ML18152A932

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Attachment 6: Second Level Undervoltage Time Delay Relays 162-153 and 162-154 Uncertainty Analysis
ML18152A932
Person / Time
Site: Palisades Entergy icon.png
Issue date: 05/30/2018
From:
Entergy Nuclear Operations
To:
Office of Nuclear Reactor Regulation
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ML18152A922 List:
References
PNP 2018-010
Download: ML18152A932 (24)
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PNP 2018-010 ATTACHMENT 6 Second Level Undervoltage Time Delay Relays 162-153 and 162-154 Uncertainty Analysis 23 pages follow

~Entergy Entergy Cale No:

Rev:O Engineering Calculation EA-EC11464-01 PAGE 1 OF 17 0 AN0-1 0 AN0-2 OGGNS 0 IP-2 0 IP-3 C8l PLP DJAF DPNPS ORBS DVY 0W3 CALCULATION

<1> EC # 11464

<2>Page 1 of 23 COVER PAGE Including Attachments (3) Design Basis Cale. D YES

[g] NO (4)

[g] CALCULATION DEC Markup

(

5 J Calculation No: 162-153 and 162-154 Uncertainty t

0

' Revision: O ti,

Title:

Second Level Undervoltage Time Delay Relays 162-153 and 162-154 Uncertainty Analysis to, System(s): EPS

\\!IJ Review Org (Department): Electrical Design

<10> Safety Class:

(11> Component/Equipment/Structure Type/Number:

[gl Safety / Quality Related Relay 162-153 Relay 127-8 D Augmented Quality Program D Non-Safety Related Relay 162-154 Relay 127-7 (12> Document Type: EVAL (13> Keywords (Description/Topical Codes):

Time Delay Undervoltage REVIEWS (14> Name/Signature/Date (15) Name/Signature/Date (15> Name/Signature/Date RM Hamm See EC 11464 See EC 11464 See EC 11464 Responsible Engineer D Design Verifier Supervisor/ Approval D Reviewer D Comments Attached D Comments Attached

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-===-Entergy Engineering Calculation EA-ECl 1464-01 PAGE 2 OF 17 ATTACHMENT 9.3 CALCULATION REFERENCE SHEET CALCULATION CALCULATION NO: EA-EC11464-01 REVISION: 0 REFERENCE SHEET I. EC Markups Incorporated 1,

2.
3.
4.
5.

II. Relationships:

Sht Rev Input Output Impact Tracking Doc Doc Y/N No.

1.Setting Sheet D

1C/108/J9400/162-153 2.Setting Sheet D

1 D/203/J9401/162-154

3.

D D

4.

p D

5.

D D

Ill.

CROSS

REFERENCES:

1.
2.
3.
4.
5.

IV.

SOFTWARE USED:

Title:

N/A Version/Release:

Disk/CD No.

V.

DISK/CDS INCLUDED:

Title:

N/A Version/Release Disk/CD No.

VI.

OTHER CHANGES:

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~ ntergy Engineering Calculation EA-EC11464-01 PAGE 3 OF 17 ATTACHMENT 9.4 RECORD OF REVISION Sheet 1 of 1 RevisiQh R~cord of Revrilon Initial issue.

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-===--Entergy Engineering Calculation EA-EC11464-01 PAGE 4 OF 17 TABLE OF CONTENTS 1.0 PURPOSE

  • .*.*.......********.*....**.*.*..*.**....****.***.**..*.**********.*....****.*********.*** 6

2.0 BACKGROUND

  • .*.*.********.*.*.***.*********************..*.******.******.*.*.*.********************* 6 3.0 APPROACH ***.*****.*.**..*.******.*.******.*.......**.*.*********.*.**.....*.*...*.**......*.*.*.*. 7 4.0 DESIGN INPUTS ****.***********************...*.**.*.******.******.*.**.*.********.*.*.**....**.**.*** 8 4.1 TIME DELAY RELAY DESIGN SPECIFICATIONS.*.......*.*.....**.**....*.*...*****.*...* 8 4.2 QUALITY REQUIREMENTS ********..***....****.*.*.**.*.*****..**.*.*...*.*...**************..*.* 8 4.3 TEMPERATURE DATA............................................................................... 9 4.4 DC VOLTAGE SUPPLY ***.*.*.**....*..*...********.*..*.*.*.**....*.***.*****..*.****.**.**.*...*. 9 4.5 CALIBRATION INSTRUMENT DATA ***...***.*********************.***.***************.***.*.*** 9 5.0 ASSUMPTIONS - NONE.......................................................................... 10 6.0 ANALYSIS

