Text

Response to Request for Additional Information (RAI) Regarding License Amendment Request to Revise Technical Specification 3.3.1, Reactor Trip System (RTS) Instrumentation
	ML16022A179
Person / Time
Site:	McGuire, Mcguire
Issue date:	01/07/2016
From:	Capps S; Duke Energy Carolinas
To:	; Document Control Desk, Office of Nuclear Reactor Regulation
References
	MNS-16-003
	Download: ML16022A179 (22)
	v • d • e

DUK Steven D.

Capps ENERGYE McGuire Nuclear Station Duke Energy MGO1VP 1 12700 Hagers Ferry Road Huntersville, NC 28078 o: 980.875.4805 f: 704.875.4809 Steven.Capps@duke-energy.com Serial No: MNS-16-003 10CFR 50.90 January 7, 2016 U.S. Nuclear Regulatory Commission (NRC)

Washington, D.C. 20555-0001 ATTENTION: Document Control Desk Duke Energy Carolinas, LLC (Duke Energy)

McGuire Nuclear Station, Units 1 and 2 Docket Nos. 50-369 and 50-370 Renewed Facility Operating Licenses NPF-9 and NPF-17

SUBJECT:

Response to Request for Additional Information (RAI) Regarding License Amendment Request to Revise Technical Specification 3.3.1, "Reactor Trip System (RTS) Instrumentation" In a letter dated July 9, 2015, Duke Energy requested a change to TS 3.3.1, "Reactor Trip System (RTS) Instrumentation) for McGuire Nuclear Station, Units 1 and 2. In an email dated November 10, 2015, the NRC submitted RAIs. Enclosure 1 of this letter provides Duke Energy's response to those RAls.

Pursuant to 10 CFR 50.91, a copy of this RAI response is being sent to the designated official of the State of North Carolina.

No regulatory commitments are associated with this RAI response.

If there are any questions or if additional information is needed, please contact Brian Richards at 980-875-5171.

I declare under the penalty of perjury that the foregoing is true and correct. Executed on January 7, 2016.

Sincerely, Steven D. Capps

}

U.S. Nuclear Regulatory Commission January 7, 2016 Page 2 xc with enclosure:

C. Haney, Region II Administrator U.S. Nuclear Regulatory Commission Marquis One Tower 245 Peachtree Center Avenue NE, Suite 1200 Atlanta, Georgia 30303-1 257 G. Ed Miller, Project Manager (MNS)

U.S. Nuclear Regulatory Commission One White Flint North, Mailstop 8 G9A 11555 Rockville Pike Rockville, MD 20852-2738 J. Zeiler NRC Senior Resident Inspector McGuire Nuclear Station W. L. Cox Ill, Section Chief North Carolina Department of Environment and Natural Resources Division of Environmental Health Radiation Protection Section 1645 Mail Service Center Raleigh, NC 27699-1 645

ENCLOSURE 1 Response to Requests for Additional Information

Enclosure I Page 1 of 4 REQUEST FOR ADDITIONAL INFORMATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION TECHNICAL SPECIFICATIONS AMENDMENT CHANGES TO REVISE TECHNICAL SPECIFICATION 3.3.1, "REACTOR TRIP SYSTEM INSTRUMENTATION" DUKE ENERGY CAROLINAS, LLC MCGUIRE NUCLEAR STATION, UNITS 1 AND 2 (DOCKET NOS. 50-369 AND 50-370)

By letter dated July 9, 2015 (Agencywide Documents Access and Management System Accession No. ML15198A151 ) Duke Energy Carolinas, LLC (the licensee) submitted a license amendment request (LAR) to revise Technical Specifications (TS) 3.3.1, "Reactor Trip System (RTS) Instrumentation," to resolve an Operable But Degraded Non-conforming issue associated with the Reactor Coolant Pump (RCP) Underfrequency trip setpoint Allowable Value (AV) for McGuire Nuclear Station, Units 1 and 2.

The LAR proposes to modify the allowable value for Function 11, Undervoltage RCPs, and incorporate Option A of TSTF-493, Revision 4, "Clarify Application of Setpoint Methodology for LSSS Functions," calibration requirements for Functions 11 and 12, Undervoltage RCPs and Underfrequency RCPs, respectively, within Table 3.3.1-1, Reactor Trip System Instrumentation.

The staff of the Instrumentation and Controls Branch is reviewing the applicant's submittal for the areas under our scope and determined that additional information is needed to complete the review, as outlined in the enclosure.

RAIl1:

The LAR states that changes are required to resolve a latent design error, which resulted when the RCP Underfrequency and Undervoltage relays were replaced with more accurate relays.

Please describe the latent design error, how it was identified, and what actions were taken to prevent a similar error from occurring in the future.

McGuire Response:

While performing an engineering change to replace the undervoltage and underfrequency relays, the setpoint uncertainty calculation of record was not recognized as being affected.

Therefore, it did not get revised as appropriate. This condition was identified when a similar change was being made at a sister plant (Catawba). Since the administrative procedure governing engineering changes was determined to include sufficient guidance to ensure that the appropriate calculations are reviewed and updated as appropriate, this omission was found to be an isolated historical issue not indicative of current performance.

