But rather just the opposite. As new and better equipment and processes are instituted, the operability criteria magnitudes would be expected to decrease to reflect the increased capabilities of the replacement equipment. For example, if the plant purchased some form of equipment that allowed the determination of relative drift in the field, it would be expected that the rack operability would then be based on the RD value.
Sections 4.1 and 4.2 are basically consistent with the recommendations of the Westinghouse paper presented at the June 1994, ISAIEPRI conference in Orlando, FL(I) . In addition, the plant operability determination processes described in Sections 4.2 and 4.3 are consistent with the basic intent of the ISA paper (I) .
Therefore the AVs for the Turkey Point Units 3 and 4 Technical Specifications are "performance based" and are determined by adding (or subtracting) the calibration accuracy (RCA) of the device tested during the Channel Operational Test to the NTS in the non-conservative direction (i.e., toward or closer to the SAL) for the application.
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Two examples of the AV calculations are as follows:
SPAN = 120% RTP AV=NTS+RCA AV = 109% RTP + 0.6% RTP AV = 109.6% RTP
- Steamline Pressure - Low (S1)
NTS = 614 psig SAL = 432.2 psig RCA = 7 psig (0.5 % span)
SPAN = 1400 psig AV=NTS-RCA A V = 614 psig - 7 psig AV = 607 psig WCAP-17070-NP August 2010 53 Revision 0
4.4 References / Standards
- 1. Tuley, C. R., Williams, T. P., "The Allowable Value in the Westinghouse Setpoint Methodology
- Fact or Fiction?" presented at the Thirty-Seventh Power Instrumentation Symposium (4 th Annual ISAIEPRI Joint Controls and Automation Conference), Orlando, FL, June 1994.
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Text
Turkey Point Units 3 and 4 L-2010-113 Docket Nos. 50-250 and 50-251 Turkey Point Units 3 and 4 LICENSE AMENDMENT REQUEST FOR EXTENDED POWER UPRATE ATTACHMENT 12 WCAP-17070-NP, Revision 0, Westinghouse Setpoint Methodology for Protection Systems for Turkey Point Units 3 and 4 Power Uprate to 2644 MWt-Core Power August 2010 This coversheet plus 57 pages
WESTINGHOUSE NON-PROPRIETARY CLASS 3 Westinghouse Non-Proprietary Class 3 WCAP-17070-NP August 2010 Revision 0 Westinghouse Setpoint Methodology for Protection Systems Turkey Point Units 3 & 4 (Power Uprate to 2644 MWt - Core Power)
Westinghouse Electric Company LLC P.O. Box 355 Pittsburgh, PA 15230-0355
© 2010 Westinghouse Electric Company LLC All Rights Reserved
WESTINGHOUSE NON-PROPRIETARY CLASS 3 WCAP-17070-NP Revision 0 Westinghouse Setpoint Methodology for Protection Systems Turkey Point Units 3 & 4 (Power Uprate to 2644 MWt - Core Power)
D. R. Spaulding Setpoints and Uncertainty Analysis M. P. Drudy Setpoints and Uncertainty Analysis Z. C. King Setpoints and Uncertainty Analysis J. R. Reagan*
Setpoints and Uncertainty Analysis August 2010 Reviewer: T. P. Williams*
Setpoints and Uncertainty Analysis Approved: D. C. Olinski*, Acting Manager Setpoints and Uncertainty Analysis
- Electronically Approved Records Are Authenticated in the Electronic Document Management System Westinghouse Electric Company LLC P.O. Box 355 Pittsburgh, PA 15230-0355
© 2010 Westinghouse Electric Company LLC All Rights Reserved
TABLE OF CONTENTS LIST OF TABLES ................................................................................................................................. ii
1.0 INTRODUCTION
.................................................................................................................................. 1 1.1 References I Standards ............................................................................................................. 2 2.0 COMBINATION OF UNCERTAINTY COMPONENTS .................................................................. 3 2.1 Methodology ............................................................................................................................. 3 2.2 Sensor Allowances ................................................................................................................... 5 2.3 Rack Allowances ...................................................................................................................... 6 2.4 Process Allowances .................................................................................................................. 7 2.5 References I Standards ............................................................................................................. 8 3.0 PROTECTION SYSTEM SETPOINT METHODOLOGY ................................................................. 9 3.1 Instrument Channel Uncertainty Calculations ......................................................................... 9 3.2 Definitions for Protection System Setpoint Tolerances .......................................................... 9 3.3 References I Standards ........................................................................................................... 17 4.0 APPLICATION OF THE SETPOINT METHODOLOGY ............................................................... 50 4.1 Uncertainty Calculation Basic Assumptions I Premises ....................................................... 50 4.2 Process Rack Operability Determination Program and Criteria ........................................... 51 4.3 Application to the Plant Technical Specifications ................................................................. 52 4.4 References I Standards ........................................................................................................... 54 WCAP-17070-NP August 2010 Revision 0
LIST OF TABLES Table 3-1 Power Range Neutron Flux - High Setpoint.. ............................................................................. 18 Table 3-2 Overtemperature klT ................................................................................................................... 20 Table 3-3 Overpower klT ............................................................................................................................24 Table 3-4 High Steam Line Flow - SI, Steam Line Isolation ...................................................................... 27 Table 3-5 Steam Flow / Feedwater Flow Mismatch ................................................................................... 30 Table 3-6 Steam Generator Water Level- Low, Low-Low ........................................................................ 33 Table 3-7 Steam Generator Water Level- High-High ................................................................................ 35 Table 3-8 Steamline Pressure - Low (SI) Outside Containment Steam Break .......................................... 37 Table 3-9 Steamline Pressure - Low (SI) Inside Containment Steam Break .............................................. 39 Table 3-10 Reactor Coolant Flow - Low .................................................................................................... 41 Table 3-11 Reactor Trip System / Engineered Safety Features Actuation System Channel Error Allowances .......................................................................................... 43 Table 3-12 Overtemperatue klT Calculations ............................................................................................ .45 Table 3-13 Overpower klT Calculations .................................................................................................... .47 Table 3-14 M Measurements Expressed in Flow Units .............................................................................. 48 WCAP-17070-NP August 2010 11 Revision 0
1.0 INTRODUCTION
This report has been prepared to document the instrument uncertainty calculations for the Reactor Trip System (RTS) and Engineered Safety Features Actuation System (ESFAS) trip functions identified on Table 3-11 of this report for Turkey Point Units 3 and 4 Nuclear Power Stations (FPLlFLA) for a power uprate to 2644 MWt.
This document is divided into four sections. Section 2.0 identifies the general algorithm used as a base to determine the overall instrument uncertainty for an RTSIESFAS trip function. This approach is defined in a Westinghouse paper presented at an Instrument Society of AmericalElectric Power Research Institute (ISA/EPRI) conference in June, 1992(1). This approach is consistent with American National Standards Institute (ANSI), ANSIIISA-67.04.01-2006(2). The basic uncertainty algorithm is the Square-Root-Sum-of-the-Squares (SRSS) of the applicable uncertainty terms, which is endorsed by the ISA standard. All appropriate and applicable uncertainties, as defined by a review of the plant baseline design input documentation, have been included in each RTS/ESFAS trip function uncertainty calculation. ISA-RP67.04.02-2000(3) was utilized as a general guideline, but each uncertainty and its treatment is based on Westinghouse methods which are consistent or conservative with respect to this document. The latest version of NRC Regulatory Guide 1.105 (Revision 3(4)) endorses the 1994 version ofISA S67.04, Part 1. Westinghouse has evaluated this NRC document and has determined that the RTS/ESFAS trip function uncertainty calculations contained in this report are consistent with the guidance contained in Revision 3(4). It is believed that the total channel uncertainty (Channel Statistical Allowance or CSA) represents a 95/95 value as requested in Regulatory Guide 1.105(4).
Section 3.0 of this report provides a list of the defined terms and associated acronyms used in the RTSIESFAS trip function uncertainty calculations. Appropriate references to industry standards have been provided where applicable. Included in this section are detailed descriptions of the uncertainty terms and values for each RTSIESFAS trip function uncertainty calculation performed by Westinghouse.
Provided on each table is the function specific uncertainty algorithm which notes the appropriate combination of instrument uncertainties to determine the CSA. A summary Table (3-11) is provided which includes a listing of the Safety Analysis Limit (SAL), the Nominal Trip Setpoint (NTS), the Total Allowance (the difference between the SAL and NTS, in % span), margin, and the Allowable Value (A V). In all cases, it was determined that positive margin exists between the SAL and the NTS after accounting for the channel instrument uncertainties.
