L-HU-06-030, Response to Generic Letter 2006-02, Grid Reliability and the Impact on Plant Risk and the Operability of Offsite Power.

Response to Generic Letter 2006-02, Grid Reliability and the Impact on Plant Risk and the Operability of Offsite Power.

ML062050349
Person / Time
Site:	Monticello, Palisades, Point Beach, Prairie Island
Issue date:	07/21/2006
From:	Weinkam E Nuclear Management Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
GL-06-002, L-HU-06-030
Download: ML062050349 (125)

Text

Nuclear Management Company, LLC L-HU-06-030 July 21, 2006 10 CFR 50.54(f)

U. S. Nuclear Regulatory Commission ATTN: Document Control Desk 11555 Rockville Pike Rockville, Maryland 20852 Point Beach Nuclear Plant Units 1 and 2 Palisades Nuclear Plant Dockets 50-266 and 50-301 Docket 50-255 Renewed License Nos. DPR-24 and DPR-27 License No. DPR-20 Prairie Island Nuclear Generating Plant Monticello Nuclear Generating Plant Units 1 and 2 Docket 50-263 Dockets 50-282 and 50-306 License No. DPR-22 License Nos. DPR-42 and DPR-60 Response to Generic Letter 2006-02, Grid Reliability and the Impact on Plant Risk and the Operability of Offsite Power By letter dated February 1, 2006, the Nuclear Regulatory Commission (NRC) issued Generic Letter (GL) 2006-02, Grid Reliability and the Impact on Plant Risk and the Operability of Offsite Power. The NRC requested that specific information be provided within 60 days of the date of this GL. The Nuclear Management Company, LLC (NMC) submitted the requested information by letter L-HU-06-010 dated April 3, 2006.

In response to an NRC request, NMC submits this letter and enclosures which replace NMC letter L-HU-06-010 dated April 3, 2006 and its enclosures in their entirety.

Enclosures 1 through 4 provide the requested information for the Point Beach Nuclear Plant, Palisades Nuclear Plant, Prairie Island Nuclear Plant and Monticello Nuclear Plant, respectively.

Some of the questions in GL 2006-02 seek information about analyses, procedures, and activities concerning grid operation of which the Nuclear Management Company, LLC (NMC) does not have first-hand knowledge and of which are beyond the control of NMC. In providing information responsive to such questions, NMC makes no representation as to their accuracy or completeness.

Some GL 2006-02 questions are directed toward compliance with 10CFR Part 50, Appendix A, General Design Criteria, (GDC) Criterion 17. The NMC-operated plants were licensed prior to the formal publication of the GDC. As noted in SECY-92-223, all plants with Construction Permits issued prior to May 21, 1971 are not subject to these provisions and each licensee has its own licensing basis. As a Systematic Evaluation 700 First Street Hudson, Wisconsin 54016 Telephone: 715-377-3300

Document Control Desk Page 2 Program (SEP) plant, the Palisades Nuclear Plant complies with GDC 17 to the extent described in the Technical Specification Bases and the Final Safety Analysis Report.

Generally, the NMC-operated plants were licensed to comply with the Atomic Energy Commission General Design Criteria as proposed on July 10, 1967 (AEC GDC) as described in the plant Final (Updated) Safety Analysis Report. AEC GDC proposed Criterion 39, which provides guidance applicable to the design of the AC electrical power system supplies to the engineered safety features, states:

Alternate power systems shall be provided and designed with adequatle independency, redundancy, capacity, and testability to permit the functioning required of the engineered safety features. As a minimum, the onsite power system and the offsite power system shall each, independently, provide this capacity assuming a failure of a single active component in each power system.

Thus, many of the provisions of GDC Criterion 17 are not applicable to the NFJC-operated plants, the responses to the questions reflect that the plants are not committed to GDC Criterion 17, and the responses do not in any manner commit to or imply compliance with GDC Criterion 17 for the NMC-operated plants.

Summary of Commitments This letter contains no new commitments and no revisions to existing commitments.

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

Executed on 21 ~ulG2006.

&r$.~. Wdkam Director, Nuc ear Licensing and Regulatory Services Nuclear Management Company, LLC Enclosures (4) cc: Administrator, Region Ill, USNRC Project Manager, Point Beach Nuclear Plant, Palisades Nuclear Plant, Prairie Island Nuclear Generating Plant, and Monticello Nuclear Generating Plant, USNRC Senior Resident Inspector, Point Beach Nuclear Plant, Palisades Nuclear Plant, Prairie Island Nuclear Generating Plant, and Monticello Nuclear Generating Plant, USNRC PBNP Response to Requested Information GL 2006-02, July 21, 2006 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).

Question 1

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 Yes. The Transmission System Operator (TSO) to which the Point Beach Nuclear Plant agreement or protocol with (PBNP) supplies power is the American Transmission Company (ATC, referred to as the TSO your TSO? in this response). The PBNP is owned by We Energies and operated by Nuclear Management Company, LLC (NMC). Although NMC is the plant operating entity, references to management actions on behalf of PBNP in the remainder of this document are referred to as PBNP.

PBNP does have a formal agreement with We Energies and ATC. In addition, PBNP and the TSO follow the approved Midwest Independent System Operator (MISO) communication and mitigation protocols for nuclear plant/electric system interfaces that describe the notification requirements.

(b) Describe any grid The TSO is required to notify PBNP immediately whenever the real time voltage on the PBNP conditions that would trigger 345 kV bus goes outside of specified voltage limits (high or low). These limits are intended to a notification from the TSO to ensure that adequate voltage is present to supply safety related equipment and prevent the NPP licensee and if there actuation of the degraded grid voltage relays. Specific examples of known potentially is a time period required for degrading conditions identified in the agreement include:

1 of 29 PBNP Response to Requested Information GL 2006-02, July 21, 2006 Question 1 the notification 1. The TSO will notify PBNP within 15 minutes after verification, if it is determined that the loss of any single transmission element or generator connected to the TSO transmission system would cause the PBNP 345 kV bus voltage to go outside of the specified limits. If the condition triggering the notification is resolved within the notification time requirement, then notification is not required.

2. The TSO will notify PBNP of forced outages on either end of any 345 kV transmission line connected to the PBNP switchyard as well as other critical transmission lines.

3. Notifications for VAR adjustments are routinely made by the TSO through We Energies Power System Supervisors (WEPSS) to PBNP. In an emergency the TSO may communicate directly to PBNP.

(c) Describe any grid Grid conditions and status are the primary responsibility of the TSO and Reliability Coordinator conditions that would cause (MISO). PBNP does not typically initiate communication with the TSO based upon grid the NPP licensee to contact conditions. PBNP relies upon the agreements and protocols to be notified of grid conditions the TSO. as described in the response to question 1(b) above. PBNP procedures address conditions that could affect the grid and that require communication with the TSO. These Describe the procedures communications are normally through WEPSS. Reasons for notifications include: removal associated with such a from service or testing of emergency diesel generators or the gas turbine generator, either unit communication. If you do not voltage regulator placed in manual, or power system stabilizer out of service on either unit.

have procedures, describe how you assess grid conditions that may cause the NPP licensee to contact the TSO.

(d) Describe how NPP Review of the procedure for electrical communications, switchyard access and work planning operators are trained and is typically performed in initial license operator training as a result of an association to the task tested on the use of the that is being trained. Senior Reactor Operators (SROs) are trained and evaluated via the On-2 of 29 PBNP Response to Requested Information GL 2006-02, July 21, 2006 Question 1 procedures or assessing grid the-Job Training (OJT) and Task Performance Evaluation (TPE) process on coordinating with conditions in question 1(c). TSO/WEPSS for load changes.

Control Operators (and instant SROs) are trained and evaluated via the OJT and TPE process on performing a Technical Specification (TS) Test of the Emergency Diesel Generators (EDG).

Contained within the TS procedures are Initial Conditions and a procedural step requiring notifications to TSO and WEPSS of testing EDGs.

Control Operators (and instant SROs) are trained and evaluated via the OJT and TPE process on performing a start of the gas turbine. Contained within the Operating Instructions are Precautions and Limitations and a procedural step directing notification to WEPSS of operating the gas turbine generator.

During classroom training on the 345 kV sstem, operators are presented an overview of the procedure for electrical communications, switchyard access and work planning.

During classroom training on normal power operations, operators discuss the responsibilities of the WEPSS regarding 345 kV voltage control as listed in plant procedures.

Selected procedural topics may also be reviewed as part of task-based training in the classroom or simulator. Recent examples of training as part of a task review are:

During licensed operator continuing training on Loss of Offsite Power and Significant Operating Event Report (SOER) 99-01, Loss of Grid, in 2006: a review of the procedural communication responsibilities for the TSO, PBNP Production Planning Group, and PBNP Shift Supervision was conducted as part of a discussion on the lessons learned from the August 2003 Loss of Grid event outlined in SOER 99-01 addendum.

During licensed operator continuing training on Post Trip Stabilization in 2004: operators implemented the procedural steps requiring them to notify the TSO when the main generator disconnects are opened.

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

formal agreement or protocol 3 of 29 PBNP Response to Requested Information GL 2006-02, July 21, 2006 Question 1 with your TSO, describe why 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.

(f) If you have an existing As previously stated in response to question 1(a), PBNP does have a formal TSO agreement.

formal interconnection Grid conditions in which the TSO will notify PBNP are described in the response to question agreement or protocol that 1(b) above. This includes conditions in which real-time voltage or the contingent loss of any ensures adequate single transmission element or generator connected to the TSO transmission system would communication and result in PBNP 345 kV bus voltage above or below the specified limits.

coordination between the NPP licensee and the TSO, describe whether this agreement or protocol requires that you be promptly 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 At PBNP, degraded voltage is not sensed in the switchyard. The degraded voltage protection 4 of 29 PBNP Response to Requested Information GL 2006-02, July 21, 2006 Question 1 switchyard voltage conditions scheme senses voltage at the 4.16 kV safety related buses. Initiation of the degraded voltage that would initiate operation protection would occur if the 345 kV system (switchyard) voltage would drop to a point where of plant degraded voltage safety related 4.16 kV bus voltage would reach the degraded voltage relay dropout setpoint.

protection. Current PBNP Technical Specification degraded voltage allowable values are: Greater than or equal to 3937 Volts; time delay of less than 6.47 seconds with a Safety Injection (SI) signal present; time delay of less than 54 seconds without an SI signal present. Therefore, if switchyard voltage was at or below minimum per operating procedures, the degraded voltage protection scheme may initiate depending upon plant operating conditions (normal operation, loss of coolant accident (LOCA), unit trip, etc.). The degraded voltage protection scheme ensures that the safety related equipment will have sufficient voltage to perform their designated safety functions while supplied from offsite power, or the equipment will be separated from offsite power and supplied from the onsite emergency power system.

Question 2

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 NPPs TSO Yes. The TSO makes use of analysis tools to predict grid conditions that would make the use any analysis tools, an PBNP offsite power system non-functional. These tools are not available to the PBNP.

online analytical transmission The TSO currently uses both offline (PSSE, Areva, POM/OPM, VSAT, etc.) and online (Areva system studies program, or energy management system) analytical tools to determine grid conditions under a variety of other equivalent predictive situations. The online analysis is performed approximately once every 5 minutes while the methods to determine the offline analysis is performed on an as needed basis. Note that the TSO can change the grid conditions that would selection and use of the analytical tools, provided they perform the functions required to make the NPP offsite power support the agreements and protocols.

system inoperable during 5 of 29 PBNP Response to Requested Information GL 2006-02, July 21, 2006 Question 2 various contingencies?

If available to you, please provide a brief description of the analysis tool that is used by the TSO.

(b) Does your NPPs TSO Yes. The TSO uses the above analysis tools, in conjunction with procedures, as the basis for use an analysis tool as the determining when conditions warrant PBNP notification. Notifications are made based on grid basis for notifying the NPP configurations being outside of predefined procedure requirements or based on unsatisfactory licensee when such a monitoring and predictive analysis computer program tool results. Refer to the response to condition is identified? If not, question 1(b) above.

how does the TSO determine if conditions on the grid warrant NPP licensee notification?

(c) If your TSO uses an The analysis tools identify when a trip of either PBNP unit would result in switchyard voltages analysis tool, would the falling below the specified limit. The analysis tools determine grid voltages that would occur analysis tool identify a immediately as the result of the unit trip, based upon the current grid configuration.

condition in which a trip of the Following a unit trip, the analysis tools would continue to monitor grid configuration and would NPP would result in identify N-1 contingencies that would result in switchyard voltages falling below the specified switchyard voltages limit.

(immediate and/or long-term) falling below TS nominal trip setpoint value requirements (including NPP licensees using allowable value in its TSs) and consequent 6 of 29 PBNP Response to Requested Information GL 2006-02, July 21, 2006 Question 2 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 The TSOs current online analysis tool updates approximately every 5 minutes. It will analysis tool, how frequently immediately update following the operation of any breaker 100 kV or greater, or as initiated by does the analysis tool the system operator. The TSO completes off-line studies on an as needed basis. Note that program update? the TSO can change the selection and use of the analytical tools, provided they perform the functions required to support the agreements and protocols.

(e) Provide details of analysis The contingencies that are modeled and studied include the loss of any single TSO tool-identified contingency transmission line or transformer as well as any generator connected to the TSOs system.

conditions that would trigger The contingency definition for the loss of either PBNP unit includes the transfer of its auxiliary an NPP licensee notification load from the main auxiliary transformer to the associated reserve auxiliary transformer.

from the TSO. PBNP is notified whenever any N-1 contingency results in voltages outside of predefined limits.

(f) If an interface agreement Yes. If the TSO loses the ability to monitor and predict the operation of the transmission exists between the TSO and system, they would validate that MISO maintained this ability and would also notify PBNP. If the NPP licensee, does it MISO also lost this ability, the TSO would continue to monitor the grid and would perform require that the NPP licensee offline studies or would confirm that the real-time conditions were within the existing study be notified of periods when assumptions. Therefore, if the on-line analysis tools were out-of-service, operability would the TSO is unable to continue to be evaluated.

determine if offsite power 7 of 29 PBNP Response to Requested Information GL 2006-02, July 21, 2006 Question 2 voltage and capacity could be inadequate?

If so, how does the NPP licensee determine that the offsite power would remain operable when such a notification is received?

(g) After an unscheduled No. For post event analysis, the TSO does not verify by procedure the switchyard voltages inadvertent trip of the NPP, are bounded by the analysis tools. Following an inadvertent trip of one or both PBNP units, are the resultant switchyard any unexpected actuations or equipment operation associated with supply voltage would be voltages verified by documented and evaluated in accordance with the corrective action process.

procedure to be bounded by the voltages predicted by the analysis tool?

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

available to the NPP licensees TSO, do you know if there are any plans for the TSO to obtain one? If so, when?

(i) If an analysis tool is not Not applicable to PBNP since the TSO analysis tools are presently in use.

available, does your TSO perform periodic studies to verify that adequate offsite 8 of 29 PBNP Response to Requested Information GL 2006-02, July 21, 2006 Question 2 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 provisions discussed in question 1 above?

(j) If your TSO does not use, Not applicable to PBNP since the TSO utilizes analysis tools and communicates the applicable or you do not have access to results to PBNP.

the results of an analysis tool, or your TSO does not perform and make available to you periodic studies that determine the adequacy of offsite power capability, 9 of 29 PBNP Response to Requested Information GL 2006-02, July 21, 2006 Question 2 please describe why you believe you comply 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.