Page 2 of 4

RAI 2

The LAR states the existing TS AV was determined based on the original setpoint methodology for the prior model relays. When a revision to this setpoint calculation was prepared for the more precise replacement relays, using the original setpoint methodology, the existing TS Underfrequency AV was no longer conservative. To address this non-conservatism, a new setpoint uncertainty calculation was developed based on the more current setpoint methodology.

a. Please describe the differences between the original setpoint methodology and the revised setpoint methodology. Please describe the reasons behind these differences.

b. Please describe what aspects of the original setpoint methodology result in a non-conservative AV for the Underfrequency RCPs.

McGuire Response:

a. The original setpoint methodology used two methods (Methods 2 and 3 as described in Section 7.3 Figure 6 of ISA RP67.04-1 994, Part II) to calculate the AV. The more limiting of the two calculations was then used as the AV for the channel. This usually resulted in the limiting AV being established by Method 3.

When the more precise replacement equipment was considered in the AV calculation using Method 3, the result was found to be more limiting than the value given in the Technical Specifications. This occurred due to the smaller uncertainties of the replacement relays and their impact on the Method 3 calculation. With the advent of TSTF-493, the As-Found tolerance essentially replaces the AV calculation using Method 3 from the standard. Therefore, when the methodology was revised to include TSTF-493, the calculation of the AV using Method 3 was dropped. The current methodology (which includes TSTF-493) calculates the AV using only one method (Method 2 as described in Section 7.3 Figure 6 of ISA RP67.04-I1994, Part II).

b. See response to RAI 2.a. above.

Page 3 of 4

RAI 3

The LAR states the setpoint calculations were performed in accordance with Duke Energy Engineering Directives Manual (EDM)-1 02, "Instrument SetpointlUncertainty Calculations,"

Revision 4. The LAR further states EDM-1 02 is consistent with the intent of Instrument Society of America (ISA) Standard RP67.04-1 994 Part II, "Methodologies for the Determination of Setpoints for Nuclear Safety-Related Instrumentation."

a. Please describe how EDM-1 02 is consistent with the intent of ISA RP67.04-1 994, Part II, and identify the sections of ISA RP67.04-1994, Part II, used to develop EDM-1 02.

b. Please describe how EDM-102 differs from ISA RP67.04-1 994, Part II.

McGuire Response:

a.

EDM-102 was originally developed using the recommended practices described in ISA RP67.04-1 994, Part I1. The considerations and methods used in the EDM are similar to, if not identical to, those described in the standard. Similar to the standard, the EDM describes a process and methodology for performing setpoint and uncertainty calculations. Sections 3 through 10 and Appendices A through L of the standard were used to develop EDM-1 02.

b. The primary difference between EDM-102 and ISA RP67.04-1 994, Part II is that EDM-102 was revised to include discussion of the TSTF-493, Revision 4 methodology.

Material was added to describe the methodology for the use of As-Found and As-Left tolerances for RPS/ESFAS functions described in the Technical Specifications.

With the advent of TSTF-493, the AV determination in EDM-1 02 has been limited to Method 2 as described in Section 7.3, Figure 6 of the ISA standard.

Definitions were added and others modified for clarification from those described in the ISA standard. Generally, these changes are related to TSTF-493 implementation.

RAt 4:

Page 5 of 12 of LAR Enclosure 1 includes the equations for the Total Loop Uncertainty (TLU) and lists the sources of instrument uncertainty and biases that go into the TLU calculation. This page also includes a table containing the values of some of the uncertainty contributions (in %

span).

For Underfrequency RCPs and Undervoltage RCPs, please provide a summary calculation of the TLU listing the values of all the variables that are part of the equation, and showing how they were combined to arrive at the TLU values. Please include the conversion from % span to voltage and frequency.

McGuire Response:

The applicable sections of the uncertainty calculation for the Underfrequency and Undervoltage relays are included as Attachment A of this enclosure. Reference Sections 7.2 and 7.3 of the calculation.

Page 4 of 4

RAI 5

The LAR proposes to revise the Undervoltage RCPs AV from '> 5016 V', to '> 4870 V'. Page 7 of 12 of LAR Enclosure 1 includes the equation for the AV and lists the factors that are part of the equation. This page also includes a table containing the calculated AV values for the Underfrequency RCPs and Undervoltage RCPs.

a. Please provide the Analytical Limit values for the Underfrequency RCPs and the Undervoltage RCPs.

b. Please provide summary calculations for the Underfrequency RCPs AV and the Undervoltage RCPs AV, listing the values of all the variables that are part of the equation and showing how they were combined to arrive at the AVs.

McGuire Response:

a. As documented in the uncertainty calculation, the analytical limit for reactor coolant pump trip setpoint conservatively corresponds to a frequency of 55.0 Hz.

