Text

Southern Nuclear Operating Co., 60-Day Response to Generic Letter 2006-02, Grid Reliability and Impact on Plant Risk and the Operability of Offsite Power
	ML060900618
Person / Time
Site:	Hatch, Vogtle, Farley
Issue date:	03/31/2006
From:	Sumner H; Southern Nuclear Operating Co
To:	; Document Control Desk, Office of Nuclear Reactor Regulation
References
	GL-06-002, NL-06-0540
	Download: ML060900618 (86)
	v • d • e

H. 1. Sumner, Jr. Southern Nuclear Vice President Operating Company, Inc.

Hatch Project Post Office Box 1295 Birmingham, Alabama 35201 March 31, 2006 SOUTHERN COMPANY A

Energy to Serve YourWorld Docket Nos.: 50-321 50-348 50-424 50-366 50-364 50-425 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D. C. 20555-000 1 Edwin I. Hatch Nuclear Plant Joseph M. Farley Nuclear Plant Vogtle Electric Generating Plant Southern Nuclear Operating Company 60-Day Response to Generic Letter 2006-02 Grid Reliability and Impact on Plant Risk and the O~erabilityof Offsite Power Ladies and Gentlemen:

On February 1, 2006, the Nuclear Regulatory Commission (NRC) issued Generic Letter 2006-02. The NRC required that written responses be submitted within 60 days of this date and that responses be submitted in accordance with 10CFR50.54(f).

Attached are three enclosures, one for each of the three Southern Nuclear Operating Company (SNC) sites. These enclosures provide the SNC 60-day response to GL 2006-02 for Hatch Nuclear Plant (HNP) (Enclosure l), Farley Nuclear Plant (FNP)

(Enclosure 2), and Vogtle Electric Generating Plant (VEGP) (Enclosure 3).

SNC does not have first hand knowledge of the operation of the Southern Company transmission grid beyond the protocols, procedures and agreements described in the enclosures and has relied on Southern Company Transmission for the information contained in the attached enclosures regarding analyses, procedures, and activities concerning grid operations.

(Affirmation and signature are on the following page.)

U. S. Nuclear Regulatory Commission NL-06-0540 Page 2 Mr. H. L. Sumner, Jr. states he is a Vice President of Southern Nuclear Operating Company, is authorized to execute this oath on behalf of Southern Nuclear Operating Company and to the best of his knowledge and belief, the facts set forth in this letter are true.

This letter contains no NRC commitments. If you have any questions, please advise.

Respectfully submitted, SOUTHERN NUCLEAR OPERATING COMPANY sL$%,-

A oi&

H. L. Sumner, Jr.

Enclosures:

Appendix A - Abbreviations

~ p p e n d i xB - Description of Southern Company and the Electrical Grid

1. Edwin I. Hatch Nuclear Plant 60-day Response

2. Joseph M. Farley Nuclear Plant 60-day Response

3. Vogtle Electric Generating Plant 60-day Response cc: Southern Nuclear Operating Comvany Mr. J. T. Gasser, Executive Vice President Mr. L. M. Stinson, Vice President - Plant Farley Mr. D. E. Grissette., Vice President - Plant Vogtle Mr. J. R. Johnson, General Manager - Plant Farley Mr. D. R. Madison, General Manager - Plant Hatch Mr. T. E. Tynan, General Manager - Plant Vogtle RType: CFA04.054; CHA02.004; CVC7000; LC# 14414 U. S. Nuclear Regulatory Commission Dr. W. D. Travers, Regional Administrator Mr. R. E. Martin, NRR Project Manager - Farley Mr. C. Gratton, NRR Project Manager - Hatch Mr. C. Gratton, NRR Project Manager - Vogtle Mr. C. A. Patterson, Senior Resident Inspector - Farley Mr. D. S. Simpkins, Senior Resident Inspector - Hatch Mr. G. J. McCoy, Senior Resident Inspector - Vogtle

Appendix A Edwin I. Hatch Nuclear Plant Joseph M. Farley Nuclear Plant Vogtle Electric Generating Plant Southern Nuclear Operating Company 60-Day Response to Generic Letter 2006-02 Grid Reliability and Impact on Plant Risk and the Operability of Offsite Power Abbreviations

Appendix A Abbreviations ACC Alabama Power Company Transmission Control Center (Birmingham)

AOP Abnormal Operating Procedure APC Alabama Power Company ARP Annunciator Response Procedure ATWS Anticipated Transient Without Scram BPO Bulk Power Operations CRD Control Rod Drive EDG Emergency Diesel Generator EOOS Equipment Out-of-Service Risk Tool EOP Emergency Operating Procedure FNP Joseph M. Farley Nuclear Plant FSAR Updated Final Safety Analysis Report GPC Georgia Power Company HNP Edwin I. Hatch Nuclear Plant LOCA Loss of Coolant Accident LOOP Loss of Offsite Power (also LOSP)

NERC North American Electric Reliability Council NTCC Northern Transmission Control Center (GPC, Atlanta)

PCC Power Control Center (SCT, Birmingham)

PQG Power Quality Guide RPS Reactor Protection System RTCA Real Time Contingency Analysis SCA Southern Control Area SCADA Supervisory Control and Data Acquisition SCT Southern Company Transmission SERC Southeastern Electric Reliability Council SNC Southern Nuclear Operating Company SOP System Operating Procedure STCC Southern Transmission Control Center (GPC, Valdosta)

TS Technical Specifications UOP Unit Operating Procedure VEGP Vogtle Electric Generating Plant TSO is used as an abbreviation that represents several entities which are part of Southern Company Transmission. These are known individually as Bulk Power Operations (BPO), which includes the PCC (Power Control Center, located in Birmingham, Al.); ACC (Alabama Power Company Transmission Control Center located in Birmingham, Al.); NTCC (Georgia Power Company Northern Transmission Control Center, located in Atlanta, Ga.); and STCC, (Georgia Power Company Southern Transmission Control Center, located in Valdosta, Ga.).

A brief description of the Southern Company Grid is located in Appendix B.

Appendix B Edwin I. Hatch Nuclear Plant Joseph M. Farley Nuclear Plant Vogtle Electric Generating Plant Southern Nuclear Operating Company 60-Day Response to Generic Letter 2006-02 Grid Reliability and Impact on Plant Risk and the Operability of Offsite Power Description of Southern Company and the Electrical Grid

Appendix B Description of Southern Company and the Electrical Grid The Southern Company transmission grid can be briefly described as follows:

Southern Company is a vertically integrated electric utility consisting of five operating companies: Alabama Power Co. (APC), Georgia Power Co. (GPC), Gulf Power Company, Mississippi Power Company, Savannah Electric and Power Co, and Southern Power (an electric wholesale subsidiary). Other entities within Southern Company include Southern Nuclear Operating Company (SNC), which operates and provides technical support to the nuclear plants within Southern Company; Southern Company Generation, which operates and provides technical support to the fossil and hydro plants within Southern Company; and Southern Company Services, Inc. which provides engineering and other common services for all Southern companies, including Transmission Planning and Bulk Power Operations (BPO).

The individual operating companies own the generation and transmission assets within the Southern Company, including the nuclear facilities. Farley Nuclear Plant (FNP) is owned by APC while Hatch Nuclear Plant (HNP) and Vogtle Electric Generating Plant (VEGP) are owned by GPC (along with co-owners), but all are operated by SNC.

Similarly, the electrical transmission assets owned by the operating companies within the Southern Control Area (SCA), as well as assets within the Integrated Transmission System in the state of Georgia that are co-owned by GPC and other non-Southern entities, are operated by Southern Company Transmission (SCT), a division of the Southern Company. The SCA is located within (and via the operating companies is a member of) the Southeastern Electric Reliability Council (SERC), one of the regional coordinating councils within the North American Electric Reliability Council (NERC).

The SNC-operated nuclear plants are connected to the SCA. The SCA is operated by the BPO organization within SCT. The BPO control center is called the Power Coordination Center (PCC) and is located in Birmingham, Alabama. SCT is thus the Transmission Service Operator (TSO) for Southern Company and the SCA and will be designated as the TSO for the remainder of this response.

GPC and APC have agreements with the TSO for the operation of transmission facilities interconnected with FNP, HNP & VEGP. The agreement between the operating companies and the TSO is implemented by TSO operating procedures. These procedures and agreements include explicit and detailed responsibilities for offsite power supply to the nuclear plants. The TSO is required to maintain an assured source of offsite power, to monitor nuclear plant voltages, and to notify nuclear plant personnel prior to any significant grid changes. SNC has provided the TSO with power quality guides for each of the nuclear plants that specify the detailed voltage and other requirements specific to each plant. Each plant also has detailed coordination agreements and procedures in place with the local transmission maintenance organizations within the TSO to ensure proper coordination of transmission maintenance activities at all levels.

Enclosure 1 Edwin I. Hatch Nuclear Plant Southern Nuclear Operating Company 60-Day Response to Generic Letter 2006-02 Grid Reliability and Impact on Plant Risk and the Operability of Offsite Power

HNP Response to GL 2006-02 Requested Information Use of protocols between the NPP licensee and the TSO, ISO, or RC/RA and the use of analysis tools by TSOs to assist NPP licensee in monitoring grid conditions to determine the operability of offsite power systems under plant Technical Specifications.

GDC 17, 10 CFR Part 50, Appendix A, requires that licensees minimize the probability of the loss of power from the transmission network given a loss of the power generated by the nuclear power unit(s).

1. Use of protocols between the NPP licensee and the TSO, ISO, or RC/RA to assist the NPP licensee in monitoring grid conditions to determine the operability of offsite power systems under plant Technical Specifications.

(a) Do you have a formal agreement or protocol Yes. HNP does have a formal agreement with the TSO. This agreement is implemented with your TSO? by applicable procedures and guidelines.

(b) Describe any grid conditions that would Normal day to day operational communications between the TSO and HNP are the same trigger a notification from the TSO to the NPP as those for other generating plants and are associated with topics such as: work licensee and if there is a time period required for coordination, switching, generation dispatch, and planning.

the notification TSO procedures require timely notification to HNP if any of the conditions noted below exist:

1. System real time contingency analysis (RTCA) tools will be unavailable for > 8 hours9.259259e-5 days 0.00222 hours 1.322751e-5 weeks 3.044e-6 months under normal conditions or >1 hour during severe weather or abnormal system conditions.

2. The RTCA tools predict a next contingency low voltage or system stability alarm condition.

3. Actual low voltage observed in the HNP switchyard.

4. Identification of common and plant specific abnormal weather conditions that could lead to violation of plant specific requirements as listed in plant power quality guides.

5. Other notifications to nuclear plants would be issued as they would be for all other generating plants as required for reliable, safe system operations.

In addition, the TSO has guidance for different levels of system alerts and will notify all generating plants for any conditions that could adversely affect system reliability. If one of the 230KV or 500KV lines feeding HNP trips, the TSO would contact the Control Room. HNP has annunciation in the Control Room for all breakers in the HNP switchyard.

HNP Response to GL 2006-02Requested Information (c) Describe any grid conditions that would The TSO is notified by HNP for any of the following conditions:

cause the NPP licensee to contact the TSO.

1. Main generator VR in manual, and voltage cannot be maintained within limits Describe the procedures associated with such a 2. Unit offline communication. If you do not have procedures, 3. Panel breaker and bus alarms for 2301500KV switchyard describe how you assess grid conditions that may 4. Panel alarms for emergency bus low voltage cause the NPP licensee to contact the TSO. 5. Adverse weather conditions

6. Degraded 4KV bus voltage conditions

7. Security threavattack

8. Airborne security threavattack

9. Loss of metering Anytime a low bus voltage annunciator is received on a 4KV bus, a check is made of the 230KV and 500KV bus voltages. A notification is made to the TSO of the present condition with a request to raise system voltage.

(d) Describe how NPP operators are trained and HNP operators are trained and subject to testing on the following:

tested on the use of the procedures or assessing grid conditions in question l(c). 1. Main generator VR in manual, and voltage cannot be maintained within limits

2. Unit offline

3. Panel breaker and bus alarms for 2301500KV switchyard

4. Panel alarms for emergency bus low voltage

5. Adverse weather conditions

6. Degraded 4KV bus voltage conditions

7. Security threavattack

8. Airborne security threavattack

9. Loss of metering

HNP Response to GL 2006-02 Requested Information (e) If you do not have a formal agreement or HNP does have a formal agreement with the TSO; thus, this question is not applicable.

protocol with your TSO, describe why you GDC compliance was established in the NRC SER dated February 23,1995 (TAC No.

believe you continue to comply with the M80948).

provisions of GDC 17 as stated above, or describe what actions you intend to take to assure compliance with GDC 17.

(f) If you have an existing formal interconnection As previously stated, HNP does have a formal agreement with the TSO. The TSO is agreement or protocol that ensures adequate responsible for monitoring the transmission system around each plant to ensure that communication and coordination between the under any single contingency, sufficient power is available at all times to enact a safe and NPP licensee and the TSO, describe whether this controlled shutdown of the plant. Timely notification regarding pre-trip analysis of agreement or protocol requires that you be predicted post-trip voltage that results in below acceptance limits is included. HNP has promptly notified when the conditions of the guidelines to implement these communications.

surrounding grid could result in demaded voltage (i.e., below TS nominal trip setpoint value requirements; including NPP licensees using allowable value in its TSs) or LOOP after a trip of the reactor unit(s).

p)Describe the low switchyard voltage The TSO is capable of monitoring a number of different points in the low voltage conditions that would initiate operation of plant switchyard (230KV) and maintains the voltage levels between 101.3% and 104.9% of degraded voltage protection. 230KV. The TSO has an energy management system that will display alarms to the TSO operators if voltages on the 230KV busses are above or below the required voltages. The low voltage requirement of 101.3% (233KV) provides a 4KV bus voltage well above even the 4KV low voltage anticipatory alarm setpoints.

Plant operators monitor both 230KV and 4160V voltages. If the 4160V voltage dips below 2800V (called loss of voltage setpoint) for greater than 6.5 seconds, operation of the plant loss of voltage protection devices would be initiated. Also, if plant voltage 1 dipped below 3280V (called degraded voltage setpoint) for greater than 21.5 seconds, operation of the plant degraded voltage protection devices would be initiated. If the plant voltage dips below 3825V (called emergency bus undervoltage) for greater than 65 seconds, an anticipatory alarm is received. The alarms actuate when the 4160V bus voltages approach the minimum required voltage for normal; i.e., non-LOCA conditions.

This ensures that manual actions will be initiated to restore the bus voltages or to initiate a ~ l a nshutdown.

t

HNP Response to GL 2006-02 Requested Information

2. Use of criteria and methodologies to assess whether the offsite power system will become inoperable as a result of a trip of your NPP.

(a) Does your NPP's TSO use any analvsis tools, According to RIS 2005-20, the term 'Operable/Operability' is defined in the Technical an online analytical transmission system studies Specifications and applied ONLY to TS Structures, Systems, or Components (SSCs).

program, or other equivalent predictive methods Thus, the transmission grid cannot be referred to as 'operable' or 'inoperable', because to determine the grid conditions that would make the grid is not a TS SSC. Everything that is non-TS is referred to as Functional or non-the NPP offsite power system inoperable during Functional.

various contingencies? The TSO makes use of analysis tools to predict grid conditions that would impact the If available to you, please provide a brief HNP offsite power supply. The tools presently used by the TSO to manage the grid description of the analysis tool that is used by the programs, control the transmission related activities, and monitor grid actions are outside TSO. the control of the HNP and include the following:

1 - a grid SCADA system and state estimator 2 - a fully commissioned real-time contingency analysis (RTCA) program in conjunction with periodic studies of all single outages and a reasonable set of multiple contingencies specifically tailored for HNP worst case conditions 3 - a voltage stability analysis program 4 - a near real time dynamic stability analysis program 5 - bounding analyses produced by transmission planning studies The real time contingency analysis package utilized by TSO includes monitoring /

predictive analysis computer programs that can predict HNP switchyard voltages expected to occur upon realization of any single contingencies and a number of possible multiple contingencies on the grid, such as:

(1) - a trip of the HNP generator(s), (2)- a trip of another large generator(s), or (3) - the loss of an important transmission line.

Monitoring / predictive analysis computer program tools operate based on raw data from transducers across the system that is processed through a state estimator to generate a current state snapshot of the system. This output is then processed through a contingency analysis program that generates a set of new results with all single elements of the system out of service and a predefined set of multiple contingencies. These results are then screened against a predetermined set of acceptance limits. Postulated scenarios which then do not meet the acceptance limits are alarmed for review by TSO operators.