Question 3

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

(a) If the TSO notifies the By procedure, PBNP will declare the associated offsite power circuits inoperable and enter the NPP operator that a trip of associated Technical Specification Action Condition (TSAC) when the TSO notifies PBNP that the NPP, or the loss of the a single element (most limiting) failure can cause the 345 kV system to drop below the most critical transmission line specified minimum voltage. This procedural control, which enters the TSAC based on a or the largest supply to the postulated single element failure, is more restrictive than the plant licensing basis which states grid would result in that the sudden loss of any single generating unit will not affect the ability of the transmission switchyard voltages system to supply power to the PBNP auxiliary systems.

(immediate and/or long-term) below TS nominal trip setpoint value requirements 10 of 29 PBNP Response to Requested Information GL 2006-02, July 21, 2006 Question 3 (including NPP licensees using allowable value in its TSs) and would actuate plant degraded voltage protection, is the NPP offsite power system declared inoperable under the plant TSs? If not, why not?

(b) If onsite safety-related The plant accident analyses evaluate a loss of offsite power (LOOP) occurring coincident with equipment (e.g., emergency various accidents. A postulated double sequencing event is outside the plants licensing basis diesel generators or safety- and has not been evaluated. Equipment operability is based on performance of safety related motors) is lost when functions and safety support functions required within the plant licensing basis.

subjected to a double sequencing (LOCA with delayed LOOP event) as a result of the anticipated system performance 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?

(c) Describe your evaluation Double sequencing is not in the PBNP licensing basis and PBNP is not designed or analyzed of onsite safety-related for double sequencing scenarios.

equipment to determine 11 of 29 PBNP Response to Requested Information GL 2006-02, July 21, 2006 Question 3 whether it will operate as designed during the condition described in question 3(b).

(d) If the NPP licensee is No. Technical Specification Conditions are not entered for grid conditions other than those notified by the TSO of other mentioned above.

grid conditions that may impair the capability or availability of offsite power, are any plant TS action statements entered? If so, please identify them.

(e) If you believe your plant Not applicable to PBNP since offsite power sources will be declared inoperable as described TSs do not require you to in the response to question 3(a) above in accordance with the plant licensing basis and declare your offsite power Technical Specifications.

system or safety-related equipment inoperable in any of these circumstances, explain why you believe you comply with the provisions of GDC 17 and 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 12 of 29 PBNP Response to Requested Information GL 2006-02, July 21, 2006 Question 3 inadequate.

(f) Describe if and how NPP The compensatory actions discussed in response to questions 3(a) through 3(e) involve operators are trained and entering Technical Specification Conditions. PBNP operators are trained in the interpretation tested on the compensatory and use of plant Technical Specifications and associated compensatory measures.

actions mentioned in your answers to questions 3(a) through (e).

Question 4

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 Yes. Procedural guidance is provided to the PBNP operators. Guidance is provided in the have any guidance or PBNP normal power operation procedure for controlling the generator voltage regulators and procedures in plant TS bases the power system stabilizers and notifying the TSO through WEPSS when the voltage sections, the final safety regulators are placed in manual or the power system stabilizers are disabled.

analysis report, or plant PBNP does not have tap changing transformers, capacitor banks or VAR compensators.

procedures regarding situations in which the Operator training on electrical communications, switchyard access and work planning occurs condition of plant-controlled as indicated in the response to question 1(d). The power system stabilizers are relatively new or -monitored equipment pieces of equipment at PBNP. Operators were trained on the power system stabilizers after (e.g., voltage regulators, auto their installation.

tap changing transformers, capacitors, static VAR 13 of 29 PBNP Response to Requested Information GL 2006-02, July 21, 2006 Question 4 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, Not applicable. PBNP does have procedural guidance that provides the operator with written the final safety analysis direction for responding to equipment malfunctions and manipulation of controls that can report, and plant procedures adversely affect the operability of the PBNP offsite power system.

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.

14 of 29 PBNP Response to Requested Information GL 2006-02, July 21, 2006 Use of NPP licensee/TSO 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.

Question 5

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 Yes. The effect on the maintenance risk assessment of plant activities, environmental qualitative grid reliability conditions, or grid conditions that affect offsite power reliability at PBNP is included evaluation performed at your quantitatively, but this is done by using a qualitatively-derived multiplier for the LOOP NPP as part of the frequency in the calculation. PBNP utilizes a software tool to perform on-line risk maintenance risk assessment management. The safety monitor tool calculates the risk of a particular plant configuration required by 10 CFR using the probabilistic risk assessment (PRA) model for the appropriate unit. The complete 50.65(a)(4) before performing plant configuration includes which equipment is unavailable, the alignment of running and grid-risk-sensitive standby plant equipment, and any environmental/test factors in effect. Four of the maintenance activities? This environmental/test factors in Safety Monitor increase the LOOP frequency in the PRA includes surveillances, post- calculation above the base value by using either one of two multipliers. The intent of these maintenance testing, and multipliers is to move the LOOP frequency to the upper end of the statistical distribution while preventive and corrective the associated testing, grid condition or environmental condition is in effect. By including the maintenance that could impact this way, the PRA results are made more sensitive to those other activities that affect increase the probability of a the ability of PBNP to mitigate the impact of a loss of offsite power, such as maintenance on plant trip or LOOP or impact an emergency diesel generator or on a turbine driven auxiliary feedwater pump.

LOOP or SBO coping capability, for example, before taking a risk-significant piece of equipment (such as an EDG, a battery, a steam-15 of 29 PBNP Response to Requested Information GL 2006-02, July 21, 2006 Question 5 driven pump, an alternate AC power source) out-of-service?

(b) Is grid status monitored by Notifications of operating criteria violations are made as described above in the response to some means for the duration question 1(b) above. Risk would be reassessed upon this notification. In addition the online of the grid-risk-sensitive risk management tool contains factors that can be applied for onsite switchyard work, some maintenance to confirm the types of grid work, peak demand, severe weather, and severe cold. Online risk is monitored continued validity of the risk on a real time basis by the shift technical advisors to validate the planned risk assessment.

assessment and is risk reassessed when warranted?

If not, how is the risk assessed during grid-risk-sensitive maintenance?

(c) Is there a significant Typically the grid carries more power during summer months due to heavier loading. However variation in the stress on the the stress on the grid is a function of what equipment is in service and the ability of the grid to grid in the vicinity of your handle the increased loading. Grid stress varies and can be affected by weather-related or NPP site caused by seasonal other equipment failures, planned outages, or periods of high demand. Planned outages and loads or maintenance maintenance consider grid conditions and seasonal demand to manage overall grid stress.

activities associated with Existing procedures and protocols used by the TSO provide guidance on the grid operations critical transmission to maintain grid reliability and stability.

elements? Current industry data is inconclusive relative to the degree of seasonal variation in LOOP Is there a seasonal variation frequency. Because LOOP frequency for PBNP is very low and because outages and (or the potential for a maintenance are effectively managed, there is no identified seasonal variation in LOOP seasonal variation) in the frequency.

LOOP frequency in the local transmission region?

If the answer to either 16 of 29 PBNP Response to Requested Information GL 2006-02, July 21, 2006 Question 5 question is yes, discuss the time of year when the variations occur and their magnitude.

(d) Are known time-related Seasonal variations in the LOOP probability are not significant at PBNP and therefore do not variations in the probability of provide a usable basis for an adjustment in the safety monitor LOOP frequency determined a LOOP at your plant site solely from those variations. The safety monitor tool has environmental/test factors for grid considered in the grid-risk- work, switchyard work, peak demand, and severe weather to account for other variations in sensitive maintenance LOOP probability. Criteria for when to include these factors are contained in the on-line safety evaluation? If not, what is assessment procedure.

your basis for not considering them?

Yes. PBNP coordinates with the TSO to schedule and implement major work in the PBNP (e) Do you have contacts with switchyard. PBNP will contact the TSO when scheduling work activities that remove the G-05 the TSO to determine current gas turbine or an EDG from service to verify that line outages and other work which may and anticipated grid reduce reliability of the offsite power supplies is not scheduled concurrently.

conditions as part of the grid reliability evaluation performed before conducting grid-risk-sensitive maintenance activities?

(f) Describe any formal The TSO will notify PBNP in accordance with the agreement discussed in response to agreement or protocol that question 1(a) based upon grid conditions described in the response to question 1(b) above.

you have with your TSO to These notifications would be provided to PBNP whether or not maintenance is on-going.

assure that you are promptly alerted to a worsening grid 17 of 29 PBNP Response to Requested Information GL 2006-02, July 21, 2006 Question 5 condition that may emerge during a maintenance activity.

(g) Do you contact your TSO PBNP does not routinely contact the TSO during grid-risk-sensitive maintenance activities.

periodically for the duration of PBNP would be notified of grid conditions described in the response to question 1(b) above the grid-risk-sensitive and would follow procedures to reassess risk or take required actions.

maintenance activities?

(h) If you have a formal There is no formal training provided to the plant operators and maintenance personnel on the agreement or protocol with details of the formal agreement between PBNP and the TSO and/or MISO. Portions of the your TSO, describe how NPP formal agreement which impact operations and/or maintenance have, however, been operators and maintenance extracted from the agreement and incorporated into plant procedures. Training on this personnel are trained and procedural material is provided as discussed below.

tested on this formal Operations personnel receive training on the communication requirements outlined in the agreement or protocol. PBNP procedures for electrical communications, switchyard access, work planning and normal power operations. These procedures include the requirements for PBNP to communicate with the TSO and WEPSS for notifications from the TSO concerning operability of offsite power. Refer to the responses to questions 1(d) and 3(f) for descriptions of the training provided.

No training is provided to maintenance personnel.

(i) If your grid reliability A formal agreement for communication exists which would result in notification of grid evaluation, performed as part conditions that would be considered as part of maintenance risk assessment. Therefore, this of the maintenance risk question is not applicable.

assessment required by 10 CFR 50.65(a)(4), does not 18 of 29 PBNP Response to Requested Information GL 2006-02, July 21, 2006 Question 5 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 Not applicable to PBNP. The TSO communicates grid conditions to the plant shift supervision (when warranted) based on and that information is incorporated into online risk assessments as described above (see continuing communication answer to question 5(d)).

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 No alternative actions to be taken.

5(i) and 5(j), you 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 19 of 29 PBNP Response to Requested Information GL 2006-02, July 21, 2006 Question 5 maintenance activities, respectively.

Question 6

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 Yes. The TSO communicates with PBNP to schedule online work; including switching and transmission system grounding activities that may affect the diversity of the power feed to PBNP, and work on the maintenance activities that transmission elements that affect PBNP.

can have an impact on the NPP operation with the NPP operator?

(b) Do you coordinate NPP Work at PBNP is coordinated through WEPSS for activities involving the 345 kV switchyard, maintenance activities that Unit load changes, operation or removal from service of the gas turbine, or loading an EDG.

can have an impact on the WEPSS coordinates with the TSO. The PBNP production planning group also communicates transmission system with the with the TSO to schedule online work involving switchyard equipment owned by the TSO.

TSO?

(c) Do you consider and Yes. The online safety assessment process would reevaluate in-progress and scheduled grid-implement, if warranted, the risk-sensitive maintenance activities following notification of grid conditions as described in the rescheduling of grid-risk- response to question 1(b) above. Risk management actions are taken such as limiting sensitive maintenance voluntary TSAC entries, trip transient evolutions, or work on or near components that could 20 of 29 PBNP Response to Requested Information GL 2006-02, July 21, 2006 Question 6 activities (activities that could affect generation or offsite power.

(i) increase the likelihood of a plant trip, (ii) 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 The PBNP online safety assessment procedure contains guidance for risk assessment, need to perform grid-risk- contingency actions and compensatory measures to take if the plant is in an elevated risk sensitive maintenance condition. Alternate power sources such as the EDG and gas turbine generator would be activities under existing or verified to be available. Critical equipment would be posted as protected. Additional risk imminent conditions of mitigation strategies would be used to address human error probability such as pre-job briefs, degraded grid reliability, or supervisory oversight, and peer checks.

continue grid-risk-sensitive 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 PBNP has procedures that address coordination of maintenance activities with the TSO, risk 21 of 29 PBNP Response to Requested Information GL 2006-02, July 21, 2006 Question 6 associated with questions assessment and associated risk mitigation strategies for both online and shutdown unit work, 6(a) through 6(d) above that protecting critical equipment, and managing human performance risk. Communication occurs would be taken, state between PBNP and the TSO when PBNP or the TSO schedules maintenance activities whether each action is affecting the transmission system, as required in the procedures. Risk assessment is governed by documented performed for scheduled and emergent work, which includes assessment of grid conditions.

procedures and identify the Actions would be taken to assess and mitigate risk for changes in grid conditions included in procedures, and explain why the communication protocols. These actions would be effective and consistently these actions are effective accomplished because they are part of the existing work management process and are and will be consistently implemented effectively for online and outage work.

accomplished.

(f) Describe how NPP Reference the answer to question 1(d) for operations training on the procedure for electrical operators and maintenance communications, switchyard access and work planning.

personnel are trained and The ILT course on Transient Accident Analysis and Mitigating Core Damage contains a tested to assure they can classroom lesson plan on Shutdown Safety Assessment, which includes a review of the accomplish the actions procedure for protected critical equipment. The course also includes a classroom lesson on described in your answers to probabilistic safety assessment and on-line safety monitoring per associated procedures.

question 6(e).

In ILT, shutdown safety assessment and on-line safety assessment are trained and evaluated by trainee completion of the OJT/TPE qualification card for SROs, Licensed Shift Technical Advisors (STAs), and Non-Licensed STAs.

SRO, Authorize performance of maintenance STA, Perform On-Line Safety Monitoring STA, Perform Shutdown Safety Assessments Licensed Operator Continuing Training:

The procedure for managing work activity risk is among the administrative topics listed in the Licensed Operator Continuing program that are selected for training by the Operations Manager. A training review of the procedure for managing work activity risk occurred most 22 of 29 PBNP Response to Requested Information GL 2006-02, July 21, 2006 Question 6 recently in Administrative Procedure Review for SROs in 2005.

The shutdown safety assessment procedure was last reviewed by Licensed Operator Continuing training in SRO/STA Task Review during 2005.

The requirements of the procedure for protected critical equipment are customarily reinforced during cycle training and evaluations by identifying protected critical equipment with placards per the plant procedure when equipment is removed from service for training or evaluation scenarios in the simulator.

The procedure for on-line safety monitoring was last reviewed with licensed operators during 2001.

No training is provided to maintenance personnel related to this question.

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

regarding transmission system maintenance or NPP maintenance 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 As discussed in response to questions 6(a) through 6(d), PBNP effectively implements effectively implement appropriate risk management actions.

appropriate risk management actions during the conditions described above, explain why 23 of 29 PBNP Response to Requested Information GL 2006-02, July 21, 2006 Question 6 you believe you effectively addressed the relevant provisions of the associated NRC-endorsed industry guidance.

(i) You may, as an alternative No alternative actions to be taken.

to questions 6(g) 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).

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.

Question 7

7. Procedures for identifying local power sources that could be made available to resupply your plant following a LOOP 24 of 29 PBNP Response to Requested Information GL 2006-02, July 21, 2006 Question 7 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 (a) Briefly describe any We Energies has an agreement with PBNP to ensure that PBNP is provided with an assured agreement made with the source of off-site power, sufficient to meet the requirements of the Operating License and TSO to identify local power NRC regulations.

sources that could be made The TSO participates in the development and implementation of the black start and system available to re-supply power restoration plan established for the loss of all or part of the transmission system with the MISO to your plant following a Power System Restoration Working Group (PSRWG) to re-supply PBNP Switchyard following LOOP event. a LOOP event. The MISO PSRWG includes the TSO and We Energies (owner of PBNP) as well as MISO and other utilities in the TSO footprint.