.......................................................................................... 10 6.1 FIXED DELAY EFFECT ****.****.....*******************.*.*.********************.*********.******* 10 6.2 REFERENCE ACCURACY........................................................................ 10 6.3 VARIATION IN TIMING WITH CHANGE IN AMBIENT TEMPERATURE ****.******** 11 6.4 VARIATION IN TIMING WITH CHANGE IN CONTROL VOLTAGE ***.*..*.*.*..****.. 12 6.5 MEASUREMENT AND TEST EQUIPMENT ERROR....................................... 12 6.6 SEISMIC, HUMIDITY AND RADIOLOGICAL ERROR..................................... 12 6.7 DRIFT ERROR

................................................................................... 13 6.8 SETTING TOLERANCE............................................................................ 13 6.9 CALCULATION OF TOTAL TIME DELAY ERROR.*.******....************.***.*..**.*.*. 14 7.0 CONCLUSION........................................................................................ 14

8.0 REFERENCES

........................................................................................ 16 8.1 GENERAL REFERENCES........................................................................ 16 8.2 PROCEDURES

  • .****..*.*.*...********.***..*..**.*.*.****.*..***.***.****.********************** 16 8.3 CALCULATIONS *.************.*.***...*.*************.***.**.***************.*****...************* 17 8.4 VENDOR INFORMATION.......................................................................... 17

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~ Entergy Engineering Calculation EA-EC11464-01 PAGE 5 OF 17 ATTACHMENTS A.

Letter GJBrock to RJPienkos, 6/25/96, 2nd Level Undervoltage Relay Design Documentation B.

Setting Sheets 1C/108-J9400/162-153, Rev 3 and 1 D/203-J9401 /162-154, Rev 2.

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-===-Entergy Engineering Calculation EA-EC11464-01 PAGE 6 OF 17 1.0 Purpose The purpose of this calculation is to determine the setpoint uncertainty associated with the ABB-62T Second Level Bus Undervoltage Time Delay Relays tagged 162-153 (BUS 1C) and 162-154 (BUS 1D).

2.0

Background

Engineered Safeguards buses 1 C and 1 D are equipped with two levels of undervoltage relay protection consisting of three relays each, configured in a preventative 3-out-of-3 coincidence logic to avoid unnecessary trips. The First Level Under-voltage Relays (FLUR), tagged 127-1 & 127-2, are electro-mechanical inverse time bus undervoltage relays, set to trip their corresponding breakers upon a bus voltage drop below a certain potential - in this case, 77% of the nominal bus voltage - or a complete loss of power. After a time delay, the Emergency Diesel Generators (EOG) are started and all bus loads are shed.

Second Level Under-voltage Relays (SLUR), tagged 127-7 and 127-8, are provided

  • to trip their corresponding breakers when the bus voltage drops to about 93% of nominal voltage. If bus voltage degradation occurs - though not enough to activate the FLUR - the SLUR will start the associated Emergency Diesel Generators after a short time delay of.65 seconds. If bus undervoltage exists after an additional six seconds, the time delays, tagged 162-153 and/or 162-154, trip the incoming bus breaker and shed all associated bus loads. These six-second time delays are the subject of this calculation.

The ABB-62T (Farwell & Hendricks, INC) time delay relays were originally ITE-62K (Goulds Manufacturing). In 1996, evaluations FES96-059 and FES96-060 determined that the ITE-62K existing undervoltage relays failed their reset timing tests. Furthermore, the ITE-62K timing delay relay had since become obsolete.

The analog circuitry based ITE-62K was superseded by a digital based ABB-62T.

The ABB-62T timing relay has a reset time of approximately 10 milliseconds.

Because the approximate 10 millisecond reset time is not significant when compared to the overall six second timer setting, the acceptance criteria is set at a conservative 30 milliseconds, or 0.3% of the range.

[Ref.8.1.6 & 8.4.1]

Action Request AR01018231 [Ref. 8.1.4] identified that the actuation times and voltages associated with both the 1st and 2nd level undervoltage relays have the potential to be set outside of the Technical Specifications Allowable Values (TSAV).

The relay settings sheets allow leaving these settings at a value equal to the TSAV.

However, setting the relays at the TSAV does not account for the inherent errors associated with the calibration, repeatability or drift of the relay settings. It is

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--===-- ntergy Engineering Calculation EA-EC11464-01 PAGE 7 OF 17 possible that these errors could result in actual times being outside of the Technical Specification limits.

Furthermore, Action Request AR01018858 [Ref. 8.1.5] was written to ensure the evaluation for AR1018231 [Ref. 8.1.4] includes considerations for the ABB-62T timers, tagged 162-153 and 162-154. This calculation will determine the setpoint uncertainty of these time delay relays.

3.0 Approach Uncertainty values for the second level time delay relays will be calculated in accordance with the Palisades Instrument Loop Uncertainty and Setpoint Methodology, Rev. 1. [Ref. 8.1.1]

The Time Delays tagged 162-153 and 162-154 do not have a technical specification. Palisades Nuclear Plant FSAR 8.6 [Ref. 8.1.3] specifies a six second time delay as follows:

"If a bus undervoltage exists after an additional six seconds, then the respective incoming bus circuit breaker will be tripped and a bus load shed will be initiated."