HNP Response to GL 2006-02 Requested Information (b) Does your NPP's TSO use an analysis tool as Yes. The TSO uses the above analysis tools, in conjunction with procedures, as the basis the basis for notifying the NPP licensee when for determining when conditions warrant HNP notification. Notifications are made such a condition is identified? If not, how does based on grid conditions being outside of predefined procedure requirements under real the TSO determine if conditions on the grid time or first contingency conditions or based on unavailability of computer program tools warrant NPP licensee notification? and contingency analyses. Conditions impacting HNP offsite power supplies that are identified by the contingency analysis, EMS monitoring, or other means are promptly communicated to HNP.

(c) If your TSO uses an analysis tool, would the Yes. Procedures and monitoring I predictive analysis tools are in place for both planning analysis tool identify a condition in which a trip and real time environments. The TSO analysis tools, in conjunction with HNP plant of the NPP would result in switchyard voltages analysis, identify conditions which would result in 230KV voltages below 233KV or (immediate andlor long-term) falling below TS above 240.3 KV. TSO System operators are trained on the required bus voltage nominal trip setpoint value requirements requirements at HNP and will respond appropriately if either actual system voltages or (including NPP licensees using allowable value post-contingency voltages violate HNP requirements.

in its TSS)and consequent actuation of plant degraded voltage If not, discuss how such a condition would be identified on the grid.

(d) If your TSO uses an analysis tool, how The state estimator and contingency analysis application tools run continuously with frequently does the analysis tool program each new case taking approximately five minutes to solve.

update?

(e) Provide details of analysis tool-identified The notification from the TSO is based upon either actual switchyard voltages or RTCA contingency conditions that would trigger an grid conditions. RTCA grid conditions are based upon the predicted post-trip NPP licensee notification from the TSO. contingency switchyard voltages given any single element of the system out of service or a predefined set of multiple contingency conditions.

The following contingencies were identified from a recent system-wide steady-state and dynamic stability analyses as being the most limiting cases for both the nuclear plants and for the overall grid system:

HNP Response to GL 2006-02 Requested Information Hatch 1 Hatch -Duval500KV Hatch 2 Thalmann-Duval500KV Vogtle 1 N. Tifton-Farley 500KV Vogtle 2 S. Bainbridge-Farley 230KV Farley 1 Pinckard 23011 15KV Banks #I Farley 2 and #2 Farley 1 and Farley 5001230KV Bank Webb 23011 15KV If the HNP voltage requirement cannot be met under any of the contingencies considered, HNP will be notified. The same minimum required switchyard voltage limit bases that are used in the grid operating procedures are also used in the predictive analysis computer programs. In addition, the TSO also runs a full N-1 contingency analysis which would identify the loss of any single line or bus anywhere in the system which would result in the voltage at the HNP bus dropping below the minimum requirements or rising above the maximum requirements.

(f) If an interface agreement exists between the Yes. As described above, TSO procedures and the HNP power quality guide require TSO and the NPP licensee, does it require that notification to HNP if the RTCA program will be out of service for more than 8 hours9.259259e-5 days 0.00222 hours 1.322751e-5 weeks 3.044e-6 months the NPP licensee be notified of periods when the during normal system conditions or f;lr more than 1 hour1.157407e-5 days 2.777778e-4 hours 1.653439e-6 weeks 3.805e-7 months if bad weather conditions exist.

TSO is unable to determine if offsite power Upon notification that the tools are unavailable to the TSO, actions to minimize load voltage and capacity could be inadequate? swings at HNP are started.

If so, how does the NPP licensee determine that Existing requirements for operability of the offsite power supplies as stated in GDC 17 the offsite power would remain operable when and NUREG 0800 require that "results of the grid stability analysis indicate (d) that the such a notification is received? loss of the largest generating capacity being supplied from the grid, loss of the most critical transmission line, or loss of the unit itself will not cause grid instability." This does not require that a continuous analysis be performed to demonstrate grid stability exists.

TSO current practice is to perform a yearly grid stability analysis to ensure that this requirement is met, given changes and improvements to the Southern Company transmission grid. The actions described in response to notification that on-line tools are unavailable are intended to assist the grid operator in maintaining stable circumstances and to inform the HNP operating staff, but are not a factor in determining functionality of offsite vower sources.

HNP Response to GL 2006-02 Requested Information (g) After an unscheduled inadvertent trip of the No. For post event analysis, the TSO does not verify by procedure the switchyard NPP, are the resultant switchyard voltages voltages are bounded by the analysis tools. Nonetheless, such analyses have been verified by procedure to be bounded by the performed on a case by case basis to validate predicted results. Also, the system operator voltages predicted by the analysis tool? monitors both actual conditions and contingency (predictions) values and identifies problems found. At HNP, the switchyard voltages are currently not specifically required to be examined or recorded by the post-trip procedures. Hourly electrical rounds will record the switchyard voltage, but the voltage numbers are not sent to the TSO for evaluation of the actual vs. predicted voltages. Fault data recorders in the HNP switchyard are triggered by a unit trip, and would record the data, but there is currently no procedural action to retrieve this data.

(h) If an analysis tool is not available to the NPP Not applicable to HNP, since TSO analysis tools are presently in use.

licensee's TSO, do you know if there are any s the TSO to obtain one? If so. when?

~ l a n for (i) If an analysis tool is not available, does your Not applicable to HNP, since TSO analysis tools are presently in use.

TSO perform periodic studies to verify that adequate offsite power capability, including adequate NPP post-trip switchyard voltages (immediate and/or long-term), will be available to the NPP licensee over the projected timeframe of the study?

(a) Are the key assumptions and parameters of these periodic studies translated into TSO guidance to ensure that the transmission system is operated within the bounds of the analyses?

(b) If the bounds of the analyses are exceeded, does this condition trigger the notification

~rovisionsdiscussed in auestion 1 above?

HNP Response to GL 2006-02 Requested Information (i) If your TSO does not use, or you do not have According to RIS 2005-20, the term 'OperableIOperability' is defined in the Technical access to the results of an analysis tool, or your Specifications and applied ONLY to TS SSCs. Thus, the HNP transmission grid cannot TSO does not perform and make available to you be referred to as 'operable' or 'inoperable', because the grid is not a TS SSC. Everything periodic studies that determine the adequacy of that is non-TS is referred to as Functional or non-Functional.

offsite power capability, please describe why you believe you com~lywith the provisions of GDC Not applicable to HNP, since the TSO utilizes analysis tools and communicates the

-17 as stated above, or describe what applicable results / conclusions to the HNP.

compensatory actions you intend to take to ensure that the offsite power system will be See the response to Question 1(e) regarding compliance with GDC-17.

sufficiently reliable and remain operable with high probability following a trip of your NPP.

3. Use of criteria and methodologies to assess whether the NPP's offsite power system and safety-related components will remain operable when switchyard voltages are inadequate.

(a) If the TSO notifies the NPP operator that According to RIS 2005-20, the term 'OperableIOperability' is defined in the Technical Specifications and applied ONLY to TS SSCs. Thus, the HNP transmission grid cannot a trip of the NPP, or be referred to as 'operable' or 'inoperable', because the grid is not a TS SSC. Everything the loss of the most critical transmission line or that is non-TS is referred to as Functional or non-Functional.

the largest supply to the grid The requirements for switchyard voltages are not directly contained in the HNP TSs, but would result in switchyard voltages (immediate are in Section 8.2.1 of the Hatch Unit 2 FSAR. The normal offsite operating voltage and/or long-term) below TS nominal trip setpoint range is 101.3% to 104.9% of 230KV. The switchyard minimum voltage requirements value requirements (including NPP licensees are well above emergency bus degraded voltage relays. In addition, HNP has installed a using allowable value in its TSs) set of low voltage alarm relays that actuate above the analyzed minimum 4KV bus voltages. HNP TS require that 4KV busses be declared inoperable if actual low voltage and anticipatory alarms are received and do not clear within a specified time frame, and this is discussed in the HNP SER dated 02/23/1995.

would actuate plant degraded voltage protection, As described in the HNP SER response, the TSO begins to take actions upon receiving is the NPP offsite power system declared low switchyard voltage alarms. In addition, there are prescribed actions for the HNP inowrable under the plant TSs? If not, why not? operators to take if the required switchyard voltage cannot be maintained. Actions include more frequent monitoring of the actual in-plant emergency bus voltages. There is no existing licensing requirement or commitment to enter an LC0 or declare any portion of the offsite power system inoperable solely because of projected or actual low switchyard voltages.

HNP Response to GL 2006-02 Requested Information (b) If onsite safety-related equipment (e.g., No. Double sequencing such as might occur as the result of a LOCA followed by a emergency diesel generators or safety-related delayed LOOP is not in the HNP licensing basis and HNP is not designed or analyzed for motors) is lost when subjected to a double a double sequencing scenario. The HNP licensing basis, as described in the bases of the sequencing (LOCA with delayed LOOP event) TS, is a LOCA coincident with a LOOP. If onsite safety related equipment is lost, as as a result of the anticipated system performance governed by the plant TS, then the equipment is declared inoperable.

and is incapable of performing its safety functions as a result of responding to an emergency actuation signal during this condition, is the equipment considered inoperable? If not, why not?

L (c) Describe your evaluation of onsite safety- Not applicable, beyond design basis and current licensing basis.

related equipment to determine whether it will operate as designed during the condition described in question 3(b).

(d) If the NPP licensee is notified by the TSO of HNP notifies the TSO in case of a credible threat to the facility that would potentially put other grid conditions that may impair the the tie to the offsite grid in jeopardy. TS are not entered, as described in 3(a) above, for capability or availability of offsite power, are grid conditions that might occur.

any plant TS action statements entered? If so, please identify them.

(e) If you believe your plant TSs do not require The Hatch SER dated 02/23/1995 (TAC No. M80948) contains an analysis of the actions you to declare your offsite power system or that would be taken as described in 3(a) and concluded that an acceptable method of safety-related equipment inoperable in =of complying with GDC 17 degraded voltage requirements existed. This method as these circumstances, explain why you believe described in the SER does not require that the offsite power source be declared you comply with the provisions of GDC 17 and inoperable.

your plant TSs, or describe what compensatory actions you intend to take to ensure that the offsite power system and safety-related components will remain operable when switchyard voltages are inadequate.

HNP Response to GL 2006-02 Requested Information (f) Describe if and how NPP operators are HNP operators are trained and subject to being tested on compensatory actions for trained and tested on the compensatory actions degraded grid conditions. Classroom and simulator training is provided. Procedure mentioned in your answers to questions 3(a) actions include minimizing activities that may have an impact of large load changes at through (e). the plant, returning inoperable emergency diesel generators to operable status, avoiding maintenance on critical on-site equipment, increased frequency of monitoring emergency bus voltages, initiating required actions if minimum voltages cannot be maintained, and initiating shutdown if minimum voltages not met within one hour.

4. Use of criteria and methodologies to assess whether the offsite power system will remain operable following a trip of your NPP.

(a) Do the NPP operators have anv midance or The HNP switchyard contains two capacitor banks for the 230KV system and two shunt procedures in plant TS bases sections, the final reactor banks for the 500KV system. None of these devices can be controlled from the safety analysis report, or plant procedures HNP control room; they are under the remote control of the PCC. The system operating regarding situations in which the condition of procedures for the generator regulator voltage controls have limitations intended to limit plant-controlled or -monitored equipment (e.g., the impact on grid reliability and on station service bus voltages. Operators are trained voltage regulators, auto tap changing and subject to testing on operation with the main generator voltage regulator in manual, transformers, capacitors, static VAR which includes notifying the TSO.

compensators, main generator voltage regulators) can adversely affect the operability of the NPP The TSO procedure for voltage schedules in the Southern Control Area (Southern offsite power system? If so, describe how the Company Bulk Power Operations Procedure BPO-1) specifies the requirements for the operators are trained and tested on the guidance HNP operators in conjunction with TSO operators to maintain the voltage schedule to and procedures. assist in maintaining the availability and reliability of the grid, and to ensure voltages are maintained within the band specified in the HNP Power Quality Guide.

(b) If your TS bases sections, the final safety The Hatch SER dated 02/23/1995 (TAC No. M80948) contains an analysis of the actions analysis report, and plant procedures do not that would be taken as described in 3(a) and concluded that an acceptable method of provide guidance regarding situations in which complying with GDC 17 degraded voltage requirements existed. This method as the condition of plant-controlled or -monitored described in the SER does not require that the offsite power source be declared equipment can adversely affect the operability of inoperable.

the NPP offsite power system, explain why you Also 4(a) discusses the guidance contained in plant procedures.

believe you comply with the provisions of GDC 17 and the plant TSs, or describe what actions you intend to take to provide such guidance or procedures.

HNP Response to GL 2006-02 Requested Information Use of NPP licenseeRSO protocols and analysis tool by TSOs to assist NPP licensees in monitoring grid conditions for consideration in maintenance risk assessments The Maintenance Rule (10 CFR 50.65(a)(4)) requires that licensees assess and manage the increase in risk that may result from proposed maintenance activities before ~erformingthem.

5. Performance of grid reliability evaluations as part of the maintenance risk assessments required by 10 CFR 50.65(a)(4).

(a) Is a quantitative or qualitative grid reliability I Yes. 10CFR 50.65(a)(4) requires performance of a risk assessment prior to maintenance evaluation performed at your NPP as part of the I activities. Maintenance is defined broadly and would include surveillances, post I maintenance risk assessment requiredby 10 CFR maintenance testing, and preventive and corrective maintenance. Relative t o increasing 50.65(a)(4) before performing grid-risk-sensitive the initiating event frequency, such as the frequency of a plant trip, the industry maintenance activities? This includes guidance, NUMARC 93-01, in Section 11.3.2.2., states that the following should be surveillances, post-maintenance testing, and considered:

preventive and corrective maintenance that could increase the probability of a plant trip or LOOP The likelihood of an initiating event or accident that would require the or impact LOOP or SBO coping capability, for performance of the affected safety function.

example, before taking a risk-significant piece of equipment (such as an EDG, a battery, a stearn- The likelihood that the maintenance activity will significantly increase the driven pump, an alternate AC power source) frequency of a risk-significant initiating event (e.g., by an order of magnitude or out-of-service? more as determined by each licensee, consistent with its obligation to manage maintenance-related risk).

The first bullet above is generally met by using the PRA and associated configuration risk management tools, which explicitly consider initiating event frequencies for transients and accidents. LOOP sequences are important elements of PRAs, and are thoroughly modeled and assessed during plant peer reviews. Risk management personnel are sensitized to the importance of these sequences.

The second bullet clarifies that if a maintenance activity is expected to increase initiating-event likelihood by an order of magnitude, then it should be considered in the assessment. Otherwise, the baseline initiating event frequencies may be used. These frequencies are based on generic data updated with plant specific data, and would take into account the plant specific LOOP and trip frequencies.

HNP Response to GL 2006-02 Requested Information Protocols require that any maintenance on the HNP 230KV and 500KV substations or maintenance on any substation that is one substation away be approved by the HNP Operations Shift Manager. Requests are processed through the designated individuals in the Daily Scheduling Department. These individuals must grant approval prior to allowing work to proceed. This process results in substation maintenance being identified on the daily work schedule and risk reviewed by a combination of quantitative and qualitative measures. This assures that the requested substation maintenance does not conflict with the planned plant maintenance or create an unknown or unanticipated increase in risk. Procedures contain guidance on performing qualitative assessments for determining the risk impact.

(b) Is grid status monitored by some means for Yes. NUMARC 93-01 does not define "grid-risk-sensitive maintenance", so there is no the duration of the grid-risk-sensitive unique guidance for such activities.

maintenance to c o n f m the continued validity of the risk assessment and is risk reassessed when Designated individuals in Daily Scheduling and a TSO representative review planned warranted? If not, how is the risk assessed switchyard activities on a weekly basis and each group provides daily updates for during grid-risk-sensitive maintenance? significant changes to the schedule and risk assessment as appropriate. In practice, scheduled switchyard activities are monitored by the designated individuals in Daily Scheduling on a daily basis to assure that work activities are progressing as scheduled and risk assessed as needed for both substation maintenance and plant maintenance activities.

(c) Is there a significant variation in the stress on Yes. Stress on the transmission grid as measured by loading in the Southern Control the grid in the vicinity of your NPP site caused Area (SCA) is seasonal with the peak loads typically occurring during the summer by months (typically June through August). The all time instantaneous peak load for the Southern Control Area of 44,167 MW occurred on July 26,2005. By contrast, the all seasonal loads time instantaneous peak load for winter of 39,192 MW that occurred on 1/24/2003 was roughly 89% of the summer peak. Shoulder periods in the fall and spring typically have or daily peak loads as low as 25,000 MW (roughly 57% of the all time peak) or less.

maintenance activities associated with critical transmission elements? Maintenance on generating plants and transmission equipment is also seasonal. It typically occurs during the shoulder months in spring and fall when control area loads Is there a seasonal variation (or the potential for are low and equipment can be removed from service without adversely impacting grid 12 of 20

HNP Response to GL 2006-02 Requested Information a seasonal variation) in the LOOP frequency in operations. All scheduled outages are registered with the TSO and examined under the local transmission region? contingency conditions to ensure they will not impact grid reliability prior to their occurrence. The transmission network is operated to maintain first contingency If the answer to either question is yes, discuss the conditions throughout all of these conditions and the TSO does not anticipate any time of year when the variations occur and their significant variation to the nuclear plant offsite power supply based on seasonal magnitude. variation.