(b) Are your NPP operators The TSO is responsible for restoration of power to the Point Beach Switchyard in the event of trained and tested on a LOOP. PBNP operators are not trained on the specifics of restoring power to the identifying and using local switchyard.

power sources to resupply PBNP procedures identify available power sources and provide guidance for re-supplying your plant following a LOOP needed on-site buses from the available power sources. Among the sources are EDGs, unit event? If so, describe how. cross-tie lines, and the G-05 Gas Turbine Generator. Operators are trained and tested on the use and alignments of these power sources for restoration following a LOOP or Station Blackout. Specific procedures include:

25 of 29 PBNP Response to Requested Information GL 2006-02, July 21, 2006 Question 7 In initial licensed operator training:

In the Integrated Operations training course associated with applying the procedure for declining grid frequency, trainees respond in a training scenario to a declining grid frequency. Their response is limited to pre-trip actions since the trainees have not yet been introduced to emergency operating procedures.

During the Emergency Operating Procedures course, trainees respond to a unit blackout and restore safeguards power from the G-05 Gas Turbine Generator per the procedure for Loss of All AC Power.

In licensed operator continuing training:

In 2006, a dual unit training scenario on a complete loss of the offsite power grid required operators to manually restore both trains of safeguards power to Unit 2 from the emergency diesel generators. In addition, due to an extended loss of offsite power, operators had to start the G-05 Gas Turbine Generator, restore important non-safeguards buses for both units per the abnormal operating procedure, and then parallel with offsite power after it was restored.

In 2005 operating crews were tested on their ability to respond to a complete loss of the offsite power grid and dual unit station blackout. Crews were timed on their ability to meet the sites one hour coping strategy by implementing the procedures to restore safeguards buses to both units and safety-related DC battery chargers from the G-05 Gas Turbine Generator.

(c) If you have not PBNP has established agreements as described in the response to question 7(a) above.

established an agreement Therefore this question is not applicable to PBNP.

with your plants TSO to identify local power sources that could be made available to resupply power to your 26 of 29 PBNP Response to Requested Information GL 2006-02, July 21, 2006 Question 7 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.

Question 8

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

(a) Has your NPP No. No total Loss of Offsite Power events caused by grid failure have occurred since the experienced a total LOOP plants coping duration was initially determined in an April 17, 1989 letter and subsequently caused by grid failure since revised in later correspondence.

the plants coping duration was initially determined under 10 CFR 50.63?

27 of 29 PBNP Response to Requested Information GL 2006-02, July 21, 2006 Question 8 (b) If so, have you Not applicable.

reevaluated the NPP using the 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 Not applicable.

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

(d) If your NPP has Not applicable.

experienced a total LOOP caused by grid failure since the plants 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 28 of 29 PBNP Response to Requested Information GL 2006-02, July 21, 2006 Question 8 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 Based on the responses provided above, NMC considers that operation and maintenance of any action is warranted to the PBNP is in compliance with the noted regulatory requirements to the extent described in bring your NPP into the plants licensing basis.

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.

29 of 29 PNP Response to Requested Information GL 2006-02, July 21, 2006 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).

Question 1

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 Yes. The Transmission System Operator (TSO) to which the Palisades Nuclear Plant (PNP) agreement or protocol with supplies power is owned by the Michigan Electric Transmission Company (METC) and your TSO? operated and maintained by the Consumer Energy Company. The PNP is owned by Consumers Energy Company and operated by Nuclear Management Company, LLC (NMC).

Although NMC is the plant operating entity, references to management actions on behalf of PNP in the remainder of this document are referred to as PNP.

PNP does have a formal agreement with METC, the owner of the transmission system to which PNP is connected. The agreement is documented in Amendment and Restatement of the April 1, 2001 Generator Interconnection Agreement, between Michigan Electric Transmission Company and Consumers Energy Company.

In addition, Midwest Independent System Operator (MISO) and the MISO interconnected nuclear power plants and their associated Transmission Owners (TOs) have developed a generic communication protocol, Communication and Mitigation Protocols for Nuclear Plant/Electric System Interfaces, to address roles and responsibilities in grid monitoring and communication The TOs are signatories to the MISO Transmission Owners Agreement. Appendix E Section 1 of 31 PNP Response to Requested Information GL 2006-02, July 21, 2006 Question 1 C, states, For Members and Users who are operators of nuclear generating facilities, the MISO shall enter into written agreements, which define scheduling protocols, limitations, and restrictions necessary to ensure the safety and reliability of such facilities. Efforts to develop these agreements with each nuclear plant are in progress.

(b) Describe any grid The TSO is required by the agreement to immediately notify PNP whenever an impaired or conditions that would trigger potentially degraded grid condition is recognized by the TSO. Specific examples of known a notification from the TSO to potentially degrading conditions identified in the agreement include:

the NPP licensee and if there 1. Voltage calculated to be less than a specified value following a trip of the PNP unit; and is a time period required for the notification 2. Deficient operating reserve requiring canceling maintenance activities which could jeopardize generating equipment.

In addition, The MISO Communication Protocol states MISO will monitor the appropriate system conditions and notify the nuclear plants operating personnel via the transmission operator when operating conditions are outside of established limits, as well as, when they are restored to within acceptable criteria.

(c) Describe any grid Grid conditions and status are the primary responsibility of the TSO and Reliability Coordinator conditions that would cause (MISO). The observable parameters of the PNP operator include only voltage and frequency, the NPP licensee to contact generator reactive output, breaker status, line status, and certain switchyard alarm points.

the TSO. Relative to this question, grid conditions is assumed to be changes that impact the TSOs Describe the procedures analysis of the grid interface. PNP notifies the TSO for changes in the following plant or grid associated with such a conditions:

communication. If you do not

• Inability to maintain voltage schedule; have procedures, describe how you assess grid

• Operation with the controls for the main generator or turbine in manual; conditions that may cause the

• Removal of generator protective relaying from service; and NPP licensee to contact the 2 of 31 PNP Response to Requested Information GL 2006-02, July 21, 2006 Question 1 TSO.

• Voltage approaching the value where trip of the unit could result in low grid voltage.

Requirements for these communications are included in PNP procedures associated with Main Turbine and Generating Systems and Station Power.

(d) Describe how NPP As part of their initial training, Licensed Operators are instructed on the requirements operators are trained and associated with grid voltage. Training related to these requirements is provided in association tested on the use of the with training on the appropriate procedures which specify the requirements. This training is procedures or assessing grid provided in the following lesson plans:

conditions in question 1(c).

• Station Power; and

• Main Generator.

Additionally, annual training is provided in Summer Readiness training as required by a Nuclear Management Fleet Policy on Seasonal Readiness. This training contains instruction on the following applicable items:

• Review of switchyard components and operation;

• Review of symptoms of grid disturbance, and the potential affect on generator and generator auxiliaries; and

• Review of station procedures for response to grid anomalies.

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

formal agreement or protocol with your TSO, describe why you believe you continue to comply with the provisions of GDC 17 as stated above, or describe what actions you 3 of 31 PNP Response to Requested Information GL 2006-02, July 21, 2006 Question 1 intend to take to assure compliance with GDC 17.

(f) If you have an existing As previously stated in response to question 1(a), PNP does have a formal TSO agreement.

formal interconnection The agreement requires that the TSO promptly notify PNP when grid conditions are such that agreement or protocol that a trip of PNP unit would result in an unacceptable voltage in the switchyard.

ensures adequate These communication requirements are included in the plant procedure addressing station communication and power.

coordination between the NPP licensee and the TSO, Additionally, The MISO Communication Protocol states, "the MISO or the Transmission describe whether this Operator will initiate communication with each other to verify study results that indicate a post-agreement or protocol contingent violation of operating criteria." Upon verification, the Transmission Operator and requires that you be promptly the MISO will immediately initiate steps to mitigate the pre and post contingent operating notified when the conditions criteria violation.

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 At PNP, degraded voltage is not sensed in the switchyard. The degraded voltage protection switchyard voltage conditions scheme senses voltage at the 2400 V safety related buses. The nominal setting for the relays that would initiate operation is 93% of rated voltage. When bus voltage decreases below the setpoint, and following a 0.65 of plant degraded voltage second delay, the emergency diesel generators are started and a timer is initiated. If voltage protection. does not recover above the degraded voltage reset value (nominally 93.5%) within 6 seconds, 4 of 31 PNP Response to Requested Information GL 2006-02, July 21, 2006 Question 1 load shed is actuated, the emergency diesel generator (EDG) breaker is closed and safety related loads are sequenced onto the safety related buses.

Question 2

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 NPPs TSO Yes. The TSO makes use of analysis tools to predict grid conditions that would make a PNP use any analysis tools, an offsite power circuit inoperable. These tools are not available to the PNP.

online analytical transmission The following description is based on conversations with and a demonstration of the real time system studies program, or system analysis tool.

other equivalent predictive methods to determine the The TSO maintains a computer simulation of the METC transmission system. The computer grid conditions that would model evaluates real time system conditions obtained from the Supervisory Control and Data make the NPP offsite power Acquisition (SCADA) system and predicts post contingency voltages and load flows for system inoperable during approximately 650 contingencies. These contingencies include transmission system element various contingencies? failures including a trip of the PNP main generator. The real-time analysis, referred to as the Security Analysis, is run every 15 minutes. For the contingency of the PNP main generator If available to you, please tripping, an alarm is provided to the System Control Operator if the case indicates that the provide a brief description of Palisades Switchyard voltage would decrease below a specified value.

the analysis tool that is used by the TSO. Additionally, MISO Energy Management System (EMS) includes a State Estimator (SE) that currently runs every 90 seconds and Real-Time Contingency Analysis (RTCA) program that runs every 5 minutes. The Contingency Analysis analyzes over 7000 contingencies based on the transmission owners criteria. One of the contingencies analyzed by the MISO EMS is the trip of PNP. The analysis provides results with respect to thermal, voltage, and voltage drop 5 of 31 PNP Response to Requested Information GL 2006-02, July 21, 2006 Question 2 limit violations.

(b) Does your NPPs TSO Yes. The TSO uses the above analysis tools, in conjunction with procedures, as the basis for use an analysis tool as the determining when conditions warrant PNP notification. The Security Analysis, described in basis for notifying the NPP response to question 2(a) above, generates a critical alarm if the PNP trip results in a post licensee when such a contingency voltage less than a specified value. The TSO is required by procedure to notify condition is identified? If not, PNP promptly if this alarm is received, while MISO is required to promptly notify the TSO if how does the TSO determine their alarm is received.

if conditions on the grid warrant NPP licensee notification?

(c) If your TSO uses an Yes. Both the TSO and MISO analysis tools, in conjunction with PNPs analysis, identifies analysis tool, would the conditions which would potentially actuate the degraded voltage protection logic and initiate analysis tool identify a separation from an offsite power source upon a PNP trip concurrent with a loss of coolant condition in which a trip of the accident (LOCA).

NPP would result in Following a trip of the PNP unit, the TSO would typically increase generation elsewhere to switchyard voltages restore the system to near nominal operating conditions precluding further long-term decrease (immediate and/or long-term) in voltage. Such actions are under the control of the TSO.

falling below TS nominal trip setpoint value 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 6 of 31 PNP Response to Requested Information GL 2006-02, July 21, 2006 Question 2 on the grid.

(d) If your TSO uses an Based on discussions with the TSO, the Security Analysis program presently updates the PNP analysis tool, how frequently trip contingency on a 15 minute time interval. The analysis can also be initiated on demand.

does the analysis tool The MISO RTCA runs every 5 minutes.

program update?

(e) Provide details of analysis The only analysis-tool identified contingency which would trigger notification from the TSO or tool-identified contingency MISO is the voltage alarm generated by the PNP trip contingency.

conditions that would trigger an NPP licensee notification from the TSO.

(f) If an interface agreement The agreement does not specifically require notification for periods of time when grid exists between the TSO and conditions are indeterminate. However, procedurally the TSO is required to notify PNP if the the NPP licensee, does it Security Analysis is not operating or considered unreliable.

require that the NPP licensee If informed by the TSO that the Security Analysis is unreliable, PNP defaults to grid system be notified of periods when studies which identify the maximum expected voltage drop following a plant trip. This voltage the TSO is unable to is then used to determine operability of offsite power sources.

determine if offsite power voltage and capacity could be The TSO can also call on the support of MISO to evaluate conditions and re-dispatch inadequate? generation as required to support PNPs voltage. MISO actions to support PNP voltage requirements are provided in MISO Standard Operating Guide, Palisades 345 kV Bus If so, how does the NPP Voltage.

licensee determine that the offsite power would remain Per the MISO Nuclear Plant Communication protocol, should the TO lose its ability to monitor operable when such a or predict the operation of the transmission system affecting off-site power to the nuclear plant, notification is received? the TO shall notify the MISO, validate MISOs ability to monitor and predict the operation of the 7 of 31 PNP Response to Requested Information GL 2006-02, July 21, 2006 Question 2 transmission system and then communicate to the nuclear plant. TO will communicate to the nuclear plant and MISO when this capability is restored. This communication should be as soon as practicable or per established agreements with the TO. Should MISO lose its ability to monitor or predict the operation of the transmission system affecting off-site power to the nuclear plant, MISO shall notify the TO.

The MISO has developed Abnormal Operating Procedures (AOPs) to guide its transmission system operation for failures of different components of analytical and communication tools.

For loss of the MISO RTCA, MISO will consider the results of the local transmission operators analytical tools. For loss of both sets of tools, MISO Operating Engineers will attempt to use off-line power flow tools to replicate operating conditions and predict contingent operation.

(g) After an unscheduled No. For post event analysis, the TSO does not verify by procedure the switchyard voltages inadvertent trip of the NPP, are bounded by the analysis tools.

are the resultant switchyard There is no formal process for comparing the actual post-trip voltages to the post-trip voltages verified by contingency voltage results calculated by the MISO RTCA program. Because many of the procedure to be bounded by MISO transmission owning member companies have similar RTCA programs, there are many the voltages predicted by the opportunities to compare the results. This results in a high confidence that the RTCA results analysis tool? are accurate. However, if the resultant voltages are outside of the criteria, when they are predicted to be within, MISO would be initiating an investigation.

(h) If an analysis tool is not Not applicable to PNP since TSO analysis tools are presently in use.

available to the NPP licensees TSO, do you know if there are any plans for the TSO to obtain one? If so, when?

8 of 31 PNP Response to Requested Information GL 2006-02, July 21, 2006 Question 2 (i) If an analysis tool is not Not applicable to PNP since TSO analysis tools are presently in use.

available, does your 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 provisions discussed in question 1 above?

(j) If your TSO does not use, Not applicable to PNP since the TSO utilizes analysis tools, performs periodic studies and or you do not have access to communicates the applicable results to PNP.

the results of an analysis tool, 9 of 31 PNP Response to Requested Information GL 2006-02, July 21, 2006 Question 2 or your TSO does not perform and make available to you periodic studies that determine the adequacy of offsite power capability, please describe why you believe you comply 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.

