NL-20-0173, License Amendment Request to Revise Technical Specification Surveillance Requirement 3.3.5.2 Allowable Values

License Amendment Request to Revise Technical Specification Surveillance Requirement 3.3.5.2 Allowable Values

ML21089A388
Person / Time
Site:	Vogtle
Issue date:	03/30/2021
From:	Gayheart C Southern Nuclear Operating Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
NL-20-0173
Download: ML21089A388 (17)

Text

Cheryl A. Gayheart 3535 Colonnade Parkway Regulatory Affairs Director Birmingham, AL 35243 205 992 5316 cagayhea@southernco.com March 30, 2021 NL-20-0173 10 CFR 50.90 Docket Nos.: 50-424 50-425 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D. C. 20555-0001 Southern Nuclear Operating Company Vogtle Electric Generating Plant - Units 1 and 2 License Amendment Request to Revise Technical Specification Surveillance Requirement 3.3.5.2 Allowable Values Ladies and Gentlemen:

Pursuant to the provisions Section 50.90 of Title 10 Code of Federal Regulations (CFR),

Southern Nuclear operating Company (SNC) hereby requests a license amendment to Vogtle Electric Generating Plant (VEGP) Unit 1 renewed operating license NFP-68 and Unit 2 renewed operating license NFP-81. The proposed amendment revises Technical Specification (TS) 3.3.5, Loss of Power (LOP) Instrumentation, Surveillance Requirement (SR) 3.3.5.2 Allowable Values. The current Allowable Values listed in SR 3.3.5.2 are the same as the Analytical Limits for their respective trip functions. SNC proposes to change the values in SR 3.3.5.2 to Allowable Values, ensuring an appropriately conservative trip setpoint.

Using Analytical Limits as Allowable Values is not consistent with the standard technical specifications (NUREG-1431, Standard Technical Specifications, Westinghouse Plants, Revision 4). This creates the possibility that the trip setpoints will be insufficient to perform their required trip function. Therefore, in accordance with the guidance in NRC Regulatory Guide 1.239, Licensee Actions to Address Non-Conservative Technical Specifications, this license amendment request is required to resolve the non-conservative TS and is not a voluntary request to change the VEGP licensing basis. Currently, plant operations are administratively controlled as described in Regulatory Guide 1.239.

SNC requests approval of the proposed amendment by April 1, 2022. The proposed changes would be implemented within 60 days after issuance of the amendments.

In accordance with 10 CFR 50.91, a copy of this application is being provided to the designated Georgia Official.

U. S. Nuclear Regulatory Commission NL-21-0173 Page 2 This letter contains no regulatory commitments. If you have any questions, please contact Jamie Coleman at 205.992.6611.

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

___ day of March 2021.

Respectfully submitted, C. A. Gayheart Director, Regulatory Affairs Southern Nuclear Operating Company CAG/kgl/cg

Enclosure:

Basis for Proposed Changes Attachments: 1. Proposed Technical Specification Changes (Marked-up Pages)

2. Revised Technical Specification Pages (Clean Typed)

3. Proposed Technical Specification Bases Changes (Marked-up Pages for Information Only) cc: Regional Administrator, Region ll NRR Project Manager - Vogtle 1 & 2 Senior Resident Inspector - Vogtle 1 & 2 State of Georgia Environmental Protection Division RType: CVC7000

ENCLOSURE Vogtle Electric Generating Plant - Units 1 and 2 Revise Technical Specification Surveillance Requirement 3.3.5.2 Allowable Values Basis for Proposed Changes

Basis for Proposed Changes 1.0

SUMMARY

DESCRIPTION In accordance with 10 CFR 50.90, Application for amendment of license, construction permit, or early site permit, Southern Nuclear Operating Company (SNC) requests an amendment to Renewed Facility Operating Licenses NFP-68 and NFP-81 for Vogtle Electric Generating Plant (VEGP) Units 1 and 2, respectively. The proposed amendment revises Technical Specification (TS) 3.3.5, Loss of Power (LOP) Instrumentation, Surveillance Requirement (SR) 3.3.5.2 Allowable Values. The current values listed in SR 3.3.5.2 are the same as the Analytical Limits for their respective trip functions. SNC proposes to change these values to Allowable Values, ensuring an appropriately conservative trip setpoint.