The calculation states that the reactor coolant pump undervoltage trip setpoint is not credited in any transients, so an analytical limit has not been established. However, the calculation goes on to state that for analyses where modeling the actual undervoltage setpoint is required, an analytical limit of 4800 V should be used.

b. The applicable sections of the uncertainty calculation for the Underfrequency and Undervoltage relays are included as Attachment A of this enclosure. The AV determinations for the Underfrequency and Undervoltage relays are found in Section 7.4.

RAI 6

Page 8 of 12 of LAR Enclosure 1 includes two tables containing the As-found and As-left Tolerances for the Underfrequency RCPs and the Undervoltage RCPs setpoints.

Please provide summary calculations for the following:

a. As-found Tolerance for the Underfrequency RCPs setpoint.

b. As-found Tolerance for the Undervoltage RCPs setpoint.

c. As-left Tolerance for the Underfrequency RCPs setpoint.

d. As-left Tolerance for the Undervoltage RCPs setpoint.

McGuire Response:

The applicable sections of the uncertainty calculation for the Underfrequency and Undervoltage relays are included as Attachment A of this enclosure.

As-found and as-left tolerances for the Underfrequency and Undervoltage RCP setpoints are found in Sections 7.2.1.1 and 7.2.1.2.

Attachment A Applicable Sections of Reactor Coolant Pump Underfrequency and Undervoltage Relay Loop Uncertainty Calculation

~McGuire Nuclear Station Units I and 2[

NCP Underfrequency.and Undervoltage Relay Uncertain'tyI

7.

Calculation 7.1 Instrument Loop and Logic The EME System is div~ided into four independent and physically separate channels. Each channel is comprised of one under-voltage relay, one underfrequency relay, five a uxiliary relays (as shown in Sectiorn 1.2), two test blocks, one selector test switch, five indicating lights, and three sliding in~k terminal blocks.

input signals to the Undervoltage relays are taken from the motor side of the reactor coolant pump motor feeder breakers and transformed via 7200/120 VAC potential transformers. Input signals to the underfrequency relays are taken from the bus side of the reactor coolant pump motor feeder breakers and transformed by an identical set of potential transformers. Control power for the relays are supplied by the EPL system - 125 VDC Vital I&C Power (Ref. 5.K.b).

Redunadancy requirements are met by employing a 2/4* logic scheme to initiate reactor protective action. Further, separation requirements are met by~physically separating the components inside the reactor coolant pump power monitoring cabinet from the components in the other channels. All cabling and associated wiring was designed to observe the four channel separation.

Separation and channel independence are maintained from the point of the "process sensor"; the PTs which transfor~m the voltage from 6900V to 120V AC are the pro~e~ss sensors for the EME system. Input from the process sensor-s are directed to the undervoltage and~ underfrequency relays and in turn to the Reactor Protection System.

7.2 Device!Loop.Uncertainty Term Identification This portion of the calculation will be divided into the underfrequency relay section and the under-voltage relay section, Uncertainty terms for the entire under-frequency and under-voltage relay for each relay will be proyided.

Each individUal uncertainty ter-m will be identified and d~ocumnented. Then the individual uncertainty terms will be statistically combined to determine a total loop uncertainty for underfreqUency and undervoltage relays.

7.2.1I EME System All, uncertainties in this section are for the underfrequency (Reference 5.C) and under-voltage relays (Reference

.5:D). Since the undervoltage and underfrequency relays are stand-alone devices, a specific uncertainty for the rac'k and transmitter are not calculated. However, a total ioop uncertainty for each device will be calculated.

From Reference 5.C, the.freqUency may vary from 54 to 63 Hz. (i.e., a span of 9.0 Hz) with the output circuit rating of 5 Amperes continuous at 125 Vdc for the underfrequency relay.

From Reference 5.D, the input circuit rating can vary from 60 to 11I0 Volts (i.e. 50 Volt-operating range), with an output contact rating of 5 Amperes continuous at 125 Vdc for the under-voltage relay.

All uncertainties given below are random-independent terms unless stated otherwise.

Attachment A Page 1 ofl14

t

~

McGuire Nuclear Station U nitslI and 2 NCP Under-frequency and Under-voltage Relay Uncer-tainty 7,2A.l1 Underfrequency Relay A - AccUracy

.Per Reference 5.C, calibrated accuracy for the specified range: are as follows.

Accuracy :,0.008 Hlz If Range :=9.0 Hz AR Accuracyj AFR - 0.089 %

span D - Drift Since vendor data is unavailable, drift :is assumed to be equal to the reference :accuracy as stated in assumption 6.1.2. As a result, underfrequency relay drift is as :follows. Per assumption 6,.14, drift is not extrapolated for the 25% grace period.

DFR := AFR D_FR =0.089 %

span M&TE - Measuring and Test Equipment Per Reference 5.E, the following calibrated test equipment iis used for-th~e calibration of the underfrequency relay.

DMM, Keithley 2001 'or equiValent (*:/= 0.2% Tolerance)

Dynamic Fault Rec~nstructor.(DFR-!I), Powertech or equivalent (harmonic voltage distortion </= 0.3%)

Per Assumption 6.1.6, the M&TE uncertainty for the Keithley 2001 is as follows.