Section 4.0 provides a description of the methodology utilized in the determination of Turkey Point Units 3 and 4 Technical Specifications with regards to an explanation of the relationship between a trip setpoint and the allowable value.
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1.1 References / Standards
- 1. Tuley, C. R., Williams, T. P., "The Significance of Verifying the SAMA PMC 20.1-1973 Defined Reference Accuracy for the Westinghouse Setpoint Methodology," Instrumentation, Controls and Automation in the Power Industry, Vol. 35, Proceedings of the Thirty-Fifth Power Instrumentation Symposium (2 nd Annual ISAIEPRI Joint Controls and Automation Conference),
Kansas City, Mo., June 1992, p. 497.
- 2. ANSIIISA-67.04.01-2006, "Setpoints for Nuclear Safety-Related Instrumentation," May 2006.
- 3. ISA-RP67.04.02-2000, "Methodologies for the Determination of Setpoints for Nuclear Safety-Related Instrumentation," January 2000.
- 4. Regulatory Guide 1.105, Revision 3, "Setpoints for Safety-Related Instrumentation," 1999.
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2.0 COMBINATION OF UNCERTAINTY COMPONENTS This section describes the Westinghouse setpoint methodology for the combination of the uncertainty components utilized for Turkey Point Units 3 and 4. The methodology used in the determination of the overall CSA, for the functions listed in Table 3-11 of this report, is in Section 2.1 below. All appropriate and applicable uncertainties, as defined by a review of Turkey Point Units 3 and 4 baseline design input documentation have been included in each RTS/ESFAS trip function CSA calculation.
2.1 Methodology The methodology used to combine the uncertainty components for a channel is an appropriate combination of those groups which are statistically and functionally independent. Those uncertainties which are not independent are conservatively treated by arithmetic summation and then systematicalIy combined with the independent terms.
The basic methodology used is the SRSS technique. This technique, or others of a similar nature, has been used in WCAP-l 0395 (I) and WCAP-8567 (2). WCAP-8567 is approved by the NRC noting acceptability of statistical techniques for the application requested. Also, various ANSI, American Nuclear Society (ANS), and ISA standards approve the use of probabilistic and statistical techniques in determining safety-related setpoints (3,4). The basic methodology used in this report is essentialIy the same as that identified in a Westinghouse paper presented at an ISAIEPRI conference in June, 1992(5).
Differences between the algorithm presented in this paper and the equations presented in Tables 3-1 through 3-10 are due to Turkey Point Units 3 and 4 specific characteristics in design and should not be construed as differences in approach.
The generalized relationship between the uncertainty components and the calculated uncertainty for a channel is noted in Eq. 2.1:
PMA 2 +PEA 2 +SRA 2 +(SMTE+SDY + (SMTE+ SCAY +
CSA = SPE 2 +STE 2 +(RMTE+RDY + (RMTE + RCAY + Eq.2.1 RTE2
+EA+Bias WCAP-17070-NP August 2010 3 Revision 0
- where, CSA Channel Statistical Allowance PMA Process Measurement Accuracy PEA Primary Element Accuracy SRA Sensor Reference Accuracy SCA Sensor Calibration Accuracy SMTE Sensor Measurement and Test Equipment Accuracy SPE Sensor Pressure Effects STE Sensor Temperature Effects SD Sensor Drift RCA Rack Calibration Accuracy RMTE Rack Measurement and Test Equipment Accuracy RTE Rack Temperature Effects RD Rack Drift EA Environmental Allowance BIAS One directional, known magnitude allowance Each of the above terms is defined in Section 3.2, Definitions for Protection System Setpoint Tolerances.
Eq. 2.1 is based on the following: 1) The sensor and rack measurement "nd test equipment uncertainties are treated as dependent parameters with their respective drift and calibration accuracy allowances. 2)
While the environmental allowances are not considered statistically dependent with all other parameters, the equipment qualification testing generally results in large magnitude, non-random terms that are conservatively treated as limits of error which are added to the statistical summation. Westinghouse generally considers a term to be a limit of error if the term is a bias with an unknown sign. The term is added to the SRSS in the direction of conservatism. 3) Bias terms are one directional with known magnitudes (which may result from several sources, e.g., drift or calibration data evaluations) and are also added to the statistical summation. 4) The calibration terms are treated in the same radical with the other terms based on the assumption that general trending, i.e., drift and calibration data are evaluated on a periodic and timely basis. This evaluation should confirm that the distribution function characteristics assumed as part of treatment of the terms are still applicable. 5) Turkey Point Units 3 and 4 will monitor the "as left" and "as found" data for the sensors and process racks. This process provides performance information that results in a net reduction of the CSA magnitude (over that which would be determined if data review was not performed). Consistent with the request of Regulatory Guide 1.105(6), the CSA value from Eq. 2.1 is believed to have been determined at a 95 % probability at a 95 % confidence level (95/95).
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2.2 Sensor Allowances Seven parameters are considered to be sensor allowances: SRA, SeA, SMTE, so, STE, SPE and EA.
Three of these parameters are considered to be independent, two-sided, unverified (by plant calibration or drift determination processes), vendor supplied terms (SRA, STE and SPE). Based on vendor supplied data, typically product data sheets and qualification reports, these parameters are treated as 95/95 values unless specified otherwise by the vendor. Three of the remaining parameters are considered dependent with at least one other term, are two-sided, and are the result of the plant calibration and drift determination process (SeA, SMTE and SO).
The EA term is associated with the sensor exposure to adverse environmental conditions (elevated temperature and radiation) due to mass and energy loss from a break in the primary or secondary side piping, or adverse effects due to seismic events. Where appropriate, e.g., steamline break, only the elevated temperature term may be used for this uncertainty. The EA term magnitudes are conservatively treated as limits of error.
SRA is the manufacturer's reference accuracy that is achievable by the device. This term is introduced to address repeatability and hysteresis effects when performing only a single pass calibration, i.e., one up and one down(5,7). 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 drift determined under conditions in which pressure and temperature are assumed constant. For example, assume a sensor is placed in some position in the containment during a refueling outage. After placement, an instrument technician calibrates the sensor at ambient pressure and temperature conditions. Some time later with the plant shutdown, an instrument technician checks for sensor drift using the same technique as was previously used for calibrating the sensor. The conditions under which this drift determination is made are again ambient pressure and temperature. The temperature and pressure should be essentially the same at both measurements. Thus, they should have no significant impact on the drift determination and are, therefore, independent of the drift allowance.
seA and SO are considered to be dependent with SMTE due to the manner in which the instrumentation is evaluated. A transmitter is calibrated by providing a known process input (measured with a high accuracy gauge) and evaluating the electrical output with a digital multimeter (DMM) or digital voltmeter (DVM). The gauge and DVM accuracies form the SMTE terms. The transmitter response is known, at best, to within the accuracy of the measured input and measured output. Thus the calibration accuracy (SeA) is functionally dependent with the measurement and test equipment (SMTE). Since the gauge and DVM are independent of each other (they operate on two different physical principles), the two SMTE terms may be combined by SRSS prior to addition with the seA term. Transmitter drift is determined using the same process used to perform a transmitter calibration.
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That is, a known process input (measured with a high accuracy gauge) is provided and the subsequent electrical output is measured with a DMM or DVM. In most cases the same measurement and test equipment is used for both calibration and drift determination. Thus the drift value (SD) is functionally dependent with the measurement and test equipment (SMTE) and is treated in the same manner as SMTE and SCA.
While the data is gathered in the same manner, SD is independent of SCA in that they are two different parameters. SCA is the difference between the "as left" value and the desired value. SD is the difference between the "as found" value of the current calibration and the "as left" value ofthe previous calibration.
It is assumed that a mechanistic cause and effect relationship between SCA and SD is not demonstrated and that any data evaluation will determine the distribution function characteristics for both SCA and SD and confirm that SD is random and independent of SCA.
