ML20205S373

Application for Amends to Licenses NPF-68 & NPF-81,revising SR 3.3.5.2 & Associated Bases to Allow Loss of Voltage & Degraded Voltage Trip Setpoints to Be Treated as Nominal Values in Same Manner as Trip Setpoints for RTS & ESFAS

ML20205S373
Person / Time
Site:	Vogtle
Issue date:	04/19/1999
From:	Beasley J SOUTHERN NUCLEAR OPERATING CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
Shared Package
ML20205S375	List: ML20205S373 ML20205S379
References
LCV-1303, NUDOCS 9904260200
Download: ML20205S373 (7)

Text

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1 O J

, J. Bernie Beasley, Jr.. P.E Southern Nuclear

1. Vice President Operating Company,Inc.

Vogtle Project 40 inverness Center Parkway P0. Box 1295 Birmingharn. Alabama 35201 Tel 205.992.7110 Fax 205.992.0103 SOUTHERN COMPANY l Energy to Serve Your World*

LCV-1303 April 19,1999 j Docket Nos. 50-424 50-425 U. S. Nuclear Regulatory Commission )'

ATTN: Document Control Desk Washington, D. C. 20555 Ladies and Gentlemen:

VOGTLE ELECTRIC GENERATING PLANT REQUEST TO REVISE TEC11NICAL SPECIFICATIONS  !'

LOSS OF POWER INSTRUMENTATION TRIP SETPOINTS In accordance with the requirements of 10 CFR 50.90, Southern Nuclear Operating Company (SNC) proposes to revise the Vogtle Electric Generating Plant (VEGP) Unit I and Unit 2 Technical Specifications (TS). The proposed change would revise Surveillance Requirement j (SR) 3.3.5.2 and associated Bases to allow the loss of voltage and degraded voltage trip setpoints to be treated as nominal values in the same manner as the trip setpoints for the Reactor Trip System (RTS) and Engineered Safety Feature Actuation System (ESFAS) instrumentation.

Specifically, the proposed change would:

• Delete the inequalities applied to the loss of voltage and degraded voltage trip setpoints; e Apply the term " Nominal" wherever Trip Setpoints are specified in SR 3.3.5.2; and.

. Apply the following Note to SR 3.3.5.2: ,

"A channel is OPERABLE with an actual Trip Setpoint value outside its 1 calibration tolerance band provided the Trip Setpoint value is conservative .

I with respect to its associated Allowable Value and the channel is readjusted to within the established calibration tolerance band of the Nominal Trip Setpoint. A Trip Setpoint may be set more conservative than the Nominal l Trip Setpoint as necessary in response to plant conditions."

• Revise the Bases associated with LCO 3.3.5 and SR 3.3.5.2 as necessary to 3j-support the proposed change to SR 3.3.5.2. \0 The proposed change is essentially identical to Amendments 101 and 79, tyhich were approved by the NRC on June 1,1998. These amendments revised Limiting Conditions for Operation (LCO) 3.3.1, Reactor Trip System Instrumentation and LCO 3.3.2, Engineered 9904260200 990419 PDR ADOCK 05000424 P PDR _

d. S. Nuclear Regulatory Commission LCV-1303

- Page 2 Safety Feature Actuation System Instrumentation, to allow the trip setpoints speciDed therein to be treated as nominal values.

The basis for the proposed changes is provided in Enclosure 1. Pursuant to 10 CFR 50.92, an evaluation that demonstrates that the proposed changes do not involve a significant hazard consideration is provided in Enclosure 2. The proposed changes are marked on the affected TS and Bases pages and are provided in Enclosure 3. In addition, clean typed TS and Bases pages are provided in Enclosure 4.

SNC requests approval of the proposed change by September 1,1999.

Mr. J. B. Beasley, Jr. states that he is a Vice President of Southern Nuclear Operating Company and is authorized to execute this oath on behalf of Southern Nuclear Operating Company and that, to the best of his knowledge and belief, the facts set forth in this letter are true.

SOUTilERN NUCLEAR OPERATING COMPANY By: l 1 }/

4' YB. Bfsly,Mr.

Sworn to andsubscribed before me this day of__ ,1999.