K_2001_MTE =0.36 % span Per corrective action #4 of PIP.M-98-01363,: Powertech is now~known as Manta Test Systems and the*DFR-I test set~to calibrate RCP UV/UF Relays is now known as the MTS-1710. Per Reference'5.O, the uncertainty for the MTS-1710 for a.60 hz range is 0.0142 hz. For the underfrequency relays 9.0hz range, this uncertainlty is as follows.

0.0 142.-Hz MTS__1710_freq_.MTE.

f Range MTS-_1710_freq_.MTE =,0.158% span There~fore, the overall M&TE for the Underfrequency Relay is as,follows.

MTE_FR= */=01MTE2 +

TS70_freqMTE.

MTEFR = 0.39 %

span Attachment A Page 2 of 14

McGuire Nuclear Station Units I and 2 NCP Underfrequency and Undervoltage Relay Uncertainty TE - Temperature Effect Per Reference 5.K.a, the EME System underfrequency relay is mounted in the control room and is rated to operate for a temperature:range~of-4 F to 131 F (-20 to +-55 C as stated in Reference SC~a). Thus; temperature effect is expected to be negligible. Further proof of this is apparent in the Reference 5.C.c temperature test.

Therefore the temperature effect is negligible for the underfrcquency trip.

The temperature effect is asSumed to be negligible under normaal conditions. Since this device is only required

,during normala conditions for the loss of flow analysis (Re.f. 5.J) and calibration will occur under normal conditions, the temperature effect is assumed to be negligible during calibration and when the system is rcquired to operate.

TE_FR :0.0% span RES - Resolution/Readability Since the underfrequency relay is no_._

providing indication for the trip function, there will be n..o resolution associated with the underfrequency relays.

RESFR 0=

0.%

span PSE - Power Supply Effect The plant power supply to the relays is from the vital inverters. Per Reference 5.C, at 125 V nominal, the

.allowable variation in voltage is from 100 to 140 VDC. Since the voltage variation from the 125 VDC Vital I&C Power will remain between 100 and 140 VDC, the PSE is negligible and specified as +I-- 0.0%.

PSE_FR 0=

0.%

span S - Seismic Effect (Not needed in Calculation - Included as added information only)

Per Section 2.4.2 of Reference 5.K.a, the enclosure was seismically tested. The panel and enclosed equipment shall remainstructuraily sound, operate functionally correct, and provide minimum seismic amplification during and after a safe shutdown earthquake. Also, it is assurmed that. following a seismic event the plant will be shutdown and all effected instrumentation re-calibrated. Therefore, the seismic allowance will be assumed to be 0.0% of span.

S_FR :=0.0%

Span R - Radiation.Effect Since the instrument is mounted in the control room (Reference 5.K.a - Section 2.3.10), the normal radiation effect is negligible, As. a result, the radiation effects are considered negligible.

RFR ;=0.0%

span EA - Environmental Allowance (Not needed in Calculation - Included as aidded infor~mation only)

The EA term is considered as a bias in either the posiiive or negative direction depending upon. the direction of the error. Since the undervoltage relay is located in the control room (Reference 5.K.a Section 2.3.10), an environmental term is not included in the uncertainty calculation for the NCP motor bus underfrequency trip:

EAFR :=0.0%

span Attachment A Page 3 of 14

McGuire Nuclear Station Units 1 and 2 NCP Underfrequency and Undervoltage Relay Uncertainty CL-Currenit Lekalga Effect (Not needed in Calculation -Incl'uded as added information only)

The current leakage effect occurs due to elevated humidity and temperature conditions associated with a high energy line break. The underfrequency relays:are credited in the Loss of Flow Analysis (Reference 5.J.a) which does not involve a high energy line break. Thus, current leakage will not be present when this equipment is needed.

CL FR :--0.0%

span As Found (AYE) and As Left (ALT) Tolerances

"'As-Found" is the condition in which a channel, or portion of a channel, is found after a period of operation and before recalibration, if necessary. The.As-Found Tolerance is the~allowance that the channel, or portion there~of, is expected to be within based on uncertainty calculations which ensure the channel is capable of prdducing a trip prior to reaching the Safety Analysis Analytical Limit.

.Per Reterence 5.A.a, the uncertainty terms which make up the As-:Found Tolerance for the portion of t he channel under surveillance would typically include the square root sum of square~s combination of reference accuracy, drift and measurement and test equipm~ent uncertainty effects (e.g. M&TE Uncertainty and. M&TE Reading Resolution).

"As-Left" is the condition in which a channel, or portion of a channel, is left after calibration or final semo~int device setpoint Verification.. The As-Left Tolerance. is the acceptahle setting variation about the se'tpoint that the technician may leave the setting following calibration.

Per Reference 5.A.a, the uncert~ainty terms which make up the As-LeftTolerance for the portion of the channel under surveitllace would typically include the square root sum of squares combination of ref'erence accuracy and measurement and test equ~ipment uncertainty effects (e.g. M&TE uncertainty an~d M&TE Reading Resolution).