2.0 DETAILED DESCRIPTION 2.1 System Design and Operation The Class 1E AC power system is divided into two independent divisions to provide AC power to the two divisions of engineered safety features (ESF) loads. The standby power source for each ESF bus is its associated emergency diesel generator set. Each 4.16-kV Class 1E bus is equipped with undervoltage relays (located at the sequencer for each Class 1E train) for diesel generator start initiation and undervoltage annunciation.

Upon recognition of a loss of, or degraded voltage on, a 4.16-kV Class 1E bus, a logic signal is initiated. Two voltage sensing schemes for each Class 1E 4.16-kV bus are employed to initiate the logic signal. One scheme will recognize a loss of voltage, and the other will recognize degraded voltage conditions. Each scheme is provided voltage signals through four potential transformers located on each bus.

Logic is provided to allow load shedding and tripping of the incoming breaker on two-out-of-four undervoltage logic signals. These devices are set to operate with a time delay of 0.8 s at a minimum of 71% of nominal voltage which is below the minimum expected voltage during diesel generator sequencing. The undervoltage sensing device design meets the applicable requirements of IEEE 279.

Additional undervoltage logic circuits are provided for each bus to recognize degraded voltage conditions. These circuits are set to operate at a minimum of 89.6% of nominal voltage with a maximum time delay of 20 s. This setpoint is above the minimum motor starting voltage during normal operation; however, the time delay has been selected to prevent unwanted tripping and undervoltage induced damage to the safety-related loads. Load shedding and tripping of the incoming breaker is provided by two-out-of-four undervoltage logic.

The Loss of Voltage and Degraded Voltage instrument Functions provide signals to their respective sequencer to ensure an adequate ESF bus voltage is maintained and provide an anticipatory automatic start of the auxiliary feedwater pumps. A two-out-of-four logic combination for Loss of Voltage or Degraded Voltage on an ESF bus will initiate sequencer circuits to start the diesel generator, shed bus loads, and sequence loading of the diesel generator if required. The two-out-of-four logic on one ESF bus will also initiate sequencer circuits to start the motor-driven auxiliary feedwater pump associated with that bus.

The LOP DG start instrumentation is required for the systems to function in any accident with a loss of offsite power.

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Basis for Proposed Changes SR 3.3.5.2 is the performance of a channel calibration. The Nominal Trip Setpoint considers factors that may affect channel performance such as rack drift, etc. Therefore, the Nominal Trip Setpoint (within the calibration tolerance) is the expected value for the channel calibration.

Therefore, a channel with an actual Trip Setpoint value that is conservative with respect to the Allowable Value is considered Operable; but the channel should be reset to the Nominal Trip Setpoint value (within the calibration tolerance) to allow for factors which may affect channel performance (such as rack drift) prior to the next surveillance.

2.2 Reason for the Proposed Change 10 CFR 50.36 states that the TSs will include items in the categories of safety limits, limiting safety system settings (LSSS), and limiting control settings. Thus, the LSSS may not be maintained in plant procedures. Rather, the LSSS must be specified as a TS-defined limit in order to satisfy the requirements of 10 CFR 50.36. For the Standard Technical Specifications, the NRC staff designated the Allowable Value as the LSSS.