Question 3

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

(a) If the TSO notifies the In accordance with the requirements of PNP operating procedures related to station power, NPP operator that a trip of control room operators would declare the appropriate offsite power source inoperable if the NPP, or the loss of the notified by the TSO that switchyard voltage, following a contingent trip of the PNP unit, would most critical transmission line be inadequate to support LOCA loads concurrent with the unit trip.

or the largest supply to the 10 of 31 PNP Response to Requested Information GL 2006-02, July 21, 2006 Question 3 grid would result in The PNP operator is not notified by the TSO and would not declare the appropriate offsite switchyard voltages power sources inoperable for a contingent loss of a transmission line or contingent loss of (immediate and/or long-term) another generating facility.

below TS nominal trip System studies performed by the TSO conclude that the system will remain stable following a setpoint value requirements trip of the largest generator, loss of a transmission line, or drop of the largest load. If any of (including NPP licensees these events were to occur in real time, the next running of the TSO Security Analysis or using allowable value in its MISO RTCA would indicate if PNPs voltage would be impacted such that substation voltage TSs) and would actuate plant would be unacceptable.

degraded voltage protection, is the NPP offsite power system declared inoperable under the plant TSs? If not, why not?

(b) If onsite safety-related No. The plant accident analyses evaluate a loss of offsite power (LOOP) occurring coincident equipment (e.g., emergency with various accidents. A postulated double sequencing event is outside the plants licensing diesel generators or safety- basis and has not been evaluated. Equipment operability is based on performance of safety related motors) is lost when functions and safety support functions required within the plant licensing basis.

subjected to a double sequencing (LOCA with delayed LOOP event) as a result of the anticipated system performance 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?

11 of 31 PNP Response to Requested Information GL 2006-02, July 21, 2006 Question 3 If not, why not?

(c) Describe your evaluation Double sequencing is not in the PNPs licensing basis and PNP is not designed or analyzed of onsite safety-related for double sequencing scenarios equipment to determine whether it will operate as designed during the condition described in question 3(b).

(d) If the NPP licensee is No. Technical Specification Conditions are not entered for grid conditions that might occur.

notified by the TSO of other The PNP operator only declares offsite power sources inoperable when the predicted voltage grid conditions that may following a unit trip is low enough to preclude initiation of LOCA loads concurrent with a unit impair the capability or trip.

availability of offsite power, are any plant TS action statements entered? If so, please identify them.

(e) If you believe your plant Not applicable to PNP since offsite power sources will be declared inoperable as described in TSs do not require you to the response to question 3(a) above in accordance with the plant licensing basis and declare your offsite power Technical Specifications.

system or safety-related equipment inoperable in any of these circumstances, explain why you believe you comply with the provisions of GDC 17 and your plant TSs, or describe what 12 of 31 PNP Response to Requested Information GL 2006-02, July 21, 2006 Question 3 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.

(f) Describe if and how NPP The compensatory actions discussed in response to questions 3(a) through 3(e) involve operators are trained and entering Technical Specification Conditions. PNP operators are trained in the interpretation tested on the compensatory and use of plant Technical Specifications and associated compensatory measures.

actions mentioned in your answers to questions 3(a) through (e).

Question 4

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 Yes. Procedural guidance is available to PNP operators.

have any guidance or PNP does not have voltage regulators, capacitors or static VAR compensators.

procedures in plant TS bases sections, the final safety As discussed in response to question 1(g), one source of offsite power is provided via a load analysis report, or plant tap changing transformer. Although procedures do not explicitly state that this source of procedures regarding offsite power is inoperable if the load tap changer is in manual, the procedure on station power 13 of 31 PNP Response to Requested Information GL 2006-02, July 21, 2006 Question 4 situations in which the requires that the voltage on the bus be maintained within required limits. If the tap changer condition of plant-controlled cannot maintain these voltage requirements, due to either the regulator being in manual or the or -monitored equipment tap changer being stuck, the source of offsite power would be declared inoperable.

(e.g., voltage regulators, auto The North American Electric Reliability Council (NERC) requires that the TSO be notified if the tap changing transformers, main generator voltage regulator is placed in manual. Operation in this mode can result in the capacitors, static VAR plant output not responding as assumed in the grid system planning analysis potentially compensators, main resulting in decreased reliability of the grid. The NERC requirement assures that the TSO is generator voltage regulators) aware of the potential for an unexpected response of the unit to grid upsets. The requirement can adversely affect the to inform the TSO of the status of the voltage regulator is specified in the plant procedure on operability of the NPP offsite the main turbine and generating systems.

power system? If so, describe how the operators Training on the guidance and procedures described above are discussed in response to are trained and tested on the question 1(d).

guidance and procedures.

(b) If your TS bases sections, Not applicable. PNP does have procedural guidance that provides the operator with written the final safety analysis direction for responding to equipment malfunctions and manipulation of controls that can report, and plant procedures adversely affect the operability of the PNP offsite power system.

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 14 of 31 PNP Response to Requested Information GL 2006-02, July 21, 2006 Question 4 intend to take to provide such guidance or procedures.

Use of NPP licensee/TSO 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.

Question 5

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 Yes a qualitative evaluation is performed. 10CFR 50.65(a)(4) requires performance of a risk qualitative grid reliability assessment prior to maintenance activities. Procedural requirements for performing the evaluation performed at your required risk assessment at PNP are included in a procedure regarding risk management and NPP as part of the risk monitoring. This information is associated with the plant procedure specifying maintenance risk assessment requirements for control of equipment. As regards grid risk sensitive maintenance, the required by 10 CFR procedure specifies that maintenance or testing on sensitive or critical equipment during 50.65(a)(4) before performing periods of severe weather forecasts, grid voltage degradation, or system generation alert grid-risk-sensitive conditions should be avoided. This guidance would be considered prior to taking a risk-maintenance activities? This significant piece of equipment (such as an EDG, a battery, a steam-driven pump, or an includes surveillances, post- alternate AC power source) out-of-service.

maintenance testing, and preventive and corrective 15 of 31 PNP Response to Requested Information GL 2006-02, July 21, 2006 Question 5 maintenance that could increase the probability of a plant trip or LOOP or impact LOOP or SBO coping capability, for example, before taking a risk-significant piece of equipment (such as an EDG, a battery, a steam-driven pump, an alternate AC power source) out-of-service?

(b) Is grid status monitored by Yes. As discussed in the response to question 2(a), the TSO and MISO, through use of real some means for the duration time analysis, continuously monitor the status of the voltage within the PNP switchyard and of the grid-risk-sensitive notifies the plant if post plant trip contingency voltages would be below acceptable values.

maintenance to confirm the Such a notification would be considered an emergent condition. For emergent conditions, the continued validity of the risk PNP risk management guidelines discussed in response to the previous question requires that assessment and is risk the risk impact be reassessed.

reassessed when warranted?

If not, how is the risk assessed during grid-risk-sensitive maintenance?

(c) Is there a significant No. Typically the grid carries more power during summer months due to heavier loading.

variation in the stress on the However the stress on the grid is a function of what equipment is in service and the ability of grid in the vicinity of your the grid to handle the increased loading with respect to winter months. Existing procedures NPP site caused by seasonal and protocols used by the TSO provide guidance on the grid operations to maintain grid loads or maintenance reliability and stability.

activities associated with Offsite power to PNP is provided from a major METC 345KV switchyard located approximately critical transmission 16 of 31 PNP Response to Requested Information GL 2006-02, July 21, 2006 Question 5 elements? one-half mile from the plant. The switchyard consists of six incoming transmission lines, 2 Is there a seasonal variation each from the east, north and south. In addition, there is an incoming line from a 1350 MW gas fired plant. These incoming lines and the PNP generator output are connected in a (or the potential for a seasonal variation) in the breaker and a half scheme powering two buses identified as Front (F) and Rear (R) bus.

LOOP frequency in the local The two transmission lines from the south are the METC interconnection with American transmission region? Electric Power (AEP). With the number of lines providing access to the grid, removal of a transmission line from service either within the Palisades Switchyard or elsewhere in the If the answer to either system does not result in a significant increase in grid stress near PNP. Prior to removal of question is yes, discuss the lines from service, the impact on the grid, including PNP operating criteria, would be evaluated time of year when the and approved by the MISO as discussed in the response to question 6(a).

variations occur and their The overriding concern of the TSO is to maintain continued grid reliability/stability. To protect magnitude.

the grid, TSO procedures require that service to residential and commercial customers be reduced by first reducing voltage at the distribution level and if required, shedding load. The residential and commercial customers may experience electrical outages at the distribution level while the grid is unaffected. Hence, offsite power would continue to be available to PNP.

Current industry data is inconclusive relative to the degree of seasonal variation in LOOP frequency. Because LOOP frequency for PNP is very low and because outages and maintenance are effectively managed, there is no identified seasonal variation in LOOP frequency.

In response to this question, MISO performed a review of Energy Emergency Alerts, as defined in NERC Standard EOP-002-0, which have occurred within the MISO Reliability footprint. This review determined that there is no correlation between grid stress and seasonal load or maintenance activities.

Seasonal variations in the LOOP probability are not significant at PNP and therefore do not (d) Are known time-related provide a useable basis for determination of risk based solely on the season. Other time variations in the probability of related variations such as system generation alert conditions, grid voltage degradation and a LOOP at your plant site severe weather are considered as part of risk management. For these conditions, procedural considered in the grid-risk-guidance is provided to the operators regarding actions to be taken to minimize risk.

17 of 31 PNP Response to Requested Information GL 2006-02, July 21, 2006 Question 5 sensitive maintenance evaluation? If not, what is your basis for not considering them?

(e) Do you have contacts with Yes. Switchyard activities are administratively controlled by procedure. This procedure the TSO to determine current identifies the interface arrangements between PNP and the various TSO operations, and anticipated grid maintenance and test organizations. PNP maintains contacts with these various TSO conditions as part of the grid organizations to coordinate maintenance and testing activities and to determine grid status.

reliability evaluation These organizations are specifically called upon when performing switchyard maintenance.

performed before conducting Taking lines out of service in the switchyard always involves the coordination and direction of grid-risk-sensitive the TSOs System Control. System Control is the organization most knowledgeable of current maintenance activities? system conditions.

As regards maintenance of plant installed critical equipment, the need to request input from System Control as to current or projected grid conditions prior to performing risk sensitive maintenance activities would be dependent on grid conditions at the time. There are specific procedural requirements for times when PNP control room operators are required to contact the TSO System Control. These occur when the unit is unable to maintain their voltage schedule, or when voltage lowers to a trigger point where loss of the unit could potentially reduce voltage below the required minimum.

As a result of the dynamic nature of loads and active generation on the power-grid, the TSO is only able to comment on the grid conditions shortly before (on the order of hours) maintenance tasks commence. The TSO can provide commentaries on grid conditions at any time maintenance tasks are underway. The same dynamic nature of loads and active generation make prediction of grid conditions days or weeks ahead of time highly uncertain.

(f) Describe any formal The TSO will notify PNP in accordance with the agreement discussed in response to question agreement or protocol that 18 of 31 PNP Response to Requested Information GL 2006-02, July 21, 2006 Question 5 you have with your TSO to 1(a) based upon grid conditions described in the response to question 1(b) above.

assure that you are promptly Additionally, MISO has established a communication protocol for nuclear power plants that alerted to a worsening grid requires the MISO to communicate to the local transmission owner (TSO) whenever the MISO condition that may emerge has determined that the pre and/or post contingent voltage for the nuclear power plants is during a maintenance activity. outside of the acceptable voltage range.

These notifications would be provided to PNP whether or not maintenance is on-going.

(g) Do you contact your TSO PNP does not contact the TSO solely based on the type of plant maintenance being periodically for the duration of performed. As described earlier, there are specific procedural requirements for times when the grid-risk-sensitive PNP control room operators are required to contact the TSO System Control. These occur maintenance activities? when the unit is unable to maintain their voltage schedule, or when voltage lowers to a point where loss of the unit could potentially reduce voltage below the required minimum.

(h) If you have a formal There is no formal training provided to the plant operators and maintenance personnel on the agreement or protocol with details of the formal agreement between PNP and the TSO and/or MISO. Portions of the your TSO, describe how NPP formal agreement which impact operations and/or maintenance have, however, been operators and maintenance extracted from the agreement and incorporated into plant procedures. Training on this personnel are trained and procedural material is provided as discussed below.

tested on this formal Training on the maintenance rule, risk management and probabilistic safety assessment agreement or protocol. (PSA) is provided to plant operators as part of initial license training. This training is encompassed within the lesson plan entitled Equipment Out of Service Overview. This lesson plan provides the operators training on the EPRI developed Equipment Out of Service (EOOS) monitor. This monitor provides the operators with a risk score based on the PSA model. The EOOS system is provided with the capability to input grid conditions manually to account for potentially degraded grid conditions. Additional training is provided periodically as part of Licensed Operator News training. Recent training in this area was provided which addressed risk management.

19 of 31 PNP Response to Requested Information GL 2006-02, July 21, 2006 Question 5 Additionally, as part of summer readiness training, the following topics are addressed:

• Review of switchyard components and operation;

• Review of symptoms of grid disturbance, and the potential affect on generator and generator auxiliaries; and

• Review of station procedures for response to grid anomalies.

No training is provided to maintenance personnel.

(i) If your grid reliability A formal agreement for communication exists which would result in notification of grid evaluation, performed as part conditions that would be considered as part of maintenance risk assessment. Therefore, this of the maintenance risk question is not applicable.

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 Not applicable to PNP. The TSO communicates grid conditions to the plant shift supervision (when warranted) based on and that information is incorporated into online risk assessments as described above (see continuing communication answer to question 5(d)).

with the TSO throughout the duration of grid-risk-sensitive maintenance activities, explain why you believe you have effectively implemented 20 of 31 PNP Response to Requested Information GL 2006-02, July 21, 2006 Question 5 the relevant provisions of the endorsed industry guidance associated with the maintenance rule.

(k) With respect to questions No alternative actions to be taken.

5(i) and 5(j), you 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.

Question 6

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 Yes. PNP coordinates maintenance in the PNP switchyard with the TSO. Maintenance transmission system activities in the switchyard are controlled in accordance with PNP procedure on control of maintenance activities that switchyard activities. The procedure outlines the planning and communication required for can have an impact on the work to be performed to assure that the PNP Technical Specifications and operating 21 of 31 PNP Response to Requested Information GL 2006-02, July 21, 2006 Question 6 NPP operation with the NPP requirements for switchyard equipment are met. The procedure requires that the TSO inform operator? PNP of schedules for performing work in the switchyard, and that the maintenance personnel contact PNP prior to removing equipment from service.

With respect to transmission system maintenance beyond the PNP switchyard, MISO is responsible for approving the maintenance schedule of transmission facilities and coordinating the scheduling of generation facilities. The decision to approve transmission and generation facility maintenance schedules is based on the ability of the MISO to operate the system within the criteria set forth by the transmission owner, NERC and the applicable regional reliability coordinator.

The outage scheduling process analyzes the outages under expected grid operating conditions. One day prior and on the outage day, the system is analyzed by MISO before permitting the equipment to be switched out of service. Once the equipment is switched out of service, grid status is automatically captured by the MISO SE and continually evaluated by the MISO RTCA program.

(b) Do you coordinate NPP Short of inducing a trip of the main generator, no work at PNP is able to make a significant maintenance activities that change to the status of the grid in the vicinity of the plant or the grid at-large. For activities can have an impact on the that may result in a change in plant power output or have a higher risk of a plant trip, such as transmission system with the turbine valve testing, the TSO System Control would be notified prior to performing the activity.

TSO?