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Notary Puhic ymapg8 11-104E A& commission expires:

JBB/NJS Enclosure 1 - Basis for Proposed Changes Enclosure 2 - SigniGcant 1lazards Consideration Evaluation

, Enclosure 3 - Marked-up TS and Bases Pages Enclosure 4 - Clean Typed TS and Bases Pages xc: Southern Nuclear Operating Company Mr. J. T. Gasser Mr. M. Sheibani SNC Document Management

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l N. S. Nucleir Regulatory Commission LCV-1303

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! " S. Nuclear Regulatory Commission

! ,,,r. L A. Reyes, Regional Administrator Mr. R. R. Assa, Project Manager, NRR j Mr. John Zeiler, Senior Resident inspector, Vogtle State of Georgia Mr. L C. Barrett, Commissioner, Department of Natural Resources l

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Eccles:r: 1

- Vogtle Electric Generating Plant Request to Revisc Technical Specifications

, , Loss of Power Instrumentation Trip Setpoints B, asis for Proposed Change Proposed Charme The proposed change would revise Surveillance Requirement (SR) 3.3.5.2 and associated Bases to allow the loss of voltage and degraded voltage trip setpoints to be treated as nominal values in the same manner as the trip setpoints for the Reactor Trip System (RTS) and Engineered Safety Feature Actuation System (ESFAS) instrumentation.

Specifically, the proposed change would: )

e Delete the inequalities applied to the loss of voltage and degraded voltage trip setpoints; e Apply the term " Nominal" wherever Trip Setpoints are specified in SR 3.3.5.2; and, e Apply the following Note to SR 3.3.5.2:

"A channel is OPERABLE with an actual Trip Setpoint value outside its calibration tolerance band provided the Trip Setpoint value is conservative with respect to its associated Allowable Value and the channel is readjusted to within i the established calibration tolerance band of the Nominal Trip Setpoint. A Trip Setpoint may be set more conservative than the Nominal Trip Setpoint as  ;

necessary in response to plant conditions." )

e Revise the Bases associated with LCO 3.3.5 and SR 3.3.5.2 as necessary to support the proposed change to SR 3.3.5.2.

Basis  !

Four channels ofinstrumentation monitor the voltage of each 4.16 kV Engineered Safety Featum (ESF) bus. Four bistables are set to trip on e loss of voltage (a setpoint equivalent to 2 71.5 % of bus voltage after a time delay) and four additional bistables are set to trip on a degraded voltage signal (a setpoint equivalent to 2 90 % of bus voltage after a time delay). Given a loss of voltage or degrwhd voltage condition, this function will initiate sequencer operation to start the emergency diesel generators (EDGs), shed loads from the 4.16 kV ESF buses, and sequence  !

loading of these buses after the EDGs are ready to load. This ensures that the ESF systems required to function in any accident or transient involving a loss of offsite power will be available.

The proposed change is essentially identical to Amendments 101 and 79, which were approved I by the NRC on June 1,1998. These amendments revised Limiting Conditions for Operation ,

(LCO) 3.3.1, Reactor Trip System Instrumentation, and LCO 3.3.2, Engineered Safety Feature I Actuation System Instrumentation, to allow the trip setpoints specified therein to be treated as j nominal values. The allowable values specified in SR 3.3.5.2 were used as analytical limits in the loe of voltage and degraded grid studies. The trip setpoints specified in SR 3.3.5.2 were then developed from these allowable values using a basic uncertainty equation essentially identical to that used to develop the trip setpoints specified for the RTS in LCO 3.3.1 and the ESFAS in LCO 3.3.2. These calculations contain a setting tolerance term applied as a two-sided tolerance around the trip setpoint. At the present, SNC calibrates the st.bject trip setpoints so that the as-left value is in compliance with the inequality specified in SR 3.3.5.2. Ilowever, this forces a "one-sided" calibration. Therefore, since the methodology that was used to determine the trip setpoints provides for a two-sided calibration, the proposed change wot ' facilitate full use of the El-1

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Etclosure 1 l

Vogtle Electric Generating Plant Request to Revise Technical Specifications

, , Loss of Power Instrumentation Trip Setpoints Basis for Proposed Change calibration tolerance band identical to the calibrations for the RTS and ESFAS trip setpoints since Amendments 101 and 79.

The proposed note to be added to SR 3.3.5.2 is ideatical to the note that was added to the RTS and ESFAS trip setpoints in Amendments 101 and 79. This note will allow a channel to be considered operable if the as-found value is outside the calibration tolerance around the nominal trip setpoint, but conservative with respect to the allowable value. Ilowever, the note requires the trip setpoint value to be restored to withir. the calibration tolerance band. This is consistent with the safety analysis because the allowable value is the analytical limit in the safety analysis. As long as that channel actually trips within the analytical limit, the required ESF equipment remains capable of performing its function. Restoring the channel trip setpoint to within the calibration tolerance band restores that channel to a condition that is consistent with the setpoint methodology for the next surveillance interval, in addition, the proposed footnote would allow the trip setpoints to be set conservatively to the nominal value in the same fashion as the RTS and ESFAS setpoints.