2.3 Rack Allowances Four parameters are considered to be rack allowances: RCA, RMTE, RTE and RD. RRA is the manufacturer's reference accuracy that is achievable by the process rack instrument string. This term is introduced to address repeatability and hysteresis effects when performing only a single pass calibration, i.e., one up and one down(5). Review of a sample of Turkey Point Units 3 and 4 specific calibration procedures has concluded that the calibration tolerance identified in the procedures is sufficient to encompass "as left" deviation and the hysteresis and repeatability effects without an additional allowance. Thus this term has been included in the RCA term in the uncertainty calculations. RTE is considered to be an independent, two-sided, unverified (by plant calibration or drift determination processes), vendor supplied parameter. The process racks are located in an area with ambient temperature control, making consistency with the rack evaluation temperature easy to achieve. Based on Westinghouse Eagle process rack data and Hagan rack data, this parameter is treated as a 95/95 value.
RCA and RD are considered to be two-sided terms dependent with RMTE. The functional dependence is due to the manner in which the process racks are evaluated. To calibrate or determine drift for the process rack portion of a channel, a known input (in the form of a voltage, current or resistance) is provided and the point at which the trip bistable changes state is measured. The input parameter is either measured by the use of a DMM or DVM (for a current or voltage signal) or is known to some degree of precision by use of precision equipment, e.g., a precision decade box for a resistance input. For simple channels, only a DMM or DVM is necessary to measure the input and the state change is noted by a light or similar device. For more complicated channels, multiple DVMs may be used or a DVM in conjunction with a decade box. The process rack response is known at best to within the accuracy ofthe measured input and indicated output. Thus the calibration accuracy (RCA) is functionally dependent with the measurement and test equipment (RMTE).
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In those instances where mUltiple pieces of measurement and test equipment are utilized, the uncertainties are combined via SRSS when appropriate.
The RCA term represents the total calibration uncertainty for the channels which are calibrated as a single string. Drift for the process racks is determined using the same process used to perform the rack calibration and in most cases utilizes the same measurement and test equipment. Thus the drift value (RD) is also functionally dependent with the measurement and test equipment (RMTE) and is treated in the same manner as RMTE and RCA.
While the data is gathered in the same manner, RD is independent of RCA in that they are different parameters. RCA is the difference between the "as left" value and the desired value. RD is the difference between the "as found" of the current calibration and the "as left" values of the previous calibration. The RD term represents the drift for all process rack modules in an instrument string, regardless of the channel complexity. For multiple instrument strings there may be multiple RD terms, e.g., Overtemperature i1T. It is assumed that a mechanistic cause and effect relationship between RCA and RD is not demonstrated and that any data evaluation will determine the distribution function characteristics for both RCA and RD and will confirm that RD is random and independent of RCA.
2.4 Process Allowances The PMA and PEA parameters are considered to be independent of both sensor and rack parameters.
The PMA terms provide allowances for the non-instrument related effects; e.g., neutron flux, calorimetric power uncertainty assumptions and fluid density changes. There may be more than one independent PMA uncertainty allowance for a channel if warranted. The PEA term typically accounts for uncertainties due to metering devices, such as elbows, venturis, and orifice plates. In this report, this type of uncertainty is limited in application by Westinghouse to RCS Flow (Cold Leg Elbow Taps), high steam flow, and steam flow / feedwater flow mismatch. In these applications, the PEA term has been determined to be independent of the sensors and process racks. It should be noted that treatment as an independent parameter does not preclude determination that a PMA or PEA term should be treated as a bias. Ifthat is determined appropriate, Eq. 2.1 would be modified such that the affected term would be treated by arithmetic summation with appropriate determination and application ofthe sign of the uncertainty.
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2.5 References / Standards
- 1. Grigsby, J. M., Spier, E. M., Tuley, C. R., "Statistical Evaluation of LOCA Heat Source Uncertainty," WCAP-10395 (Proprietary), WCAP-10396 (Non-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. ANSI/ISA-67.04.01-2006, "Setpoints for Nuclear Safety-Related Instrumentation," May 2006.
- 5. Tuley, C. R., Williams, T. P., "The Significance of Verifying the SAMA PMC 20.1-1973 Defined Reference Accuracy for the Westinghouse Setpoint Methodology," Instrumentation, Controls and Automation in the Power Industry, Vol. 35, Proceedings of the Thirty-Fifth Power nd Instrumentation Symposium (2 Annual ISAIEPRI Joint Controls and Automation Conference),
Kansas City, Mo., June 1992, p. 497.
- 6. Regulatory Guide 1. 105 Revision 3, "Setpoints for Safety Related Instrumentation," 1999.
- 7. ANSI/ISA-51.1-1979 (R1993), "Process Instrumentation Terminology," Reaffirmed May 26, 1995, p. 61.
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3.0 PROTECTION SYSTEM SETPOINT METHODOLOGY This section contains a list of defined terms used in the Turkey Point Units 3 and 4 RTS/ESF AS trip function uncertainty calculations. Also included in this section are detailed tables and a summary table of the uncertainty terms and values for each calculation that Westinghouse performed. It was determined that in all cases sufficient margin exists between the nominal trip setpoint and the safety analysis limit after accounting for uncertainties.
3.1 Instrument Channel Uncertainty Calculations Tables 3-1 through 3-10 provide individual component uncertainties and CSA calculations for the protection functions noted in Tables 2.2-1 and Table 3.3-3 of Turkey Point Units 3 and 4 Technical Specifications. Table 3-11 of this report provides a summary of the Reactor Trip System / Engineered Safety Features Actuation System Channel Uncertainty Allowances for Turkey Point Units 3 and 4. This table lists the Safety Analysis Limit, Nominal Trip Setpoint, and Allowable Value (in engineering units),
and Channel Statistical Allowance, Margin, Total Allowance and uncertainty terms (in % span).
Westinghouse reports the values in Tables 3-1 through 3-10 and Table 3-11 to one decimal place using the technique of rounding down values less than 0.05 % span and rounding up values greater than or equal to 0.05 % span. Parameters reported as "0.0" have been identified as having a value of s 0.04 %
span. Parameters reported as "0" or "---" in the tables are not applicable (i.e., have no value) for that channel.
3.2 Definitions for Protection System Setpoint Tolerances For the channel uncertainty values used in this report, the following definitions are provided in alphabetical order:
- As Found The condition in which a transmitter, process rack module, or process instrument loop is found after a period of operation. For example, after one cycle of operation, a Steam Generator Level transmitter's output at 50 % span was measured to be 12.05 rnA. This would be the "as found" condition.
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- As Left The condition in which a transmitter, process rack module, or process instrument loop is left after calibration or bistable trip setpoint verification. This condition is typically better than the calibration accuracy for that piece of equipment. For example, the calibration point for a Steam Generator Level transmitter at 50 % span is 12.0 +/- 0.04 rnA. A measured "as left" condition of 12.03 rnA would satisfy this calibration tolerance. In this instance, if the calibration was stopped at this point (i.e., no additional efforts were made to decrease the deviation) the "as left" error would be + 0.03 rnA or + 0.19 % span, assuming a 16 rnA (4 to 20 rnA) instrument span.
- Channel The sensing and process equipment, i.e., transmitter to bistable, for one input to the voting logic of a protection function. Westinghouse designs protection functions with voting logic made up of multiple channels, e.g. 2 out of 3 Steam Generator Level - Low-Low channels for one steam generator must have their bistables in the tripped condition for a Reactor Trip to be initiated.
- Channel Statistical Allowance (CSA)
The combination of the various channel uncertainties via SRSS and algebraic techniques. It includes instrument (sensor and process rack) uncertainties and non-instrument related effects (Process Measurement Accuracy), see Eq. 2.1. This parameter is compared with the Total Allowance for determination of instrument channel margin.
- Environmental Allowance (EA)
The change in a process signal (transmitter or process rack output) due to adverse environmental conditions from a limiting accident condition or seismic event. Typically this value is determined from a conservative set of enveloping conditions and may represent the following:
- Temperature effects on a transmitter
- Radiation effects on a transmitter
- Seismic effects on a transmitter
- Temperature effects on a level transmitter reference leg
- Temperature effects on signal cable insulation
- Seismic effects on process racks WCAP-17070-NP August 2010 10 Revision 0
- Margin The calculated difference (in % instrument span) between the Total Allowance (TA) and the CSA.
Margin = T A - CSA
- Nominal Trip Setpoint (NTS)
A bistable trip setpoint in plant procedures. This value is the nominal value to which the bistable is set, as accurately as reasonably achievable.