Although these peak load and maintenance periods do stress the transmission grid, there is no time when the system is not operated in a reliable manner under first contingency criteria. HNP voltages and other critical parameters are monitored continuously during these periods to assure that no violation of Power Quality Guide requirements occur. All requirements of the protocols and other agreements between TSO and the HNP are met during peak load and maintenance periods in the same manner as they are at all other I times.

(d) Are known time-related variations in the The risk assessment for the purposes of 10CFR50.65(a)(4) does not vary the LOOP probability of a LOOP at your plant site frequency strictly as a function of "time-related" issues.

considered in the grid-risk-sensitive maintenance evaluation? If not, what is your basis for not Substation and switchyard activities are scheduled through Daily Scheduling as far in considering them? advance as possible and included as part of the long term schedule (cycle schedule), as well as the daily schedule. Along with substation activities, plant activities that have increased the potential for a unit or generator trip are also identified and risk assessed prior to the start of work. If concurrent work activities result in an increased level of risk (greater than green), then higher levels of plant management approval are required, up to the Plant Hatch General Manager.

To the extent possible, substation and switchyard activities are not scheduled during the same time frame with maintenance activities associated with the Emergency Diesel Generator, HPCI, RCIC, or safety-related electrical bus activities. Major system outages are assigned designated time frames and noted on the plant's cycle schedule. If conflicts arise between planned substation and switchyard activities and planned major system outages, one of the activities is rescheduled. Additionally, major substation and switchyard work activities are normally scheduled outside of summer peaks (May lSt through Sevtember 3 0 ~ .

HNP Response to GL 2006-02 Requested Information (e) Do you have contacts with the TSO to Yes. TSO relies on contingency analysis tools for evaluating requested transmission and determine cumnt and anticipated grid conditions generator scheduled outages. Typically, the TSO has the ability to take snapshots of the as part of the grid reliability evaluation state estimator program and use today's peak load snapshot to study tomorrow's performed before conducting grid-risk-sensitive requested outages. Obviously, the TSO can provide commentaries on grid conditions at maintenance activities? anytime maintenance tasks are underway. The same dynamic nature of loads and active generation make prediction of grid conditions days or weeks ahead of time uncertain; however, such studies form the base cases from which additional analyses are performed as updated information is received. Routine work related to activities performed in the substation and in the switchyard are scheduled through Daily Scheduling.

(0 Describe any formal agreement or protocol Notification occurs whether or not maintenance is on-going. The Power Quality Guide that you have with your TSO to assure that you lists criteria for notification in the event of degraded grid conditions.

are promptlv alerted to a worsening grid condition that may emerge a maintenance activity.

(g) Do you contact your TSO periodically for the Designated individuals in Daily Scheduling and a TSO representative review planned duration of the grid-risk-sensitive maintenance switchyard activities on a weekly basis and each group provides daily updates for activities? significant changes to the schedule as appropriate. In practice, scheduled switchyard activities are monitored by the designated individuals in Daily Scheduling on a daily basis to assure that work activities are progressing as scheduled and risk assessed as needed for both substation maintenance and plant maintenance activities.

(h) If you have a formal agreement or protocol HNP operators are trained and subject to being tested on pertinent aspects of the with your TSO, describe how NPP operators and agreements such as TSO notification of worsening grid conditions, switching orders, and maintenance personnel are trained and tested on scheduling of maintenance. Training addresses procedures associated with scheduling this formal agreement or protocol. maintenance, operation with degraded system voltage, and substation switching.

Work Week Coordinators are responsible for coordinating the scheduling of maintenance activities with the TSO. Coordinators are trained using a discussion guide in which topics are discussed with qualified Work Week Coordinators and the Scheduling Supervisor. Knowledge checks are conducted by the qualified Work Week Coordinator or Scheduling Supervisor during the discussions.

HNP Response to GL 2006-02 Requested Information (i) If your grid reliability evaluation, performed Not applicable. Per the discussion in 5@),routine discussions occur.

as part of the maintenance risk assessment required by 10 CFR 50.65(a)(4), does not consider or rely on some arrangement for communication with the TSO, explain why you believe you comply with 10 CFR 50.65(a)(4).

(j) If risk is not assessed (when warranted) based Not applicable. Per the discussion in 5@), routine discussions occur.

on continuing communication with the TSO throughout the duration of grid-risk-sensitive maintenance activities, explain why you believe you have effectively implemented the relevant provisions of the endorsed industry guidance associated with the maintenance rule.

(k) With respect to questions 5(i) and 5(j), you No alternative actions.

may, as an alternative, describe what actions you intend to take to ensure that the increase in risk that may result from proposed grid-risk-sensitive activities is assessed before and during grid-risk-sensitive maintenance activities, respectively.

6. Use of risk assessment results, including the results of grid reliability evaluations, in managing maintenance risk, as required by 10 CFR 50.65(a)(4).

(a) Does the TSO coordinate transmission Yes. As described in the response to 5(a), HNP receives work requests from the TSO for system maintenance activities that can have an transmission line work and for substation work. Personnel within these organizations impact on the NPP operation with the NPP submit transmission system switching requests for the required line or equipment operator? clearances. The TSO provides HNP with copies of all transmission system switching requests within one substation away from HNP. HNP must approve both the work and the requested date. These requests are normally submitted at least four (4) weeks in advance so that they can be screened for risk significance. Those work requests that are risk significant or that will result in alarms or indications in the HNP Control Room, are placed into the plant Plan of the Day (POD). This allows HNP to assess the transmission switching requests in combination with in-plant work as required by 10 CFR 65(a)(4).

HNP Response to GL 2006-02 Requested Information (b) Do you coordinate NPP maintenance Yes. One (1) HNP in-plant activity has been identified as potentially impacting activities that can have an impact on the transmission system operation. This activity is the operation of the generator voltage transmission system with the TSO? regulator. HNP procedures require notification of and coordination with the TSO whenever the voltage regulator is not in automatic. This includes routine surveillance where the regulator is taken out of automatic and the raiseAower functions manually exercised.

(c) Do you consider and implement, if warranted, Yes. As discussed above, planned transmission outages are assessed and scheduled as to the rescheduling of grid-risk-sensitive not violate HNP requirements. When notified of emergent outages due to equipment maintenance activities (activities that could (i) failures, the risk assessment process requires that the current configuration be re-increase the likelihood of a plant trip, (ii) examined to determine additional actions needed.

increase LOOP probability, or (iii) reduce LOOP or SBO coping capability) under existing, imminent, or worsening degraded grid reliability conditions?

(d) If there is an overriding need to perform grid- As discussed in 5(a) above, the consideration of risk is reviewed daily by Daily Scheduling risk-sensitive maintenance activities under andlor Operations. Depending on the risk level, higher levels of management approval is existing or imminent conditions of degraded grid required for planned activities. In addition, if risk levels warrant, the following actions are reliability, or options that could be taken:

continue grid-risk-sensitive maintenance when grid conditions worsen, do you implement Rescheduling the grid risk activities if work has not started.

appropriate risk management actions? If so, Stopping an on-going work activity and restoring the equipment to service as soon describe the actions that you would take. (These as possible.

actions could include alternate equipment Stopping work or traffic in areas of the plant that are near sensitive plant protection and compensatory measures to limit components or equipment.

or minimize risk.)

(e) Describe the actions associated with The Hatch PQG (A-45587) that is provided to the TSO contains a listing of the questions 6(a) through 6(d) above that would be transmission and switchyard elements that HNP considers potentially risk significant.

taken, state whether each action is governed by The HNP Switchyard Agreements (site procedure 90AC-OAM-002-0, attachment 8) also documented procedures and identify the contain that listing.

procedures, and explain why these actions are I effective and will be consistently accomplished.

HNP Response to GL 2006-02 Requested Information The TSO transmits all work requests within one substation of HNP to the HNP work week scheduling group, normally 3-4 weeks prior to the requested start date. HNP must reply with an approval for the work to take place. This process has evolved since the maintenance rule requirements became effective but is not currently contained in a formal procedure or agreement.

By having approval authority over planned TSO work in the vicinity of the plant, HNP can screen the requests, identify those that are potentially risk significant, and include the risk significant activities in the work scheduling and risk assessment processes described in plant procedures NMP-GM-006 and 90AC-OAM-002-0. Because they then become part of the normal work management process, emergent conditions that may require TSO activities to be rescheduled or the risk level to be reassessed are conducted the same as for in-plant work. Attachment 2 of plant procedure 90AC-OAM-002-0 contains specific requirements for assessing the risk of switchyard components.

This process provides an effective and consistent approach to managing and coordinating transmission grid work that could affect HNP.

(f) Describe how NPP operators and HNP operators are trained and subject to being tested on procedural requirements for maintenance personnel are trained and tested to scheduling maintenance, which includes requirements for managing risk. Work Week assure they can accomplish the actions described Coordinators are responsible for coordinating the scheduling of maintenance activities in your answers to question 6(e). with the TSO. Work Week Coordinators are trained on these responsibilities using a discussion guide in which topics are discussed with qualified Work Week Coordinators and the Scheduling Supervisor. Knowledge checks are conducted by the qualified Work Week Coordinators or the Scheduling Supervisor during these discussions.

(g) If there is no effective coordination between Not applicable. There is effective coordination between the HNP operator and the TSO the NPP operator and the TSO regarding regarding transmission system maintenance or HNP maintenance activities. Such transmission system maintenance or NPP coordination is in accordance with the agreements.

maintenance activities, please explain why you believe you comply with the provisions of 10 CFR 50.65(a)(4).

HNP Response to GL 2006-02Requested Information (h) If you do not consider and effectively As discussed in questions 6(a)--6(d), HNP effectively implements appropriate risk implement appropriate risk management actions management actions.

during the conditions described above, explain why you believe you effectively addressed the relevant provisions of the associated NRC-endorsed industry guidance.

(i) You may, as an alternative to questions 6(g) No alternative actions.

and 6(h) describe what actions you intend to take to ensure that the increase in risk that may result from grid-risk-sensitive maintenance activities is managed in accordance with 10 CFR 50.65(a)(4).

I Offsite power restoration procedures in accordance with 10 CFR 50.63 as developed in Section 2 of RG 1.155 I Pursuant to 10 CFR 50.63, the NRC requires that each NPP licensed to operate be able to withstand an SBO for a specified duration and recover from the SBO. NRC RG 1.155 gives licensees guidance on developing their approaches for complying with 10 CFR 50.63.

1 7. Procedures for identifying local power sources1 that could be made available to resupply your plant following a LOOP event.

Note: Section 2, "Offsite Power," of RG 1.155 (ADAMS Accession No. ML003740034) states:

Procedures should include the actions necessary to restore offsite power and use nearby power sources when offsite power is unavailable.

As a minimum, the following potential causes for loss of offsite power should be considered:

- Grid under-voltage and collapse

- Weather-induced power loss

- Preferred power distribution system faults that could result in the loss of normal power to essential switchgear buses 1

This includes items such as nearby or onsite gas turbine generators, portable generators, hydro generators, and black-start fossil power plants.

HNP Response to GL 2006-02 Requested Information (a) Briefly describe any agreement made with the Not applicable. Because of the configuration of the transmission system around HNP, TSO to identify local power sources that could there are no local power sources available to re-energize the HNP switchyards in case of be made available to re-supply power to your an LOOP. The TSO maintains a LOOP recovery procedure for HNP that lists three plant following a LOOP event. methods of providing power to HNP after a LOOP event. This procedure contains detailed switching guidance to align the grid from other plant sites that have generation units capable of a black start (sites with multiple combustion turbine units). These sites are located approximately 100 miles from HNP. HNP also has procedures for the restoration of power to the plant from the 230KV switchyard to complement the TSO procedures. An agreement is in place to restore power to the HNP on a priority basis as soon as possible. In addition, a grid operations procedure provides detailed instructions for prompt HNP offsite power restoration. The procedure specifies various means of accomplishing the required power restoration. Grid operators train on this procedure twice annually per NERC training requirements.

(b) Are your NPP operators trained and tested on No. Actions to restore power to the switchyards are not performed by HNP operators.

identifying and using local power sources to HNP operators are trained and subject to being tested on how to re-energize the startup resupply your plant following a LOOP event? If transformers and in-plant busses once offsite power is available to the switchyard.

so, describe how.

(c) If you have not established an agreement with your plant's TSO to identify local power sources that could be made available to resupply power to your plant following a LOOP event, explain why you believe you comply with the provisions of 10 CFR 50.63, or describe what actions you intend to take to establish compliance.

Losses of offsite power caused by grid failures at a frequency of equal to or greater than once in 20 site-years in accordance with Table 4 of Regulatory Guide 1.155 for complying with 10 CFR 50.63 Pursuant to 10 CFR 50.63, the NRC requires that each NPP licensed to operate be able to withstand an SBO for a specified duration and recover from the SBO. NRC RG 1.155 gives licensees guidance on developing their approaches for complying with 10 CFR 50.63.

HNP Response to GL 2006-02 Requested Information

8. Maintaining SBO coping capabilities in accordance with 10 CFR 50.63.

(a) Has your NPP experienced a total LOOP No. HNP has not experienced a partial or total LOOP from any cause since the submittal caused by grid failure since the plant's coping of the 10 CFR50.63 response.

duration was initially determined under 10 CFR 50.63?

(b)If so, have you reevaluated the NPP using the Not applicable.

guidance in Table 4 of RG 1.155 to determine if your NPP should be assigned to the P3 offsite power design characteristic group?

(c) If so, what were the results of this Not applicable.

reevaluation, and did the initially determined coping duration for the NPP need to be adjusted?

(d) If your NPP has experienced a total LOOP Not applicable.

caused by grid failure since the plant's coping duration was initially determined under 10 CFR 50.63 and has not been reevaluated using the guidance in Table 4 of RG 1.155, explain why you believe you comply with the provisions of 10 CFR 50.63 as stated above, or describe what actions you intend to take to ensure that the NPP maintains its SBO coping capabilities in accordance with 10 CFR 50.63.

Actions to ensure compliance

9. If you determine that any action is Not applicable.

warranted to bring your NPP into compliance with NRC regulatory requirements, including TSs, GDC 17, 10 CFR 50.65(a)(4),

10 CFR 50.63,10 CFR 55.59 or 10 CFR 50.120, describe the schedule for implementing it.

Enclosure 2 Joseph M. Farley Nuclear Plant Southern Nuclear Operating Company 60-Day Response to Generic Letter 2006-02 Grid Reliability and Impact on Plant Risk and the Operability of Offsite Power

FNP Response to GL 2006-02 Requested Information rotocol with your TSO? Yes. FNP does have a formal agreement with the TSO. This agreement is implemented by applicable procedures and guidelines.

(b)Describe any grid conditions that would trigger a notification from t h e Normal day to day operational communications between the TSO and FNP are the same as TSO to the NPP licensee and if there is a those for other generating plants and are associated with topics such as:

time period required for the notification work coordination, switching, generation dispatch, and planning.

The TSO is required to notify FNP whenever an impaired or potentially degraded grid condition is recognized by the TSO. Specific examples of known potentially degrading conditions identified in the agreement are:

loss of system security monitoring tools, severe weather, line or equipment outages impacting FNP, very low system load, very high system load, identification of system security contingency alarms, FNP voltage support problems, or significant grid frequency problems.

The occurrence of a grid contingency that impacts FNP requires timely FNP notification. If the TSO's real-time contingency analysis shows that the off-site power to FNP will be impaired or degraded upon the occurrence of a credible contingency, the TSO practice is to notify FNP immediately of the analysis results.

FNP Response to GL 2006-02 Requested Information

[NOTE: The TSO may need to perform a few verifications before confirming a credible contingency. Once the contingency is determined to be credible, the TSO will initiate remedial actions and should notify FNP immediately of the condition and estimated time to restore the grid to an acceptable range. If the condition can be immediately resolved (within several minutes), no notification to FNP is required.]

(c) Describe any grid conditions t h a t would cause the N P P licensee to contact Grid conditions and status are the primary responsibility of the TSO and Reliability the TSO. Coordinator (RC). The grid parameters observable to a FNP operator include only voltage and frequency, generator real and reactive output, breaker status, line status and certain switchyard Describe the procedures associated with alarm points-such a communication. If you do not have procedures, describe how you Relative to this question, "grid conditions" is assumed to be FNP changes that impact the TSO assess grid conditions t h a t may cause analysis of the grid interface. FNP notifies the TSO for changes in the following grid conditions:

the N P P licensee to contact t h e TSO.