The existing calculation sheets for the time delay relays are provided in Ref. 8.3.1 and 8.3.2. These calculations specify that the relays should be set to a time delay of six seconds. The acceptance criterion is no more than +/-.3 seconds. The design criterion for the setting is that the time delay will be less than 6.5 seconds. A more thorough discussion on the six second time delay design criteria can be found in Ref. 8.1.7.

References 8.3.1 and 8.3.2 will be superseded by this calculation.

Referenced 8.3.1 and 8.3.2 also specify the acceptance criteria for the reset time of 30 milliseconds or less. The manufacturer specifies a reset time of approximately 10 milliseconds for the ABB-62T [Ref. 8.4.1]. That reset time is very small compared to the six second timer setpoint, and well within the required 30 millisecond limit. The reset time of the relay is not a safety related function, thus the 30 millisecond reset time will not be justified by this calculation.

This calculation determines the uncertainty associated with the six second timer setpoint. Errors that will be taken into account include the fixed time delays, temperature effects, control voltage effects, repeatability, drift effect, and measurement and test equipment errors.

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"'::::;:'" Entergy Engineering Calculation EA-EC11464-01 PAGE 80F 17 4.0 Design Inputs 4.1 Time Delay Relay Design Specifications The following specifications are taken directly from the Vendor's Manual (Ref.

8.4.1)

Catalog Number: 417T2170 Timer Range: 0.01 - 9.99 Sec Reset Time: Approximately 10 milliseconds Repeatability:+/-.5%, OR +/-15 milliseconds OR +/-1 digit, whichever is greater.

Fixed Delays Timer Stage=.5x the least significant digit.

Output Stage= 5-16 milliseconds (typical ?ms)

Variation in Timing with Change in Ambient Temperature:

-20 to +70 degrees C, +/- 2% OR+/- 20 milliseconds OR+/- 1 digit, whichever is greater.

Variation in Timing with Change in Control Voltage:

' -20%, + 10% voltage variation, +/- 2% OR +/- 15 milliseconds OR +/- 1 digit, whichever is greater.

4.2 Quality Requirements Quality Requirements Safety Related:

Yes Seismic:

QA Class:

See Ref. 8.4.2, the Certificate of Conformance for the ABB-62T relay. Included in the certificate is an Equipment Seismic Testing Summary Data Sheet.

Q-Listed, Quality Program Applies. Class 1-E (Safety Related).

(See Ref. 8.1.8)

According to Ref. 8.4.2, the ABB-62T relay is suitable for use in the following mild environment conditions. "Generic radiation levels ( 1x 10 4 RADS Tl D) are below threshold levels for non-metallic materials in this device... Non-condensing humidity levels (0-95%) are not known to produce failures in devices of this type...

Generic mild environment temperature (Max. 40°C) is below the manufacturer's maximum rated temperature (Max. 70°C) of this device... "

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-===--Entergy Entergy Engineering Calculation EA-EC11464-01 PAGE 9 OF 17 4.3 Temperature Data The undervoltage relays are located in the 1 /e and 1 /D switchgear rooms which are mild environments. The ambient temperature in these rooms ranges between 50°F and 104°F (Reference FSAR Table 9-13).

The temperature inside the cabinets housing the ABB 62T Time Delay Relays is assumed to be 5°F above the ambient temperature. This is reasonable as the only energized equipment within the cabinet are a 62T Time Delay Relay and the 27N Undervoltage relays. These relays draw less than 0.05 amps at 125 voe As there are 3 27N and 1 ABB 62 Relays in the cabinet, the heat input is on the order of 25 Watts. The cabinet housing the relays is 48"X36"X16" mounted on a concrete wall with a 6" conduit venting it at the top. A 5°F rise inside the cabinet is conservative for the size of the cabinet and the low power input to the cabinet.

Therefore for temperature related errors, it is assumed that the relays operate between 50°F and 109°F.

4.4 DC Supply Voltage According to FSAR Section 8.4.2.3, the batteries have ample capacity to supply required de loads and preferred ac loads during a complete loss of ac power for at least four hours, assuming neither diesel emergency generator is available. The batteries are designed to furnish their maximum load down to an operating temperature of 70°F without dropping below 105 volts, and the equipment supplied by the batteries is capable of operating satisfactorily at this voltage rating. The sediment space in the individual battery cells is sized such that the battery cannot develop an internal short circuit during its normal life.

Additionally, Section 8.4.2.2 of the FSAR establishes an upper voltage limit:

"Normal Operation - The batteries are kept fully charged at approximately 131 volts by the battery chargers. Periodically, the voltage is raised to approximately 138 volts for equalization of the charge on the individual battery cells." Therefore, control power to the relays for Bus 1 e and 1 D will vary from 105 voe to 138 voe.