- Normalization The process of establishing a relationship, or link, between a process parameter and an instrument channel. This is in contrast with a calibration process. A calibration process is performed with independent known values, i.e., a bistable is calibrated to change state when a specific voltage is reached. This voltage corresponds to a process parameter magnitude with the relationship established through the scaling process. A normalization process typically involves an indirect measurement, e.g., determination of Steam Flow via the ~P drop across a flow restrictor. The flow coefficient for this device, (effectively an orifice which has not been calibrated in a laboratory setting), is not known. Therefore a mass balance between Feedwater Flow and Steam Flow must be made. The mass Feedwater Flow is known through measurement via the ~P across the venturi, Feedwater Pressure and Feedwater Temperature. Presuming no mass losses prior to the measurement of the Steam Flow, the mass Steam Flow can be claimed to equal the mass Feedwater Flow. Measurement of the Steam Flow ~P and the Steam Pressure (to correct for density) can then be utilized to translate to a volumetric flow.
- Primary Element Accuracy (PEA)
Uncertainty due to the use of a metering device. In Westinghouse calculations, this parameter is limited to use on a venturi, orifice, elbow or potential transformer. Typically, this is a calculated or measured accuracy for the device.
- Process Loop (Instrument Process Loop)
The process equipment for a single channel of a protection function.
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- Process Measurement Accuracy (PMA)
Allowance for non-instrument related effects which have a direct bearing on the accuracy of an instrument channel's reading, e.g., temperature stratification in a large diameter pipe, fluid density in a pipe or vessel.
- Process Racks The analog modules downstream of the transmitter or sensing device, which condition a signal and act upon it prior to input to a voting logic system. For Hagan analog process systems, this includes all the equipment contained in the process equipment cabinets, e.g., conversion resistor, loop power supply, lead/lag, rate, lag functions, function generator, summator, control/protection isolator, and bistable. The go/no go signal generated by the bistable is the output of the last module in the analog process rack instrument loop and is the input to the voting logic.
- Rack Calibration Accuracy (RCA)
Rack calibration accuracy is defined as the two-sided calibration tolerance of the process racks.
It is assumed that the individual modules in a loop are calibrated to a particular tolerance and that the process loop as a string is verified to be calibrated to a specific tolerance. The tolerance is typically less than the arithmetic sum or SRSS of the individual module tolerances. This forces calibration of the process loop in such a manner as to exclude a systematic bias in the individual module calibrations, i.e., as left values for individual modules must be compensating in sign and magnitude when considered as an instrument string.
Review of a sample of Turkey Point Units 3 and 4 specific calibration procedures concluded that the calibration process and the identified RCA allowance is sufficient to encompass the as left deviation and the hysteresis and repeatability effects without an additional RRA allowance.
WCAP-17070-NP August 2010 12 Revision 0
- Rack Drift (RD)
The change in input-output relationship over a period of time at reference conditions, e.g., at constant temperature. For example, assume that a Water Level channel at SO % span (presuming a 1 to S V span) has an "as found" value of3.01 V for the current calibration and an "as left" value of2.99 V from the previous calculation. The magnitude of the drift would be {(3.01 -
2.99)(100/4) = + 0.5 % span} in the positive direction. For Turkey Point Units 3 and 4 plant specific surveillance procedures, Florida Power and Light will implement an additional requirement to compare the as found to the previous as left value to determine if drift allowance assumptions were exceeded since the last calibration activity.
- Rack Measurement & Test Equipment Accuracy (RMTE)
The accuracy of the test equipment (typically a transmitter simulator, voltage or current power supply, and DVM) used to calibrate a process loop in the racks. When the magnitude ofRMTE meets the requirements of SAMA Standard PMC 20.1-1973(9) or ANSIIlSA-Sl.1-1979 (RI993)(10) it is considered an integral part of RCA. Uncertainties due to M&TE that are 10 times more accurate than the device being calibrated are considered insignificant and are not included in the uncertainty calculations.
- Rack Reference Accuracy (RRA)
Rack Reference Accuracy is the reference accuracy, as defined by SAMA Standard PMC 20.1-1973(1) for a process loop string. It is defined as the reference accuracy or accuracy rating that is achievable by the instrument string as specified in the manufacturer's specification sheets.
Inherent in this definition is the verification of the following under a reference set of conditions;
- 1) conformity(2) or (6), 2) hysteresis(3) or (7) and 3) repeatability(4) or (8). An equivalent to the SAMA definition of reference accuracy is the ANSI/ISA-S 1.1-1979 (R1993)(5) term "accuracy rating,"
specifically as applied to Note 2 and Note 3.
Review of a sample of Turkey Point Units 3 and 4 specific calibration procedures and calibration assumptions concludes that the identified calibration allowance is sufficient to encompass the Rack Reference Accuracy without an additional allowance.
- Rack Temperature Effects (RTE)
Change in input-output relationship for the process rack module string due to a change in the ambient environmental conditions (temperature, humidity), and voltage and frequency from the reference calibration conditions. It has been determined that temperature is the most significant, with the other parameters being second order effects. For process instrumentation, a typical WCAP-17070-NP August 2010 13 Revision 0
value of[ ]a,e is used for analog channel temperature effects which allows for a +/- 50 of ambient temperature deviation.
- Range The upper and lower limits of the operating region for a device, e.g., for a Steamline Pressure transmitter, 0 to 1400 psig. This is not necessarily the calibrated span of the device, although lO quite often the two are close. For further information see ANSIIISA-51.1-1979 (RI993i ).
- Safety Analysis Limit (SAL)
The parameter value in the UFSAR safety analysis or other plant operating limit at which a reactor trip or actuation function is assumed to be initiated.
- Sensor Calibration Accuracy (SeA)
The calibration accuracy for a sensor or transmitter as defined by the plant calibration procedures. For transmitters, this accuracy is typically [ ]a,e. Utilizing Westinghouse recommendations for Resistance Thermal Detector (RTD) cross-calibration, this accuracy is typically [ t,e for the Hot and Cold Leg RTDs.
- Sensor Drift (SD)
The change in input-output relationship over a period of time at reference calibration conditions, e.g., at constant temperature. For example, assume a Water Level transmitter at 50 % level (presuming a 4 to 20 rnA span) has an "as found" value of 12.05 rnA from the current calibration and an "as left" value of 12.01 rnA from the previous calibration. The magnitude of the drift would be {(l2.05 - 12.01)(100/16) = + 0.25 % span} in the positive direction.
- Sensor Measurement & Test Equipment Accuracy (SMTE)
The accuracy of the test equipment (typically a high accuracy local readout gauge and DVM) used to calibrate a sensor or transmitter in the field or in a calibration laboratory. When the magnitUde ofSMTE meets the requirements of ANSIIISA-51.1-1979 (RI993PO) it is considered an integral part of SCA. Uncertainties due to M&TE that are 10 times more accurate than the device being calibrated are considered insignificant and are not included in the uncertainty calculations.
WCAP-17070-NP August 2010 14 Revision 0
- Sensor Pressure Effects (SPE)
The change in input-output relationship due to a change in the static head pressure from the calibration conditions or the accuracy to which a correction factor is introduced for the difference between calibration and operating conditions for a ilp transmitter.
- Sensor Reference Accuracy (SRA)
The reference accuracy that is achievable by the device as specified in the manufacturer's specification sheets. This term is introduced into the uncertainty calculation to address repeatability effects when performing only a single pass calibration, i.e., one up and one down, or repeatability and hysteresis when performing a single pass calibration in only one direction.
- Sensor Temperature Effects (STE)
The change in input-output relationship due to a change in the ambient environmental conditions (temperature, humidity), and voltage and frequency from the reference calibration conditions. It has been determined that temperature is the most significant, with the other parameters being second order effects. Note that the ambient temperature effects were evaluated using +/- 60 °P.
- Span The region for which a device is calibrated and verified to be operable, e.g., for a Steamline Pressure transmitter, 1400 psi.
- Square-Root-of-the-Sum-of-the-Squares (SRSS)
That is,
&=~(al +(b l +(c l as approved for use in setpoint calculations by ANSVISA-67.04.01-2006(1l).
- Total Allowance (TA)
The absolute value of the difference (in % instrument span) between the Safety Analysis Limit (SAL) and the Nominal Trip Setpoint (NTS).