FNP power uprate and derate changes. (Both real and reactive power)

Changes to Switchyard Voltage, Switchyard Breaker alignment, Generator VAR loading Modifications resulting in changes to generator electrical characteristics Changes in FNP post trip offsite power minimum required switchyard voltage or loading Change in status of FNP offsite power voltage regulating devices High voltage equipment problems that could impact FNP output, stability, or availability (i.e.: large power transformer problems, main generator problems, isophase bus problems, etc.)

Other notifications associated with internal plant electrical or equipment alignments are also made when applicable; however, these are not related to "grid conditions".

(d) Describe how N P P operators a r e trained a n d tested on t h e use of t h e Typically, FNP operators are trained and are subject to testing on procedures associated with procedures or assessing grid conditions assessing grid conditions. This training may be evaluated either by written examinations or

FNP Response to GL 2006-02 Requested Information in question l(c). during performance in the simulator.

(e) If you do not have a formal agreement or protocol with your TSO, FNP does have a formal agreement with the TSO; thus, this question is not applicable.

describe why you believe you continue to with the provisionsof GDC 17 as Compliance with GDC-17 is not predicated on this agreement; the SER for FNP dated May 2, stated above, or describe what actions 1975 concluded that the offsite power system satisfied the requirements of GDC 17 and was you intend to take to assure compliance acceptable.

with GDC 17.

( f ) If you have an existing formal As previously stated, FNP does have a formal agreement with the TSO. Timely notification interconnection agreement or protocol regarding pre-trip analysis of predicted post-trip voltage that results in below acceptance limits t h a t ensures adequate communication is included. FNP has guidelines to implement these communications.

and coordination between the NPP licensee and the TSO, describe whether this agreement or protocol requires t h a t you be promvtly notified when the conditions of the surrounding grid could result in degraded voltage (i.e., below TS nominal trip setpoint value requirements; including N P P licensees using allowable value i n its TSs) or LOOP after a trir, of the reactor unit(s).

(g) Describe the low switchyard voltage conditions that would initiate operation Actions for degraded grid voltage protection would be initiated by alarms received in the control of plant degraded voltage protection. room. Nominal setpoint for the degraded grid voltage alarm on the 4160 V emergency bus is 3850 V. Procedural guidance is provided for monitoring the abnormal condition, and for taking proper actions based on actual bus voltage. Procedures require that the reactor be taken to Mode 3 within 6 hours6.944444e-5 days 0.00167 hours 9.920635e-6 weeks 2.283e-6 months if emergency bus voltage is below 3850 V for more than 1 hour1.157407e-5 days 2.777778e-4 hours 1.653439e-6 weeks 3.805e-7 months .

FNP Response to GL 2006-02 Requested Information At a nominal setpoint of 3675 V degraded grid protection is actuated to prevent safety-related components from operating at less than designed voltages for extended periods of time. When this occurs, the buses are isolated from the off-site power system causing a loss of off-site power (LOOP)and allowing the buses to be powered from the on-site emergency diesel generators.

At a nominal setpoint of 3255 V selected load breakers trip (load shed) and a start signal is sent to the diesel generator associated with each emergency bus. The diesel generators restore power to the emergency buses, and the load breakers re-close by either the loss of off-site power sequencer or the emergency safeguards system sequencer.

FNP Response to GL 2006-02 Requested Information at 2ne&odu=51bs to whi~iher% h & - apower t e sys&xa win become i&&wble its \a mm$t af a (a) Does your NPP's TSO use anv analvsis tools, an online analytical According to RIS 2005-20, the term 'OperableIOperability' is defined in the Technical transmission system studies propam, or Specifications and applied ONLY to TS systems, structures & components (SSCs). Thus, the other equivalent predictive methods to FNP offsite power system cannot be referred to as 'operable' or 'inoperable', because the grid determine the grid conditions that would is not a TS SSC. Everything that is non-TS is referred to as Functional or non-Functional.

make the NPP offsite power system inoperable during various contingencies? Yes. The TSO makes use of analysis tools to predict grid conditions that would impact the If available to you, please provide a brief FNP offsite power supply. The tools presently used by the TSO to manage the grid programs, control the transmission related activities, and monitor grid actions are outside the control of description of the analysis tool that is FNP and include the following:

used by the TSO.

a grid SCADA system and state estimator a fully commissioned real-time contingency analysis (RTCA) program conjunction with periodic studies of all single outages and a reasonable set of multiple contingencies specifically tailored for FNP worst case conditions a voltage stability analysis program a near realtime dynamic stability analysis program bounding analyses produced by Transmission Planning studies.

The real-time contingency analysis package utilized by the TSO includes monitoring I predictive analysis computer programs that can predict FNP switchyard voltages expected to occur upon realization of any single contingencies and a number of possible multiple contingencies on the grid, such as a trip of the F'NP generators, a trip of other large generators, or the loss of important transmission lines.

Monitoring I predictive analysis computer program tools operate based on raw data from transducers across the system that is processed through a state estimator to generate a verified current state snapshot of the system. This output is then processed through a contingency

FNP Response to GL 2006-02 Requested Information analysis program that generates a set of new results with all single elements of the system out of service and a predefined set of multiple contingencies. These results are then screened against a predetermined set of acceptance limits. Postulated scenarios which then do not meet the acceptance limits are alarmed for review by the TSO operators.

(b) Does your NPP's TSO use an analysis tool as the basis for notifying the NPP Yes. The TSO uses the above analysis tools, in conjunction with procedures, as the basis for licensee when such a condition is determining when conditions warrant FNP notification.

identified? If not, how does the TSO determine if conditions on the grid Refer to the response to question l(b).

warrant NPP licensee notification?

Notifications are made based on grid conditions being outside of predefined procedure requirements or based on unsatisfactory monitoring I predictive analysis computer program tool results (contingency analyses).

(c) If your TSO uses an analysis tool, would the analysis tool identifv a Yes. Procedures and monitoring I predictive analysis tools are in place for this purpose in condition in which a trip of the NPP both planning and realtime environments. The TSO analysis tools, in conjunction with FNP would result in switchyard voltages plant analysis, identify conditions which could actuate the FNP degraded voltage alarms or (immediate andlor long-term) falling protection logic and initiate separation from an offsite power source upon a trip of one or both below TS nominal trip setpoint value FNP units.

requirements (including NPP licensees using allowable value in its TSs) and consequent actuation of plant degraded voltage protection?

If not, discuss how such a condition would be identified on the grid.

(dl If your TSO uses an analysis tool, how frequently does the analysis tool The state estimator and contingency analysis application tools run continuously with each program update? new case taking approximately five minutes to solve.

(e) Provide details of analysis tool-identified contingency conditions that The notification from the TSO is based upon either actual switchyard voltages or RTCA grid would trigger an NPP licensee conditions. RTCA grid conditions are based on the predicted post-contingency switchyard

1 FNP Response to GL 2006-02 Requested Information notification from the TSO. voltage given any single element of the system out of service or a predefined set of multiple contingency conditions.

The analyzed contingencies that are evaluated against the FNP voltage requirements include:

loss of another generator, loss of a significant transmission line, loss of a capacitor bank, or loss of one or both FNP units.

If the FNP voltage requirement cannot be met under any of the contingencies considered, FNP will be notified. The same minimum required switchyard voltage limit bases that are used in the grid operating procedures are also used in the predictive analysis computer programs.

(f) If an interface agreement exists between the TSO a n d the N P P licensee, According to RIS 2005-20, the term 'OperableIOperability' is defined in the Technical does it require that the NPP licensee be Specifications and applied ONLY to TS SSCs. Thus, the FNP offsite power system cannot be notified of periods when the TSO is referred to as 'operable' or 'inoperable', because the grid is not a TS SSC. Everything that is unable to determine if offsite power non-TS is referred to as Functional or non-Functional.

voltage and capacity could be inadequate? Yes. The agreement does specifically require FNP notification for periods of time when analysis tools are unavailable and grid conditions are indeterminable. FNP follows abnormal If so, does the NPP licensee operating procedure (AOP) requirements when notified by the TSO that analysis tools are determine that the power unavailable and grid conditions are indeterminable. FNP operates within the bounds of its remain operable when such a long term steady state and transient stability analyses and that 'ensures that FNP meets design notification is received? and Technical Specification requirements.

Any abnormal grid conditions that may impair the capability or availability of offsite power that are reported by the PCC or the ACC would require actions in accordance with FNP's abnormal operating procedures. Typically the time requirements for these actions are more restrictive than Technical Specification action statements.

FNP Response to GL 2006-02 Requested Information Existing requirements for functionality of the offsite power supplies as stated in GDC 17 and NUREG 0800 require that "results of the grid stability analysis indicate(d) that the loss of the largest generating capacity being supplied from the grid, loss of the most critical transmission line, or loss of the unit itself will not cause grid instability." This does not require that a continuous analysis be performed to demonstrate grid stability exists.

The TSO current practice is to perform a yearly grid stability analysis to ensure that this requirement is met, given changes and improvements to the Southern Company transmission grid. The actions described in response to notification that on-line tools are unavailable are intended to assist the grid operator in maintaining stable circumstances and to inform the FNP operating staff, but are not a factor in determining functionality of offsite power sources.

(g) After a n unscheduled inadvertent trip of the NPP, a r e the resultant No. For post event analysis, the TSO does not verify by procedure that the switchyard switchyard voltages verified bv voltages are bounded by the analysis tools. Nonetheless, such analyses have been performed procedure to be bounded by the voltages on a case by case basis to validate predicted results. Also, the system operator monitors both predicted by the analysis tool? actual conditions and contingency (predictions) values and identifies problems found.

(h)If a n analysis tool is not available to the NPP licensee's TSO, do you know if Not applicable to FNP, since TSO analysis tools are presently in use.

there are any plans for the TSO to obtain one? If so, when?

(i) If a n analysis tool is not available, does your TSO perform periodic studies Not applicable to FNP, since TSO analysis tools are presently in use.

to verify that adequate offsite power capability, including adequate N P P post-trip switchyard voltages (immediate andlor long-term), will be available to the NPP licensee over the projected

FNP Response to GL 2006-02 Requested Information timeframe of the study?

(a) Are the key assumptions and parameters of these periodic studies translated into TSO guidance to ensure that the transmission system is operated within the bounds of the analyses?

(b) If the bounds of the analyses are exceeded, does this condition trigger the notification provisions discussed i n question 1above?

(j) If your TSO does not use, or you do not have access to the results of a n According to RIS 2005-20, the term 'OperableIOperability' is defined in the Technical analysis tool, or your TSO does not Specifications and applied ONLY to TS SSCs. Thus, the FWP offsite power system cannot be perform and make available to you referred to as 'operable' or 'inoperable', because the grid is not a TS SSC. Everything that is periodic studies t h a t determine the non-TS is referred to as Functional or non-Functional.

adequacy of offsite power capability, please describe why you believe you Not applicable to FNP, since the TSO utilizes analysis tools and communicates the applicable comply with the provisions of GDC 17 as results I conclusions to the FWP.

stated above, or describe what See the response to Question l(e) regarding compliance with GDC-17.

compensatory actions you intend to take to ensure that the offsite power system will be sufficiently reliable and remain operable with high probability following a trip of your NPP.

FNP Response to GL 2006-02 Requested Information According to RIS 2005-20, the term 'OperablelOperability' is defined in the Technical Specifications and applied ONLY to TS SSCs. Thus, the FNP offsite power system cannot be a trip of the NPP, or referred to as 'operable' or 'inoperable', because the grid is not a TS SSC. Everything that is the loss of the most critical non-TS is referred to as Functional or non-Functional.

transmission line or the largest supply to the grid No, the offsite power system is not declared inoperable per Technical Specifications at FNP.

Specific values for switchyard voltages are not addressed in FNP's Technical Specifications.

As specified in the Power Quality Guide the switchyard minimum voltage requirements are would result in switchyard voltages established with margin above the settings for the degraded grid relays in the emergency (immediate TS buses. If FNP is notified by the TSO that a contingency prediction has resulted in a possible nominal trip setpoint value switchyard voltage below the minimum voltage requirement, then the degraded grid requirements NPP licensees procedure actions include more frequent monitoring of actual in-plant emergency bus using allowable value in its TSs) voltages. These procedures provide guidance for monitoring the abnormal condition and for taking proper actions (including plant shutdown if required based on actual bus voltage) which and could address an operability concern with the emergency buses.

would actuate plant degraded voltage protection, is the NPP offsite power system declared inoperable under t h e plant TSs? If not, why not?

FNP Response to GL 2006-02 Requested Information (b) If onsite safety-related equipment (e.g., emergency diesel generators or According to RIS 2005-20, the term 'OperableIOperability' is defined in the Technical safety-related motors) is lost when Specifications and applied ONLY to TS SSCs. Thus, the FNP offsite power system cannot be subjected to a double (LOCA referred to as 'operable' or 'inoperable', because the grid is not a TS SSC. Everything that is with delayed LOOP event) as a result of "0"-TS is referred to as Functional or non-Functional.

the anticipated system performance a n d is incapable of performing its safety No. Double sequencing is not in FNP's licensing basis and FNP is not designed or analyzed functions as a result of responding to a n for double sequencing scenarios. If onsite safety related equipment is lost (as governed by plant Technical Specifications), then the equipment is declared inoperable. The onsite safety emergency actuation signal during this related equipment has sufficient independence, redundancy and testability to ensure is the equipment considered performance of safety functions assuming a single failure in compliance with GDC-17, as inoperable? If not, why not? documented in the FNP licensing basis and the plant Technical Specifications.

(c) Describe your evaluation of onsite Not applicable.

safety-related equipment to determine whether it will operate as designed during the condition described in question 3(b).

(d) If the NPP licensee is notified by the TSO of other &d conditions that may According to RIS 2005-20, the term 'OperableIOperability' is defined in the Technical impair the capability or availability of Specifications and applied ONLY to TS SSCs. Thus, the FNP offsite power system cannot be offsite power, are any plant TS action referred to as 'operable' or 'inoperable', because the grid is not a TS SSC. Everything that is statements entered? If so, please non-TS is referred to as Functional or non-Functional.

identify them.

No. Technical Specifications are not entered for grid conditions that might occur. Technical Specification action statements would only be entered if the limiting condition for operation is not met. Concerning grid conditions, FNP would enter the action statements if five of six off-site power sources were lost from the grid, or one or both off-site power sources were lost from the high voltage switchyard.

(e) If you believe your plant TSs do not Not applicable.

require you to declare your offsite power system or safety-related equipment As stated in RIS 2005-20, "Operability Determination Process," Appendix C. 1, "Relationship Between the General Design Criteria and the Technical Specifications," "The general design

FNP Response to GL 2006-02 Requested Information inoperable in any of these circumstances, criteria (GDC) and the TSs differ in that the GDC specify requirements for the design of explain why you believe you comply with nuclear power reactors, whereas the TSs specify requirements for the operation of nuclear the provisions of GDC 17 and your plant reactors."

TSs, or describe what compensatory actions you intend to take to ensure t h a t FNP was designed and licensed to the requirements of GDC 17, as documented in the NRC the offsite power system and safety- SER dated May 2, 1975. Taking the plant offline decreases the reliability of the grid.

related components will remain operable when switchyard voltages are inadeauate.

(0 Describe if and how NPP operators Similar to 1.d above, licensed personnel at FNP participate in an accredited training program are trained and tested on the to maintain their senior reactor operator license or reactor operator license current. Grid compensatory actions mentioned i n your events discussed in questions 3(a) through (e) are presented in initial training, continuing answers to questions 3(a) through (e). training, and examination scenarios on the plant simulator. These include degraded grid conditions, severe weather conditions, loss of off-site power, and loss of all power. Testing is performed using simulator evaluations and written examinations. Every simulator session is critiqued to ensure the minimum expectations are met, and any enhancements to crew performance or procedural guidance are addressed through the corrective action process.

FNP Response to GL 2006-02 Requested Information

.@\ & @fd%ria5&3 'me%M&b$ies ta &seao +h~&S$theioffaite @oi&rqy&~ru will mmriinog&&Bila QWo* a -%kipof ymi2 ,we*

(a) Do t h e NPP operators have anv guidance or procedures i n plant TS bases Yes. Procedural guidance is available to FNP operators.

sections, t h e final safety analysis report, or plant procedures regarding situations The TSO procedure for voltage schedules (Southern Company Bulk Power Operations in which the condition of plant-controlled Procedure BPO-1) in the applicable Southern Control Area specifies the requirements for the or -monitored equipment(e.g., voltage FNP operators to maintain the voltage schedule to assist in the availability and reliability of regulators, auto t a p changing the grid, and to ensure voltages are maintained within the band specified in the Power Quality transformers, capacitors, static VAR Guide for FNP.

compensators, main generator voltage The capacitor bank in the high voltage switchyard is operated in the automatic or manual regulators) can adversely affect the mode, and its operation is exclusively controlled by the TSO. The shunt reactor bank in the operability of the N P P offsite power high voltage switchyard is operated manually. Its operation is directed by the TSO, and it is system? If so, describe how the placed in service and removed from service through coordinated actions by the TSO and FNP

'perators are trained and tested On the Operations personnel. A high voltage switchyard activities procedure provides guidance for guidance a n d procedures. this activity.