(c) Do you consider and Yes. The PNP procedure on control of plant equipment identifies the actions to be taken implement, if warranted, the when notified by Electric Source and Trading or the (TSO) System Control of a System rescheduling of grid-risk- Critical status due to generation or transmission availability constraints. When notified of this sensitive maintenance status, the procedure requires that maintenance on batteries, emergency diesel generators, activities (activities that could and the auxiliary feedwater system be rescheduled. Additionally the procedure requires (i) increase the likelihood of a rescheduling activities that have the potential of causing a reactor trip such as reactor plant trip, (ii) increase LOOP protective system testing, switchyard manipulations, turbine valve testing or feedwater heater 22 of 31 PNP Response to Requested Information GL 2006-02, July 21, 2006 Question 6 probability, or (iii) reduce level control manipulations.

LOOP or SBO coping capability) under existing, imminent, or worsening degraded grid reliability conditions?

(d) If there is an overriding Yes. Risk management compensatory actions for higher risk activities are provided in Risk need to perform grid-risk- Management and Risk Monitoring, guidelines. The actions identified within these guidelines sensitive maintenance include:

activities under existing or 1. Actions to provide increased risk awareness and control:

imminent conditions of degraded grid reliability, or

• Discuss planned maintenance activity with operating shift and obtain operator continue grid-risk-sensitive awareness and approval of planned evolution; maintenance when grid

• Conduct pre-job briefing of maintenance personnel, emphasizing risk aspects of conditions worsen, do you planned maintenance evolution; implement appropriate risk management actions? If so,

• Request the system engineer or subject matter expert (SME) to be present for the describe the actions that you maintenance activity, or applicable portions of the activity, and would take. (These actions

• Obtain plant management approval for the proposed activity.

could include alternate equipment protection and 2. Actions to reduce duration of maintenance activity:

compensatory measures to

• Pre-stage parts and materials; limit or minimize risk.)

• Walk-down tagout and maintenance activity prior to conducting maintenance;

• Conduct training on mock-ups to familiarize maintenance personnel with the activity.

• Perform maintenance around the clock; and

• Establish contingency plans to restore out-of-service equipment rapidly.

23 of 31 PNP Response to Requested Information GL 2006-02, July 21, 2006 Question 6

3. Actions to minimize magnitude of risk increase:

• Minimize work in areas that could cause a plant trip or transient, or a loss of power (sub-station, switchgear rooms, or EDG rooms) to lower the frequency of initiating events that are mitigated by the safety function served by the out-of-service equipment;

• Minimize other work in areas that could affect the redundant systems (place protected train boundaries);

• Walk-downs of key safety systems by on-shift Senior Reactor Operator (SRO) personnel and management before and during higher risk evolutions: and

• Increased surveillance frequencies of key safety functions by testing alternate equipment prior to the planned work or frequent inspections of standby equipment during work.

(e) Describe the actions Actions to be taken are addressed within each of the responses to questions 6(a) through 6(d) associated with questions above. The PNP procedures which control these activities are:

6(a) through 6(d) above that Control of Plant Equipment; and would be taken, state whether each action is Control of Switchyard Maintenance.

governed by documented NMCs management expectation is that procedural requirements be strictly adhered to.

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

(f) Describe how NPP Training on the maintenance rule, risk management and PSA is provided to plant operators as operators and maintenance part of initial license training. This training is encompassed within the lesson plan entitled personnel are trained and Equipment Out of Service Overview. This lesson plan provides the operators training on the 24 of 31 PNP Response to Requested Information GL 2006-02, July 21, 2006 Question 6 tested to assure they can EPRI EOOS monitor. This monitor provides the operators with a risk score based on the PSA accomplish the actions model. The EOOS system is provided with the capability to input grid conditions manually to described in your answers to account for potentially degraded grid conditions. Additional training is provided periodically as question 6(e). part of Licensed Operator News training. Recent training in this area was provided which addressed risk management.

Additionally, as part of summer readiness training, the following topics are addressed:

• Review of switchyard components and operation;

• Review of symptoms of grid disturbance, and the potential affect on generator and generator auxiliaries; and

• Review of station procedures for response to grid anomalies.

No training is provided to maintenance personnel on risk management.

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

regarding transmission system maintenance or NPP maintenance 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 As discussed in response to questions 6(a) through 6(d), PNP effectively implements effectively implement appropriate risk management actions.

appropriate risk management 25 of 31 PNP Response to Requested Information GL 2006-02, July 21, 2006 Question 6 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 No alternative actions to be taken.

to questions 6(g) 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).

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.

26 of 31 PNP Response to Requested Information GL 2006-02, July 21, 2006 Question 7

7. Procedures for identifying local power sources 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 (a) Briefly describe any PNP has a formal agreement with METC as discussed in response to question 1(a) above.

agreement made with the The agreement requires that METC provide PNP the highest possible priority during Black TSO to identify local power Light Procedures for restoration of the Palisades Substation. Following a total system sources that could be made collapse (Black Light), the TSO System Restoration Manual provides for the use of a nearby available to re-supply power black start capable pumped storage facility to provide power to the PNP switchyard.

to your plant following a The following discussion of the region wide restoration process was provided by MISO:

LOOP event.

The MISO restoration process will provide the development of individual TSO Restoration Plans. MISO conducts reviews, workshops and drills to ensure the effectiveness of the restoration plan.

The MISO restoration process will provide updates to the TO and PNP on transmission system status during emergency restoration, and will give the highest priority to restoring power to affected nuclear facilities per NERC standard EOP-005-0.

However, due to the myriad of possible restoration scenarios, no specific power sources to re-supply PNP will be identified. The MISO restoration process allows for the fact that the blacked out area may or may not be separated from the remainder of the system. The MISO restoration process allows the use of black start unit or cranking path from the non-blacked out 27 of 31 PNP Response to Requested Information GL 2006-02, July 21, 2006 Question 7 areas. Regardless of the scenario, there is a clear recognition of the importance of expeditious restoration of a nuclear power plant offsite power source.

(b) Are your NPP operators The TSO is responsible for restoration of power to the Palisades Switchyard in the event of a trained and tested on LOOP. PNP operators are not trained on the specifics of restoring power to the switchyard.

identifying and using local The operators are trained and tested on the use of the Emergency Operating Procedure power sources to resupply (EOP) on Station Blackout Recovery. This training includes a simulator exercise on Station your plant following a LOOP Blackout Recovery.

event? If so, describe how.

(c) If you have not PNP has an established agreement with the TSO related to restoration of power to the PNP established an agreement switchyard. Thus this item is not applicable.

with your plants 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 28 of 31 PNP Response to Requested Information GL 2006-02, July 21, 2006 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.

Question 8

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

(a) Has your NPP There have been no grid related losses of offsite power at PNP since the NRC Safety experienced a total LOOP Evaluation Report on Station Blackout was issued on June 25,1992. (Reference Table A.1 caused by grid failure since NUREG/CR-6890, December 2005) the plants coping duration was initially determined under 10 CFR 50.63?

(b) If so, have you Not applicable.

reevaluated the NPP using the 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 Not applicable.

results of this reevaluation, and did the initially determined coping duration for the NPP need to be 29 of 31 PNP Response to Requested Information GL 2006-02, July 21, 2006 Question 8 adjusted?

(d) If your NPP has Not applicable.

experienced a total LOOP caused by grid failure since the plants 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 Based on the responses provided above, NMC considers that operation and maintenance of any action is warranted to the PNP is in compliance with the noted regulatory requirements to the extent described in the bring your NPP into plants licensing basis.

compliance with NRC 30 of 31 PNP Response to Requested Information GL 2006-02, July 21, 2006 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.

31 of 31 PINGP Response to Requested Information GL 2006-02, July 21, 2006 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).

Question 1

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 Yes. The Transmission System Operator (TSO) to which the Prairie Island Nuclear agreement or protocol with Generating Plant (PINGP) supplies power is owned and operated by Xcel Energy, Inc. PINGP your TSO? is owned by Northern States Power Company (NSP), a wholly owned subsidiary of Xcel Energy, Inc. (Xcel), and operated by Nuclear Management Company, LLC (NMC). Although NMC is the plant operating entity, references to management actions on behalf of PINGP in the remainder of this document are referred to as PINGP.

PINGP does have a formal agreement with the TSO (all references to TSO, ISO, Reliability Controller or Control Center, or Balancing Authority etc. throughout this document refer to Excel Energys Northern States Power System Control Center). The agreement is documented in the Voltage Support Agreement, June 12, 1990 and NMC - Xcel Nuclear Power Plant Operating Services Agreement, November 23, 1999.

(b) Describe any grid The TSO is required to notify PINGP whenever an impaired or potentially degraded grid conditions that would trigger condition is recognized by the TSO. Specific examples of known potentially degrading a notification from the TSO to conditions identified in the agreement include:

the NPP licensee and if there 1 of 31 PINGP Response to Requested Information GL 2006-02, July 21, 2006 Question 1 is a time period required for 1. If a Real Time Contingency Analysis (RTCA) post contingent alarm is received the notification indicating that the post-trip grid voltage at the Prairie Island Substation will be below the calculated minimum voltage for the present plant substation lineup; and

2. If grid conditions, as established by Energy Supply (Energy Supply is the power marketing arm of NSP), enters into or leaves a system condition designated as orange or red. (These are the two most stressed grid conditions)

The occurrence of a grid contingency that impacts PINGP requires immediate notification.

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

Describe the procedures The TSO is contacted per procedure for response to any grid conditions that result in associated with such a substation alarms. Plant Abnormal Operating Procedures (AOP) direct communication with communication. If you do not the TSO in response to loss of major substation components.

have procedures, describe Relative to this question, grid conditions is assumed to be any changes within the jurisdiction how you assess grid of PINGP that impact the TSO analysis of the grid interface. The PINGP Shift Supervisor also conditions that may cause the notifies the TSO for changes in the following grid conditions:

NPP licensee to contact the TSO.

• Changes to switchyard voltage, switchyard breaker alignment that affects the RTCA setpoint as per operating procedure;

• If generator real and reactive power loading must be changed due to generator limitations or plant maintenance;

• Change in status of the 10 Bank Transformer offsite power voltage regulating devices (such as load tap changers (LTCs) in manual versus auto.);

• Modifications resulting in changes to generator electrical characteristics or substation 2 of 31 PINGP Response to Requested Information GL 2006-02, July 21, 2006 Question 1 operating characteristics; and

• Transfer of the generator voltage regulator to manual.

(d) Describe how NPP Since 1996, PINGP has trained the operators annually on loss of offsite power on the operators are trained and simulator. PINGP has also taught on loss of all safeguards AC power recovery with and tested on the use of the without safety injection, but this was on a 3-year frequency and was last discussed in 2004.

procedures or assessing grid The Loss of Grid INPO Significant Operating Event Report (SOER) was discussed by conditions in question 1(c). operations in 2002, 2003, and 2005 In 2005, classroom and simulator training included:

• discussion of SOER 99-1, loss of grid events, and, SOER 02-3, transformer reliability;

• virtual tour of the NSP System Control Center and the Mid-Continent Area Power Pool (MAPP) system. Plant operators interviewed TSO operators and asked what information the TSO operators like to hear from the plant control room during upset conditions;

• reviewed work procedures for substation work;

• discussed the plant response to degrading grid conditions and reviewed the system operating codes and the procedure for responding to degraded grid conditions using the plant station load reduction procedure;

• during two simulator sessions in that same cycle, training focused on degraded grid conditions entering the system operating code procedure and the plant station load reduction procedure. This was followed by a loss of offsite power and other electrical switching operations. The crews had practice in implementing various plant electrical AOPs;

• Switchyard distribution is taught on a 3 year frequency and was last taught in January of 2005; 3 of 31 PINGP Response to Requested Information GL 2006-02, July 21, 2006 Question 1

• Operators were evaluated on the simulator during a simulated loss of offsite power condition;

• Training was conducted on motor and transformer theory; and

• Transformer reliability was taught based on SOER 02-3 in 2002 which has been incorporated into the transformer lesson plan.

Examples of training in 2004 include multiple simulator scenarios that used electrical switching as their base operation: (Listed are tasks trained on the simulator)

• Loss of Offsite and Onsite Power; Response To Faulty Generator Voltage Regulator; Op Restrictions/Limitations Loss of 345 kV Bus 1 and 2; Loss of Offsite Power; Loss of All AC. Power Recovery w/o SI Required; Restart DG With Automatic Start Signal Present;

• Reenergize a Dead 4.16 KV Bus; Response To Instrument Inverter Bypass; Response To Loss of an Instrument Bus; Op Restrictions/Limitations Loss of CT1/CT11/CT12 Transformers;

• Response To System Underfrequency Disturbance: Operating Restrictions/Limitations Loss of 10 Bank Transformer; Response to a Loss of 1R/2RX/2RY; and

• Rapid Load Reduction.

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

formal agreement or protocol with your TSO, describe why 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 4 of 31 PINGP Response to Requested Information GL 2006-02, July 21, 2006 Question 1 compliance with GDC 17.

(f) If you have an existing As previously stated in response to question 1(a), PINGP does have a formal TSO agreement formal interconnection which ensures prompt communications between the TSO and the Shift Supervisor in the event agreement or protocol that of changes in the grid alignment that may affect the post contingent setpoint or result.

ensures adequate Although the notification time is not specifically called out in the operating procedure, past communication and practice has been to immediately notify the PINGP control room in the event of a post coordination between the contingent voltage violation. An event notification (i.e., failure to meet minimum post NPP licensee and the TSO, contingent voltages) includes predicted post-trip voltage at the Prairie Island Substation. The describe whether this TSO will also promptly notify PINGP when grid conditions become more stressed agreement or protocol necessitating changes to the grid condition system operating code.

requires that you be promptly 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 At PINGP, degraded voltage is not sensed in the switchyard. The degraded voltage protection switchyard voltage conditions scheme senses voltage at the 4.16 kV safety related buses. The two conditions at PINGP will that would initiate operation initiate a degraded voltage logic initiation on the plant 4.16 kV Safeguards Buses are:

of plant degraded voltage

• Bus undervoltage nominal allowable value: 75% with a fixed nominal time delay of 4 protection. seconds.

• Bus degraded voltage nominal allowable value: 95.5% with a nominal conditional time 5 of 31 PINGP Response to Requested Information GL 2006-02, July 21, 2006 Question 1 delay of 8 seconds (Safety Injection (SI) signal present) or 60 seconds (no SI signal present).

Question 2

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 NPPs TSO Yes. The TSO makes use of analysis tools to predict grid conditions that would make the use any analysis tools, an PINGP offsite power system non-functional. These tools are not available to the PINGP.

online analytical transmission The tools presently used by the TSO to manage the grid programs, control the transmission system studies program, or related activities, and monitor grid actions that are outside the control of the PINGP include other equivalent predictive the following:

methods to determine the grid conditions that would

• a fully commissioned RTCA program; make the NPP offsite power

• a grid state estimator and System Control and Data Acquisition (SCADA) system in system inoperable during conjunction with periodic studies of a reasonable number of contingencies; and various contingencies?

• bounding analyses.

If available to you, please provide a brief description of The following is a brief description of the RTCA operation:

the analysis tool that is used The Security Analysis (SA) is a real time load flow program that takes data from the SCADA by the TSO. network to establish the various state variable parameters required to analyze the network.

Once all the state input data is set, the program calculates the voltages at all of the nodes in the network. As in any load flow analysis, the program may take a few iterations to reach a solution. For purposes of this explanation, this is referred to as the Base Real Time Analysis.

Upon reaching the base solution the program then sequentially steps through a sequence of 6 of 31 PINGP Response to Requested Information GL 2006-02, July 21, 2006 Question 2 N contingencies to recalculate resultant node voltages for a series of what if scenarios.