In association with the trip setpoint and limiting conditions for operation (LCOs), the LSSS establishes the threshold for protective system action to prevent acceptable limits being exceeded during design basis accidents. The LSSS therefore ensures that automatic protective action will correct the abnormal situation before a safety limit is exceeded. The Allowable Value is the limiting value that the trip setpoint can have when tested periodically, beyond which the instrument channel is considered inoperable and corrective action must be taken in accordance with the TSs. The LSSS should be developed in accordance with the setpoint methodology used in the licensing basis, with the LSSS listed in the TS.

Therefore, using Analytical Limits as Allowable Values conflicts with the Standard Technical Specifications and creates the possibility that the trip setpoints will be insufficient to perform their required trip function. In accordance with the guidance in NRC Regulatory Guide 1.239, Licensee Actions to Address Non-Conservative Technical Specifications, (Reference 1), this license amendment request is required to resolve non-conservative TS and is not a voluntary request to change the VEGP licensing basis. Currently, plant operations are administratively controlled as described in Regulatory Guide 1.239.

2.3 Description of the Proposed Change The loss of voltage and degraded voltage limits for the LOP channel calibration performed by SR 3.3.5.2 are below. A channel with an actual Trip Setpoint value that is conservative with respect to the Allowable Value is considered Operable Current SR 3.3.5.2 A. Loss of voltage Allowable Value > 2912 V with a time delay of < 0.8 second.

B. Degraded voltage Allowable Value > 3683 V with a time delay of < 20 seconds.

SNC proposes to change the Allowable Value for each of the functions in SR 3.3.5.2 as shown below. The Allowable Values for the loss of voltage and the degraded voltage setpoints are calculated in accordance with the VEGP Setpoint Program and are substituted for the existing values in SR 3.3.5.2. Note that the time delay does not change in either function.

Proposed SR 3.3.5.2 A. Loss of voltage Allowable Value > 2958.2 V with a time delay of < 0.8 second.

B. Degraded voltage Allowable Value > 3729.2 V with a time delay of < 20 seconds.

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Basis for Proposed Changes The current SR for channel calibration of the loss of voltage and the degraded voltage Allowable Value limits are equivalent to the Analytical Limits for loss of voltage and degraded voltage, and should be more conservative than the Analytical Limits.

3.0 TECHNICAL EVALUATION

Setpoint calculations establish a Nominal Trip Setpoint based on the Analytical Limit of the Safety Analysis to ensure that trips or protective actions will occur prior to exceeding the process parameter value assumed by the Safety Analysis calculations. These setpoint calculations also calculate an allowed limit of expected change (i.e., the as-found tolerance) between performances of the surveillance test for assessing the value of the setpoint setting.

The least conservative as-found instrument setting value that a channel can have during calibration without requiring performing a TS remedial action is the setpoint Allowable Value.

Discovering an instrument setting to be less conservative than the Allowable Value indicates that there may not be sufficient margin between the setting and the Analytical Limit. TS channel calibrations, channel operational tests, and trip actuation operational tests (with setpoint verification) are performed to verify channels are operating within the assumptions of the setpoint methodology calculated Nominal Trip Setpoint and that channel settings have not exceeded the TS Allowable Values. When the measured as-found setpoint is non-conservative with respect to the Allowable Value, the channel is inoperable and the actions identified in the TS must be taken. The Allowable Values and Nominal Trip Setpoints are included in the VEGP TSs. The Allowable Values indicate the least conservative value that the as-found trip point may have during testing for the channel to be Operable. The Allowable Values listed in the TS satisfy the 10 CFR 50.36 requirements that the LSSS be in the TSs. Additionally, to ensure proper use of the Allowable Value, field setting, and Nominal Trip Setpoint, the methodology for calculating the as-left and as-found tolerances are specified in plant specific setpoint methodology.

SNC has performed an analysis to determine the Allowable Value setpoint for SR 3.3.5.2 using the plant specific setpoint methodology. This methodology was submitted to the NRC (Reference 2) and reviewed by the NRC (Reference 3). The uncertainty methodology is based on the square root of the sum of the square method (SRSS).