System Operating Procedures for the turbine generators provide limitations on the generator voltage regulators, which are intended to limit the impact on grid reliability, and on station service bus voltages.

Any abnormal conditions that impact the successful accomplishment of the above items are documented in the plant's corrective action program. These condition reports are closed by corrective actions addressed to personnel, or procedures.

Licensed personnel at FNP participate in an accredited training program to maintain their senior reactor operator license or reactor operator license current. Conditions discussed in question 4(a) are presented in initial training, continuing training, and examination scenarios through the use of the plant simulator, and on-the-job training. These include normal, abnormal, and emergency plant operations. All training sessions are critiqued to ensure the minimum expectations are met, and any enhancements to crew performance or procedural guidance are addressed through the corrective action process.

FNP Response to GL 2006-02 Requested Information Testing is performed using simulator evaluations and written examinations.

(b) If your TS bases sections, the final According to RIS 2005-20, the term 'Operable/Operability' is defined in the Technical safety analysis report, and plant Specifications and applied ONLY to TS SSCs. Thus, the FNP offsite power system cannot be procedures do not provide guidance referred to as 'operable' or 'inoperable', because the grid is not a TS SSC. Everything that is regarding situations in which the non-TS is referred to as Functional or non-Functional.

condition of plant-controlled or -

monitored equipment can adversely Not applicable. See the response to question 4(a).

affect the operability of the NPP offsite power system, explain why you believe you comply with t h e provisions of GDC 17 and the plant TSs, or describe what actions you intend to take to provide such guidance or procedures.

FNP Response to GL 2006-02 Requested Information Use of NPP licenseenso protocols and analysis tool by TSOs to assist NPP licensees in monitoring grid conditions for consideration in maintenance risk assessments The Maintenance Rule (10 CFR 50.65(a)(4)) requires that licensees assess and manage the increase in risk that may result from proposed maintenance activities before performing them.

5; - >, P & Q ~ @ W ~ ~@K&ility (a) Is a quantitative or qualitative grid ey&aa~~m%lis,prn-~f*@m&~&&m# g& @&ma& iq&erita%y 30 GBR $O~&~CP](.C~.>~

reliability evaluation performed at your NPP as Yes. 10CFR 50.65(a)(4) requires performance of a risk assessment prior to maintenance part of the maintenance risk assessment activities. Maintenance is defined broadly and would include surveillances, post maintenance required by 10 CFR 50.65(a)(4) before testing, and preventive and corrective maintenance. Relative to increasing the initiating event performing grid-risk-sensitive maintenance frequency, such as the frequency of a plant trip, the industry guidance, NUMARC 93-01 activities? This includes surveillances, post- (endorsed without exception by NRC Regulatory Guide 1.182, states Section 11.3.2.2 that the maintenance testing, and preventive and following should be considered:

corrective maintenance that could increase the probability of a plant trip or LOOP or impact The likelihood of an initiating event or accident that would require the performance of LOOP or SBO coping capability, for example, the affected safety function.

before taking a risk-significant piece of equipment (such as an EDG, a battery, a steam- The likelihood that the maintenance activity will significantly increase the frequency driven pump, an alternate AC power source) of a risk-significant initiating event (e.g., by an order of magnitude or more as out-of-service? determined by each licensee, consistent with its obligation to manage maintenance-related risk).

The first bullet above is generally met by using the PRA and associated configuration risk management tools, which explicitly consider initiating event frequencies for transients and accidents. LOOP sequences are important elements of PRAs, and are thoroughly modeled and assessed during plant peer reviews. Risk management personnel are sensitized to the importance of these sequences.

The second bullet clarifies that if a maintenance activity is expected to increase initiating-event likelihood by an order of magnitude, then it should be considered in the assessment.

Otherwise, the baseline initiating event frequencies may be used. These frequencies are based on generic data updated with plant specific data, and would take into account the plant

FNP Response to GL 2006-02 Requested Information specific LOOP and trip frequencies.

(b) Is grid status monitored by some means for the duration of the grid-risk-sensitive Yes. NUMARC 93-01 does not define "grid-risk-sensitive maintenance", so there is no maintenance to confirm the continued validity unique guidance for such activities. The following guidance is included in Section 11.3.2.8 of the risk assessment and is risk reassessed (emphasis added):

when warranted? If not, how is the risk assessed during grid-risk-sensitive Emergent conditions may result in the need for action prior to conduct of the assessment, maintenance? or could change the conditions of a previously performed assessment. Examples include plant configuration or mode changes, additional SSCs out of service due to failures, or significant changes in external conditions (weather, offsite power availability). The following guidance applies to this situation:

The safety assessment should be performed (or re-evaluated) to address the changed plant conditions on a reasonable schedule commensurate with the safety significance of the condition. Based on the results of the assessment, ongoing or planned maintenance activities may need to be suspended or rescheduled, and SSCs may need to be returned to service.

Performance (or re-evaluation) of the assessment should not interfere with, or delay, the operator and/or maintenance crew from taking timely actions to restore the equipment to service or take compensatory actions.

If the plant configuration is restored prior to conducting or re-evaluating the assessment, the assessment need not be conducted, or re-evaluated if already performed.

Note that emergent conditions are defined as "significant" changes to conditions assumed in the original risk assessment. How the plant determines whether grid conditions are changed, or whether these changes are significant enough to warrant re-assessment, are not prescribed in the NRC endorsed guidance. Plant procedures would address these issues.

(c) Is there a significant variation in the stress on the grid in the vicinity of your NPP site Yes. Stress on the transmission grid as measured by loading in the Southern Control Area is

FNP Response to GL 2006-02 Requested Information caused by seasonal with the peak loads typically occurring during the summer months (typically June through August). The all time instantaneous peak load for the Southern Control Area of seasonal loads 44,167 MW occurred on July 26,2005. By contrast, the all time instantaneous peak load for winter of 39,192 MW that occurred on January 24,2003 was roughly 89% of the summer or peak. Shoulder periods in the fall and spring typically have daily peak loads as low as 25,000 MW (roughly 57% of the all time peak) or less.

maintenance activities associated with critical transmission elements? Maintenance on generating plants and transmission equipment is also seasonal. It typically occurs during the shoulder months in spring and fall when control area loads are low and Is there a seasonal variation (or the potential equipment can be removed from service without adversely impacting grid operations. All for a seasonal variation) in the LOOP scheduled outages are registered with Southern Transmission and examined under frwuencv in the local transmission region? contingency conditions to ensure they will not impact grid reliability prior to their occurrence.

If the answer to either question is yes, discuss Although these peak load and maintenance periods do stress the transmission grid, there is no the time of year when the variations occur and time when the system is not operated in a reliable manner under first contingency criteria.

their magnitude. FNP voltages and other critical parameters are monitored continuously during these periods to assure that no violation of Power Quality Guide requirements occur. All requirements of BPO-2 and other agreements between Southern Transmission and FNP are met during peak load and maintenance periods in the same manner as they are at all other times.

(d) Are known time-related variations in the probability of a LOOP at your plant site There are no significant time-of-day or day-of-week variation in the frequency of LOOP at considered in the grid-risk-sensitive FNP.Thus, the risk assessment for the purposes of 10CFR50.65(a)(4)does not vary the maintenance evaluation? If not, what is your LOOP frequency strictly as a function of "time-related" issues.

basis for not considering them?

However, as part of the FNP's configuration risk management program, the Equipment Out of Service (EOOS) program, time related variations (e.g., grid instability, severe weather) are always considered a configuration change. They are always explicitly evaluated.

Severe weather, switchyard maintenance and test activities, and other events (not only grid specific) outside the plant are routinely considered within the EOOS model.

FNP's EOOS program requires increased controls on maintenance during the described conditions. Risk is usually not calculated solely due to changes in grid reliability (i.e.,

FNP Response to GL 2006-02 Requested Information assessed in conjunction with plant equipment being out of service). When an unacceptable risk condition is calculated (e.g. Orange risk condition), then activities are re-scheduled, or managed to avoid any pre-planned, unacceptable risk conditions. If unacceptable risk conditions occur due to emergent issues (e.g. tornado warning, transmission line failures, etc.), then the plant equipment outages are prioritized, and returned to service in a priority manner.

(e) Do you have contacts with the TSO to determine current and anticivated grid conditions as part of the grid reliability Yes. TSO relies on Contingency Analysis tools for evaluating requested transmission and evaluation performed before conducting grid- generator scheduled outages. Typically, the TSO has the ability to take snapshots of the State risk-sensitive maintenance activities? Estimator program output and modify today's peak load snapshot to study tomorrow's requested outages.

The TSO can provide commentaries on grid conditions at anytime maintenance tasks are underway. The same dynamic nature of loads and active generation make prediction of grid conditions days or weeks ahead of time uncertain, however, such studies form the base cases from which additional analyses are performed as updated information is received.

(f) Describe any formal agreement or protocol that you have with your TSO to assure that you are promvtlv alerted to a worsening grid Notification occurs whether or not maintenance is on-going. The Power Quality Guide lists condition that may emerge during a criteria for notification in the event of degraded grid conditions.

maintenance activity.

(g) Do you contact your TSO periodically for The Southern Company Electric System Transmission Power Quality Guide for FNP states the duration of the grid-risk-sensitive that FNP operators have the responsibility to notify TSO when they become aware of maintenance activities? conditions that could jeopardize plant safety andlor the electrical grid reliability. The specific actions are governed by system and plant procedures. For example, the plant procedure for an extended Emergency Diesel Generator Allowed Out of Service Time specifies the notification of the Transmission System Operator prior to removing the Emergency Diesel Generator from service that any maintenance must be carefully evaluated and approved by FNP Management prior to release for work to ensure offsite power is not jeopardized. During

FNP Response to GL 2006-02 Requested Information the extended Emergency Diesel Generator Allowed Out of Service Time, FNP operators are to periodically verify with the TSO that no maintenance is in progress in the FNP high or low voltage switchyards that would challenge off site power to the FNP units and that no impending extremely severe weather or system instabilities as defined in the procedure exist.

(h) If you have a formal agreement or protocol with your TSO, describe how NPP operators The FNP Power Quality Guide outlines typical responsibilities of the various organizations and maintenance personnel are trained and involved in maintaining the FNPIgrid interface.

tested on this formal agreement or protocol.

Operator training at FNP is based upon plant procedures. Operator training programs have degraded and loss of grid events embedded in the program. Operations personnel are trained and have procedural guidance covering notifying the TSO for certain grid-related configurations.

A discussion of the Power Quality Guide for FNP has been included in the continuing training program and plant procedure changes are evaluated for training impact and added to training committee agendas for evaluation. Operator training is evaluated either by written examinations or during performance in the simulator.

Work Control personnel are familiar with the Power Quality Guide, but are currently not formally trained on the Power Quality Guide.

(i) If your grid reliability evaluation, performed as part of the maintenance risk assessment Not Applicable required by 10 CFR 50.65(a)(4), does consider or rely on some arrangement for communication with the TSO, explain why you believe you comply with 10 CFR 50.65(a)(4).

(j) If risk is assessed (when warranted) based on continuing communication with the Not Applicable TSO throughout the duration of grid-risk-sensitive maintenance activities, explain why you believe you have effectively implemented

FNP Response to GL 2006-02 Requested Information the relevant provisions of the endorsed industry guidance associated with the maintenance rule.

(k) With respect to questions 5(i) and 5(j), you may, as an alternative, describe what actions you intend to take to ensure that the increase in No alternative actions.

risk that may result from proposed grid-risk-sensitive activities is assessed before and during grid-risk-sensitive maintenance activities, respectively.

FNP Response to GL 2006-02 Requested Information

$ - dri,&:aessmk raids, MClg&ag ;&e raa1b sE@a.&&iqs&uatiqrn* in&@agj m&ta$nm risk, %-mW& by 1U CFR

.&{axj~%

(a) Does the TSO coordinate transmission system maintenance activities that can have an Yes. FNP offsite power requirements are considered in all planned transmission outage imvact on the NPP omration with the NPP assessments. Requests identified as potentially impacting FNP requirements are coordinated operator? directly with FNP.

(b) Do you coordinate NPP maintenance activities that can have an impact on the Yes. The responsible FNP Shift Manager notifies the TSO of planned Emergency Diesel transmission svstem with the TSO? Generator outages, maintenance activities that could impact generator real or reactive power output and other significant system maintenance that could result in an unacceptable risk situation.

(c) Do you consider and implement, if warranted, the rescheduling of grid-risk- Yes. Maintenance that has an associated trip risk is performed when the on-shift FNP sensitive maintenance activities (activities that personnel conclude that the risk of the work is small compared to the safety benefit. When could (i) increase the likelihood of a plant trip, the maintenance work is done in response to a Technical Specification, the risk assessment is (ii) increase LOOP probability, or (iii) reduce informative for sequencing tasks, but not controlling.

LOOP or SBO coping capability) under existing, imminent, or worsening degraded grid Maintenance that has an associated trip risk would be activities such as the following:

reliability conditions? RPS calibrations, ATWS, CRD testing, main turbine control testing or switchyard breaker cycling.

Emergent issues are managed to maintain a high level of plant safety. At times appropriate management means rescheduling activities, at other times the shift-supervisor will order the on-shift FNP staff to back-out of the task and restore the safety-related function of the equipment. It is important that stations know the detail and content of maintenance activities so that an informed assessment can be completed.

FNP Response to GL 2006-02 Requested Information (d) If there is an overriding need to perform Yes. Same response as 6(c).

grid-risk-sensitive maintenance activities under existing or imminent conditions of degraded TSO would take appropriate actions to ensure the required voltage would be maintained per grid reliability, or continue grid-risk-sensitive the Power Quality Guide.

maintenance when grid conditions worsen, do you implement appropriate risk management actions? If so, describe the actions that you would take. (These actions could include alternate equipment protection and compensatory measures to limit or minimize risk.)

(e) Describe the actions associated with questions 6(a) through 6(d) above that would Scheduled maintenance activities on the transmission grid are entered into the Equipment be taken, state whether each action is governed Outage Scheduler (EOS) and assessed across the 0 to 13 month Operational Planning horizon by documented procedures and identify the for their impact on transmission system reliability. All scheduled outages are included in the procedures, and explain why these actions are base case developed each day by the TSO and assessments are performed to identify adverse effective and will be consistently impacts on FNP.

accomplished.

As documented in the Power Quality Guide for FNP, the TSO is responsible for maintenance activities in the FNP substation. These activities are performed by Alabama Power Company (APCo). APCo is responsible for:

Maintaining accesses control to the FNP switchyards, Performance of corrective maintenance, preventive maintenance surveillance inspections and testing of all substation equipment including the switchyard house and yard lights.

In conjunction with FNP, establishing guidelines for the use of vehicles and heavy equipment within the switchyard area to ensure operation, movement, or use of such equipment will be performed in a manner to reduce the possibility of loss of power to plant systems or switchyards.

Providing status of corrective maintenance items to FNP.

These responsibilities are documented in the Power Quality Guide for FNP. Maintenance at the FNP switchyard is performed per the requirements of APCo procedures.

Regarding the coordination and communication of grid-related activities with the TSO, FNP Operations personnel are trained and have procedural guidance covering when and how to

FNP Response to GL 2006-02 Requested Information notify the TSO for configurations identified as being grid related in Unit Operating Procedures (UOPs), System Operating Procedures (SOPS), Abnormal Operating Procedures (AOPs), Emergency Operating Procedures (EOPs), and Annunciator Response Procedures (ARPs).

Regarding the scheduling of grid-sensitive maintenance activities, the major switching or pre-planned maintenance that occurs in the electrical switchyard is approved through

- the TSO and is communicated to designated F'NP staff members. The maintenance is then included in the plant work control risk assessment process. A qualitative safety assessment using the following guidelines is performed. These guidelines establish an envelope which bounds out of service equipment within the assumptions of the Maintenance Rule performance criteria, Technical Specifications, and accident analyses.

Avoid maintenance on the protected train.

Avoid removing from service multiple safety-significant components in the same train at the same time.

Place standby components in service, where available, to perform the function of equipment removed from service.

Maintain out of service hours within the Maintenance Rule performance criteria and evaluate the impact of these out of service hours on NRC performance indicators. )

Avoid maintenance on sensitive or critical equipment during periods of severe weather forecasts, grid degradation, or system alert conditions.

The qualitative safety assessment should also consider the effects of work, plant conditions, and weather conditions that are judged to have a significant impact on the probability of a reactor trip, turbine trip, or loss of off-site power (e.g., tornado watch, hurricane forecast, high risk switchyard work, MSIV/MFlV/EHC work, etc.).