Each contingency calculation considers the loss of one of the major components in the base analysis at a time, hence the term N-1 Contingency Analysis. It calculates the resultant voltage at each node based on the loss of one of the components from the base real time solution. This list of contingencies may be several hundred elements long and runs immediately after the base solution is calculated. The contingency of primary concern to the nuclear plant is the trip of the plant and the effect on the resultant voltage at the plants substation. For the purpose of this discussion this will be referred to as the Primary Contingency. For each of the N-1 contingencies, the resultant voltage at each of the nodes of concern is compared to pre-established voltage limits and if any voltage falls out of that range, the system operator receives an alarm. If an alarm is received upon running of the primary contingency the system operator is instructed to contact the nuclear plant in accordance with established protocols.

(b) Does your NPPs TSO Yes. The TSO uses the above analysis tools, in conjunction with procedures, as the basis for use an analysis tool as the determining when conditions warrant PINGP notification.

basis for notifying the NPP Refer to the response to question 1(b).

licensee when such a condition is identified? If not, how does the TSO determine if conditions on the grid warrant NPP licensee notification?

(c) If your TSO uses an Yes. The TSO analysis tool, in conjunction with PINGP plant analysis, identifies contingent analysis tool, would the conditions which would actuate the PINGP degraded voltage protection logic and initiate analysis tool identify a separation from an offsite power source upon a postulated dual-unit PINGP trip. The RTCA condition in which a trip of the predicts the loss of both units generation and the immediate assumption of offsite support of NPP would result in auxiliary station loads. This is a static analysis that calculates a postulated post trip steady 7 of 31 PINGP Response to Requested Information GL 2006-02, July 21, 2006 Question 2 switchyard voltages state voltage that is assumed constant.

(immediate and/or long-term) The brief description of how the RTCA functions provides insights that the analysis is valid falling below TS nominal trip only for a few minutes (on the order of 8 or 9 minutes) until the next data update and setpoint value requirements recalculation is run. The RTCA does not perform a look ahead calculation to determine post (including NPP licensees contingent voltages for projected grid conditions hours or days in advance. System wide using allowable value in its studies that take into account projected plant outages, major transmission line maintenance, TSs) and consequent etc. are performed for market planning and for establishing a daily system condition. These actuation of plant degraded studies are independent of the RTCA analysis.

voltage protection?

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

(d) If your TSO uses an The TSO RTCA program presently updates and recalculates the PINGP dual unit trip analysis tool, how frequently contingency on a time interval of approximately 7 to 8 minutes.

does the analysis tool The TSO SCADA information available as an input to the RTCA is essentially real time and program update? provides updates to the RTCA each time it runs.

(e) Provide details of analysis The notification from the TSO is based upon the predicted post-trip switchyard voltage falling tool-identified contingency below the required voltage identified in plant operating procedures.

conditions that would trigger PINGP operating procedures provide previously calculated setpoints dependent on plant an NPP licensee notification internal load configuration.

from the TSO.

(f) If an interface agreement Yes. The agreement does specifically require PINGP notification for periods of time when the exists between the TSO and RTCA is out of service or grid conditions are indeterminate.

the NPP licensee, does it 8 of 31 PINGP Response to Requested Information GL 2006-02, July 21, 2006 Question 2 require that the NPP licensee PINGP follows plant abnormal operating procedure requirements when notified by the TSO be notified of periods when that the RTCA is out of service or grid conditions are indeterminate. The abnormal operating the TSO is unable to procedures provide acceptable operating parameter guidelines to conservatively predict that determine if offsite power post trip substation voltages, based on current real and reactive power conditions will remain voltage and capacity could be above degraded voltage relay setpoints.

inadequate?

If so, how does the NPP licensee determine that the offsite power would remain operable when such a notification is received?

(g) After an unscheduled No. For post event analysis, the TSO does not verify by procedure the switchyard voltages inadvertent trip of the NPP, are bounded by the analysis tools. However, post trip voltages are verified as being adequate are the resultant switchyard as part of the plant emergency procedures for trip recovery and any low voltage conditions voltages verified by existing on the safeguards buses would be alarmed and the appropriate alarm response procedure to be bounded by would be followed. Following an inadvertent trip of one or both PINGP units, any unexpected the voltages predicted by the actuations or equipment operation associated with supply voltage would be documented and analysis tool? evaluated in accordance with the corrective action process.

(h) If an analysis tool is not Not applicable to PINGP since TSO analysis tools are presently in use.

available to the NPP licensees TSO, do you know if there are any plans for the TSO to obtain one? If so, when?

9 of 31 PINGP Response to Requested Information GL 2006-02, July 21, 2006 Question 2 (i) If an analysis tool is not Not applicable to PINGP since TSO analysis tools are presently in use.

available, does your 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 provisions discussed in question 1 above?

(j) If your TSO does not use, Not applicable to PINGP since the TSO utilizes analysis tools and communicates the or you do not have access to applicable results to PINGP.

the results of an analysis tool, 10 of 31 PINGP Response to Requested Information GL 2006-02, July 21, 2006 Question 2 or your TSO does not perform and make available to you periodic studies that determine the adequacy of offsite power capability, please describe why you believe you comply 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.

Question 3

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

(a) If the TSO notifies the If notified that a contingent PINGP trip would drive voltage below the degraded voltage NPP operator that a trip of protection setpoint, the PINGP operator declares one or both offsite paths inoperable for the NPP, or the loss of the postulated contingent dual unit trip per existing operating procedure and the PINGP operator most critical transmission line would enter the applicable TS 3.8.1 Condition.

or the largest supply to the 11 of 31 PINGP Response to Requested Information GL 2006-02, July 21, 2006 Question 3 grid would result in If a contingent line loss or the contingent loss of a remote generating unit would predict a post-switchyard voltages trip voltage PINGP below the degraded voltage protection setpoint (e.g. an N-2 contingency (immediate and/or long-term) evaluation), the PINGP operator would not enter any Technical Specification (TS) Conditions below TS nominal trip because Technical Specifications do not require entry into a TS Condition until an event setpoint value requirements actually happens.

(including NPP licensees using allowable value in its TSs) and would actuate plant degraded voltage protection, is the NPP offsite power system declared inoperable under the plant TSs? If not, why not?

(b) If onsite safety-related The plant accident analyses evaluate a LOOP occurring coincident with various accidents. A equipment (e.g., emergency postulated double sequencing event is outside the plants licensing basis and has not been diesel generators or safety- evaluated. Equipment operability is based on performance of safety functions and safety related motors) is lost when support functions required within the plant licensing basis subjected to a double sequencing (LOCA with delayed LOOP event) as a result of the anticipated system performance 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?

12 of 31 PINGP Response to Requested Information GL 2006-02, July 21, 2006 Question 3 If not, why not?

(c) Describe your evaluation Double sequencing is not in the PINGPs licensing basis and PINGP is not designed or of onsite safety-related analyzed for double sequencing scenarios equipment to determine whether it will operate as designed during the condition described in question 3(b).

(d) If the NPP licensee is No. Technical Specification Conditions are not entered for grid conditions that might occur.

notified by the TSO of other The PINGP operator only declares offsite path(s) inoperable when the RTCA predicted voltage grid conditions that may following a dual unit trip of PINGP is low enough to preclude initiation of loss of coolant impair the capability or accident (LOCA) loads concurrent with a dual unit trip.

availability of offsite power, are any plant TS action statements entered? If so, please identify them.

(e) If you believe your plant Not applicable to PINGP since offsite power sources will be declared inoperable as described TSs do not require you to in response to question 3(a) above in accordance with the plant licensing basis and Technical declare your offsite power Specifications.

system or safety-related equipment inoperable in any of these circumstances, explain why you believe you comply with the provisions of GDC 17 and your plant TSs, or describe what 13 of 31 PINGP Response to Requested Information GL 2006-02, July 21, 2006 Question 3 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.

(f) Describe if and how NPP The compensatory actions discussed in response to questions 3(a) through 3(e) involve operators are trained and entering Technical Specification Conditions. PINGP operators are trained in the interpretation tested on the compensatory and use of plant Technical Specifications and associated compensatory measures.

actions mentioned in your answers to questions 3(a) through (e).

Question 4

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 Yes. Procedural guidance is provided to the PINGP operators. The procedures require that have any guidance or the TSO be informed if the tap changer on 10 Bank Transformer is placed in manual and to do procedures in plant TS bases so only at the direction of the TSO so that the Security Analysis tool can be assessed for sections, the final safety accuracy. In addition, procedural guidance is provided for the abnormal operating condition of analysis report, or plant taking the generator voltage regulator to manual which includes requirements to contact the procedures regarding TSO in such an event.

situations in which the Operator training is provided within the context of general training on specific systems and condition of plant-controlled or 14 of 31 PINGP Response to Requested Information GL 2006-02, July 21, 2006 Question 4

-monitored equipment (e.g., operating procedures.

voltage regulators, auto tap changing 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, Not applicable. PINGP does have procedural guidance that provides the operator with written the final safety analysis report, direction for responding to equipment malfunctions and manipulation of controls that can and plant procedures do not adversely affect the operability of the PINGP offsite power system.

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.

15 of 31 PINGP Response to Requested Information GL 2006-02, July 21, 2006 Use of NPP licensee/TSO 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.

Question 5

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 Yes. The PINGP scheduling group ensures that all maintenance activities affecting grid qualitative grid reliability reliability or equipment designed to mitigate loss of offsite power scenarios are assessed for evaluation performed at your their impact on risk before those activities are performed. As part of this assessment, grid NPP as part of the reliability is considered and adjusted if appropriate (for severe weather, grid instability, or maintenance risk assessment offsite supply lines unavailable).

required by 10 CFR Maintenance activities associated with equipment supporting offsite power sources to the 50.65(a)(4) before performing safeguards buses, such as removing a transformer have been determined to be significant grid-risk-sensitive and are quantitatively incorporated into online risk assessment calculations. Removal from maintenance activities? This service of any of the four 345 kV lines to the substation is also quantitatively included in the includes surveillances, post- online risk assessment calculations. The scheduling group contacts the risk analysis group for maintenance testing, and support when a condition arises that requires a detailed assessment beyond the capability of preventive and corrective the normal online assessment tool (EOOS, EPRI software program Equipment Out Of maintenance that could Service that is used to provide risk analysis for maintenance activities).

increase the probability of a plant trip or LOOP or impact Plant procedures that provide guidance on the assessment and management of risk LOOP or SBO coping associated with maintenance activities include EOOS software to model equipment capability, for example, configurations. This includes equipment (transformers, breakers) that forms the paths from before taking a risk-significant the grid to the safety-related buses.

piece of equipment (such as When maintenance is being performed on one of the 345 kV lines, the EOOS variable an EDG, a battery, a steam-16 of 31 PINGP Response to Requested Information GL 2006-02, July 21, 2006 Question 5 driven pump, an alternate AC "Environmental Variances - Switchyard Maintenance" is set to a specific multiplier as called power source) out-of-service? out in the procedure. When maintenance is being performed on two of the 345 kV lines, the multiplier is set to a different value to account for the increased risk.

(b) Is grid status monitored by Yes. Per the responses provided in response to question 2, the grid status is continuously some means for the duration being monitored by the TSO with the operation of the RTCA. The TSO will inform the PINGP of the grid-risk-sensitive shift supervison if grid conditions significantly change that will place the grid into an elevated maintenance to confirm the system condition or that the minimum post contingent substation voltage is not met. Changes continued validity of the risk to the grid conditions are monitored internally by the work week manager and the risk assessment and is risk assessment would be revised accordingly in response to the changing or emergent grid reassessed when warranted? conditions as reported by the TSO.

If not, how is the risk assessed during grid-risk-sensitive maintenance?

(c) Is there a significant Typically the grid carries more power during summer months due to heavier loading. However variation in the stress on the the stress on the grid is a function of what equipment is in service and the ability of the grid to grid in the vicinity of your handle the increased loading with respect to winter months. Existing procedures and NPP site caused by seasonal protocols used by the TSO provide guidance on the grid operations to maintain grid reliability loads or maintenance and stability. These guidelines include direction on adjustments of real and reactive power activities associated with generation, load shedding, etc. to maintain a stable grid and reliable power to the PINGP.

critical transmission The overriding concern of the TSO is to maintain continued grid reliability/stability. To protect elements? the grid, TSO procedures require that service to residential and commercial customers be Is there a seasonal variation reduced by first reducing voltage at the distribution level and if required, shedding load. The (or the potential for a residential and commercial customers may experience electrical outages at the distribution seasonal variation) in the level while the grid is unaffected. Hence, offsite power would continue to be available to LOOP frequency in the local PINGP.

transmission region? Current industry data is inconclusive relative to the degree of seasonal variation in LOOP 17 of 31 PINGP Response to Requested Information GL 2006-02, July 21, 2006 Question 5 If the answer to either frequency. EPRI TR-1011759, dated December 2005 and EPRI TR-1009890, dated August question is yes, discuss the 2004, have shown that there is no statistically significant seasonal-regional variation in time of year when the recorded LOOP events from 1997 to 2004. Other recent documents and studies (i.e.,

variations occur and their NUREG/CR 6890) has indicated a statistical significant increase in frequency and associated magnitude. CDF during summer months. Current PINGP data from EPRI TR-1009889 does not breakdown or quantify a daily time dependent or seasonal variation in LOOP probability.

(d) Are known time-related The estimated likelihood of losing offsite power to PINGP is adjusted for certain conditions, variations in the probability of such as degraded grid stability, severe weather, and maintenance activities that impact offsite a LOOP at your plant site power reliability, and this adjusted offsite power reliability information is factored into the online considered in the grid-risk- risk monitoring tool for quantitative risk assessments. The thresholds for implementing sensitive maintenance quantitative adjustments to the online risk assessments are fairly well established, but some evaluation? If not, what is conditions may arise that need to be addressed on a case by case basis.

your basis for not considering PINGP adjusts the loss of offsite power (LOOP) frequency when grid stability degrades to a them? red level, as defined by the TSO. Nominal values are used when grid stability is green, yellow or orange.

The frequency of offsite power loss is adjusted (quantitatively assessed in the online risk monitoring model) for tornado, severe thunderstorm or high wind watches. Less severe conditions are treated on a case by case basis, and may be quantitatively assessed if conditions are determined to warrant an adjustment.

The online risk analysis model incorporates maintenance activities that remove the 345 kV lines to the substation from service or remove components such as transformers, or isolate breakers from offsite power lines that supply the safeguards buses. Passive activities such as working in the substation area are qualitatively assessed and generally determined to have a negligible impact on risk.

PINGP makes no adjustments to the loss of offsite power estimates as a function of time of day, day of week, or season.

18 of 31 PINGP Response to Requested Information GL 2006-02, July 21, 2006 Question 5 (e) Do you have contacts with Yes. The NSP TSO informs PINGP of planned maintenance through NSP's Transmission the TSO to determine current Work Request (TWR) process. If unplanned conditions take out a PINGP 345 kV transmission and anticipated grid line, the NSP TSO will also inform the PINGP control room.

conditions as part of the grid PINGP procedures require the NSP TSO to inform PINGP shift supervision if the N-1 reliability evaluation contingent voltage goes below the setpoint for a dual unit PINGP trip or if grid conditions performed before conducting change that may require suspension or postponement of maintenance and/or surveillance grid-risk-sensitive procedures affecting grid sensitive equipment.

maintenance activities?

Other maintenance activities that could result in a trip of PINGP or grid instabilities are not specifically coordinated with the TSO; however these activities are reviewed for risk sensitivity as described in 5(a) and 6(c).