4.5 Calibration Instrument Data A Wilmar solid state digital timer is used to measure the relay time delay. When measuring the time for a change in state of a dry contact in milliseconds, the accuracy of the timer is specified as+/- (0.06% of reading +1 LSD+ 1 msec). For a measurement of 1 second (1 OOOmsec), this results in an accuracy of:

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-::-;:;:--Entergy Engineering Calculation EA-EC11464-01 PAGE 10 OF 17 Etimer = +/- (0.0006*(1000) + 1 + 1) msec Etimer = +/- 2.6 msec To allow flexibility, an error of 34 msec (2 cycles will be used for the timer accuracy.

This allows for flexibility in choosing test equipment.

Etimer = +/- 34 msec 5.0 ASSUMPTIONS-NONE 6.0 ANALYSIS 6.1 Fixed Delay Effect The ABB-62T timer has a fixed input timer stage delay error {T1nErr) of 0.5 multiplied

, by the least significant digit. The least significant digit is 0.01 second [Ref. 8.4.1 ].

This is a bias term.

T1nErr =.5 X.01 sec=.005 sec The ABB-62T timer also has a fixed Output Stage delay. It has a range of 5-16 milliseconds. Typically, it is 7 milliseconds. This is also a bias term.

T OutErr = 0.016 sec Thus:

T Fixed Delay=+.021 Sec a bias term 6.2 Ref ere nee Accuracy The repeatability error of the ABB-62T timer is +/-0.5%, or+/- 15 milliseconds, or +/-1 digit, whichever is greater. Per Ref. 8.1.1, the manufacturer stated repeatability is equal to device reference accuracy. As a minimum, the RA term will normally consider repeatability. For a bistable, linearity, hysteresis and dead band do not apply, since the only point of interest is the setpoint value, and it is only needed to be tested in one direction. Per Ref. 8.1.1, Section 9.1,

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-===--Entergy Engineering Calculation EA-EC11464-01 PAGE 11 OF 17 Reference accuracy is considered to be a random independent error component unless specifically indicated otherwise by a manufacturer and is normally stated in terms of percent of span for the instrument.

Using the ABB-62T timer range, the instrument span is calculated to be 9.98 seconds.

Instrument Span = 9.99 sec-0.01 sec

= 9.98 sec The Reference Accuracy (RA), in seconds, calculates as follows:

RA

= +/- (RA x Span)

= +/-(0.5%) x (9.98 sec)

= +/-0.0499 sec 6.3 Variation in Timing with Change in Ambient Temperature The ABB-62T has Temperature Error (TE) of +/-2% or +/-20 milliseconds, or+/- 1 digit, whichever is greater over the range of -20°C to 70°C. The relay temperature specification spans a temperature of 90°C. Therefore, the temperature coefficient is calculated as follows:

Allowable Relay Temperature Span => 70°C-(-20°C) = 90°C T

t C

ff..

t

+/- 2 %

+/- 2 %

+/-.022 %

empera ure oe 1c1en =>

=

=---

Relay Span 90°C 1 °C The Time Delay Relays for Bus 1 C and 1 D are located in Junction Boxes J9400 and J9401. The temperature of these junction boxes can vary from 10°C to 42.2°C a range of 32.2°C [See Section 4.3].

TE% =

Temp Effect x Temp Span

=

+/- (0.022 %) (32.2 °C)

=

+/-0.708 % Span

=

+/- (0.708%) (9.98 sec)

=

+/-0.071 sec = +/-71 msec The vendor also states that the Temperature Error can vary by+/- 20 milliseconds over the -20 ° to 70 °C temperature span.

The vendor also states that the Temperature Error can vary by+/- 1 digit over the -

20 ° to 70 °C temperature span. One digit corresponds to +/-0.01 O sec.

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PAGE 12 OF 17 For conservatism, the largest error of +/- 71 milliseconds calculated for the maximum room temperature change will be used.

TE

=

+/-0.071 sec 6.4 Variation in Timing with Change in Control Voltage Per Reference 8.4.1, the ABB-62T Time Delay Relay is rated for a 125V nominal voltage and allows for a 100-140 DC Voltage variation. For a -20% to +10% (100-137.5Vdc) power supply voltage variation, the Power Supply Voltage Effect (PSE) is +/-2% error.

llAllowableRelayRange= 137.5 Vdc-100 Vdc = 37.5 Vdc.

The DC Voltage Supply [See Section 4.4] can vary from 138 Vdc to 105 Vdc.

lloc Power Supply Range= 138 Vdc - 105 Vdc = 33 Vdc The PSE as a percentage of span is:

PSE ~+/-2%( DCPowerSupplyRange)=+/-2%x~=+/-l.76%

Allowable Relay Range 37.5 The Power Supply Error in timing due to variation in voltage is equal to the percentage of span multiplied by the range of the timer.