FNP Response to GL 2006-02 Requested Information (f) Describe how NPP operators and FNP operators are trained and subject to testing on procedural requirements for scheduling maintenance personnel are trained and tested to maintenance, which includes requirements for managing risk. Work Week Coordinators are assure they can accomplish the actions responsible for coordinating the scheduling of maintenance activities with the TSO. Work described in your answers to question 6(e). Week Coordinators are trained on these responsibilities using a discussion guide in which topics are discussed with qualified Work Week Coordinators or the Scheduling Supervisor.

(g) If there is no effective coordination between the NPP operator and the TSO Not applicable. There is effective coordination between the FNP operator and the TSO regarding transmission system maintenance or regarding transmission system maintenance and F'NP maintenance activities. Such NPP maintenance activities, please explain coordination is in accordance with the agreements.

why you believe you comply with the provisions of 10 CFR 50.65(a)(4).

(h) If you do not consider and effectively implement appropriate risk management Not applicable. As discussed in questions 6(a)--6(d), F'NP effectively implements actions during the conditions described above, appropriate risk management actions.

explain why you believe you effectively addressed the relevant provisions of the associated NRC-endorsed industry guidance.

(i) You may, as an alternative to questions 6(g) and 601) describe what actions you intend to Not applicable. No alternative actions.

take to ensure that the increase in risk that may result from grid-risk-sensitive maintenance activities is managed in accordance with 10 CFR 50.65(a)(4).

FNP Response to GL 2006-02 Requested Information Offsite power restoration procedures in accordance with 10 CFR 50.63 as developed in Section 2 of RG 1.155 Pursuant to 10 CFR 50.63, the NRC requires that each NPP licensed to operate be able to withstand an SBO for a specified duration and recover from the SBO. NRC RG 1.155 gives licensees guidance on developing their approaches for complying with 10 CFR 50.63.

7 -

- 3 .

Z&k i d w w g lw&@w~*sQ& &&%&a ~~av&le tQ r&&@y your plmt fa~b'wSgkLOW Note: Section 2, "Offsite Power," of RG 1.155 (ADAMS Accession No. ML003740034) states:

Procedures should include the actions necessary to restore offsite power and use nearby power sources when offsite power is unavailable. As a minimum, the following potential causes for loss of offsite power should be considered:

- Grid under-voltage and collapse

- Weather-induced power loss

- Preferred power distribution system faults that could result in the loss of normal power to essential switchgear buses (a) Briefly describe any agreement made with the TSO to identify local power sources that Existing plant procedures and commitments are adequate. The TSO will utilize the best could be made available to re-supply power to sources available for specific events to restore offsite power and to determine the specific your plant following a LOOP event. power sources and paths, since there is no way to predict the extent and characteristics of a specific blackout. The TSO has many options available to restore offsite power and would not be limited to identified local power sources.

An agreement is in place to restore power to FNP on a priority basis. In addition, a grid operations procedure provides detailed instructions for prompt FNP offsite power restoration.

The procedure specifies various means of accomplishing the required power restoration. Grid operators train on this procedure per NERC requirements.

(b) Are your NPP operators trained and tested on identifying and using local power sources to No. Actions to restore power to the switchyard are not performed by FNP operators. FNP 2

This includes items such as nearby or onsite gas turbine generators, portable generators, hydro generators, and black-start fossil power plants.

FNP Response to GL 2006-02 Requested Information resupply your plant following a LOOP event? operators are trained and subject to being tested on how to reenergize the startup If so, describe how. transformers and in-plant busses once offsite power is available to the switchyard.

(c) If you have not established an agreement with your plant's TSO to identify local power Not applicable; an agreement exists.

sources that could be made available to resupply power to your plant following a The TSO has the responsibility to restore offsite power to FNP as a priority. The TSO will LOOP event, explain why you believe you utilize the best sources available for specific events to restore offsite power and to determine comply with the provisions of 10 CFR 50.63, the specific power sources and paths, since there is no way to predict the extent and or describe what actions you intend to take to characteristics of a specific blackout. The TSO has many options available to restore offsite establish compliance. power and would not be limited to identified local power sources

FNP Response to GL 2006-02 Requested Information (b) If so, have you reevaluated the NPP using the guidance in Table 4 of RG 1.155 to Not applicable.

determine if your NPP should be assigned to the P3 offsite power design characteristic group?

(c) If so, what were the results of this reevaluation, and did the initially determined Not applicable.

coping duration for the NPP need to be adjusted?

(d) If your NPP has experienced a total LOOP caused by grid failure since the plant's coping Not applicable.

duration was initially determined under 10 CFR 50.63 and has not been reevaluated using the guidance in Table 4 of RG 1.155, explain why you believe you comply with the provisions of 10 CFR 50.63 as stated above, or describe what actions you intend to take to ensure that the NPP maintains its SBO coping capabilities in accordance with 10 CFR 50.63.

Enclosure 3 Vogtle Electric Generating Plant Southern Nuclear Operating Company 60-Day Response to Generic Letter 2006-02 Grid Reliability and Impact on Plant Risk and the Operability of Offsite Power

VEGP Response to GL 2006-02Requested Information (a) Do you have a formal agreement o r protocol with your TSO? Yes. VEGP does have a formal agreement with the TSO. This agreement is implemented by applicable procedures and guidelines.

(b) Describe any grid conditions that would trigger a notification from the TSO Normal day to day operational communications between the TSO and VEGP are the to the NPP licensee a n d if there is a time same as those for other generating plants and are associated with topics such as:

period required for the notification work coordination, switching, generation dispatch, and planning.

The TSO is required to notify VEGP whenever an impaired or potentially degraded grid condition of the following type is recognized by the TSO. Specific examples of known potentially degrading conditions identified in the agreement fall into two basic categories:

loss of system security monitoring tools, severe weather, line or equipment outages impacting VEGP, very low system load, very high system load, identification of system security contingency alarms, VEGP voltage support problems, or significant grid frequency problems.

The occurrence of a grid contingency that impacts VEGP requires timely VEGP notification. If the TSO's real-time contingency analysis shows that the off-site power to the VEGP will be impaired or degraded upon the occurrence of a credible contingency, the TSO practice is to notify VEGP immediately of the analysis results.

VEGP Response to GL 2006-02 Requested Information

[NOTE: The TSO may need to perform certain verifications before confirming a credible contingency. Once the contingency is determined to be credible, the TSO will initiate remedial actions and should notify VEGP immediately of the condition and estimated time to restore the grid to an acceptable range. If the condition can be immediately resolved (within several minutes), no notification to VEGP is required.]

(c) Describe any grid conditions that would cause t h e NPP licensee to contact the Grid conditions and status are the primary responsibility of the TSO and Reliability TSO. Coordinator (RC). The grid parameters observable to a VEGP operator include only voltage and frequency, generator real and reactive output, breaker status, line status, and Describe t h e procedures associated with certain switchyard alarm points local to VEGP.

such a communication. If you do not have procedures, describe how you assess grid Relative to this question, "grid conditions" is assumed to be VEGP changes that impact conditions that may cause t h e NPP the TSO analysis of the grid interface. VEGP notifies the TSO for changes in the following grid conditions:

licensee t o contact t h e TSO.

VEGP power uprate and derate changes. (Both real and reactive power)

Switchyard Breaker alignment Modifications resulting in changes to generator electrical characteristics Changes in VEGP post trip offsite power minimum required switchyard voltage or loading Change in status of VEGP offsite power voltage regulating devices High voltage equipment problems that could impact VEGP output, stability, or availability (i.e.: large power transformer problems, main generator problems, isophase bus problems, etc.)

Other notifications associated with internal plant electrical or equipment alignments are also made when applicable; however, these are not related to "grid conditions".

VEGP has procedures which implement these communications.

(d) Describe how NPP operators a r e VEGP Training trained a n d tested on t h e use of t h e procedures or assessing grid conditions in VEGP operators are trained and subject to testing on procedures associated with

VEGP Response to GL 2006-02 Requested Information question l(c). assessing grid conditions.

This training may be evaluated either by written examinations or during performance in the simulator.

(e) If you do not have a formal agreement or protocol with your TSO, describe why VEGP does have a formal agreement with the TSO; thus, this question is not applicable.

you believe you continue to comply with the provisions of GDC 17 as stated above, or describe what actions you intend to take to assure compliance with GDC 17.

(0 If you have an existing formal interconnection agreement or protocol that As previously stated, VEGP does have a formal agreement with the TSO. Timely ensures adequate communication and notification regarding pre-trip analysis of predicted post-trip voltage that results in below coordination between the NPP licensee acceptance limits is included.

and the TSO, describe whether this agreement or protocol requires that you be VEGP has guidelines to implement these communications.

promptlv notified when the conditions of the surrounding grid could result in degraded voltage (i.e., below TS nominal trip setpoint value requirements; including NPP licensees using allowable value in its TSs) or LOOP after a trip of the reactor unit(s).

(g) Describe the low switchyard voltage Plant Support (DB. 8.3.1-18 of FSAR) conditions that would initiate operation of plant degraded voltage protection. 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

VEGP Response to GL 2006-02 Requested Information potential transformers located on each safety related bus.

To sense a loss of voltage, four solid state type undervoltage devices are provided. 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 70 percent of nominal voltage which is below the minimum expected voltage during diesel generator sequencing. The undervoltage relay design meets the applicable requirements of IEEE 279.

Four additional undervoltage logic circuits are provided for each safety related bus to recognize degraded voltage conditions. These circuits are set to operate at a minimum of 88.5 percent 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.

A two-out-of-four undervoltage logic set at 93.1 percent of nominal voltage with a time delay of 10 s is also provided to initiate an alarm in the control room to warn the operators of a degraded voltage condition. A Safety Injection Signal (SIS) subsequent to the initiation of this alarm does not separate the auxiliary power system from the offsite power system. Studies have been performed which indicate that at the degraded voltage trip setpoint indicated above, based on the worst case motor thermal damage curve, the permanently connected Class 1E loads will not be damaged. These studies also indicate that adequate voltage is provided to allow starting of the loads.

On a loss of offsite power, after a diesel generator has been started and reaches rated voltage and frequency, the generator circuit breaker connecting it to the corresponding 4.16-kV bus closes, energizing that bus and the associated load center transformers.

Each diesel generator is designed to accept loads within 9.5 s after receipt of a start signal, and all automatically sequenced loads are connected to the Class 1E bus within 30.5 s thereafter.

VEGP Response to GL 2006-02 Requested Information a, ; * ,A> t &&mk-,d&

s -A*> x,xa% m6th&&$o&athV&&&q thbb@j* 'k~d$ df a

.dy~b:WP?

(a) Does your NPP's TSO use anv analvsis tools, an online analytical transmission According to RIS 2005-20, the term 'OperableIOperability' is defined in the Technical system studies program, or other Specifications and applied ONLY to TS SSCs. Thus, the VEGP offsite power system equivalent predictive methods to cannot be referred to as 'operable' or 'inoperable', because the grid is not a TS SSC.

determine the grid conditions that would Everything that is non-TS is referred to as Functional or non-Functional.

make the NPP offsite power system inoperable during various contingencies? Yes. The TSO makes use of analysis tools to predict grid conditions that impact the If available to you, please provide a brief VEGP offsite power supply. The tools presently used by the TSO are outside the control of the VEGP and include the following:

description of the analysis tool t h a t i s used by the TSO.

a grid SCADA system and state estimator a fully commissioned real-time contingency analysis (RTCA) program a voltage stability analysis program a near real time dynamic stability analysis program bounding analyses produced by Transmission Planning studies.

The real time contingency analysis package utilized by TSO includes monitoring 1 predictive analysis computer programs that can predict VEGP switchyard voltages expected to occur under any single contingency and a number of possible multiple contingencies on the grid, such as:

a trip of the VEGP generators, a trip of other large generators, or the loss of important transmission lines.

Monitoring 1predictive analysis computer program tools operate based on raw data from transducers across the system that is processed through a state estimator to generate a verified current state snapshot of the system. This output is then processed through a contingency analysis program that generates a set of new results with all single elements of the system out of service and a predefined set of multiple contingencies. These results are then screened against a predetermined set of acceptance limits. Postulated scenarios

VEGP Response to GL 2006-02 Requested Information which do not meet acceptance limits are alarmed for review by the TSO operator.

(b) Does your NPP's TSO use an analysis tool as the basis for notlfylng the NPP Yes. The TSO uses the above analysis tools, in conjunction with procedures, as the basis licensee when such a condition is for determining when conditions warrant VEGP notification.

identified? If not, how does the TSO determine if conditions on the grid Refer to the response to question l(b).

warrant NPP licensee notification?

Notifications are made based on grid conditions being outside of predefined procedure requirements or based on unsatisfactory monitoring I predictive analysis computer program tool results (contingency analysis).

(c) If your TSO uses an analysis tool, would the analysis tool identifv a Yes. Procedures and monitoring I predictive analysis tools are in place for this purpose in conditionin which a trip of the Npp would both planning and real time environments. The TSO analysis tools, in conjunction with result in switchyard voltages (immediate VEGP plant analysis, identify conditions which would actuate the VEGP degraded andlor long-term) falling below TS voltage protection logic and initiate separation from an offsite power source upon a trip nominal trip setpoint value requirements of one or both VEGP units.

(including NPP licensees using allowable value in its TSs) and consequent actuation of plant degraded voltage protection?

If not, discuss how such a condition would be identified on the grid.

(d) If your TSO uses an analysis tool, how frequently does the analysis tool program The state estimator and contingency analysis application tools run continuously with update? each new case taking approximately five minutes to solve.

(e) Provide details of analysis tool-identified contingency conditions that The notification from the TSO is based upon either actual switchyard voltages or RTCA would trigger an NPP licensee notification grid conditions RTCA grid conditions are based on predicted post-trip contingency from the TSO. switchyard voltages given any single elements of the system out of service or a predefined set of multiple contingency conditions.

VEGP Response to GL 2006-02 Requested Information The analyzed contingencies that are evaluated against the VEGP voltage requirements include:

loss of any other single generator or selected multiple generators, loss of a any transmission line or selected multiple significant transmission lines, loss of a capacitor bank, or loss of the VEGP (one or both units).

If the VEGP voltage requirement cannot be met under any of the contingencies considered, the VEGP licensee will be notified. The same minimum required switchyard voltage limit bases that are used in the grid operating procedures are also used in the predictive analysis computer programs.

Refer to the response to question l(e).

(0 If a n interface agreement exists <

between the TSO a n d t h e N P P licensee, does it require that t h e NPP licensee be notified of periods when the TSO is unable to determine if offsitepower voltage and According to RIS 2005-20, the term 'OperableIOperability' is de ne in Specifications and applied ONLY to TS SSCS. Thus, the VEGP ffsi 1~ echnical er system cannot be referred to as 'operable' or 'inoperable', because the grid& ot a TS SSC.

Everything that is non-TS is referred to as Functional or non-Functional.

capacity could be inadequate?

If so, how does the N P P licensee Yes. The agreement does specifically require VEGP notification for periods of time determine that t h e offsite power would when analysis tools are unavailable and grid conditions are indeterminable.

remain operable when such a notification The VEGP Final Safety Analysis Report (FSAR), sections 8.2.2.2, "VEGP Voltage i s received? Operating Range" and 8.2.2.3, "VEGP Transient Stability" define the established licensing basis for the voltage operating range for VEGP. An abnormal operating procedure is in place that includes operator actions for degraded grid conditions. Based on the licensing basis and the abnormal operating procedure, the TSO notifies VEGP any time that the grid is one contingency away from degraded grid conditions as defined in FSAR 8.2.2.3, although this condition does not require notification because the grid is still stable and if necessary, the plant can still be safely shutdown. The degraded voltage setpoints specified in the VEGP Technical Specifications were established so that

VEGP Response to GL 2006-02 Requested Information electrical loads essential for the safe shutdown of the plant under normal and emergency conditions remain capable of performing their functions. Therefore, this condition does not meet the reporting criteria of 10 CFR 50.72. However, if VEGP reaches a degraded grid voltage setpoint, then the NRC would be notified of this condition in accordance with 10 CFR 50.72.

VEGP follows Technical Specifications requirements when notified by the TSO that analysis tools are unavailable and grid conditions are indeterminable. The VEGP operates within the bounds of its long term stability analyses and that ensures that the VEGP meets design and Technical Specification requirements.

(g) After a n unscheduled inadvertent trip of the NPP, are the resultant switchyard No. For post event analysis, the TSO does not verify by procedure the switchyard voltages verified by procedure to be voltages are bounded by the analysis tools. Nonetheless, such analyses have been bounded by the voltages by the performed on a case by case basis to validate predicted results. Also, the system operator analysis tool? monitors both actual conditions and contingency (predictions) values and identifies problems found.

(h) If an analysis tool is not available to the NPP licensee's TSO, do you know if Not applicable to VEGP, since TSO analysis tools are presently in use.

there are any plans for the TSO to obtain one? If so, when?