(f) Describe any formal The TSO will notify PINGP in accordance with the agreement discussed in response to agreement or protocol that question 1(a) based upon grid conditions described in the response to question 1(b) above.

you have with your TSO to These notifications would be provided to PINGP whether or not maintenance is on-going.

assure that you are promptly The type of alerts provided to the PINGP conforms to the accepted practice promulgated by alerted to a worsening grid the North American Electric Reliability Council (NERC). Important alerts such as the one condition that may emerge suggested by this question would be made to all generators in the control area.

during a maintenance activity.

Changes to the grid operations, transmission lines out of service, generators taken off line, etc. are provided as real-time inputs to the RTCA via the SCADA system. Any change to the actual grid configuration that will cause a change in the grid system conditions codes or the dual unit post trip substation voltage to not meet degraded voltage requirements will trigger immediate notification to the Shift Supervisor from the TSO.

(g) Do you contact your TSO No, per the discussion in response to question 5(b). The TSO will inform the PINGP of any periodically for the duration of significant changes in the grid condition. Planned grid-risk sensitive maintenance activities the grid-risk-sensitive are identified beforehand to the TSO via the TWR notification as described in response to 19 of 31 PINGP Response to Requested Information GL 2006-02, July 21, 2006 Question 5 maintenance activities? question 5(e). Also plant surveillance and maintenance activities are reviewed when grid conditions may change as described in response to question 6(c).

(h) If you have a formal There is no formal training provided to the plant operators and maintenance personnel on the agreement or protocol with details of the formal agreement between PINGP and the TSO and/or MISO. Portions of the your TSO, describe how NPP formal agreement which impact operations and/or maintenance have, however, been operators and maintenance extracted from the agreement and incorporated into plant procedures. Training on this personnel are trained and procedural material is provided as discussed below.

tested on this formal Senior Rector Operators (SROs) have been trained in risk management and operability agreement or protocol. determination over the past few years at PINGP. This training has not been specific to the electrical grid, but has trained the SROs in the methodology that would be used when presented with the conditions stated above.

Operators were trained on the addition of switchyard maintenance to EOOS for doing a probabilistic risk assessment (PRA).

No training is provided to maintenance personnel.

(i) If your grid reliability A formal agreement for communication exists which would result in notification of grid evaluation, performed as part conditions that would be considered as part of maintenance risk assessment. Therefore, this of the maintenance risk question is not applicable.

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).

20 of 31 PINGP Response to Requested Information GL 2006-02, July 21, 2006 Question 5 (j) If risk is not assessed Not applicable to PINGP. The TSO communicates grid conditions to the plant shift (when warranted) based on supervision and that information is incorporated into online risk assessments as described continuing communication above (see answer to question 5(d)).

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 No alternative actions to be taken.

5(i) and 5(j), you 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.

21 of 31 PINGP Response to Requested Information GL 2006-02, July 21, 2006 Question 6

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 Yes. The NSP TSO informs PINGP of planned maintenance through NSP's TWR process. If transmission system unplanned conditions take out a PINGP 345 kV transmission line, the NSP TSO will also maintenance activities that inform the PINGP control room.

can have an impact on the PINGP procedures require the NSP Transmission System Operator (TSO) to inform the NPP operation with the NPP PINGP control room if the contingent voltage goes below the setpoint for a dual unit PINGP operator? trip. If this situation develops, PINGP declares the affected path from the grid (TS 3.8.1 Condition A) inoperable.

(b) Do you coordinate NPP Yes. See protocols as referenced in Question 1(a) and response to question 5(e).

maintenance activities that PINGP informs the NSP TSO of planned maintenance through NSP's TWR process. It should can have an impact on the be noted that this would apply to maintenance of substation transformers, breakers and other transmission system with the equipment in the substation that is owned and maintained by Xcel, the parent utility that also TSO?

operates the transmission system.

(c) Do you consider and Yes. Although rescheduling is not in the Maintenance Rule definitions, the risk informed implement, if warranted, the Maintenance Rule allows many choices.

rescheduling of grid-risk- Grid-risk sensitive maintenance is performed when the on-shift personnel conclude that the sensitive maintenance risk of the work is small compared to the safety benefit. When the maintenance work is done activities (activities that could in response to a Technical Specification, the risk assessment is informative for sequencing (i) increase the likelihood of a tasks, but not controlling.

plant trip, (ii) increase LOOP probability, or (iii) reduce Emergent issues with the grid are managed to maintain a high level of plant safety. When LOOP or SBO coping notified of elevated grid color code, appropriate management means rescheduling activities altogether, at other times the shift-supervisor will order the on-shift maintenance staff to back 22 of 31 PINGP Response to Requested Information GL 2006-02, July 21, 2006 Question 6 capability) under existing, out of the task and restore the safety-related function of the equipment until the grid imminent, or worsening awareness conditions have reduced.

degraded grid reliability As described in in response to questions 5(a) through 5(g) above, the risk assessment and the conditions? continuous monitoring of grid conditions will cause PINGP move activities into and out of the maintenance schedule as required to either minimize the risk or manage the risk with appropriate compensatory actions.

Yes. All grid-risk sensitive maintenance activities are subject to a rigorous review prior to work (d) If there is an overriding start as outlined in various PINGP and TSO procedures and guidance documents per the need to perform grid-risk-interface agreement.

sensitive maintenance activities under existing or Xcel grid (transmission/generation) system status color codes provide an indication of grid imminent conditions of status. This code is based on the combination of: 1) system generation availability versus degraded grid reliability, or demand; and 2) transmission system load versus operating limits. A color code of Green continue grid-risk-sensitive indicates normal system status. Yellow is a warning status. Orange is a danger status. Red maintenance when grid is an emergency status.

conditions worsen, do you implement appropriate risk PINGPs work management group utilizes the EOOS software program (described in response management actions? If so, to question 5) to determine the probability of a core damaging event based on plant and grid describe the actions that you configurations during the maintenance activities. The small probability of the loss of the grid would take. (These actions system when the status changes from green to yellow has been determined to be negligible.

could include alternate However; the likelihood of a loss of offsite power is assessed to be significantly higher when equipment protection and the grid system status is changed to orange or red.

compensatory measures to limit or minimize risk.) If there is an overriding need to perform or continue in progress work during imminent or degraded grid conditions, then, written guidance would direct the necessary actions to be taken for the given system condition code.

(e) Describe the actions Actions to be taken are addressed within each of the responses to questions 6(a) through 6(c) 23 of 31 PINGP Response to Requested Information GL 2006-02, July 21, 2006 Question 6 associated with questions above. The procedures that govern these actions are also discussed in the same responses.

6(a) through 6(d) above that Strict procedure adherence is an expectation of both NMC and Xcel management.

would be taken, state For 6(d), the risk management procedure at PINGP directs that additional risk evaluations be whether each action is performed taking into account elevated grid conditions (described as yellow, orange or red) as governed by documented provided by the TSO to assess the core damage frequency (CDF) associated with the procedures and identify the proposed maintenance activity. A similar maintenance risk color identifier is assigned (per the procedures, and explain why EOOS evaluation) to the unit for equipment out-of-service configuration based on the these actions are effective configurations of both plant and grid to establish a specific CDF. A maintenance risk color and will be consistently category of red indicates that the risk rate is too high, and must be reduced immediately by accomplished. placing equipment back in service or by implementing contingency or compensatory measures. The color category actions are assigned based on the length of the risk-informed allowable out-of-service time, as follows:

• Red - Do not voluntarily enter these configurations. Plant Operations Review Committee must authorize operation for any length of time in this condition.

Immediately restore equipment to service, or implement risk management actions to restore at least an orange color category.

• Orange - Plant Manager approval required to commence planned activity.

• Yellow - Shift Manager approval required to commence planned activity.

• Green - Normal work control procedures apply.

Maintenance activities performed by Xcel on grid reliability sensitive equipment are also governed by similar restrictions based on the system condition color code and are coordinated with plant maintenance or curtailed appropriately, and specific elevated grid condition operating procedures are initiated depending on the severity of the system code.

By maintaining the lowest out-of-service times and the lowest CDF risk with appropriate risk informed decisions, reasonable assurance is provided that grid sensitive maintenance activities will be effectively managed.

24 of 31 PINGP Response to Requested Information GL 2006-02, July 21, 2006 Question 6 (f) Describe how NPP SROs have been trained in risk management and operability determination over the past few operators and maintenance years at PINGP. This training has not been specific to the electrical grid, but has trained the personnel are trained and SROs in the methodology that would be used when presented with the conditions stated tested to assure they can above.

accomplish the actions Operators trained on the addition of switchyard maintenance to EOOS for doing PRA.

described in your answers to question 6(e). No training is provided to maintenance personnel related to this question.

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

regarding transmission system maintenance or NPP maintenance 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 As discussed in response to questions 6(a) through 6(d), PINGP effectively implements effectively implement appropriate risk management actions.

appropriate risk management actions during the conditions described above, explain why you believe you effectively addressed the relevant provisions of the associated NRC-endorsed industry 25 of 31 PINGP Response to Requested Information GL 2006-02, July 21, 2006 Question 6 guidance.

(i) You may, as an alternative No alternative actions to be taken.

to questions 6(g) 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).

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.

Question 7

7. Procedures for identifying local power sources 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 26 of 31 PINGP Response to Requested Information GL 2006-02, July 21, 2006 Question 7 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 PINGP is also owned by the parent owner of the grid TSO; therefore no formal agreements agreement made with the exist other than the agreements identified in response to question 1(a). The Xcel Corporate TSO to identify local power System Restoration Plan states in Section 7.2 that, The nuclear plants could receive auxiliary sources that could be made power as soon as the system and frequency stabilize. However, if either or both nuclear sites available to re-supply power were to request power because of failures or problems with their emergency station to your plant following a generators, power would be routed to their respective substations.

LOOP event. The plant would get top priority for restoration of offsite power if the emergency diesel generators were not operable. The priority would not be for re-starting the plant, but rather to restore power to the safe shutdown equipment. The TSO will utilize the best sources available for specific events to restore offsite power and to determine the specific 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 owner controlled local power sources.

It should be noted that due to the indeterminate nature of a LOOP, the actions that could take place in the event of a LOOP at PINGP are not prescriptively identified in any procedure.

(b) Are your NPP operators The TSO is responsible for restoration of power to the Prairie Island Substation in the event of trained and tested on a LOOP.

identifying and using local PINGP operators have been trained to use Emergency Operating Procedures (EOPs) and power sources to resupply AOPs to address issues related to the grid and to restoration of power to the essential buses your plant following a LOOP in the event of a LOOP. This is comprised of classroom training on the abnormal procedures 27 of 31 PINGP Response to Requested Information GL 2006-02, July 21, 2006 Question 7 event? If so, describe how. and training in the Simulator.

(c) If you have not PINGP is an asset owned by the same company that owns and operates the Transmission established an agreement System and has established agreements to maintain adequate voltage and current support as with your plants TSO to described in response to question 1(a).

identify local power sources The TSO has the responsibility to restore offsite power to PINGP as a priority as described in that could be made available response to question 7(a). Identifying local power sources that could be made available to to resupply power to your resupply power to PINGP following a LOOP is not part of the PINGP licensing basis.

plant following a LOOP event, explain why you believe you The requirement for procedures to restore AC power to PINGP is met by providing instructions comply with the provisions of to the system dispatcher to give the highest possible priority for restoring offsite power to 10 CFR 50.63, or describe PINGP in the event of a grid collapse and a simultaneous loss of emergency diesel generators what actions you intend to (EDGs) at the site. The TSO System restoration and blackout procedures also contain this take to establish compliance. guidance and identify initial power sources for restoration.

The TSO is required by NERC standards to maintain a system restoration plan. The plan provides for priority restoration of power to nuclear units in the event of a system blackout.

PINGPs SBO and LOOP Abnormal Operating Procedures provide for communication between the system operator and PINGP Operations with regard to efficient restoration of AC power from the grid. Load restoration at the plant level is also addressed within the SBO and LOOP AOPs.

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.

28 of 31 PINGP Response to Requested Information GL 2006-02, July 21, 2006 Question 8

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

(a) Has your NPP One, due to weather related conditions external to the plant. Refer to LER 1996012. It should experienced a total LOOP be noted, however, that one 345 kV line and one 161 kV line remained energized throughout caused by grid failure since the event maintaining some limited power to the non-safeguards buses throughout the event.

the plants coping duration was initially determined under 10 CFR 50.63?

(b) If so, have you No. Following the guidance of NUMARC 87-00 used in the original SBO classification, PINGP reevaluated the NPP using remains classified in Severe Weather (SW) Group 2 since the annual expectations for snow, the guidance in Table 4 of tornadoes and severe storms has not changed; therefore, no reevaluation was required.

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 No reevaluation was required since the annual expectations for snow, tornadoes and severe results of this reevaluation, storms have not changed.

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

(d) If your NPP has Per the guidance of NUMARC 87-00, PINGP remains classified as SW Group 2 since the 29 of 31 PINGP Response to Requested Information GL 2006-02, July 21, 2006 Question 8 experienced a total LOOP annual expectations for snow, tornadoes and severe storms have not changed; therefore, caused by grid failure since PINGP remains in compliance with the provisions of 10 CFR 50.63.

the plants 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 Based on the responses provided above, NMC considers that operation and maintenance of any action is warranted to the PNP is in compliance with the noted regulatory requirements to the extent described in the bring your NPP into plants licensing basis.

compliance with NRC regulatory requirements, including TSs, GDC 17, 10 CFR 50.65(a)(4),

10 CFR 50.63, 10 CFR 55.59 30 of 31 PINGP Response to Requested Information GL 2006-02, July 21, 2006 or 10 CFR 50.120, describe the schedule for implementing it.

31 of 31 MNGP Response to Requested Information GL 2006-02, July 21, 2006 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).

Question 1

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 Yes. The Transmission System Operator (TSO) to which the Monticello Nuclear Generating agreement or protocol with Plant (MNGP) supplies power is owned and operated by Xcel Energy, Inc. (Xcel). MNGP is your TSO? owned by Northern States Power Company (NSP), a wholly owned subsidiary of Xcel Energy, Inc. (Xcel), and operated by Nuclear Management Company, LLC (NMC). Although NMC is the plant operating entity, references to management actions on behalf of MNGP in the remainder of this document are referred to as MNGP.

The MNGP formal agreement with the TSO (all references to TSO, ISO, Reliability Controller or Control Center, System Operation, Delivery System Operations, Energy Supply, Balancing Authority, etc. throughout this document refer to Xcel Energys Northern States Power System Control Center) is documented in Nuclear Power Plant Operating Services Agreement between Northern States Power Company and Nuclear Management Company, LLC for the Monticello Nuclear Generating Plant.

(b) Describe any grid The TSO is required to notify MNGP in the event of changes in the transmission system lineup conditions that would trigger or conditions that could affect plant and offsite source reliability and availability.

a notification from the TSO to 1 of 32 MNGP Response to Requested Information GL 2006-02, July 21, 2006 Question 1 the NPP licensee and if there There are triggering conditions that cause the TSO to notify MNGP of potential or developing is a time period required for grid instabilities in the area of voltage control limits or voltage rate of change for their the notification transmission lines. Procedures direct the TSO to inform MNGP of tightening energy and capacity situations and put the facility on notice that the grid is being stressed or the potential for disturbances is imminent. An operating guide directs the TSO to notify MNGP shift supervision of a contingency condition that would result in MNGP degraded voltage conditions if it occurs. Specific examples of potentially degrading conditions identified in the agreement include:

1. If a Real Time Contingency Analysis (RTCA) post contingent alarm is received and cannot be cleared by system operator action indicating that the post-trip grid voltage at the MNGP substation will be below the calculated minimum voltage for the present plant substation lineup; and

2. If grid conditions, as established by Energy Supply, enters into or leaves a system condition designated as orange or red. (These are the two most stressed grid conditions).