The Allowable Value is established by considering the terms associated with rack effects only and applies only to TS reactor protection or ESF actuation functions, which include the diesel generator start functions. The Allowable Value is performance based and serves as an operability limit for the purpose of the Channel Operational Tests. The Allowable Value allows for deviation of the "as found" setting from the Nominal Trip Setpoint during calibration. The magnitude of the Allowable Value accounts for a two-sided rack calibration accuracy (RCA) and rack drift from the most conservative allowed "as left" setting during calibration. A bistable trip setpoint found non-conservative with respect to the Allowable Value requires appropriate action by plant operating personnel.

The Allowable Value is determined by adding (or subtracting) the RCA of the device tested during the Channel Operational Test to the Nominal Trip Setpoint in the non-conservative direction (i.e., toward or closer to the Safety Analysis Limit) for the application.

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Basis for Proposed Changes The Nominal Trip Setpoint was previously calculated and is contained in SR 3.3.5.2. The Nominal Trip Setpoint is not being changed by this request. The calculation for the Allowable Value is shown below using the Nominal Trip Setpoint values from the TS.

TS Allowable Value for Loss of Voltage > [Nominal Trip Setpoint - (RCA X span voltagepri]

> [2975 VAC - [0.0032 x 5250 VAC)]

> 2958.2 VAC TS Allowable Value for Degraded Voltage > [Nominal Trip Setpoint - (RCA X span voltagepri]

> [3746 VAC - [0.0032 x 5250 VAC)]

> 3729.2 VAC The RCA is the Combined Rack Calibration Accuracy. This is based on the accuracy of the modules that make up the rack.

The voltage to current (E/I) module and the analog to digital (A/D) module provide the uncertainties that are used to calculate the RCA. The Square Root Sum of the Squares method was used to determine the RCA. This is acceptable because the E/I module and A/D module were supplied from separate vendors and are statistically independent. The percent uncertainty for the rack calibration is calculated as shown below.

RCA = [E/I module2 % + A/D module2 % + bistable2 %]1/2 Where:

E/I module = 0.25 - supplied by the module vendor, Dataforth A/D module = 0.20 - supplied by the module vendor, ABB Bistable = 0 - since the number of software bits utilized to implement its setpoints is such that its error is negligible compared to the rest of the channel Therefore, RCA = [0.252% + 0.202% + 0%]1/2 = 0.32%

The Allowable Values calculated above are requested to be incorporated in the TS in place of the current Allowable Value.

4.0 REGULATORY EVALUATION

4.1 Applicable Regulatory Requirements/Criteria Criterion 13, "Instrumentation and Control," of Appendix A, "General Design Criteria for Nuclear Power Plants," to 10 CFR Part 50, "Domestic Licensing of Production and Utilization Facilities,"

requires, among other things, that instrumentation be provided to monitor variables and systems and that controls be provided to maintain these variables and systems within prescribed operating ranges. Instrumentation and controls are provided to monitor and control neutron flux, control rod position, fluid temperatures, pressures, flows, and levels, as necessary, to assure that adequate plant safety can be maintained. Instrumentation is provided in the reactor coolant system, steam and power conversion system, containment, engineered safety features systems, radioactive waste management systems, and other auxiliary systems.

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Basis for Proposed Changes Criterion 20, "Protection System Functions," of Appendix A to 10 CFR Part 50 requires, among other things, that the protection system be designed to initiate operation of appropriate systems to ensure that specified acceptable fuel design limits are not exceeded. A fully automatic protection system with appropriate redundant channels is provided to cope with transient events where insufficient time is available for manual corrective action. The ESF actuation system automatically initiates emergency core cooling and other safety functions by sensing accident conditions, using redundant analog channels measuring diverse variables.