TA = I SAL - NTS I WCAP-17070-NP August 2010 15 Revision 0
Two examples of the calculation ofTA are:
- Power Range Neutron Flux - High SAL 115% RTP NTS -109% RTP TA I 6% RTPI = 6% RTP If the instrument span = 120% RTP, then
'T'A = (6% RTP) * (JOO%span) 1..t1 5.0 % span (120% RTP)
- Steamline Pressure - Low (SI)
SAL 566.3 psig NTS -614.0 psig TA -47.7psigl =47.7psig If the instrument span = 1400 psig, then
'T'A __ (47.7 psig) * (lOO%span) 1£1 3.4 % span (1400 psig)
WCAP-17070-NP August 2010 16 Revision 0
3.3 References / Standards
- 1. Scientific Apparatus Makers Association Standard PMC 20.1-1973, "Process Measurement &
Control Terminology," p. 4.
- 2. Ibid, p. 5.
- 3. Ibid, p. 19.
- 4. Ibid, p. 28.
- 5. ANSIIISA -5l.l-1979 (R 1993), "Process Instrumentation Terminology," Reaffirmed May 26, 1995, p. 12.
- 6. Ibid, p. 16.
- 7. Ibid, p. 36.
- 8. Ibid, p. 49.
- 9. Scientific Apparatus Makers Association Standard PMC 20.1-1973, "Process Measurement &
Control Terminology," p. 36.
- 10. ANSI/ISA-51.1-J979 (RI993), "Process Instrumentation Terminology," Reaffirmed May 26, 1995, p. 61.
II. ANSIIISA-67 .04.01-2006, "Setpoints for Nuclear Safety-Related Instrumentation," May 2006.
WCAP-17070-NP August 2010 17 Revision 0
Table 3-1 Power Range Neutron Flux - High Setpoint Parameter Allowance*
a,c Process Measurement Accuracy
[
[
Primary Element Accuracy (PEA)
Sensor Calibration Accuracy (SCA)
[ t,C Sensor Reference Accuracy (SRA)
[ t,C Sensor Measurement & Test Equipment Accuracy (SMTE)
Sensor Pressure Effects (SPE)
Sensor Temperature Effects (STE)
Sensor Drift (SD)
Rack Calibration Accuracy (RCA)
Rack Measurement & Test Equipment Accuracy (RMTE)
Rack Temperature Effect (RTE)
Rack Drift (RD)
- In percent span (120 % RTP)
WCAP-17070-NP August 2010 18 Revision 0
Table 3-1 (continued)
Power Range Neutron Flux - High Setpoint Channel Statistical Allowance =
2 PMA~ +PMA~ + PEA + (SMTE + SCA)2 + (SMTE+SD)2 +SPE 2 +STE +SRA +
2 2 (RMTE + RCA) 2 + (RMTE+ RD)2 +RTE2 a,c WCAP-17070-NP August 2010 19 Revision 0
Table 3-2 Overtemperature ~T Parameter Allowance*
Process Measurement Accuracy (PMA) a,e
[
[
[
[
[
[
Primary Element Accuracy (PEA)
Sensor Calibration Accuracy (SCA)
Sensor Reference Accuracy (SRA)
]a,e t,e Sensor Measurement & Test Equipment Accuracy (SMTE)
]a,e t,e Sensor Pressure Effects (SPE)
Sensor Temperature Effects (STE)
Sensor Drift (SD)
Bias
[
WCAP-17070-NP August 2010 20 Revision 0
Table 3-2 (continued)
Overtemperature ~T Parameter Allowance*
Rack Calibration Accuracy (RCA) a,c
[
[
Rack Measuring & Test Equipment Accuracy (RMTE)
[
Rack Temperature Effect (RTE)
[ t,C
]a,c
] a,c Rack Drift (RD)
]a,c
[
]a,c t,C
- In percent 11T span (Tavg - 75 of, Pressure - 1000 psi, 11T - 100 of = 159.4% RTP, 111 - 120% 111)
NH = # of hot leg RTDs = 2 Nc = # of cold leg RTDs = 1 WCAP-17070-NP August 2010 21 Revision 0
Table 3-2 (continued)
Overtemperature .L\T Channel Statistical Allowance =
2 2 2 PMA"'I1 +PMA"'12 + PMApWRCAL2 + PEA +
.-----------------------------------------,2 Y
(SCA"'T + SMTE"'T + (SD"'T + SMTE"'T + SRA"'T 2 Y f-'------'='-"-------=-"-----------'-'--------....::::..:.-'-------='---- +
NH
+
\ (SCA"'T +SMTE"'TY + (SD"'T +SMTE"'Tf +SRA",/
Nc .-
2 (SMTEp +SDpY +SRA/ +SPE p +STE/ + (SMTEp +SCApY +
2 2 ( )2 -,2
( RMTE"'T +RD"'T ) +RTE"'T + RMTE"'T + RCA"'T I-'------~----~------~--~----~----~~+
NH
+
\ (RMTE"'T +RD"'TY +RTE",/ + (RMTE"'T + RCA"'T)2 Nc (RMTEp + RDp f + (RMTEp + RCA p + RTE/ + Y 2x [(RMTE "'I + RD "'I Y+ (RMTE M + RCA M Y+ RTE "'I 2J+
(RMTE N1S +RDN1SY +RTENIS2 + (RMTE N1S + RCANlsY
+ PMAbll"'T + PMAbuTavg + BIASpressllre WCAP-17070-NP August 2010 22 Revision 0
Table 3-2 (continued)
Overtemperature AT a,c WCAP-17070-NP August 2010 23 Revision 0
Table 3-3 Overpower ,1T Parameter Allowance
- Process Measurement Accuracy (PMA) a,c
[
[
[
[
[
Primary Element Accuracy (PEA)
Sensor Calibration Accuracy (SCA)
[
Sensor Reference Accuracy (SRA)
[
Sensor Measuring & Test Equipment Accuracy (SMTE)
] a,c Sensor Pressure Effects (SPE)
Sensor Temperature Effects (STE)
Sensor Drift (SD)
[
Environmental Allowance (EA)
[
Rack Calibration Accuracy (RCA)
[
[
WCAP-17070-NP August 2010 24 Revision 0
Table 3-3 (continned)
Overpower LiT Parameter Allowance*
Rack Measuring & Test Equipment Accuracy (RMTE) a,c t,C Rack Temperature Effect (RTE)
[
Rack Drift (RD)
- In percent ~T span (Tavg - 75 of, ~T - 100 of = 159.4 % RTP)
NH = # of hot leg RTDs = 2 Nc = # of cold leg RTDs = 1 WCAP-17070-NP August 2010 25 Revision 0
Table 3-3 (continued)
Overpower AT Channel Statistical Allowance =
2 PMApWRCAL2 +PEA +
2 (SCALIT +SMTELITY + (SDLlT +SMTELITY +SRA LI/
I~--~------~~--~~~----~~------~+
NH
+
(SCALIT +SMTELITY + (SD LlT +SMTELITY +SRA LI/
Nc Y
2 (RMTELIT + RDLlT)2 + RTELI/ + (RMTELIT + RCA LIT
~----~----~~----~--~----~------~~+
NH (RMTELIT + RD LIT Y+ RTELI/ + (RMTELIT + RCA LIT Y NC
+ PMA buLlT + PMAbuTavg + EA a,c WCAP-17070-NP August 2010 26 Revision 0
Table 3-4 High Steam Line Flow - SI, Steam Line Isolation Parameter Allowance*
Process Measurement Accuracy (PMA) a,e
[
[
[
Primary Element Accuracy (PEA)
Steam Flovv [
Sensor Calibration Accuracy (SCA)
Steam Flovv [
Turbine Pressure [
Sensor Reference Accuracy (SRA)
Steam Flovv [
Turbine Pressure [
Sensor Measurement & Test Equipment Accuracy (SMTE)
Steam Flovv [ t,e Turbine Pressure [ t,e Sensor Pressure Effects (SPE)
Steam Flovv ]a,e Sensor Temperature Effects (STE)
Steam Flovv [ ]a,e Turbine Pressure [ t,e Sensor Drift (SO)
Steam Flovv t,e Turbine Pressure ]a,e Environmental Allovvances (EA)
Steam Flovv Turbine Pressure Bias Steam Flovv - static pressure correction [
WCAP-17070-NP August 2010 27 Revision 0
Table 3-4 (continued)
High Steam Line Flow - SI, Steam Line Isolation Parameter Allowance*
Rack Calibration Accuracy (RCA) a,c Stearn Flovv [
Turbine Pressure [
Rack Measurement & Test Equipment Accuracy (RMTE)
Stearn Flovv [ t,c Turbine Pressure [ t,C Rack Temperature Effect (RTE)
Stearn Flovv [
Rack Drift (RD)
Stearn Flovv Turbine Pressure
- In percent flow span (135.9 % Span). Values are converted to flow via Equation 3-14.8 where Fmax = 135.9 % and FN = 114
%; therefore, gain = (1/2)(135.9/1 14) = 0.60.