(i)If an analysis tool is not available, does your TSO perform periodic studies to Not applicable to VEGP, since TSO analysis tools are presently in use.

verify that adequate offsite power capability, including adequate NPP post-trip switchyard voltages (immediate and/or long-term), will be available to the NPP licensee over the projected timeframe of the study?

(a)Are the key assumptions and

VEGP Response to GL 2006-02 Requested Information parameters of these periodic studies translated into TSO guidance to ensure that the transmission system is operated within the bounds of the analyses?

(b) If the bounds of the analyses are exceeded, does this condition trigger the notification provisions discussed in question 1above?

(j) If your TSO does use, or you do not have access to the results of an analysis Not applicable to VEGP, since the TSO utilizes analysis tools and communicates the tool, or your TSO does not perform and applicable results / conclusions to the VEGP.

make available to you periodic studies that determine the adequacy of offsite power capability, please describe why you believe you complv with the provisions of GDC 17 as stated above, or describe what compensatory actions you intend to take to ensure that the offsite power system will be sufficiently reliable and remain operable with high probability following a trip of your NPP. -

VEGP Response to GL 2006-02 Requested Information According to RIS 2005-20, the term 'OperableIOperability' is defined in the Technical Specifications (TS) and applies ONLY to TS SSCs. A TS SSC is Operable or has a trip of the NPP, or Operability when it is capable of performing its specified safety functions and when all the loss of the most critical necessary attendant instrumentation, controls, normal or emergency electrical power, transmission line or cooling and seal water, lubrication, and other auxiliary equipment that are required for the system subsystem, train, component, or device to perform its specified safety the largest supply to the grid function(s) are also capable of performing their related support functions.

would result in switchyard voltages It is not clear from this question whether the "offsite power system" refers to the grid or (immediate TS the offsite circuits required Operable by the VEGP TS. The grid is not a TS SSC and, as trip setpoint requirements such, the term Operable does not apply in accordance with RIS 2005-20. Therefore, our NPP licensees using allowable response refers to the offsite circuits required Operable by the VEGP TS.

value in its TSs)

The VEGP Technical Specifications (LC0 3.8.1) require, in part, the Operability of and "Two qualified circuits between the offsite transmission network and the onsite Class 1E AC Electrical Power Distribution System.. .." The Bases for LC0 3.8.1 define the two would actuate plant degraded voltage required offsite circuits as follows:

protection, Offsite circuit #1 and #2 each consist of a Reserve Auxiliary Transformer (RAT) fed is the NPP offsite power system declared from separate lines from the 230 kV switchyard. Each RAT can supply either 4160V inoperable under the plant TSs? If not, ESF bus. In addition to these circuits, there is also a 13.814.16 kV Standby Auxiliary why not? Transformer (SAT) which may be manually connected to supply power to any one of the 4.16 kV ESF buses for Units 1 and 2 in place of any RAT. The SAT receives power via the Georgia Power Company Plant Wilson switchyard.

The Bases for LC0 3.8.1 state that each offsite circuit must be capable of maintaining rated frequency and voltage, and accepting required loads during an accident, while connected to the Engineered Safety Feature (ESF) buses.

The VEGP Power Quality Guide summarizes the requirements of the offsite power

VEGP Response to GL 2006-02 Requested Information system for VEGP. It also delineates guidelines for use in Southern Electric System transmission planning and operational activities to ensure the safe and reliable operation of VEGP. These guidelines are designed to achieve the following:

a. Meet the power supply requirements of the safety-related (Class 1E) loads during both normal and accident conditions without reliance on the offsite power supply systems (i.e., diesel generators).

b. Meet the requirements of all station service loads during normal conditions including when a unit is off-line. This will ensure reliable plant operation during normal, startup and shutdown conditions.

The VEGP Power Quality Guide states given the expected configurations of the transmission system, a single contingency event should not result in inadequate voltage at the Class 1E loads. The contingencies evaluated include the sudden loss of a transmission element and the sudden loss of a large generating unit. Under these severe contingencies, the 230-kV bus voltage should not be less than 230-kV(100%) or greater than 242-kV(105%).

SNC is a part of a vertically integrated system of Southern Company. We have a formal agreement with the TSO to operate the grid within a required voltage range. Therefore, there is a mutual interest to maintain adequate grid voltage. If it was predicted that a certain scenario could potentially impact the grid, then VEGP along with the TSO would take compensatory measures to maintain grid voltage. Therefore, the offsite circuits required by the TS would remain Operable because they would remain capable of accepting the required loads under accident conditions without challenging degraded voltage protection. Furthermore, if both offsite circuits were to be declared inoperable, the TS would require the unit to be shut down within 30 hours3.472222e-4 days 0.00833 hours 4.960317e-5 weeks 1.1415e-5 months or less thereby potentially causing further grid degradation which could challenge degraded voltage protection.

(b) If onsite safety-related equipment (e.g.,

emergency diesel generators or safety- No. Double sequencing such as might occur as the result of a LOCA followed by a related motors) is lost when subjected to a delayed LOOP is not in the VEGP licensing basis and VEGP is not designed or analyzed double seauencinq (LOCA with delayed for double sequencing scenarios. However, as discussed in FSAR section 8.3.1, the plant LOOP event) as a result of the anticipated design is such that once load sequencing has been completed, or if the diesel generator

VEGP Response to GL 2006-02 Requested Information system performance a n d is incapable of breaker opens before all the loads are sequenced onto the bus, the load shed and performing its safety functions as a result resequence capability is automatically reinstated for an undervoltage sensed at the 4.16-of responding to an emergency actuation kV Class 1E bus. Logic has been provided that prevents more than three undervoltage signal during this condition, is t h e resequence of the required loads. The third undervoltage signal will initiate a load shed equipmentconsidered inoperable? 1f not, only. Reinstatement of sequencing can be accomplished by manually resetting a timer why not? located at the sequencer. This limitation is provided to prevent automatically exceeding the manufacturer's recommendations concerning motor start capability of two successive starts within a 2-h period. If onsite safety related equipment was lost as a result of multiple sequencing, then the equipment would be declared inoperable (as governed by plant Technical Specifications).

(c) Describe your evaluation of onsite safety-related equipment to determine Not applicable.

whether it will operate as designed during the condition described in question 3(b).

(d) If the NPP licensee is notified by the TSO of other grid conditions that may No. Technical Specifications are not entered for grid conditions that might occur.

impair the capability o r availability of offsite power, are a n y plant TS action Refer to the response to question 3(a).

statements entered? If so, please identify them.

(e) If you believe your plant TSs do not require you to declare your offsite power VEGP was designed and licensed to the requirements of GDC 17. As stated in RIS system or safety-related equipment 2005-20, "Operability Determination Process," Appendix C. 1, "Relationship Between inoperable in these circumstances, the General Design Criteria and the Technical Specifications," "The general design explainwhy you believe you complywith criteria (GDC) and the TSS differ in that the GDC specify requirements for the design of the prov~s~ons of GDC 17 and your plant nuclear power reactors, whereas the TSs specify requirements for the operation of TSs, or describe w h a t compensatory nuclear reactors." A degraded condition that would result in the offsite circuits or other actions you intend to t a k e to ensure that TS SSCs to be declared inoperable is not a failure to meet GDC17, because, as long as the affected TS SSC is restored to Operability, the design is not changed and compliance the offsite power system a n d safety-with GDC 17 is maintained. Furthermore, the stipulation that safety related components

VEGP Response to GL 2006-02 Requested Information related components will remain operable must remain Operable when switchyard voltages are inadequate is inconsistent with the when switchyard voltages are inadequate. TS definition of Operability which states that the component is Operable provided the component has either normal or emergency power. Even an actual offsite circuit undervoltage condition would not result in TS SSCs being inoperable as long as the components were capable of being powered from the emergency power source.

(f) Describe if a n d how NPP operators are trained a n d tested on the compensatory Training associated with Technical Specifications and electrical power distribution actions mentioned i n your answers t o systems associated with on and offsite power sources, emergency diesel generators, Plant questions 3(a) through (e). Wilson, and safety system sequencer is embedded in the initial and continuing training programs. This training includes compensatory actions including use of Plant Wilson and the Standby Auxiliary Transformer. Evaluation of plant conditions is discussed in relation to available off-site power sources and industry operating experience is included.

Training associated with the plant procedures associated with degraded grid and loss of off-site power is performed in the classroom and simulator. Selected specific tasks relating to the restoration of power on site have been included as "job Performance Measures". Additionally, the Continuing training program discussed the Power Quality Guide for VEGP and system voltage control during segment 3 of 2005.

Additionally the following Industry OE relating to power supply problems was covered in the continuing training program:

SEN 256 Catastrophic Main Transformer Failure Resulting in Fire and Unplanned Outage (Turkey Point)

H 15 Main Transformer Fire (Hatch)

NRC 41800 Turkey Point Transformer FireNOUE OE 18583 Palo Verde Units Trip Offline Due to Grid Disturbance OE 17846 Shutdown of North Anna Unit 1 Due To Main Transformer Degradation Testing is performed using simulator evaluations and written examinations.

VEGP Response to GL 2006-02 Requested Information pk; ,pw,uf &&

+iii

@'m&&dbo0@4~ to ,&bm & ~ t h r & $ o M p i r w e i ' w u d9,'~ &

o-bk w+w'L-irip afm*WP*

(a) Do the NPP operators have g guidance or procedures in plant TS bases Yes. Operations personnel are trained and tested and have procedural guidance covering sections, the final safety analysis report, the protocol of when, and how to notify the Transmission System Operator (TSO),

or plant procedures regarding situations PCCIGCCITMC for configurations identified as being GRID related in Unit Operating in which the condition of plant-controlled Procedures (UOPS), System Operating Procedures (SOPS), Abnormal Operating or -monitored equipment (e.g., voltage Procedures (AOPs), Emergency Operating Procedures (EOPs), and Annunciator regulators, auto tap changing Response Procedures (ARPs).

transformers, capacitors, static VAR compensators, main generator voltage regulators) can adversely affect the operability of the NPP offsite power system? If so, describe how the operators are trained and tested on the guidance and procedures.

(b) If your TS bases sections, the final safety analysis report, and plant Not applicable.

procedures do not provide guidance regarding situations in which the condition of plant-controlled or -monitored equipment can adversely affect the operability of the NPP offsite power system, explain why you believe you comply with the provisions of GDC 17 and the plant TSs, or describe what actions you intend to take to provide such guidance or procedures.

VEGP Response to GL 2006-02 Requested Information Use of NPP 1icenseePTSOprotocols and analysis tool by TSOs to assist NPP licensees in monitoring grid conditions for consideration in maintenance risk assessments The Maintenance Rule (10 CFR 50.65(a)(4)) requires t h a t licensees assess and manage the increase in risk that may result from proposed maintenance activities before performing them.

@st;g$&*&~-of&d 6.Q*#f-8-g41#

>:+; &&a& &diu~a&~&&.~~~f&-Et -Etm.ai~b~&&:m:h~&-erib -& %&@PR (a) Is a quantitative or qualitative grid reliability evaluation performed a t your Yes. 10CFR 50.65(a)(4)requires performance of a risk assessment prior to maintenance NPP as part of t h e maintenance risk activities. Maintenance is defined broadly and would include surveillances, post assessment required by 10 CFR maintenance testing, and preventive and corrective maintenance. Relative to increasing 50.65(a)(4) before performing grid-risk- the initiating event frequency, such as the frequency of a plant trip, the industry sensitive maintenance activities? This guidance, NUMARC 93-01 (endorsed without exception by NRC Regulatory Guide includes surveillances, post-maintenance 1.182, states Section 11.3.2.2 that the following should be considered:

testing, and preventive and corrective maintenance that could increase the The likelihood of an initiating event or accident that would require the performance of the affected safety function.

probability of a plant trip or LOOP or impact LOOP or SBO coping capability, The likelihood that the maintenance activity will significantly increase the for example, before taking a risk- frequency of a risk-significant initiating event (e.g., by an order of magnitude or significant piece of equipment (such a s a n more as determined by each licensee, consistent with its obligation to manage EDG, a battery, a steam-driven pump, a n maintenance-related risk).

alternate AC power source) out-of-service?

The first bullet above is generally met by using the PRA and associated configuration risk management tools, which explicitly consider initiating event frequencies for transients and accidents. LOOP sequences are important elements of PRAs, and are thoroughly modeled and assessed during plant peer reviews. Risk management personnel are sensitized to the importance of these sequences.

The second bullet clarifies that if a maintenance activity is expected to increase initiating-event likelihood by an order of magnitude, then it should be considered in the assessment. Otherwise, the baseline initiating event frequencies may be used. These

VEGP Response to GL 2006-02 Requested Information frequencies are based on generic data updated with plant specific data, and would take into account the plant specific LOOP and trip frequencies.

(b) Is grid status monitored by some means for the duration of the grid-risk- Yes. NUMARC 93-01 does not define "grid-risk-sensitive maintenance", so there is no sensitive maintenance to confirm the unique guidance for such activities. The following guidance is included in NUMARC continued validity of the risk assessment 93-01 Section 11.3-2-8:

and is risk reassessed when warranted? If not, how i s the risk assessed during grid- Emergent conditions may result in the need for action prior to conduct of the risk-sensitive maintenance? assessment, or could change the conditions of a previously performed assessment.

Examples include plant configuration or mode changes, additional SSCs out of service due to failures, or significant changes in external conditions (weather, offsite power availability). The following guidance applies to this situation:

The safety assessment should be performed (or re-evaluated) to address the changed plant conditions on a reasonable schedule commensurate with the safety significance of the condition. Based on the results of the assessment, ongoing or planned maintenance activities may need to be suspended or rescheduled, and SSCs may need to be returned to service.

Performance (or re-evaluation) of the assessment should not interfere with, or delay, the operator andlor maintenance crew from taking timely actions to restore the equipment to service or take compensatory actions.

If the plant configuration is restored prior to conducting or re-evaluating the assessment, the assessment need not be conducted, or re-evaluated if already performed.

Note that emergent conditions are defined as "significant" changes to conditions assumed in the original risk assessment. How the plant determines whether grid conditions are changed, or whether these changes are significant enough to warrant re-assessment, are not prescribed in the NRC endorsed guidance. Plant procedures would address these issues.

VEGP Response to GL 2006-02 Requested Information (c) IS there a significant variation in the Yes. Stress on the transmission grid as measured by loading in the Southern Control stress on the grid in the vicinity of your NPP site caused by , Area is seasonal with the peak loads typically occurring during the summer months (typically June through August). The all time instantaneous peak load for the Southern Control Area of 44,167 MW occurred on July 26,2005. By contrast, the all time seasonal loads instantaneous peak load for winter of 39,192 MW that occurred on 1/24/2003 was roughly 89% of the summer peak. Shoulder periods in the fall and spring typically have or daily peak loads as low as 25,000 MW (roughly 57% of the all time peak) or less.

Maintenance on generating plants and transmission equipment is also seasonal. It maintenance activities associated with typically occurs during the shoulder months in spring and fall when control area loads critical transmission elements?

are low and equipment can be removed from service without adversely impacting grid operations. All scheduled outages are registered with Southern Transmission and Is there a seasonal variation (or the examined under contingency conditions to ensure they will not impact grid reliability potential for a seasonal variation) in the prior to their occurrence.

LOOP freauencv in the local transmission region? Although these peak load and maintenance periods do stress the transmission grid, there is no time when the system is not operated in a reliable manner under first contingency If the answer to either question is yes, criteria. VEGP voltages and other critical parameters are monitored continuously during discuss the time of year when the these periods to assure that no violation of Power Quality Guide requirements occur. All variations occur and their magnitude. requirements of BPO-2 and other agreements between Southern Transmission and the VEGP are met during peak load and maintenance periods in the same manner as they are at all other times.

(d) Are known time-related variations in the probability of a LOOP at your plant VEGP's Configuration Risk Management (CRM) program procedures require increased site considered in the grid-risk-sensitive controls on maintenance during the grid risk sensitive conditions. Risk is usually not maintenance evaluation? If not, what is calculated solely due to changes in grid reliability (i.e., assessed in conjunction with your basis for not considering them? plant equipment being out of service).

According to preliminary work by the WOG, there is no statistically significant time-of-day or day-of-week variation in the frequency of LOOP at nuclear power plants. This is largely a result of a small number of LOOP events. The analysis has yet to normalize factors such as:

VEGP Response to GL 2006-02 Requested Information most tasks are done on the day-shift, and most tasks are performed from Monday to Friday.

Thus, the risk assessment for the purposes of 10CFR50.65(a)(4) does not vary the LOOP frequency strictly as a function of "time-related" issues.

(e) Do you have contacts with the TSO to determine current and anticipated grid Yes. TSO relies on Contingency Analysis tools for evaluating requested transmission conditions as pad of the grid reliability and generator scheduled outages. Typically, the TSO has the ability to take snapshots of evaluation before conducting the State Estimator program output and modify today's peak load snapshot to study grid-risk-sensitive maintenance activities? tomorrow's requested outages.