PSE = Voltage Variation Random Error ~ +/-1.76%x9.98sec = +/-O.l 76sec 6.5 Measurement and Test Equipment Error Refer to section 4.5. A Wilmar Timer is currently used to perform the calibration of the time delay relay. To allow flexibility, an error of 34 msec (2 cycles will be used for the timer accuracy. This allows for flexibility in choosing test equipment.

MTE = +/-0.034 sec 6.6 Seismic, Humidity and Radiological Error The 62T timer relays are located in a mild environment and thus are not subject radiation. Additionally, the humidity remains relatively constant as they are located within a closed cabinet. Finally, the electronics which perform the timing function

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--===-Entergy Engineering Calculation EA-EC11464-01 PAGE 13 OF 17 are considered inherently rugged and are not prone to change due to seismic events. Thus there are no errors associated with these parameters.

6.7 Drift Error Per the Vendor Technical Manual (Reference 8.4.1 ), the 62T is a solid state relay utilizing digital counting techniques to obtain accuracy. The vendor does not specify a drift tolerance.

Based on past calibrations of the relays, as shown in the table below, there has been little variation in the relay timing between calibrations. Recalibration of the relays has never been required nor performed. The maximum variation during the last 1 O years has been 0.040 seconds. Based on this small variation, a drift value equal to twice the maximum observed variation (0.080 sec) is assigned. This drift value is considered conservative.

Drift Data Month/Year 162-153 As-Found/As-Left 162-154 As-Found/As-Left 4/96 5.98 Unreadable 5/98 5.95 5.95 4/01 5.94 5.98 11/01 5.98 5.97 5/03 5.95 5.96 2/05 5.94 5.94 D= 0.080 sec 6.8 Setting Tolerance As demonstrated by past calibrations of the 62T timing relays, the relays can be calibrated within 0.1 seconds of the nominal value. Thus:

ST= 0.1 sec

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-=::;:--Entergy Engineering Calculation EA-EC11464-01 PAGE 14 OF 17 6.9 Calculation of Total Time Delay Error The ABB-62T time delay error is determined by the square root of the sum of the square method for the random errors. Bias errors are directly added to the resulting random error.

The random relay error is calculated by taking the square root of the sum of the squares of the Reference Accuracy effect (RA), Temperature Effect (TE), Power Supply Voltage variation (PSE), Measuring and Test Equipment Effect (MTE},

Setting Tolerance (ST}, and the drift term (D).

Erand = ~(RA) 2 + (TE) 2 + (PSE) 2 + (MTE) 2 + (ST) 2 + (D )

2 Erand =~(0.0499) 2 + (0.071)2 + (0.176) 2 + (0.034) + (0.100) + (0.080) 2 Erand =.J0.0561 sec = +/-0.237 sec The only non random number is the fixed delay effect of +0.021 sec. Adding this bias to the random error results in a total error of:

7.0 CONCLUSION

S ETotal = +/- 0.237 sec + 0.021 sec ETotal = + 0.258, - 0.216 seconds The above calculation determined that the maximum error associated with the 62T time delay relays is ET01a1 =+ 0.258, - 0.216 seconds. As the nominal setpoint for the relay is 6 seconds, an as-found acceptance criterion of 5.8 seconds to 6.25 seconds provides assurance that the relay is operating within its design specifications. Additionally, the maximum error associated with the time delay relay assures that the total time delay results in an overall time delay of less than the design criterion of 6.5 seconds. The basis for the 6.5 second total time delay is discussed in Reference 8.1.7.

The setting tolerance required for this application is 0.1 seconds. This corresponds to an as-left setting of 5.90 - 6.1 O seconds. These values are provided in the relay protection setting sheets.

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~Entergy Engineering Calculation EA-EC11464-01 PAGE 15 OF 17 Per the vendor manual (reference 8.4.1 ), five internal movable plugs on the printed circuit board must be placed in the correct position to obtain the desired mode of operation. These are:

Voltage Selector plugs VSP1 and VSP2 set for 125Vdc operation Pickup/Dropout selector plugs J2and J3 set for Delay-on-Pickup (PU)

Target operation selector plug J1 set for internal (INT) operation.

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162-154, RMiller/PBruce, 6/20/96 8.1.1 Letter GJBrock to RJPienkos, 6/25/96, 2nd Level Undervoltage Relay Design Documentation [Attachment A]

8.1.8 AMMS Equipment Data Sheet for equipments 162-153 and 162-154 Date 9-18-06 8.2 Procedures 8.2.1 RE-138, Palisades Nuclear Plant Technical Specification Surveillance Procedure "CALIBRATION OF BUS 10 UNDERVOLTAGE AND TIME DELAY RELAYS" -

Effective Date 2/25/04 REV.2 8.2.2 RE-137, Palisades Nuclear Plant Technical Specification Surveillance Procedure -

"CALIBRATION OF BUS 1C UNDERVOLTAGE AND TIME DELAY RELAYS" -

Effective Date 2/25/04 REV.2 8.2.3 RE-137 & RE-138 BASIS - "Calibration of Bus 1 C (1 D) Undervoltage and Time Delay Relays" Effective Date 2/4/03 Rev. 1

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~Entergy Engineering Calculation EA-EC11464-01 PAGE 17 OF 17 8.3 Calculations 8.3.1 BUS 1D Second Level Undervoltage Time Delay 1D/203-J9401/162-154 Rev. 2 (Date: 11/12/96-3/15/2005).