Paragraph (c)(1)(ii)(A) of § 50.36, "Technical Specifications," of 10 CFR Part 50 requires, in part, that, where a limiting safety system setting is specified for a variable on which a safety limit has been placed, the setting be so chosen that automatic protective action will correct the abnormal situation before a safety limit is exceeded. The safety analysis establishes an Analytical Limit in terms of a measured or calculated variable and a specific time after that value is reached to begin protective action. Satisfying these two constraints will ensure that the safety limit in 10 CFR 50.36 will not be exceeded during anticipated operational occurrences and design-basis events. The purpose of an LSSS is to assure that protective action is initiated before the process conditions reach the Analytical Limit, thereby limiting the consequences of a design-basis event to those predicted by the safety analyses. The LSSS is derived from the Analytical Limit in a manner determined by the setpoint calculation methodology. The LSSS may be the allowable value.

4.2 Precedent No identical precedent was identified.

4.3 No Significant Hazard Consideration Determination Analysis Southern Nuclear Operating Company (SNC) has evaluated the proposed changes to the Technical Specifications (TS) using the criteria in 10 CFR 50.92 and has determined that the proposed changes do not involve a significant hazards consideration.

The proposed changes revise TS 3.3.5, Loss of Power (LOP) Instrumentation, Surveillance Requirement (SR) 3.3.5.2 Allowable Values by replacing the existing Allowable Values for the loss of voltage and degraded voltage setpoints in SR 3.3.5.2. The values are revised to provide appropriately conservative setpoints to ensure that the affected equipment will perform its safety function as designed.

As required by 10 CFR 50.91(a), the SNC analysis of the issue of no significant hazards consideration is presented below:

1. Does the proposed change involve a significant increase in the probability or consequences of an accident previously evaluated?

Response: No The proposed change to the LOP functions allow the protection scheme to function as originally designed. The proposed change involves a change to the Allowable Values stated in TS SR 3.3.5.2. The proposed change does not affect the probability or consequences of any accident. Analysis was performed to determine appropriately conservative Allowable Values for the loss of voltage function and the degraded voltage function. Use of the calculated Allowable Values ensures that automatic protective action will correct the E-5

Basis for Proposed Changes abnormal situation before a safety limit is exceeded. Therefore, the diesel generators started by these loss of power functions will perform their design basis function should a loss-of-offsite power or degraded offsite power event occur with or without a concurrent accident.

The proposed changes do not adversely affect accident initiators or precursors, and do not alter the design assumptions, conditions, or configuration of the plant or the manner in which the plant is operated or maintained. The proposed changes ensure that the 4.16kV distribution system remains connected to the offsite power system when adequate offsite voltage is available.

Therefore, the proposed changes do not involve a significant increase in the probability or consequences of an accident previously evaluated.

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

Response: No The change does not involve a physical alteration of the plant (i.e., no new or different type of equipment will be installed) or a change in the methods governing normal plant operation.

The change does not alter assumptions made in the safety analysis but ensures that the diesel generator operates as assumed in the accident analysis. The proposed change is consistent with the safety analysis assumptions. Therefore, the proposed change does not create the possibility of a new or different kind of accident from any accident previously evaluated.

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

Response: No The proposed changes to the loss of voltage and degraded voltage Allowable Values continue to provide margin for the protection of equipment from loss of power and degraded voltage conditions. During an actual loss of power or degraded voltage condition, the revised Allowable Values ensure that automatic protective action will correct the abnormal situation before a safety limit is exceeded. Therefore, the proposed change does not involve a significant reduction in a margin of safety.

4.4 Conclusion In conclusion, based on the considerations discussed above, SNC concludes: (1) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner, (2) such activities will be conducted in compliance with the Commissions regulations, and (3) the issuance of the amendment will not be inimical to the common defense and security or the health and safety of the public.