Conclusion in summary, the loss of voltage and degraded voltage instrumentation channels will be considered to be " calibrated" when the two-sided as-left calibration procedural tolerance is satisfied. In this condition, the channels will be capable of performing their safety function within the envelope of the safety analysis as explained above. Therefore, the inequalities may be deleted from SR 3.3.5.2 as applied to the trip setpoints, and the terminology changed to " Nominal Trip Setpoint."

The addition of the footnote requiring the trip setpoint to be restored to within the calibration tolerance band is consistent with the setpoint methodology. Allowing trip setpoints to be set more conservative than the nominal value is simply a clarification. Setting the setpoints more ~

conservative than the nominal value will be conservative with respect to the safety analysis, and it .

is consistent with the current TS requirements.  !

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Enclosure 2 Vogtle Electric Generating Plant Request to Revise Technical Specifications

, , Loss of Power Instrumentation Trip Setpoints Significant Hazard Consideration Esaluation Proposed Change in accordance with the requirements of 10 CFR 50.90, Southern Nuclear Operating Company (SNC) proposes to revise the Vogtle Electric Generating Plant (VEGP) Unit I and Unit 2 Technical Specifications (TS) Surveillance Requirement (SR) 3.3.5.2 and associated Bases to allow the loss of voltage and degraded voltage trip setpoints to be treated as nominal values in the same manner as the trip setpoints for tb P.cactor Trip System (RTS) and Engineered Safety Feature Actuation System (ESFAS) instrumentation.

Specifically, the proposed change would:

• Delete the inequalities applied to the loss of voltage and degraded voltage trip setpoints; e Apply the term " Nominal" wherever Trip Serpoints are specified in SR 3.3.5.2: and, e Apply the following Note to SR 3.3.5.2:

"A channel is OPERABLE with an actual Trip Setpoint value outside its calibration tolerance band provided the Trip Setpoint value i:; conservative with respect to its associated Allowable Value and the channel is reedjusted to within the established calibration tolerance bard of the Nominal Trip Eetpoint. A Trip Setpoint may be set more conservative than the Nominal Trip Segoint as necessary in response to plant conditions."

e Revise the Bases associated with LCO 3.3.5 and SR 3.3.5.2 as necessary to support the proposed change to SR 3.3.5.2.

Evaluation

1. Does the pnposed change involve a significant increase in the probability or consequer..as of an accident previously evaluated?

No. The proposed change affects only the presentation of the trip setpoints for loss of voltage and degraded voltage in SR 3.3.5.2 in the VEGP Units 1 and 2 TS. The calibration of the channels whose setpoints are specified in SR 3.3.5.2 will continue to be performed in a manner consistent with the setpoint methodology used to determine the trip setpoiro There will be no adverse effect on the ability of those channels to perform their safety functions as assumed in the safety analyses. Since there will be no adverse l effect on the trip setpoints or the instrumentation associated with those trip setpoints,

! there will be no increase in the probability of any accident previously evaluated.

l Similarly, since the ability of the instrumentation to perform its safety function is not adversely affected, there will be no increase in the consequ:nces of any accident previously evaluated.

2. Does the proposed change create the possibility of a new or different kind of accident from any accident previously evaluated?

No. The proposed change affects only the presentation of the trip setpoint requirements of SR 3.3.5.2. Plant operation will not be changed, and the response of safety related equipment as assumed in the accident analyses would not be adversely affected.

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Enclosur: 2 Vogtle Electric Generating Plant Request to Revise Technical Specifications

, Loss of Power Instrumentation Trip Setpoints Significant flazard Consideration Evaluation Therefore, the proposed change does not involve a new or different kind of accident than any previously evaluated.

3. Does the proposed change involve a significant reduction in a margin of safety?

No. As described above, the loss of voltage and degraded voltage instrumentation will remain capable of performing its safety function as assumed in the accident analyses.

The treatment of trip setpoints as nominal values is consistent with the methodology used to establish those setpoints. As such, margin is not affected by the proposed change.

Conclusion Based on the above, the proposed changes do not involve a significant hazards consideration as defined in 10 CFR 50.92.

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