8.3.2 BUS 1 C Second Level Undervoltage Time Delay 1C/108-J9400/162-153 Rev. 2 (Date: 10/22/1996-2/1/2005).

8.4 Vendor Information 8.4.1 Vender Manual ABB IB 7.7.1.7-6 "Instructions Solid State Timing Relay Issue D 8.4.2 Certificate of Conformance - ABB Relay P/N: 417T2170 #96361.1 Associated with P.O.# G0207812 C/0 #2, May 2ih, 1997

To: RJPienkos, P12-906 From: GJBrock, Palisades Date: June 25, 1996

Subject:

2nd Level Undervoltage Relay Design Documentation CC:

PAG-20-23 EA-EC11464-01 Attachment A Page 1 of 4 CONSUMER POWER COMPANY Internal Corres pondence GJB*9610 Per our telephone conversation of 5/13/96 and letter RJP 04-96 "Comments on Tech Spec Revision," the following references document the bases for the 2400 volt 2nd level undervoltage relay voltage setpoints and time delays.

A review of the existing engineering analyses documenting the existing conditions with respect to the present settings of the 2nd level undervoltage relays resulted in two references. Reference 1 documents and establishes the minimum steady state voltage on the 2400 volt system. The minimum acceptable steady state degraded grid voltage on the 2400 volt system is 91 % per Reference 1. The conclusion of this engineering analysis is shown in Attachment 1. Reference 2 documents the results of the operating condition of a LOCA with offsite power available. In this scenario, load shed occurs and the ECCS (eme'rgency core cooling system) motors are block started via SUT 1-2 (worst case). The 2400 volt system voltage drops to 0.7863 pu and recovers to 0.9504 pu within 3.5 seconds.

Figure 13 of this engineering analysis (Attachment 2) shows the 2400 volt system voltage transient and the pick-up and drop-out test points (1988) of the 2nd level undervoltage relays at 0.9267 pu and 0.9142 pu. These test points were used in place of nominal values to duplicate inadvertent starts experienced on the EDGs.

The proposed changes to the Technical Specifications regarding the 2400 volt 2nd level undervoltage relay nominal pick-up and drop-out setpoints per Reference 3 are 1) the nominal drop-out setpoint changes from 0.9183 pu to 0.9273 pu and 2) the nominal pick-up setpoint changes from 0.9275 pu to 0.932 pu. The nominal drop-out setpoint of 0.9273 pu is based on the minimum allowable 2400 volt system voltage of 0.91 pu plus PT burden and other measurement errors. The nominal pick-up setpoint of 0.932 pu is a result of the relay's pick-up to drop-out ratio of 99.5%. The proposed setpoint change has no effect on the minimum allowable 2400 volt system voltage calculated in Reference 1 and no effect on the recovery voltage as calculated in Reference 2. The figure from Reference 2 (Attachment 2) shows a recovery voltage of 0.9504 pu which is above the proposed 2nd level undervoltage pick-up setpoint of 0.932 pu.

However, when all the calculated errors are added to the nominal pick-up setpoint, the maximum relay pick-up voltage is 0.9555 pu per Reference 3. Attachment 2 shows the voltage recovers to a steady state value of 0.9504 pu which is below the maximum pick-up voltage of 0.9555 pu. During this scenario, a LOCA occurs with offsite power available via the SUT 1-2 feed. Ttie worst case voltage is 345 kV based on probable historical levels

EA-EC11464-01 Attachment A Page 2 of 4 (Reference 10). For system voltages greater than approximately 347 kV (using a simplistic calculation), the undervoltage relays would pick-up. If the undervoltage relays do not pick-up, a SIS is initiated which enables the SIS-X relays and start the ECCS motors. As shown in Attachment 2, the voltage initially drops to 0.7863 pu. After 0.5 seconds, the 2nd level undervoltage relays 127-7 (127-8) drop out enabling relays 127-7/X1 and 127-7/X2 (127-8/X1 and 127-8/X2) which start the EDGs via the 306-01 or 306-02 (306-03, 306-04) relays, initiate an undervoltage alarm and the 162-153 six second timer. The 2400 volt system voltage fully recovers to a steady state value of 0.9504 pu in approximately 4 seconds. The 2nd level undervoltage relays 127-7 (127-8) do not pick up due to the assumption that they have drifted to the maximum pick-up voltage of 0.9555 pu. At 6.5 seconds, the 162-153 timer times out and load shed occurs by opening the offsite source breakers to buses 1 C and 1 D (152-105, 152-106, 152-202, 152-203). The SIS-X relays are blocked and the load shed relays operate (left channel; 194-108, 94-1909, 94-1109A, 94-11098, right channel; 194-211, 94-2013, 94-1213A, 94-12138). Assuming the EOG starts within its required time frame (approximately 11 seconds), the output EOG breaker closes when the terminal voltage reaches 2000 volts via the 127-01 (127-02) and 1060-1 (1060-2) relays and initiates the OBA sequencers.