5.0 ENVIRONMENTAL CONSIDERATION

The proposed change would change a requirement with respect to installation or use of a facility component located within the restricted area, as defined in 10 CFR Part 20, and would change an inspection or surveillance requirement. However, the proposed change does not involve (i) a significant hazards consideration, (ii) a significant change in the types or significant increase in E-6

Basis for Proposed Changes the amounts of any effluent that may be released offsite, or (iii) a significant increase in individual or cumulative occupational radiation exposure. Accordingly, the proposed change meets the eligibility criterion for categorical exclusion set forth in 10 CFR 51.22(c)(9). Therefore, pursuant to 10 CFR 51.22(b), no environmental impact statement or environmental assessment need be prepared in connection with the proposed change. Accordingly, the amendment meets the eligibility criteria for categorical exclusion set forth in 10 CFR 51.22(c)(9). Pursuant to 10 CFR 51.22(b), no environmental impact statement or environmental assessment need be prepared in connection with the issuance of the amendment.

6.0 REFERENCES

1. NRC Regulatory Guide 1.239, Licensee Actions to Address Non-Conservative Technical Specifications, November 2020

2. Letter from SNC to NRC, dated August 12, 2011, NRC Request for Additional Information for License Amendment Request for Steam Generator Water Level High-High (P-14) Setpoint Change (ML11228A119)

3. Letter from NRC to SNC, dated February 27, 2012, Issuance of Amendments Regarding Steam Generator Water Level High-High Technical Specification, Table 3.3.1-1 and Table 3.3.2-1 Setpoint Changes (ML12033A126)

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Vogtle Electric Generating Plant - Units 1 and 2 Revise Technical Specification Surveillance Requirement 3.3.5.2 Allowable Values Attachment 1 Proposed Technical Specification Changes (Marked-up Pages)

LOP Instrumentation 3.3.5 ACTIONS (continued)

CONDITION REQUIRED ACTION COMPLETION TIME D. Required Actions and D.1 Be in MODE 3. 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> associated Completion Times not met in MODES AND 1, 2, 3, or 4.

D.2 Be in MODE 5. 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br /> E. Required Action and E.1 Enter applicable Immediately associated Completion Condition(s) and Time not met when the Required Action(s) for the associated DG is associated DG made required OPERABLE by inoperable by LOP DG LCO 3.8.2. start instrumentation.

SURVEILLANCE REQUIREMENTS SURVEILLANCE FREQUENCY SR 3.3.5.1 Perform COT. In accordance with the Surveillance Frequency Control Program SR 3.3.5.2 Perform CHANNEL CALIBRATION with Nominal Trip In accordance with Setpoint and Allowable Value as follows: the Surveillance Frequency Control A. Loss of voltage Allowable Value 2912 2958.2 Program V with a time delay of 0.8 second.

Loss of voltage Nominal Trip Setpoint 2975 V with a time delay of 0.8 second.

B. Degraded voltage Allowable Value 3683 3729.2 V with a time delay of 20 seconds.

Degraded voltage Nominal Trip Setpoint 3746 V with a time delay of 20 seconds.

(continued)

Vogtle Units 1 and 2 3.3.5-2 Amendment No. 158 (Unit 1)

Amendment No. 140 (Unit 2)

Vogtle Electric Generating Plant - Units 1 and 2 Revise Technical Specification Surveillance Requirement 3.3.5.2 Allowable Values Attachment 2 Revised Technical Specification Pages

LOP Instrumentation 3.3.5 ACTIONS (continued)

CONDITION REQUIRED ACTION COMPLETION TIME D. Required Actions and D.1 Be in MODE 3. 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> associated Completion Times not met in MODES AND 1, 2, 3, or 4.

D.2 Be in MODE 5. 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br /> E. Required Action and E.1 Enter applicable Immediately associated Completion Condition(s) and Time not met when the Required Action(s) for the associated DG is associated DG made required OPERABLE by inoperable by LOP DG LCO 3.8.2. start instrumentation.