WCAP-17070-NP August 2010 28 Revision 0
Table 3-4 (continued)
High Steam Line Flow - SI, Steam Line Isolation Channel Statistical Allowance =
2 PEA SF +
(SMTESF +SCASFY +SRAs/ + (SMTEsF +SDSFY + SPEs/ +STEs/ +
2 (RMTEsF + RCA SF Y + (RMTESF + RDSF Y + RTESF +
(SMTETP +SCATPY +SRA T/ + (SMTETP +SD TP )2 +SPE T/ + STET/ +
2 (RMTETP + RCA TP Y + (RMTETP + RDTP Y + RTETP
+ PMA ISF + PMA 2SF + PMA TP + BiasI + EA a,c WCAP-17070-NP August 2010 29 Revision 0
Table 3-5 Steam Flow / Feedwater Flow Mismatch Parameter Allowance*
Process Measurement Accuracy (PMA) a,c
[
[
[
Primary Element Accuracy (PEA)
Steam Flovv [
Feed Flovv Sensor Calibration Accuracy (SCA)
Steam Flovv [
Feed Flovv [
Steam Pressure [
Sensor Reference Accuracy (SRA)
Steam Flovv [
Feed Flovv [
Steam Pressure [
Sensor Measurement & Test Equipment Accuracy (SMTE)
Steam Flovv [ ]a,c Feed Flovv [ ]a,c Steam Pressure [ t,C Sensor Pressure Effects (SPE)
Steam Flovv [
Feed Flovv [
Sensor Temperature Effects (STE)
Steam Flovv [
Feed Flovv [
Steam Pressure [
Sensor Drift (SD)
Steam Flovv [
Feed Flovv [
Steam Pressure [
WCAP-17070-NP August 2010 30 Revision 0
Table 3-5 (continned)
Steam Flow / Feedwater Flow Mismatch Parameter Allowance*
a,c Environmental Allowances (EA)
Bias Steam Flow - static pressure correction (BiasI)
Feedwater Flow - static pressure correction (Bias2)
Rack Calibration Accuracy (RCA)
Steam Flow Feed Flow Rack Measurement & Test Equipment Accuracy (RMTE)
Steam Flow Feed Flow Rack Temperature Effect (RTE)
Feed Flow Rack Drift (RD)
Steam Flow Feed Flow
- In percent flow span (135.9 % Span). Values are converted to flow span via Equation 3-14.8 where Fmax = 135.9 %, FN (steam flow) = 100 %, and FN (feedwater flow) = 80 %; therefore, gain (steam flow) = (1/2)(135.9/100) = 0.68 and gain (feedwater flow) = (112)(135.9/80) = 0.85. The gain for steam pressure = 1.2 WCAP-17070-NP August 2010 31 Revision 0
Table 3-5 (continued)
Steam Flow / Feedwater Flow Mismatch Channel Statistical Allowance =
(SMTEsp +SCAspY + SRA Sp2 + (SMTEsp +SDspY +STEs/ +
PEAs/ + (SMTEsF +SCASFY +SRAs/ + (SMTEsF +SDSFY + SPEs/ +STEs/ +
(RMTEsF + RCA SF Y + (RMTEsF + RDSF Y +
PEA F/ + (SMTEFF + SCAFF Y + SRA F/ + (SMTE FF + SD FF Y + SPE F/ + STE F/ +
2 (RMTEFF + RCA FF )2 + (RMTEFF + RDFF Y + RTEFF
+ PMA ISF + PMA 2SF + PMA FF + BiasI + Bias 2 + EA a,c WCAP-17070-NP August 2010 32 Revision 0
Table 3-6 Steam Generator Water Level- Low, Low-Low Parameter Allowance*
Process Measurement Accuracy**
a,c a,c Primary Element Accuracy (PEA)
Sensor Calibration Accuracy (SCA)
Sensor Reference Accuracy (SRA)
Sensor Measurement & Test Equipment Accuracy (SMTE)
Sensor Pressure Effects (SPE)
Sensor Temperature Effects (STE)
Sensor Drift (SD)
Environmental Allowance** (EA)
Bias**
[
Rack Calibration Accuracy (RCA)
Rack Measurement & Test Equipment Accuracy (RMTE)
Rack Temperature Effect (RTE)
Rack Drift (RD)
- In percent span (l00 %)
- [ ]a,c WCAP-17070-NP August 20lO 33 Revision 0
Table 3-6 (continued)
Steam Generator Water Level- Low, Low-Low Channel Statistical Allowance =
PEA 2 + (SMTE + SCA) 2 + SRA 2 + SPE 2 + STE 2 + (SMTE + SD) 2 +
(RMTE + RCA) 2 + RTE 2 + (RMTE + RD) 2
+ BiasI + Bias 2 + EA + PMA pp + PMA RL + PMA FV + PMA sc + PMA MD a,c WCAP-17070-NP August 2010 34 Revision 0
Table 3-7 Steam Generator Water Level- High-High Parameter Allowance*
Process Measurement Accuracy** a,c a,c Primary Element Accuracy (PEA)
Sensor Calibration Accuracy (SCA)
Sensor Reference Accuracy (SRA)
Sensor Measurement & Test Equipment Accuracy (SMTE)
Sensor Pressure Effects (SPE)
Sensor Temperature Effects (STE)
Sensor Drift (SD)
Environmental Allowance** (EA)
Bias**
[
Rack Calibration Accuracy (RCA)
Rack Measurement & Test Equipment Accuracy (RMTE)
Rack Temperature Effect (RTE)
Rack Drift (RD)
- In percent span (100 %)
- [ ]a,c WCAP-17070-NP August 2010 35 Revision 0
Table 3-7 (continued)
Steam Generator Water Level- High-High Channel Statistical Allowance =
PEA 2 + (SMTE + SCA) 2 + SRA 2 + SPE 2 + STE 2 + (SMTE + SD) 2 +
(RMTE + RCA) 2 + RTE 2 + (RMTE + RD) 2
+ Bias] + Bias 5 + EA + PMA pp + PMA RL + PMA FV + PMA sc + PMA MD + PMA DL a,c Note: Negative sign (-) denotes direction (i.e. indicated lower than actual).
WCAP-17070-NP August 2010 36 Revision 0
Table 3-8 Steam line Pressure - Low (SI)
Outside Containment Steam Break Parameter Allowance*
a,C Process Measurement Accuracy (PMA)
Primary Element Accuracy (PEA)
Sensor Calibration Accuracy (SCA)
Sensor Reference Accuracy (SRA)
Sensor Measurement & Test Equipment Accuracy (SMTE)
Sensor Pressure Effects (SPE)
Sensor Temperature Effects (STE)
Sensor Drift (SD)
Environmental Allowances (EA)
[ ] a,c Bias
[
[
Rack Calibration Accuracy (RCA)
Rack Measurement & Test Equipment Accuracy (RMTE)
Rack Temperature Effect (RTE)
Rack Drift (RD)
- In percent span (1400 psig)
WCAP-17070-NP August 2010 37 Revision 0
Table 3-8 (continued)
Steam line Pressure - Low (SI)
Outside Containment Steam Break Channel Statistical Allowance =
(RMTE+ RCAY +(RMTE+RDY +RTE2
+ EA + Bias] + Bias 2 a,c WCAP-17070-NP August 2010 38 Revision 0
Table 3-9 Steam line Pressure - Low (SI)
Inside Containment Steam Break Parameter Allowance*
a,c Process Measurement Accuracy (PMA)
Primary Element Accuracy (PEA)
Sensor Calibration Accuracy (SCA)
Sensor Reference Accuracy (SRA)
Sensor Measurement & Test Equipment Accuracy (SMTE)
Sensor Pressure Effects (SPE)
Sensor Temperature Effects (STE)
Sensor Drift (SD)
Environmental Allowances (EA)
[ ]~
Bias
[
[
Rack Calibration Accuracy (RCA)
Rack Measurement & Test Equipment Accuracy (RMTE)
Rack Temperature Effect (RTE)
Rack Drift (RO)
- In percent span (I400 psig)
WCAP-17070-NP August 2010 39 Revision 0
Table 3-9 (continued)
Steamline Pressure - Low (SI)
Inside Containment Steam Break Channel Statistical Allowance =
(RMTE+RCAY +(RMTE+RDY +RTE2
+ EA + Bias] + Bias 2 a,c WCAP-17070-NP August 2010 40 Revision 0
Table 3-10 Reactor Coolant Flow - Low Parameter Allowance*
Process Measurement Accuracy (PMA) a,C
[
[
Primary Element Accuracy (PEA)
[
Sensor Calibration Accuracy (SCA)
[ t,e Sensor Reference Accuracy (SRA)
[ ]~
Sensor Measurement & Test Equipment Accuracy (SMTE)
[ ]~
Sensor Pressure Effects (SPE)
[ ]~
Sensor Temperature Effects (STE)
[ ] a,c Sensor Drift (SO)
[ ]a,c Rack Calibration Accuracy (RCA)
[ ]~
Rack Measurement & Test Equipment Accuracy (RMTE)
[ ]~
Rack Temperature Effect (RTE)
[ r,c Rack Drift (RO)
[
- In % flow span (120 % Thermal Design Flow). Percent ilP span converted to flow span via Equation 3-14.8, with Fmax =
120 % and FN = 90 %, therefore, gain = (112) (120% /90%) = 0.67.