The difference in this scenario to previously studied scenarios is that the loss of offsite power does not happen concurrent with a SIS, offsite power is lost at 6.5 seconds into the event. The difference being the ECCS motors and MOVs are block started at time zero via SUT,1-2. The EOG start signal is also initiated at this time, three out of three 127-7 (127-8) 2nd level undervoltage relays drop out. Therefore, no extra time is added to the EOG start.

The ECCS motors start and accelerate to steady state speed and voltage at approximately 4 seconds then are load shed at 6.5 seconds when the 162-153 timer times out. The MOVs run for approximately 6 seconds. After an approximate dead bus time of 4 seconds the loads are sequenced onto the EDGs via the OBA sequencers.

Conversations with Steve Oakley - Operations, Gary Pratt - Nuclear Fuels, Rich Moceri -

System Engineering, Bob Gambrill - Valve program, Brian Sova - System Engineering confirmed the following. Nuclear Fuels' assumes a time zero at initiation of the OBA sequencer with the assumed start time of the EOG of 11 seconds. If no additional time is added during this scenario it does not impact existing studies. Operators would initially observe ECCS motors start however after 6.5 seconds the scenario would be similar to a loss of offsite power concurrent with a LOCA. The system could operate as designed and no additional time is added to the design base accident. Sections 5 "Precautions and Limitations" and 7 "Procedures" of applicable SOPs were reviewed to determine motor starting duty limitations. All motors are rated at a minimum two cold starts and one hot start. This is the maximum starting duty they will experience in this scenario. The MOVs will start and run for approximately six seconds prior to load shed. At this time the motor operator will have unseated the valve. The valves will continue to operate when the OBA sequencer signal is received.

The system operates as designed and no adverse conditions were discovered.

A review of engineering analyses regarding the bases of the 2nd level undervoltage relay time delays resulted in four references. Reference 4 summarizes the historical references

EA-EC11464-0l Attachment A Page 3 of 4 5, 6 and 7 with respect to the time delay bases for the 2400 volt 2nd level undervoltage relays. The following summarizes Reference 7 which provides the basis for the time delays (Attachment 3):

The time delay selected shall be based on the following conditions:

a.

'The allowable time delay, including margin, shall not exceed the maximum time delay that is assumed in the FSAR accident analysis.'

The proposed time delay of 6.5 seconds does not exceed this maximum time delay. This is substantiated by the licensee in this proposal.

The proposed time delay will not be the cause of any thermal damage to the safety-related equipment.

The setpoint is within voltage ranges recommended by ANSI CS.4.1-1971 for sustained operation.

b. 'The time delay shall minimize the effect of short-duration disturbances from reducing the unavailability of the offsite power source(s).'

The licensee's proposed time delay of 6.5 seconds is long enough to override any short inconsequential grid disturbances. Further, we have

~ reviewed the licensee's analysis and agree with the licensee's finding that any voltage dips caused from the starting of large motors will not trip the offsite source.

c. 'The allowable time duration of a degraded voltage condition at all distribution system levels shall not result in failure of safety systems or components.'

A review of the licensee's voltage analysis indicates that the time delay will not cause any failures of the safety-related equipment since the voltage setpoint is within the allowable tolerance of the equipment voltage rating.

References

1) EA-ELEC-VOLT-17 Rev 0, 9/1/94, "Verification that the Second Level Undervoltage Relays are Properly Set to Adequately Protect 2400 V and 480 V Safety Related Equipment from Sustained Degraded Voltages." PAG-20-85.
2) EA-ELEC-VOL T-13 Rev 0, 6/11/93, "Palisades Loss of Coolant Accident with Offsite Power Available." PAG-20-83.
3) EA-ELEC-VOL T-033, 10/94, "Second Level Undervoltage Relay Setpoint."
4) EA-D-PAL-90-122A, 2/20/92, "Palisades - Recommended Second Level Undervoltage Relay Transient Time Delay During 001 Testing to Avoid EOG Starts." PAG-20-73.

EA-EC11464-01 Attachment A Page4 of 4

5) CPCo letter to NRC, 10.2.78, "DOCKET 50-255 - License DPR Palisades Plant -

Response to Emergency Supply Generic Issues."