Per Reference 5.B & 5.E, the desired dropout frequency (Nominal Trip Setpoint) is set at 56.4 I-li ufNTSP := 56.4 Hz Reactor Coolant Pump Underfrequency As Founld Tolerance AF tOl_FR :

/AFR2 + DFR2 + MTEFR2 AF_tol_FR =O.410-%

span AF tot_FR_e :=AF tol_FR x f_Range = 0.037.Hz AF_FR value :=uf, NTSP -. AF tolFR e =56.363. Hz Attachment A Page 4 of 14

McGuire Nuclear Station Units 1 and 2 N~CP Un~defrf!equency and Undervoltage Relay UncertaintyI O

~Reactor Coolant Pump Underfrequency AS Left Tolerance ALtoL FR :*AFR2 + MTE_FR2 AL toIFR = 0.400-%

span AL_tol_FR_e := AL tolFR Ž< fRange = 0.036.Hz AL_FR_Value of UfNTSP - AL toiFR_e = 56.364-Hz CTE - Calibration Tolerance Effect PerAssumption 61!.5 the calibration tolerance effect (CTE) will be set equal to the As-Left Tolerance, CTE_FR:= AL tol_,FR-=0.4-%

span

'Random Uncertainty for Underfreouencv Relay 'Terms Combination of Undeffreguencv Relay Terms The formulas below combine the error tetras to determine the overall random uncertainty.for the underfrequency relay. The underfrequency relay is used during the loss of coolant flow event (Reference 5.J). The loss of coolant

.flow event doesno__t involve adverse containment conditions. Therefore, the uncertainty calculation for the NCP motor bus underfrequency trip is calculated for normal conditions only. Accident uncertainties are not required.

O Note" Since the seismic uncertaintyis 0.0%, underfrequency relay seismic uncertainty is the same as the normal uncertainty.

Nor'mal RUFR Nor :=

AFR2 +1O_FR2 + MTEFR2

/+TEFR2 +RES_FR2 + PSE_FR2.

+ RFR2 + CTEFR2 RU_FR_Nor = 0.57*%

span Underfrequencv Relay Bias Deadband Per Section 2.4.1 of Reference 5.K~a, the underfrequency relays incorporate a one (1)l-Iz deadband on the high side of the trip setpoint. This deadband makes i't necessary f'or the input signal to rise in frequencyby a minimum of one hertz before reset logic-would be initiated. Per Reference 5.0, the frequency can range from 54 tO 63 Hz which is a total range of 9 Hz. For a 9 Hz range, this 1 Hz rise is equivalent to an ufIcertainty of 11.11%.

HoWever, th e d eadband i's for resetting the trip and is o0 *the high side, of the trip above the trip setpo int.

Therefore, it~doesbo___t add to the uncertainty associated with the trip setpoint.,AS a result, the uncertainty in the trip setpoint due to a bias associated with the deadband or any other parameter is 0.0%.

BiasFR : 0.0%

span S

Attachment A Page 5 of 14

I McGuire Nuclear Station Units 1 and 2 NCP UnderfreqUency and Undervoitage Relay Uncertainty 7.2.1.2 Undervoltage Relay A-Undervoltage Relay AccUrat~y Per Reference 5.D, t'he pickup and dropouit settings with respect to dial markings (factory calib~ration) is +/- 2.0 %.

Per Reference' 5.F, the pickup voltage tap 'is the 90 V tap. Thus, the accuracy is as follows for a 50 V range.

Tole

= 2.0%.

span pickupV_tap :=90.V VRange:= 50-V A VR := T01_VR.(pickupVtap')

V_Range A VR =3.6.%

Per, Reference 5.D~the pickup and dropout settings also hav*e Uncertainty due to repeatability at constant temperature and constant control voltage and repeatability over "allowable' dc control power range.. Since-these values are both +1- 0.1%, thcse are considered negligible and will be.ign~ored. Similarly,, the pickup and dropout settings have an uncertainty for repeatability over a temperature range. However, since the relay will

.be in the control room, the temperature change will be relatively small and the associated repeatability uncertain'ty will be negligible.

D -Drift Since vendor data is unavailable, drift is assumed to be equal to the reference accuracy per assumption 6.1.2. A~sa result, undervoltage relay drift is as follows. Per assumption 6.1.4, drift is not extrapolat~ed for the 25% grace period.

D VR :=A VR DVR =3.6'% span M&TE -Measuring and 'Test Equipment Per Reference 5.'F, the following calibrated test equipment is used for the calibration of the undervoltage relay.

DMM, Keithilcy 2001 or equivalent (</= 0.2% Tolerance)

Dynamic Fault Reconstructor (DFR-1), Powertech or equivalent (harmonic voltage distortion <1= 0.3%)

PerAssumption 6.1.6, the M&TE uncertainty for the Keithley 2001 is as follows.