WCAP-17070-NP August 2010 41 Revision 0
Table 3-10 (continued)
Reactor Coolant Flow - Low Note the CSA equation for this function has been defined by FPL as:
Channel Statistical Allowance =
2 2 PMA j + PMA 2 +PEA 2 +
{~PEA2 +(SMTE+SCAY +(SMTE+SDY +STE 2 +SPE 2 +SRA2}2 +
2 2 2 (SMTE+SCAY +(SMTE+SDY +STE +SPE +SRA +
(RMTE+RCAY +(RMTE+RDY +RTE2 a,c WCAP-17070-NP August 2010 42 Revision 0
---- - ~~-
WESTINGHOUSE NON-PROPRIETARY CLASS 3 Page 43 Table 3-11 & Page 44 Reactor Trip System I Engineered Safety Features Actuation System Channel Error Allowances Turkey Point Units 3 & 4 (FPUFLA)
SENSOR INSTRUMENT RACK 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 MEASUREMENT MEASUREMENT PROCESS PRIMARY & TEST & TEST SAFETY CHANNEL PROTECTION CHANNEL MEASUREMENT ELEMENT CALIBRATION REFERENCE EQUIPMENT PRESSURE TEMPERATURE ENVIRONMENTAL CALIBRATION EQUIPMENT TEMPERATURE ANALYSIS ALLOWABLE TRIP TOTAL STATISTICAL ACCURACY ACCURACY ACCURACY ACCURACY ACCURACY EFFECTS EFFECTS DRIFT ALLOWANCE ACCURACY ACCURACY EFFECTS DRIFT LIMIT VALUE SETPOINT ALLOWANCE ALLOWANCE MARGIN (1) (1) (1) (1) (1) (1) (1) (1) (1) (1) (1) (1) (1) (2 or 3) (4) (4) (1) (1) (1)
- , -a,c - -"
1 POWER RANGE NEUTRON FLUX - HIGH SETPOINT 115%RTP 109.6% RTP 109%RTP 5.0 1 2 OVERTEMPERATURE LIT LlTCHANNEL 2 TAVG CHANNEL PRESSURIZER PRESSURE CHANNEL FUNCTION (11) FUNCTION (12) FUNCTION (12) 8.8.11T Span I(LlI) CHANNEL NISCHANNEL 3 OVERPOWER M LlT CHANNEL 3 I Tavg CHANNEL FUNCTION (11) FUNCTION (13) FUNCTION (13) 3.8.11T Span 4 HIGH STEAMLINE FLOW - SI, STEAM FLOW ~ 60% 1129% full 41.2%1 114.4% lull 40% 1114% full 14.7/11.0 4 STEAM LINE ISOLATION TURBINE PRESSURE steam flow steam flow steam flow flow span 5 STEAM FLOW 1FEEDWATER FLOW MISMATCH STEAM FLOW - 20.7% below rated 20% below rated -- 5 FEEDWATER FLOW steam flow steam flow STEAM PRESSURE 6 STEAM GENERATOR WATER LEVEL - LOW, LOW-LOW 4% span 15.5% span 16% span 12.0 6 7 STEAM GENERATOR WATER LEVEL - HIGH-HIGH 96.8% span (30) 80.5% span 80% span 16.8 7 8 STEAMLINE PRESSURE - LOW (SI) OUTSIDE 432.3 psig 607 psig 614 psig 13.0 8 CONTAINMENT STEAM BREAK 9 STEAMLINE PRESSURE - LOW (SI) INSIDE 566.3 psig 607 psig 614 psig 3.4 9 CONTAINMENT STEAM BREAK 10 REACTOR COOLANT FLOW - LOW '-- - 84.5% thermal 89.6% thermal 90% thermal 4.6 flow span I- - 10 design flow design flow design flow NOTES:
I. All values percent of span unless otherwise noted. 12. As noted in Table 2.2-1, Notes I and 2 of the Plant Technical Specifications. 24. [ I'" 34. [ I'"
- 2. As noted in Chapter 14 of the UFSAR. 13. As noted in Table 2.2-1, Notes 3 and 4 of the Plant Technical Specifications. 25. [ ]""
- 3. Not included in Chapter 14 of UFSAR but used in Safety Analysis. 14. [ I a,' 26. [ I'"
- 4. As noted in Tables 2.2-1 and 3.3-3 of the Plant Technical Specifications. 15. [ la" 27. [
- 5. [ I'" 16. [ I'" I'"
- 6. [ I a., 17. lncore/Excore f(M) comparison as noted in Table 4.3-1 of Plant Technical Specifications. 28. [ I a.,
- 7. [ I'" 18. [ la" 29. [
- 8. [ la" 19. [ I ~, I a.,
- 9. [ I'" 20. [ I a., 30. [ I'"
- 10. [ la" 21. [ J"" 31. [ I a.'
II. As noted in Figure 7.2-1 of the UFSAR. 22. [ la" 32. [ I'"
- 23. [ I'" I a.'
- 33. [
WCAP-17070-NP August 2010 Revision 0
Table 3-12 Overtemperature ~ T Calculations The equation for Overtemperature LlTis:
KJ (nominal) < 1.31 KJ (max) [ ] a,c o
K2 > O.023/ F K3 > O.00116/psi LlT 62.74 of smallest LlT allowance for uprate conditions LlI gain 2.37 %
PMA conversions:
a,c LlI (PMAL;l1)
M (PMAL;J2)
LlT (PMAbuL;T)
Tavg (PMAbuTavg)
- Power Cal. (PMApWR cAd a,c Pressure gain Pressure (SCAp)
Pressure (SRAp)
Pressure (SMTEp)
Pressure (STEp)
Pressure (SDp)
Pressure (RCAp)
Pressure (RMTEp)
Pressure (RTEp)
Pressure (RO p)
Pressure (BiasI)
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Table 3-12 (continued)
Overtemperature ~ T Calculatious a,C M conversion M(RCA M )
~I (RMTEill )
~I (RTEilI)
M(RDilI) a,c NIS conversion NIS (RCA NIs)
NIS (RMTE NIS)
NIS (RTE N1S )
NIS (RDNIs)
Total Allowance = [ ] a,c = 8.8 % ~T span
- Tavg bumdown allowance, T' - T ref mismatch, accounted for in safety analyses WCAP-17070-NP August 2010 46 Revision 0
Table 3-13 Overpower LlT Calculations The equation for Overpower LlTis:
~ (nominal) < 1.10
] a,c
~(max) [
Ks O.O/oF K6 > 0.00 16fOF for T > T" and K6 = 0 for T::::; T" LlT > 62.74 OF smallest LlT allowance for uprate conditions PMA conversions:
a,C Ll T (PMAbuL\T)
T avg (PMAbuTavg)
- Power Cal. (PMA pWR cAd
- = [
]
Total Allowance = [ ] a,c = 3.8 % LlT span
- Tavg burndown allowance, T' - T ref mismatch, accounted for in safety analyses WCAP-17070-NP August 2010 47 Revision 0
Table 3-14 AI> Measurements Expressed in Flow Units The ~P accuracy expressed as percent of span of the transmitter applies throughout the measured span, i.e., +/- 1.5 % of 100 inches ~P = +/- 1.5 inches anywhere in the span. Because F2 = f(L1P) 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:
where N = Nominal Flow thus Eq.3-14.l Error at a point (not in percent) is:
8FN 811PN 811PN
--- Eq.3-14.2 FN 2{FNl 211PN and I1PN {FNl Eq.3-14.3 I1p max {Fmaxl where max = maximum flow and the transmitter ~P error is:
811 PN (1001l--
'/ percent error in FuI1 Scale ~P (% E FS ~P) Eq.3-14.4 I1Pmax WCAP-17070-NP August 2010 48 Revision 0
Table 3-14 (continued)
""p Measurements Expressed in Flow Units Therefore, L'l [%& FS bY]
FS bY ] [Fmax ]2
[%&
8 FN P11lax 100
- - - ---=------= Eq.3-14.5 (2)(100) FN 2L'l P11lax [ F N ]2 Fmax Error in flow units is:
8 FN
=
FN
[%& FS bY ] [F11lax ]2 (2)(100) FN Eq.3-14.6 Error in percent nominal flow is:
8FN (100)=[%& FS bY ] [F11lax ]2 Eq.3-14.7 FN 2 FN Error in percent full span is:
8FN (100)=[ FN l[%& FS bY ] [F11lax -2 (100)
F11lax Fmax J (2)(100) FN Eq.3-14.8 Equation 3-14.8 is used to express errors in percent full span in this document.