6) NRC letter to CPCo, 12/22/81, "DOCKET 50-255, SEP TOPIC Vlll-1.A Potential Equipment Failures Associated with Degraded Grid Voltage."
7) EG&G Report, 11.81, "Degraded Grid Protection for Class 1 E Power Systems, Palisades Plant, Docket 50-255."
8) A-NL-92-111, "Degraded Grid Undervoltage Relaying Design Weaknesses."
9) Logic diagrams; E17 sh 4 rev 1 O E17 sh 10 rev 5 E17 sh 11 rev 2 E17 sh 12 rev 5 E17 sh 13 rev 8 E17 sh 14 rev 6.

1 O) EA-ELEC-VOL T-038 Rev 0, "Statistical Review of Palisades 345 kV System Voltage, Determine Normal Voltage Range." (G228/0160)

Plant Voltage Palisades 2400 Protected System:

Notes Protective Device Unit, Phase, or Zone Timer 0.01-9.99 Sec Setting Sheet DESIGN ENGINEERING SYSTEM PROTECTION - SETTINGS A/E --------------

Equip ID 162-153 Q -1 is t e d Yes Bus JC Bus IC Second Level Undervoltage Time Oday ABB/ITE-62T Catalog# 417T2170 Function or Element Setting Acceptance Criteria Time Delay 6.0 Sec 5.80 - 6.25 Reset 10 msec 30 msec or less Note: Five internal movable plugs on the printed circuit board must be placed in the correct position to obtain the desired mode of operation.

Voltage selector plugs VSPJ and vsn set for 125Vdc Pickup/Dropout plugs J2 and J3 set for delay on pickup (PU)

Target Operation selector plug JJ set for internal (INT) operation As-Left Timing shall be adjusted to 6.0 +/- 0.1 second (5.9 - 6.1 seconds)

Breaker Mfg Pole Data Cat Range PT Ratio CT Ratio Motor HP Volt Frame Data LRA FLA Starter Mfg NEMA Size Data Cal OLHTR Size KVACode:

SF Type 3-<p Short Circuit Amps Developed from Cale EA-ECI 1464-01 Settjngs issued by Approved by Rev 0

Setting Sheet I C/108-19400-J 62-153 Rev 3

RM Hamm CL Hamar

  • Indicates significant changes since last revision Date Date 01/22/09 01/22/09 Sheet 1 of I Entergy MAINTENANCE AND CONSTRUCTION - TEST RECORD Procedure Plant FC or MO Reference Documents Setting Description Remarks Test Completed by Design Engineering ESPPRcview AS FOUND (X) Accept Status Variance In Out 1n Op CALIBRATED TEST EQUIPMENT USED Serial Number
  • Rerum to De.~ign Engineering System Protection for Processing.

Rev AS LEFT Setting Variance Cal Due Date Date Date Rev O I (06/06/07)

Setting Sheet

=Entergy, DESIGN ENGINEERING SYSTEM PROTECTION - SETTINGS ENTERGY HUD.LU Plant Voltage Palisades 2400 Equip ID 162-154 A/E Q-Jisted Yes Bus ID Protected System:

Notes Protective Device Unit, Phase, or Zone Timer 0.01-9.99 Sec Bus ID Second Level Undervoltage Time Delay ABB/ITE-62T Catalog# 417T2l 70 Function or Element Setting Acceptance Criteria Time Delay 6.0Sec 5.80 - 6.25 Reset JO msec 30 msec or Jess Note: Five internal movable plugs on the printed circuit board must be placed in the correct position to obtain the desired mode of operation.

Voltage selector plugs VSPI and YSP2 set for 125Ydc Pickup/Dropout plugs 12 and J3 set for delay on pickup (PU)

Target Operation selector plug JI set for internal (INn operation As-Left Timing shall be adjusted to 6.0 +/- 0.1 second (5.9 - 6.1 seconds)

Breaker Mfg Pole Data Cat Range PT Ratio CT Ratio Motor HP Volt Frame Data LRA FLA Starter Mfg NEMASize Data Cat OLHTR Size KY A Code:

SF Type 3-qi Short Circuit Amps Developed from Cale EA-EC! 1464-01 Settings issued by Approved by Rev 0

RM Hamm Setting Sheet ID/203-19401/162-154 Rev 2

CL Hamar

  • Indicates significant changes since last revision Date Date 01/22/09 01/22/09 Sheet I of I Entergy MAINTENANCE AND CONSTRUCTION - TEST RECORD Procedure Plant FC or MO Reference Documents Setting Description Remarks Test Completed by Design Engineering ESPP Review AS FOUND Variance In (X) Acee.pt Status Out In Op CALIBRATED TEST EQUIPMENT USED Serial Number
  • Return to Design Engineering System Protection for Processing.

Rev AS LEFT Setting Variance Cal Due Date Date Date Rev OJ (06/06/07)

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