K_200i_MTE = 0.36.%

span Per corrective action #4 of PIP M-9 8-013 63* Powertech is now known as MantaTest 'Systems and the DFR-1 test set to calibrate RCP UVIUF Relays is now known as the MTS-1710. Per Reference5.0, the uncertainty for the MTS-1710 for a range of 82 VAC to 120 VAC is MTSi 1710_unc. For the M&TE associated op eratring range (MTE_.VRange); the MTS-17i0 M&TE (MTS_1710_volt_MTE) for thve uriderv01tage relay is as follows.

MTS_17I0_unc := 1.1921-V MTEV_.Range := 120.0.V - 82.0.V MTEVRange = 38V MTS171_vot ME:=MTS_1710_unc MT _170_ot T :=MTE_VRange MTS_1710_voltMTE ='3.14. %

span Attachment A Page 6 of 14

I

~

~McGuire

'Nuclear Station Units 1 and 2 NCP Underfrequency and Undervoltage Relay Uncertai~nty Therefore, the overall M&TE-for the Undervoltage Relay is~as foillows.

MTEVR :=,IK_2001_MTE 2 +- MTS_1710_volt, MTE2 MTE_VR=3.16'%

,span TE-Temperatur'e Effect Per Rcference 5.K.a Section 2.3.2, The EME System undervoltage re'lay is mounted in the control room which is a

'tempe'rature contrblled area. The undervoltage relay is rated to operate :for a temperature range of-4 F to 158 F

(-20 C to +*70 G as stated in Ref. 5.D.a). Therefore, the temperature effect is negligible for the undervoltage trip.

The temperature e'ffect is assumed to be negligible under normal conditions. Since this device is only required during normal conditions for the loss of flow analysis (Ref.,5.J) and calibration will occur under riornmal conditions, the temperature effect is a~ssumed to be.negligibte duri-ng~calibi-atio n and when the system is requilred to operate.

TE.VR :=0.0% span RES - Rcsoltution/Readabilitv Since the undervoltage relay is no___1 providing inzidiation, there Will be noo resolution associated with the u'ndervoltage relay.

RESVR= ;0.0%

span PSE -.Power Supply Effect The plant power supply to the relays *is from the. 125; VDC Vital I&C Power. Per Reference 5.D, at!125 V nominal, the allow~able variation in voltage is from 1.00 to 140 VDC. Since the voltage variation from the 125 VDC vital I&C Power will-remain between 1:00.and 140 V'DC, the PSE is negligible an~d specified as +1- 0.0%.

PSEVR;= 0.0%

span S - Seismic Effect (Not needed in Calcuflation - Included as added [information only).

Per Section 2.4.2 of Reference 5.K a, the enclosure wa* seismically tested. The panel and enclosed equiipment Shall remain striucturally sound, operate functiona~lly correct, :and provide minimum seismic amplification during and after~a safe Shutdown earthqu~ake. Also, it is assumed that following a seismic event, the plant will bec shutdown and all effected instrumentation re-calibrated. There'fore, the seismic allowance will be assumed to b~e 0.0% of span.

SVR:= 0.0%

span R.- Radiatio n Effect Silnce the instrument is mounted in th& conltrol room (Reference' 5,Ka.- Section '2.3:1O),. the normial radiation effec.t is negligible. As a result, the radiation effects are considered negligible.

RVR :=0.0%.span EA-Environmental Allowance (Not needed in Calculation - Included as added information only)

The EA term is considered as a bias in either the positive or negative direction depending upon the direction of theerror. Since the underv01tage relay is~located in the control room (Reference 5.K a - Section 2.2.8),.an environmental term is not included in thle uncertainty cailculation for the NCP motorb us und ervohtage trip.

EA_VR= 0.0%

span Attachment A Page 7 of 14

McGuire Nuclear Station Units 1 and 2 NCP Underfrequency and UndervolItage Relay Uncertainty CL.- Current Leakage Effect (Not needed in Calculation -.Included as added information only)

The currenj leakage effect occurs due to elevated humidity and temperature conditions associated with a high energy line break. The cables routed from the field sensors (potential transformers) to the relays are n~ot route~d through areas Where they couild be exposed to a *high energy line break. T*he~refore, a current leakage term is *not included in the uncertaintycaiculation.

CL_VR:

O.0%

span As Found (AFr) and As Left (ALTI Tolerances Per Reference 5.F, the desired dropout voltage (Nominal Trip Setpoint) is set at 84.7 VAC or 5082.0 VAC bus volts. As discussed in Section 7.2.1.2, the Voltage Range is 50.0 Volts. Thisrange is then converted to bus volts by multiplying bya afactor of7,200 VAC/120 VAC =60 (bus,volts/,u!t)).

bus~v_Range :=60.V Range = 3000 V uv NTSP := 84,7V-60 -- = 5082 V V

Reactor Coolant Pump Undervoltage As Found Tolerance AF toiYR :-= IAVR2 + DYVR2 + MTEYR2 AF~toI.YR = 5.991"% span AF to!_VR e := AF_to1 VR x VRange =2.995 V AFYRValue :=uv_NTSP - AF to! VR e x bsane_4902.3-V V Range Reactor CoolantPump Undervoltage As Left.Tolerance AL t0!_VR:=

A_YR2 ÷ MTE VR2 AL_to!_YR = 4.788. % Span AL to!_VR e :=AL_tolVRx VRange = 2.394V ALVR *value := uv_NTSP - AL tolYR e x

!sage=433V

_VRange CiT - Calibration Tolerance Effect PerAssumption 6.1.5 the calibration tolerance effect (CTE) will be set equal tO the As-Left Tolerance.