SURVEILLANCE REQUIREMENTS SURVEILLANCE FREQUENCY SR 3.3.5.1 Perform COT. In accordance with the Surveillance Frequency Control Program SR 3.3.5.2 Perform CHANNEL CALIBRATION with Nominal Trip In accordance with Setpoint and Allowable Value as follows: the Surveillance Frequency Control A. Loss of voltage Allowable Value 2958.2 V Program with a time delay of 0.8 second.

Loss of voltage Nominal Trip Setpoint 2975 V with a time delay of 0.8 second.

B. Degraded voltage Allowable Value 3729.2 V with a time delay of 20 seconds.

Degraded voltage Nominal Trip Setpoint 3746 V with a time delay of 20 seconds.

(continued)

Vogtle Units 1 and 2 3.3.5-2 Amendment No. (Unit 1)

Amendment No. (Unit 2)

Vogtle Electric Generating Plant - Units 1 and 2 Revise Technical Specification Surveillance Requirement 3.3.5.2 Allowable Values Attachment 3 Proposed Technical Specification Bases Changes (Mark-Up) for Information Only

LOP DG Start Instrumentation B 3.3.5 BASES BACKGROUND Trip Setpoints and Allowable Values (continued)

The Trip Setpoints used in the bistables are based on the analytical limits used in the load flow calculations for each Unit. presented in FSAR, Chapter 15 (Ref. 2). These analytical limits have been incorporated into SR 3.3.5.2 as the Allowable Values. The selection of the Trip Setpoints is such that adequate protection is provided when all sensor and processing time delays are taken into account.

The Allowable Values (AV) allow for deviation of the as found setting from the Nominal Trip Setpoint during testing, and serves as an operability limit for the purpose of the Channel Operational Test (COT). The magnitude of the AV is determined using specified allowances for rack calibration accuracy and rack drift.

APPLICABLE The LOP DG start instrumentation is required for the ESF SAFETY ANALYSES Systems to function in any accident with a loss of offsite power. Its design basis is that of the ESFAS.

(continued)

Vogtle Units 1 and 2 B 3.3.5-2 Rev. 1-3/00

LOP DG Start Instrumentation B 3.3.5 BASES ACTIONS E.1 (continued) required to be entered immediately. The actions of this LCO provide for adequate compensatory actions to support unit safety.

SURVEILLANCE SR 3.3.5.1 REQUIREMENTS SR 3.3.5.1 is the performance of a COT. A COT is performed on each required channel to ensure the entire channel will perform the intended Function. There is a plant specific program which verifies that the instrument channel functions as required by verifying the as-left and as-found setting are consistent with those established by the setpoint methodology. The Surveillance Frequency is controlled under the Surveillance Frequency Control Program.

SR 3.3.5.2 SR 3.3.5.2 is the performance of a CHANNEL CALIBRATION. The Nominal Trip Setpoint considers factors that may affect channel performance such as rack drift, etc. Therefore, the Nominal Trip Setpoint (within the calibration tolerance) is the expected value for the CHANNEL CALIBRATION. However, the Allowable Value is the value that was used for the loss of voltage and degraded grid studies.

Therefore, aA channel with an actual Trip Setpoint value that is conservative with respect to the Allowable Value is considered OPERABLE; but the channel should be reset to the Nominal Trip Setpoint value (within the calibration tolerance) to allow for factors which may affect channel performance (such as rack drift) prior to the next surveillance.

The setpoints, as well as the response to a loss of voltage and a degraded voltage test, shall include a single point verification that the trip occurs within the required time delay.

CHANNEL CALIBRATION is a complete check of the instrument loop, including the sensor. The test verifies that the channel responds to a measured parameter within the necessary range and accuracy.

There is a plant specific program which verifies that the instrument channel functions as required by verifying the as-left and as-found setting are consistent with those established by the setpoint methodology.

The Surveillance Frequency is controlled under the Surveillance Frequency Control Program.

Vogtle Units 1 and 2 B 3.3.5-8 REVISION 26