Obviously, the TSO can provide commentaries on grid conditions at anytime maintenance tasks are underway. The dynamic nature of loads and active generation make prediction of grid conditions days or weeks ahead of time uncertain, however, such studies form the base cases from which additional analyses are performed as updated information is received.

(f) Describe any formal agreement or protocol that you have with your TSO to Notification occurs whether or not maintenance is on-going. The Power Quality Guide assure that you are promptlv aleded to a lists criteria for notification in the event of degraded grid conditions.

worsening grid condition that may emerge during: a maintenance activity.

(g) Do you contact your TSO periodically for the duration of the pid-risk-sensitive The Southern Company Electric System Transmission Power Quality Guide for VEGP maintenance activities? states that VEGP Operators have the responsibility to notify Transmission System Operators when they become aware of conditions that could jeopardize plant safety and/or the electrical grid reliability. The specific actions are governed by system and plant procedures. For example, the plant procedure for an extended Emergency Diesel Generator Allowed Out of Service Time specifies the notification of the Transmission System Operator prior to removing the Emergency Diesel Generator from service that any maintenance must be carefully evaluated and approved by VEGP Management prior to release for work to ensure offsite power is not jeopardized. During the extended Emergency Diesel Generator Allowed Out of Service Time, VEGP operators are to

VEGP Response to GL 2006-02 Requested Information periodically verify with the Transmission System Operator that no maintenance is in progress in the VEGP high or low voltage switchyards that would challenge off site power to the VEGP units and that no impending extremely severe weather or system instabilities as defined in the procedure exist.

(h) If you have a formal agreement or protocol with your TSO, describe how NPP The VEGP Power Quality Guide outlines typical responsibilities of the various operators and maintenance personnelare organizations involved in maintaining the VEGPIgrid interface.

trained and tested on this formal agreement or protocol. Operator training at VEGP is based upon plant procedures. Operator training programs have degraded and loss of grid events embedded in the program. Operations personnel are trained and have procedural guidance covering notifying the Transmission System Operator for certain grid-related configurations.

A discussion of the Power Quality Guide for VEGP has been included in the continuing training program and plant procedure changes are evaluated for training impact and added to training committee agendas for evaluation. Operator training is evaluated either by written examinations or during performance in the simulator.

Work Control personnel are familiar with the Power Quality Guide, but are currently not formally trained on the Power Quality Guide.

(i) If your grid reliability evaluation, Per the VEGP Maintenance Rule Scoping Manual concerning the Division of performed as part, of the maintenance risk Responsibility of Switchyard Equipment Under the Maintenance Rule, work to be assessment required by 10 CFR performed by the Transmission Maintenance Center (TMC) on switchyard equipment 50.65(a)(4), does not consider or rely on which might affect either of the units is conveyed to the VEGP Work Week Coordinators some arrangement for communication via E-mail or a telephone call prior to the work being performed in order to obtain an with the TSO, explain why you believe you assessment on plant operation. The maintenance is then included in the plant work control risk assessment process. Per VEGP Procedure 00354-C, "Maintenance comply with 10 CFR 50.65(a)(4).

Scheduling" a qualitative safety assessment is performed.

(j) If risk is assessed (when warranted) based on continuing communication with Plant configuration maintenance and PRA personnel are well aware of the importance of the TSO throughout the duration of grid- LOOP sequences and how they are impacted by plant configuration. The

VEGP Response to GL 2006-02 Requested Information risk-sensitive maintenance activities, communication with the TSO, including the associated process, is a plant-specific and explain why you believe you have situation-specific attribute. 10CFR50.65(a)(4) is a risk informed performance based rule; effectively implemented the relevant it is not intended to be prescriptive with regard to "one size fits all" risk assessment and provisions of the endorsed industry management actions.

guidance associated with the maintenance rule. The point of risk assessment under 10CFR50.65(a)(4)is not intended to be a numerical exercise but rather to highlight the condition of the plant and ensure the plant staff is aware of the safety implications of maintenance work so that the proper risk management actions can be taken. Once the implications of the work are known, well rehearsed risk management practices can be implemented. Sometimes, the risk management action is to defer the work to another time.

(k) With respect to questions 5(i) and 5(j),

you may, as a n alternative, describe what actions you intend to take to ensure t h a t No alternative actions-the increase in risk t h a t may result &om proposed grid-risk-sensitive activities is assessed before and during grid-risk-sensitive maintenance activities, respectively.

w,ki&&

V q ufiL&$k *&sv@t,&sdb,

&y>~&&@R~$Q+&~c~x&)-

iacI$@@the kal& ofgrid ~ & r 3 . i ~ ' + ~ 1 u a 'k ~ onuin&

mt m&ka-'*Tc, (a) Does the TSO coordinate transmission system maintenance activities that can Yes. VEGP offsite power requirements are considered in all planned transmission outage have a n impacton the N p p operation with assessments. Requests identified as potentially impacting VEGP requirements are the NPP operator? coordinated directly with VEGP.

(b) Do you coordinate NPP maintenance activities that can have an impact on the Yes. For the last several years on an annual basis, meetings between VEGP and the transmission system with the TSO? Georgia Power Company Transmission Maintenance Center have been held to discuss

VEGP Response to GL 2006-02 Requested Information how maintenance and testing of emergency power systems or other equipment important to plant safety and grid maintenance and testing are coordinated between the plant and grid operators to minimize nuclear safety risks. For example, in 2005, a meeting was held between VEGP, Plant Wilson, and Georgia Power Company Transmission Maintenance Center (TMC) representatives to discuss the VEGP 2005 work plan for switchyard and large power transformer maintenance, tests, inspections and repairs. The meeting emphasized a proposed work planning schedule in relation to minimizing nuclear plant risk particularly during refueling outage periods. Also discussed were offsite power source and 230KV bus testing and included industry operating experience concerning breaker and relay testing. More frequent meetings are being scheduled for 2006.

(c) DOyou consider and implement, if warranted, the rescheduling of grid-risk- Yes. Maintenance that has an associated trip risk is performed when the on-shift VEGP sensitive maintenance activities (activities personnel conclude that the risk of the work is small compared to the safety benefit.

that could (i) increase the likelihood of a When the maintenance work is done in response to a Technical Specification, the risk plant trip, (ii) increase LOOP probability, assessment is informative for sequencing tasks, but not controlling.

or (iii) reduce LOOP or SBO coping capability) under existing, imminent, or Maintenance that has an associated trip risk would be activities such as the following:

worsening degraded grid reliability conditions? RPS calibrations, ATWS, CRD testing, main turbine control testing or switchyard breaker cycling.

Emergent issues are managed to maintain a high level of plant safety. At times appropriate management means rescheduling activities, at other times the shift-supervisor will order the on-shift VEGP staff to back-out of the task and restore the safety-related function of the equipment. It is important that stations know the detail and content of maintenance activities so that an informed assessment can be completed.

(d) If there is an overriding need to

VEGP Response to GL 2006-02 Requested Information perform grid-risk-sensitive maintenance Yes. Same response as 6(c).

activities under existing or imminent conditions of degraded grid reliability, or TSO would take appropriate actions to ensure the required voltage would be maintained continue grid-risk-sensitive maintenance per the h ~ e Quality r Guide-when grid conditions worsen, do you implement appropriate risk management actions? If so, describe the actions that you would take. (These actions could include alternate equipment protection and compensatory measures to limit or minimize risk.)

(e) Describe the actions associated with questions 6(a) through 6(d) above that Scheduled maintenance activities on the transmission grid are entered into the Equipment would be taken, state whether each action Outage Scheduler (EOS) and assessed across the 0 to 13 month Operational Planning is governed by documented procedures horizon for their impact on transmission system reliability. All scheduled outages are and identify the procedures, and explain included in the base case developed each day by the TSO and assessments are performed why these actions are effective and will be to identify adverse impacts on the VEGP.

consistently accomplished.

As documented in the Power Quality Guide for VEGP, section 6.4, the TSO is responsible for maintenance activities in the VEGP substation. These activities are performed by the Georgia Power Company (GPC) Middle Georgia Transmission Maintenance Center (TMC). The GPC TMC is responsible for :

Maintaining access control to the VEGP switchyards, Performance of corrective maintenance, preventive maintenance surveillance inspections and testing of all substation equipment including the switchyard house and yard lights.

In conjunction with VEGP, establishing guidelines for the use of vehicles and heavy equipment within the switchyard area to ensure operation, movement, or use of such equipment will be performed in a manner to reduce the possibility of loss of power to plant systems or switchyards.

Providing status of corrective maintenance items to VEGP.

Observing the guidelines stated in Appendix A (work responsibilities for VEGP and Plant Wilson switchyards)

VEGP Response to GL 2006-02 Requested Information These responsibilities are documented in the Power Quality Guide for VEGP, section 6.4. As per the requirements of Appendix A of the VEGP Power Quality Guides the GPC TMC provides a yearly forecast of scheduled equipment maintenance and provides input for outage related activities to VEGP three months in advance of scheduled outages. Maintenance at the VEGP switchyard is performed as per the requirements of the Georgia Power Company Procedures for the Maintenance of Substation Equipment.

Regarding the coordination and communication of grid-related activities with the TSO, VEGP Operations personnel are trained and have procedural guidance covering when, and how to notify the Transmission System Operator (TSO), PCCIGCCiTMC for configurations identified as being GRID related in Unit Operating Procedures (UOPs),

System Operating Procedures (SOPS), Abnormal Operating Procedures (AOPs),

Emergency Operating Procedures (EOPs), and Annunciator Response Procedures (ARPs).

Regarding the scheduling of grid-sensitive maintenance activities, the major switching or pre-planned maintenance that occurs in the electrical switchyard is approved through the Power Coordination Center and is communicated to designated VEGP staff members. The maintenance is then included in the plant work control risk assessment process. Per VEGP Procedure 00354-C, "Maintenance Scheduling" a qualitative safety assessment using the following guidelines is performed and a summary of the results are included in the POD.

These guidelines establish an envelope which bounds out of service equipment within the assumptions of the Maintenance Rule performance criteria, Technical Specifications, and accident analyses.

Avoid maintenance on the protected train.

Avoid removing from service multiple safety-significant components in the same train at the same time.

Place standby components in service, where available, to perform the function of equipment removed from service.

VEGP Response to GL 2006-02 Requested Information Maintain out of service hours within the Maintenance Rule performance criteria and evaluate the impact of these out of service hours on NRC performance indicators. )

Avoid maintenance on sensitive or critical equipment during periods of severe weather forecasts, grid degradation, or system alert conditions.

The qualitative safety assessment should also consider the effects of work, plant conditions, and weather conditions that are judged to have a significant impact on the probability of a reactor trip, turbine trip, or loss of off-site power (e.g., tornado watch, hurricane forecast, high risk switchyard work, MSIV/MFIV/EHC work, etc.).

(0 Describe how NPP operators and maintenance personnel are trained and There currently is no formal training that addresses the concerns of this question.

tested to assure they can accomplish the actions described in your answers to question 6(e).

(g) If there is no effective coordination between the NPP operator and the TSO Not applicable. There is effective coordination between the VEGP operator and the TSO regarding transmission system regarding transmission system maintenance or VEGP maintenance activities. Such maintenance or NPP maintenance coordination is in accordance with the agreements.

activities, please explain why you believe you comply with the provisions of 10 CFR 50.65(a)(4).

(h) If you do not consider and effectively implement appropriate risk management Not applicable. As discussed in questions 6 ( a ) 4 ( d ) , VEGP effectively implements actions during the conditions described appropriate risk management actions.

above, explain why you believe you effectively addressed the relevant provisions of the associated NRC-endorsed industry guidance.

(i) You may, as a n alternative to questions

VEGP Response to GL 2006-02 Requested Information 6(g) and 6(h) describe what actions you Not applicable.

intend to take to ensure that the increase in risk that may result from grid-risk-sensitive maintenance activities is managed in accordance with 10 CFR 50.65(a)(4).

VEGP Response to GL 2006-02 Requested Information Offsite power restoration procedures in accordance with 10 CFR 50.63 a s developed in Section 2 of RG 1.155 Pursuant to 10 CFR 50.63, the NRC requires that each NPP licensed to operate be able to withstand a n SBO for a specified duration and recover from the SBO. NRC RG 1.155 gives licensees guidance on developing their approaches for complying with 10 CFR 50.63.

m u

g{

LObp**at.

Note: Section 2, "Offsite Power," of RG 1.155 (ADAMS Accession No. ML003740034) states:

Procedures should include the actions necessary to restore offsite power and use nearby power sources when offsite power is unavailable. As a minimum, the following potential causes for loss of offsite power should be considered:

- Grid under-voltage and collapse

- Weather-induced power loss

- Preferred power distribution system faults that could result in the loss of normal power to essential switchgear buses (a) Briefly describe any agreement made with the TSO to identify local power The TSO will utilize the best sources available for specific events to restore offsite power sources that could be made available to re- and to determine the specific power sources and paths, since there is no way to predict supply power to your plant following a the extent and characteristics of a specific blackout. The TSO has many options LOOP event. available to restore offsite power and would not be limited to identified local power sources.

An agreement is in place to restore power to the VEGP on a priority basis. In addition, a grid operations procedure provides detailed instructions for prompt VEGP offsite power restoration. The procedure specifies various means of accomplishing the required power restoration. Grid operators train on this procedure per NERC training requirements.

This includes items such as nearby or onsite gas turbine generators, portable generators, hydro generators, and black-start fossil power plants.

VEGP Response to GL 2006-02Requested Information (b) Are your NPP operators trained and tested on identifying and using local Yes. VEGP has EOPs for LOOP and offsite power recovery; VEGP operators are power sources to resupply your plant trained and tested on these procedures.

following a LOOP event? If so, describe how. AX3BB02-00001 Power Quality Guide for VEGP summarizes the requirements of the offsite power system. It also delineates guidelines for use in Southern Electric System transmission planning and operational activities to ensure the safe and reliable operation of VEGP. This guideline includes the system power supplies that can be used to supply VEGP in the event of a LOSP.

VEGP personnel are trained on the emergency diesel generators (Operations CL-1I), and procedures (CL-37 & CL-60). Additionally simulator scenarios have been developed for practical exercises for the response to degraded grid conditions, the loss of offsite power, and restoration of power following a loss of offsite power.

System Operators are trained to be able to align the Plant Wilson switchyard, operate the Diesel Generator and operate the Combustion Turbine in the event of a "System Blackout" at VEGP. This ensures Plant Wilson will be able to supply station service for Plant Wilson, supply power to the VEGP Standby Auxiliary Transformer (SAT) by means of the 13.8 kv underground feeder circuit.

Testing is provided by written examinations, simulator evaluations and job performance measures.

(c) If you have established a n agreement with your plant's TSO to Not applicable; an agreement exists.

identify local power sources t h a t could be made available to resupply power to your The TSO has the responsibility to restore offsite power to the VEGP as a priority. The plant following a LOOP event, explain TSO will utilize the best sources available for specific events to restore offsite power and why you believe you comply with the to determine the specific power sources and paths, since there is no way to predict the provisions of 10 CFR 50.63, or describe extent and characteristics of a specific blackout. The TSO has many options available to what actions you intend to take to restore offsite power and would not be limited to identified local power sources.

establish compliance.

VEGP Response to GL 2006-02 Requested Information Losses of offsite power caused by grid failures at a frequency of equal to or greater than once in 20 site-years in accordance with Table 4 of Regulatory Guide 1.155 for complying with 10 CFR 50.63 Pursuant to 10 CFR 50.63, the NRC requires that each NPP licensed to operate be able to withstand an SBO for a specified duration and recover from the SBO. NRC RG 1.155 gives licensees guidance on developing their approaches for complying with 10 CFR 50.63.

8.'" +em'&& .jo, ~ ~ ~ ' r i ' @ i @ +

(a) Has your NPP experienced a total LOOP caused by grid failure since the No.

plant's coping duration was initially determined under 10 CFR 50.63?

(b) If so, have you reevaluated the NPP using the guidance in Table 4 of RG 1.155 Not applicable.

to determine if your NPP should be assigned to the P3 offsite power design characteristic group?

(c) If SO, what were the results of this reevaluation, and did the initially Not applicable.

determined coping duration for the NPP need to be adjusted?

(d) If your NPP has experienced a total LOOP caused by grid failure since the Not applicable.

plant's coping duration was initially determined under 10 CFR 50.63 and has not been reevaluated using the guidance in Table 4 of RG 1.155, explain why you believe you comply with the provisions of 10 CFR 50.63 as stated above, or describe

VEGP Response to GL 2006-02 Requested Information what actions you intend to take to ensure that the NPP maintains its SBO coping capabilities in accordance with 10 CFR 50.63.