CTE_YR := AL_to!_YR = 4.788. % s~pan Attachment A Page 8 of 14

~McGuire Nuclear Station Units 1 and 2 NCP Underfrequency and Undervoitage Relay Uncertainty O

Random Uncertainty for Undervoltage Relay Related Terms Combination of Undervohtage Relay Tenns The formulas below combine the error terms to determine the overall random uncertainty.for'the undeivoltage relay. The undervoltage relay is used during (he loss of cOolant flow event.(Reference 5.J).

The loss of coolant flow event does not involIve adverse containment conditions. Therefore, the uncertainty calculation for the NCP mnotor'bus und ervohtage trip is~calculate d for normal con ditions only.

Accident. uncertainti'es are not required. The random uncertainty isgivenas a negative value below Note: Since the seismic uncertainty is 0.0%, undervcfhage relay seismic uncertainty is the, same~as the normal uncertaifnty.

Normal RUVR Nor :=

_AVR2 + DVR +MTEVR2.

/+TEVR2

+ RES_VR2 + PSEVR2

1 RVR +CTE_VR 2 p

RU VR :Nor = 7.67.% span Undervoitage Relay Bias There are no applicable bias terms in the calcula~tion of the undervohtage relay total loop uncertainty.

__BiasVR:=

0.0%

span Attachment A Page 9 of 14

I McGuire Nuclear Station Units 1 'and 2 NCP UndertrequenCy and U'ndervoltage Relay Uncertainty 7.3 Total Loop Uncertainty Determination Underfrequencv. Re~lay The. total loo~p uncertainty combines the uncertainty of the~random terms and the bias terms. The bias is

.applied if it causes a delay to the trip. In !his case, the bias for the underfrequen~cy relay is zero.

However, t'hc bias is included in the total loop uncertainty eq uation0 for completeness.

Normal Conditions TLUFR Nor :=*RUFRNor2 +. Bias_FR TLUFRNor O.057.%

span TLU FR Nor e: TLU FR Nor x f Range = 0.052.Hz TLU_FR_value :=uf_NTSp - TLUFRNr~e =56.348-Hz Undervnltage Relay The total loop uncertainty combines: the uncertainty~of the random terms and the bias terms. The bias is applied if it causes a delay to the trip. In.tis case, the b'ias for the under'voltage relay is zero..

However, the bias is included in 'the total loop, uncertainty eq uatio n for comple~tene ss.

Normal Conditions TLUYRNor :-*RUVRNor 2 + Bias:_VR TLUYRNor = 7.67. % span TLU UVRNor~e := TLU_VRNor x V _Range =3.835,V TLUVR value= uv NTSP - TLU VR Nor :e. bu-R-g

- 4851.923.V Attachment A Page 10 of 14

~McGuire Nuclear Station Units 1 and 2 NCP Underfrequency and Undervoltage Relay Uncertainty 7.4 Allowable Value Determination 7,4.1 Underfrequency Relay Allowable Value MNS Technical Specifications (Ref. 5.B) defines th* Undeffrequency Nominal Trip Setp0int (u'f_ NT$P)as fol~lows.

ulTNTSP =56.4.Hz Per Reference 5.A.a the Allowable Value 'is calculated using the following equation:

AV = AL_+ (RUNT +/- Biases)

Where: AL

= Analytical!Limt RUNT = uncertainty associated with the potion of the loop no__t tested during channel 0perational test (COT), calibrationb etc.

Biases = bias/abnormal distribution uncer~tainties Per Appendix I of Reference 5,.J.a (last paragtaph on page 140), the analysis trip setpoint is modeled as a delay time which conservatively corresponds to a freqUency of55.0 HZ. Therefore the analy~tical ilimit for this and any analyses which credit this trip in the future is:

ul'_AnalyticalLimit := 55.'0 Hz Since the under-Frequency r'elay is a stand-alone~device and all of the equipment is tested Oluting the calibration, there are no untested uncertainity components.. Therefdre, uf RUNT := 0.0%

span Per the Specification Section of Reference 5.C.c, the range for the undeifrequency relay is 9 Hz (54 to 63 Hz).

f..Range = 9.Hz AV UF Trip := ufAnalyticalLimit + (uf_.RUNT + BiasFR)-(f Range)

AVUF Trip = 55.0.Hz Attachment A Page 11 of 14

McGuire Nuclear StatiOn Units 1 and 2 NCP Underfrequency and Undervoltage Relay Uncertainty I

7.4.2 Underv01tage RelayAllowable Value MNS Technical Specifications (Ref..5KB) defines the Undervoltage Nominal Trip Setpoirjt (uv_NTSP) *as follows.