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4.0 APPLICATION OF THE SET POINT METHODOLOGY 4.1 Uncertainty Calculation Basic Assumptions I Premises The equations noted in Sections 2 and 3 are based on several premises. These are:
- 1) The instrument technicians make reasonable attempts to achieve the NTS as an "as left" condition at the start of each process rack's surveillance interval.
- 2) The process rack drift will be evaluated (probability distribution function characteristics and drift magnitude) over multiple surveillance intervals.
- 3) The process rack calibration accuracy will be evaluated (probability distribution function characteristics and calibration magnitude) over multiple surveillance intervals.
- 4) The process racks, including the bistables, are verified/functionally tested in a string or loop process.
It should be noted for (1) above that it is not necessary for the instrument technician to recalibrate a device or channel if the "as left" condition is not exactly at the nominal condition but is within the plus or minus of nominal "as left" procedural tolerance. As noted above, the uncertainty calculations assume that the "as left" tolerance (conservative and non-conservative direction) is satisfied on a reasonable, statistical basis, not that the nominal condition is satisfied exactly. This evaluation assumes that the RCA and RD parameters values noted in Tables 3-1 through 3-10 are satisfied on at least a 95 %
probability 195 % confidence level basis. It is therefore necessary for the plant to periodically reverifY the continued validity of these assumptions. This prevents the institution of non-conservative biases due to a procedural basis without the plant staff's knowledge and appropriate treatment.
In summary, a process rack channel is considered to be "calibrated" when the two-sided "as left" calibration procedural tolerance is satisfied. An instrument technician may determine to recalibrate if near the extremes of the "as left" procedural tolerance, but it is not required. Recalibration is explicitly required any time the "as found" condition of the device or channel is outside of the "as left" procedural tolerance. A device or channel may not be left outside the "as left" tolerance without declaring the channel "inoperable" and appropriate action taken. Thus an "as left" tolerance may be considered as an outer limit for the purposes of calibration and instrument uncertainty calculations.
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4.2 Process Rack Operability Determination Program and Criteria The parameter of most interest as a first pass operability criterion is relative drift ("as found" - "as left")
found to be within RD, where RD is the 95/95 drift value assumed for that channel. However, this would require the instrument technician to record both the "as left" and "as found" conditions and perform a calculation in the field. This field calculation requires having the "as left" value for that device at the time of drift determination and Turkey Point Units 3 and 4 have elected to have a plant specific requirement to determine if the drift allowance assumptions were exceeded since the last calibration activity.
An alternative for the process racks is the Westinghouse method for use of a fixed magnitude, two-sided "as found" tolerance about the NTS. It would be reasonable for this "as found" tolerance to be RMTE +
RD, where RD is the actual statistically determined 95/95 drift value and RMTE is defined in the Turkey Point Units 3 and 4 procedures. However, comparison of this value with the RCA tolerance utilized in the Westinghouse uncertainty calculations would yield a value where the "as found" tolerance is less than the RCA tolerance. This is due to RD being defined as a relative drift magnitude as opposed to an absolute drift magnitude and the process racks being very stable, i.e., no significant drift. Thus, it is not reasonable to use this criterion as an "as found" tolerance in an absolute sense, as it conflicts with the second criterion for operability determination, which is the ability of the equipment to be returned to within its calibration tolerance. That is, a channel could be found outside the absolute drift criterion, yet be inside the calibration criterion. Therefore, a more reasonable approach for the plant staff was determined. The "as found" criterion based on an absolute magnitude is the same as the RCA criterion, i.e., the allowed deviation from the NTS on an absolute indication basis is plus or minus the RCA tolerance. A process loop found inside the RCA tolerance on an indicated basis is considered to be operable. A channel found outside the RCA tolerance is evaluated and recalibrated. The channel must be returned to within the procedural "as left" tolerance, for the channel to be considered operable. This criterion is incorporated into plant, function specific calibration and drift procedures as the defined "as found" tolerance about the NTS. At a later date, once the "as found" data is compiled, the relative drift
("as found"- "as left") can be calculated and compared against the RD value. This comparison can then be utilized to ensure consistency with the assumptions of the uncertainty calculations documented in Tables 3-1 through 3-10. A channel found to exceed this criterion multiple times should trigger a more comprehensive evaluation ofthe operability of the channel.
It is believed that a Turkey Point Units 3 and 4 systematic program of drift and calibration review used for the process racks is acceptable as a set of first pass criteria. More elaborate evaluation and monitoring may be included, as necessary, ifthe drift is found to be excessive or the channel is found difficult to calibrate. Based on the above, it is believed that the total process rack program used at Turkey Point Units 3 and 4 will provide a more comprehensive evaluation of operability than a simple determination of an acceptable "as found."
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4.3 Application to the Plant Technical Specifications The drift operability criteria described for the process racks in Section 4.2 would be based on a statistical evaluation of the performance of the installed hardware. Thus this criterion would change if the M&TE is changed, or the procedures used in the surveillance process are changed significantly and particularly if the process rack modules themselves are changed. Therefore, the operability criteria are not expected to be static. In fact they are expected to change as the characteristics of the equipment change. This does not imply that the criteria can increase due to increasingly poor performance of the equipment over time.
But rather just the opposite. As new and better equipment and processes are instituted, the operability criteria magnitudes would be expected to decrease to reflect the increased capabilities of the replacement equipment. For example, if the plant purchased some form of equipment that allowed the determination of relative drift in the field, it would be expected that the rack operability would then be based on the RD value.
Sections 4.1 and 4.2 are basically consistent with the recommendations of the Westinghouse paper presented at the June 1994, ISAIEPRI conference in Orlando, FL(I) . In addition, the plant operability determination processes described in Sections 4.2 and 4.3 are consistent with the basic intent of the ISA paper (I) .
Therefore the AVs for the Turkey Point Units 3 and 4 Technical Specifications are "performance based" and are determined by adding (or subtracting) the calibration accuracy (RCA) of the device tested during the Channel Operational Test to the NTS in the non-conservative direction (i.e., toward or closer to the SAL) for the application.
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Two examples of the AV calculations are as follows:
SPAN = 120% RTP AV=NTS+RCA AV = 109% RTP + 0.6% RTP AV = 109.6% RTP
- Steamline Pressure - Low (S1)
NTS = 614 psig SAL = 432.2 psig RCA = 7 psig (0.5 % span)
SPAN = 1400 psig AV=NTS-RCA A V = 614 psig - 7 psig AV = 607 psig WCAP-17070-NP August 2010 53 Revision 0
4.4 References / Standards
- 1. Tuley, C. R., Williams, T. P., "The Allowable Value in the Westinghouse Setpoint Methodology
- Fact or Fiction?" presented at the Thirty-Seventh Power Instrumentation Symposium (4 th Annual ISAIEPRI Joint Controls and Automation Conference), Orlando, FL, June 1994.
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