uv_NTSP =5082 V SafetyAnalysis do~es not currently* credit the reactor coolant pump undervoltage trip setpoint explicitly in any transients. It should be noted that the loss of coolant flowanalyses (Reference 5.J.a) assume the reactor coolant pump trips at the start of the event at time 0.0 seconds. This leads to a reactor trip within 1.5 seconds (with/without a delay of 0.65 secontds). Asa r esult, the reactor trip in the analyzed event. was based upon an elapsed time and not upon an actual voltage setpoint.. Therefore, a safety analysis analyt'ical limit for undervoltage has not been established. In future analyses, where modeling the actual undervoltage setpoiot is require~d, a safety analysis analytical limit of 4,800 'vblts for the'reactor coolant pump undervoltage should be used.

uv_:AnalyticalLimit :=4800.0 V AS. with the urnderfrequlenCy setpoint, the u ndervohtage relay is a stand-alone deVice and all of* the equipmenvt is tested during the Calibration, there are no untested uncertainty terms.

uvRUNT := 0.0% span As discussed in Section 7.2.1 the Voltage Range is 50.0 Volts.. This range is then converted to bus volts by multiplying by a factor of 7,200 VAC/120 VAC = 60 (bt~s xvlts/v01t)).

bus_v_Range = 3000 V AV UV Trip :=' uAnalytficalLimit + (uv RUNT + BiasVR)-.(bus~vRange)

AVUVTrip = 4800.0 V 7.5 Loop Scaling Per Reference 5.C, the frequency can range from 54 to 63 Hz which is a total range of 9 Hz. Thereforc, the scaling for the underfrequency relay corresponds to this 9 Hz range or span. Per Reference 5.D, the voltage range is. from60 to 110 V which is a 50 V range. Since the potential transformers for the undervoltage relay have a rat io of 60/1 (Section 2,2.1.1_.1 of Reference 5.K.a), the scaling for the voltage ran~ge of 60 to 110 VAC of the undervoltage relay.cOrresponds tO a bias voltage range of 3,600 to 6,600.hu Volts.

Attachment A Page 12 of 14

I

~McG~uire Nuclear Station Units 1 and. 2 NCP Underfrequency and Undervoltage Relay Uncertainty 7.6 Setpoint Analysis and/or Acceptability of Loop Uncertainty and Allowable Value The rabies below summarize.the TLUs, As-Ld t and As-Found tolerances and Allowable Malue resulhs for the underfrequenc~y and undervoltage trips.

Summary of Calculated Uncertainties Undlerfreciuencv Trip Uncertainty Allowance Results (NTSP = 56.4 Hz)

Underfrequency =

"Uncertainty" "Normal UOF TLU"

"'As-Left Tolerance"'

"As-Found Tolerance" UF_AllowableValue =

I "Current TS AV, Hz"I "Calculated Allowable Value, Hz"I 55.91 55.0 Undervoltane Trip Uncertainty Allowance Results (NTSP=5082 Volts)

Undervoltage=

UVAllowable_Value=

",Current TS AV, Volts" "Calculiated Allowable, Value, Volts" 5016 q800

.Based o*n t~he uncertainlties provyided above, there are no Technical Specification changes required for the underfrequency and undervo1tage reactor tri~p setpoints or Safety analysis analytical limits& Also, th~e Allowable Value results indicate thiat the current Techn'ical Specification values are mo re limit~ing, than the calculated values and revision of the Techn'ical Specification Allowable Values is not required, Attachment A Page 13 of 14

t McGuire Nuclear Station Units 1 and 2 NCP Undertrequency and.Undervoltage rRelay Uncertainty As-Left Tolerance Acceptability Underfrequency As-Left Tolerance.

The calibration procedure As-Left tolerance must be equal to orconservative with respect to the tolerance calculated above*. Per Reference 5.E, the calibration procedure As-Left tolerance is +/- 0.036 Hz about the nominal trip setpoint 0f56.4 Hz. Therefore, the procedure As-Left tolerance, matches the As-Left tolerance calculated above and no :changes to the procedure are necessary.

Undervoltage As-Left Tolerance The calibration.procedure As-Left tolerance must be equal to or conservative with respect to the tolerance calculated above.Per Reference 52F, the NTSP, As-Lecft tolerance and Allowable Value are implemented in terms of the voltage range of the instrumentation by dividing the bus volts by bus volt to instrument voltage span conversion of 60 bus volts/volt, i.e..the NTSP = 5082 volts/60 b usvolts/volt =184.7 woits. The calibration procedure As-Left tolerance is +/- 0.8 volts about the nominal trip setpoint of 84.7 volts. This equates to a tolerance of +/--

48 volts about the NTSP of 5082 vo Its. The calibration.procedure As-Left tolerance is much fighter than the tolerance calculated above of-+/- 143.65 volts. Therefore, the current~procedure As-Left tolerance is acceptable, but may be revis~ed to allow an expanded As-Left toierane.

Attachment A Page 14 of 14