(c) Describe any grid Grid conditions and status are the primary responsibility of the TSO and Reliability conditions that would cause Coordinator. The MNGP process computer continuously displays the 345 kV and 115 kV the NPP licensee to contact voltages, allowing for continuous monitoring by the plant operating staff. An alarm will the TSO. annunciate if the voltages approach unacceptable levels. In addition, the 345 kV frequency is monitored and a low frequency generates an alarm on a plant main control room panel.

Describe the procedures associated with such a The TSO is contacted per procedure for response to any grid conditions that result in communication. If you do not substation alarms. These procedures include computer alarm and annunciator response have procedures, describe procedures as well as Operations Manual procedures. In addition, Plant Abnormal Operating how you assess grid Procedures (AOP) direct communication with the TSO in response to loss of major substation conditions that may cause the components.

NPP licensee to contact the TSO.

2 of 32 MNGP Response to Requested Information GL 2006-02, July 21, 2006 Question 1 (d) Describe how NPP Licensed Operator Training includes the following:

operators are trained and Initial Training:

tested on the use of the procedures or assessing grid The following material is presented in the classroom and tested by written exam per program conditions in question 1(c). requirements:

• Main Generator: discuss the requirements for actions should transformer voltages (1R, 2R, or 1AR) be outside required action levels. Also discussed is MNGPs response to system underfrequency conditions and the actions that MNGP can take to increase plant reactive loading while remaining within the generator capacity curve;

• Substation: discuss the requirement for actions should MNGP be notified by the TSO of a 345 KV or a 115 KV System Contingency Voltage Notification, as described in 1(b) above;

• 4160 V system: discuss the requirements, precautions and actions for a system undervoltage situation; and

• Station Electrical Blackout (SEBO): discuss the bases and development of the Xcel response procedures to grid related problems.

The following are simulator sessions in the Initial Training Program that get evaluated in the simulator per program requirements:

• Degrading Grid (DG) Test, Degrading Grid and Loss of Offsite Power: This simulator session focuses on degrading grid conditions and operator actions required by these conditions. This simulator scenario degrades to the point of a complete loss of offsite power and interaction with the TSO; and

• Loss of Normal Offsite Power (LONOP) due to grid instability: This exercise simulates grid conditions present in the 2003 Northeast Blackout event and operator response.

Licensed Operator Requalification Training:

In 2005 the following training was presented:

3 of 32 MNGP Response to Requested Information GL 2006-02, July 21, 2006 Question 1 Both classroom training on the Northeast Blackout of 2003 and actions taken to prevent the same occurrence here included review of procedures for degrading transformer/grid voltages and the actions required at MNGP, and newly installed breakers in the switchyard including operation and alarms. Dynamic simulator training was conducted emphasizing degrading grid conditions. Training also included a discussion of voltage regulator and grid interaction, and loading capabilities of the turbine generator using the operating curves.

Plans for future continuing training include degraded voltage conditions.

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

formal agreement or protocol with your TSO, describe why 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.

(f) If you have an existing As previously stated in response to question 1(a), MNGP does have a formal TSO agreement.

formal interconnection Procedures exist that address the interface between the grid operator and MNGP. The TSO is agreement or protocol that required to promptly notify MNGP shift supervision in the event of changes in the transmission ensures adequate system lineup or conditions that could affect plant and offsite source reliability and availability.

communication and A procedure directs the TSO to inform MNGP of tightening energy and capacity situations coordination between the which will put the facilities on notice that the grid is being stressed or the potential for NPP licensee and the TSO, disturbances is imminent. This notification would come in advance of any MNGP substation describe whether this voltages approaching a value that would result in actuation of degraded voltage protection.

agreement or protocol requires that you be promptly In addition, the TSO continually monitors the grid for contingency conditions utilizing an RTCA 4 of 32 MNGP Response to Requested Information GL 2006-02, July 21, 2006 Question 1 notified when the conditions program. The TSO would inform MNGP if the contingency analysis results indicate the plant of the surrounding grid could would experience degraded voltage following a trip of MNGP, loss of MNGP Substation 10 result in degraded voltage Transformer, or other contingency, and the contingency condition voltages cannot be (i.e., below TS nominal trip corrected by system operator action.

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 At MNGP, degraded voltage is not sensed in the switchyard. The degraded voltage protection switchyard voltage conditions scheme senses voltage at the essential plant 4.16 kV buses. MNGP has maintained load flow that would initiate operation calculations to ensure that the Technical Specifications offsite power source minimum voltage of plant degraded voltage levels are adequate for station lineups under worst case loading and motor starting conditions:

protection.

Degraded voltage relay nominal set point: 3915 Volts on 4.16 kV nominal system voltage; and Nominal time delay: 9 seconds.

Degraded voltage protection will not initiate as long as switchyard voltages do not fall below the following values:

1. When supplied by the preferred source (2R Transformer):

115 kV system voltage < 114.7 kV or 345 kV system voltage < 342 kV; or

2. When supplied by the non-preferred source (1R Transformer):

115 kV system voltage < 116 kV or 345 kV system voltage < 342 kV.

Under the worst case loading on the plant auxiliary electrical system, these conditions would initiate operation of the plant degraded voltage protection.

5 of 32 MNGP Response to Requested Information GL 2006-02, July 21, 2006 Question 2

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 NPPs TSO Yes. The TSO makes use of analysis tools to predict grid conditions that would make the use any analysis tools, an MNGP offsite power system inoperable. These tools are not available to the MNGP.

online analytical transmission The tools presently used by the TSO to manage the grid programs, control the transmission system studies program, or related activities, and monitor grid actions include the following:

other equivalent predictive methods to determine the

• a fully commissioned RTCA program; grid conditions that would

• a grid state estimator and System Control and Data Acquisition (SCADA) system in make the NPP offsite power conjunction with periodic studies of a reasonable number of contingencies; and system inoperable during various contingencies?

• bounding analyses.

If available to you, please The following is a brief description of the RTCA operation:

provide a brief description of The Security Analysis (SA) is a real time load flow program that takes data from the SCADA the analysis tool that is used network to establish the various state variable parameters required to analyze the network.

by the TSO. Once all the state input data is set, the program calculates the voltages at all of the nodes in the network. As in any load flow analysis, the program may take a few iterations to reach a solution. For purposes of this explanation, this is referred to as the Base Real Time Analysis.

Upon reaching the base solution the program then sequentially steps through a sequence of N contingencies to recalculate resultant node voltages for a series of what if scenarios.

Each contingency calculation considers the loss of one of the major components in the base analysis at a time, hence the term N-1 Contingency Analysis. It calculates the resultant voltage at each node based on the loss of one of the components from the base real time solution. This list of contingencies may be several hundred elements long and runs immediately after the base solution is calculated. The contingency of primary concern to the nuclear plant is the trip of the plant and the effect on the resultant voltage at the plants 6 of 32 MNGP Response to Requested Information GL 2006-02, July 21, 2006 Question 2 substation. For the purpose of this discussion this will be referred to as the Primary Contingency. For each of the N-1 contingencies, the resultant voltage at each of the nodes of concern is compared to pre-established voltage limits and if any voltage falls out of that range, the system operator receives an alarm. If an alarm is received upon running of the primary contingency and cannot be cleared by system operator action, the system operator is instructed to contact the nuclear plant in accordance with established protocols.

(b) Does your NPPs TSO Yes. The TSO uses the above analysis tools, in conjunction with procedures, as the basis for use an analysis tool as the determining when conditions warrant MNGP notification.

basis for notifying the NPP licensee when such a condition is identified? If not, how does the TSO determine if conditions on the grid warrant NPP licensee notification?

(c) If your TSO uses an Yes. The TSO analysis tool, in conjunction with MNGP analysis, identifies conditions which analysis tool, would the may actuate the MNGP degraded voltage protection logic and initiate separation from an analysis tool identify a offsite power source upon a MNGP trip.

condition in which a trip of the The RTCA program used by the TSO analyzes the grid for the current real time conditions with NPP would result in one contingency condition and alarms if the MNGP switchyard voltage levels would be below switchyard voltages the thresholds established by MNGP (outlined in the response to question 1(g)) for one or (immediate and/or long-term) more contingencies. The established switchyard voltage thresholds are the levels at which falling below TS nominal trip the 4.16 kV essential bus voltage levels would dip within the analytical limits (3897 - 3933 V) setpoint value requirements of the degraded voltage set point. Two of the many contingencies used in the analysis are (1)

(including NPP licensees the loss of MNGP generation and (2) the loss of MNGP switchyard 345/115 kV transformer using allowable value in its (10 Transformer).

TSs) and consequent 7 of 32 MNGP Response to Requested Information GL 2006-02, July 21, 2006 Question 2 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 The TSO RTCA program presently updates and recalculates the MNGP trip contingency on a analysis tool, how frequently time interval of approximately 7 to 8 minutes.

does the analysis tool The TSO SCADA information available as an input to the RTCA is essentially real time and program update?

provides updates to the RTCA each time it runs.

(e) Provide details of analysis The notification from the TSO is based upon the predicted post-trip or other contingency tool-identified contingency switchyard voltage given actual (RTCA) grid conditions.

conditions that would trigger The RTCA tool applies the real time actual conditions of the grid to the analysis with one of the an NPP licensee notification major grid components (generating unit, transmission line, or transformer) removed. The tool from the TSO. will then generate an alarm if the resultant voltages at the MNGP substation 10 Transformer or MNGP generator do not meet the following thresholds:

• 342 kV on the 345 kV system;

• 114.7 kV on the 115 kV system when the plant is on its preferred source; and

• 116 kV on the 115 kV system when the plant is on its non-preferred source.

If an alarm is generated for a MNGP voltage threshold violation, the TSO operator procedurally attempts to restore the post-contingency predicted MNGP switchyard voltage levels. If the system changes do not restore the post-contingency predicted voltage levels, then the operator notifies the MNGP control room.

8 of 32 MNGP Response to Requested Information GL 2006-02, July 21, 2006 Question 2 (f) If an interface agreement Yes. The agreement specifically requires MNGP notification when grid conditions are exists between the TSO and indeterminate for 90 minutes or greater.

the NPP licensee, does it MNGP follows Technical Specifications requirements when notified by the TSO that grid require that the NPP licensee conditions are indeterminate. Operating procedures would be followed if this occurs. Voltage be notified of periods when is also monitored at the 4.16 KV buses and appropriate actions are defined in Plant the TSO is unable to Operations Manual procedures for operator action if voltage limits are not met at this system determine if offsite power level.

voltage and capacity could be inadequate?

If so, how does the NPP licensee determine that the offsite power would remain operable when such a notification is received?

(g) After an unscheduled No. For post event analysis, the TSO does not verify by procedure the switchyard voltages inadvertent trip of the NPP, are bounded by the analysis tools. Following an inadvertent trip of MNGP, any unexpected are the resultant switchyard actuations or equipment operation associated with supply voltage would be documented and voltages verified by evaluated in accordance with the corrective action process.

procedure to be bounded by the voltages predicted by the analysis tool?

(h) If an analysis tool is not Not applicable to MNGP since TSO analysis tools are presently in use.

available to the NPP licensees TSO, do you know if there are any plans for the TSO to obtain one? If so, 9 of 32 MNGP Response to Requested Information GL 2006-02, July 21, 2006 Question 2 when?

(i) If an analysis tool is not Not applicable to MNGP since TSO analysis tools are presently in use.

available, does your 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 provisions discussed in question 1 above?

(j) If your TSO does not use, Not applicable to MNGP, since the TSO utilizes analysis tools and communicates the 10 of 32 MNGP Response to Requested Information GL 2006-02, July 21, 2006 Question 2 or you do not have access to applicable results and alarms to MNGP.

the results of an analysis tool, or your TSO does not perform and make available to you periodic studies that determine the adequacy of offsite power capability, please describe why you believe you comply 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.

Question 3

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

(a) If the TSO notifies the Yes. MNGP Technical Specifications requirements are that at least two transmission lines, NPP operator that a trip of associated switchgear, and at least two offsite power sources (2R and 1R, or 1R and 1AR, or the NPP, or the loss of the 11 of 32 MNGP Response to Requested Information GL 2006-02, July 21, 2006 Question 3 most critical transmission line 2R and 1AR transformers) are fully operational and energized to carry the 4160 V AC buses.

or the largest supply to the If notified by the TSO of a contingency voltage alarm, the MNGP control room operator by grid would result in procedure declares offsite power sources inoperable for the following conditions:

switchyard voltages (immediate and/or long-term) For a 345 kV contingency voltage threshold violation, if the contingency is loss of MNGP below TS nominal trip generation, the 2R transformer is declared inoperable.

setpoint value requirements For a 115 kV contingency voltage threshold violation:

(including NPP licensees using allowable value in its

• If the contingency is loss of MNGP generation and the contingency voltage is less than or TSs) and would actuate plant equal to 114.7 kV, then the 1R transformer is declared inoperable; and degraded voltage protection,

• If the contingency is loss of 10 transformer, and the contingency voltage is less than or is the NPP offsite power equal to 114.7 kV, then the 1R transformer and 1AR transformers are not considered system declared inoperable redundant, and 1R or 1AR is declared inoperable.

under the plant TSs? If not, why not? MNGP Technical Specifications and procedures do not require declaring the offsite sources inoperable for other contingencies such as loss of a transmission line or a contingency loss of the largest supply to the grid.

(b) If onsite safety-related The plant accident analyses evaluate a loss of offsite power (LOOP) occurring coincident with equipment (e.g., emergency various accidents. A postulated double sequencing event is outside the plants licensing basis diesel generators or safety- and has not been evaluated. Equipment operability is based on performance of safety related motors) is lost when functions and safety support functions required within the plant licensing basis.

subjected to a double sequencing (LOCA with delayed LOOP event) as a result of the anticipated system performance and is incapable of performing its safety functions as a result of responding to an emergency 12 of 32 MNGP Response to Requested Information GL 2006-02, July 21, 2006 Question 3 actuation signal during this condition, is the equipment considered inoperable?

If not, why not?

(c) Describe your evaluation Double sequencing is not part of MNGPs licensing basis and MNGP is not designed or of onsite safety-related analyzed for double sequencing scenarios.

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

(d) If the NPP licensee is No. Technical Specification Conditions are not entered for grid conditions that might occur.

notified by the TSO of other The MNGP operator only declares offsite power sources inoperable when the predicted grid conditions that may voltage following a unit trip is low enough to preclude initiation of loss of coolant accident impair the capability or (LOCA) loads concurrent with a unit trip.

availability of offsite power, are any plant TS action statements entered? If so, please identify them.

(e) If you believe your plant Not applicable to MNGP since offsite power sources will be declared inoperable as described TSs do not require you to in 3(a) above in accordance with the plant licensing basis and Technical Specifications.

declare your offsite power system or safety-related equipment inoperable in any of these circumstances, explain why you believe you 13 of 32 MNGP Response to Requested Information GL 2006-02, July 21, 2006 Question 3 comply with the provisions of GDC 17 and 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.

(f) Describe if and how NPP Training on compensatory actions is encompassed within the response to question 1(d).

operators are trained and tested on the compensatory actions mentioned in your answers to questions 3(a) through (e).

Question 4

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 Yes. Procedural guidance is provided to the MNGP operators. The operators are provided have any guidance or with written direction for responding to equipment malfunctions and manipulation of controls procedures in plant TS bases that can adversely affect the operability of the MNGP offsite power system. The following list 14 of 32 MNGP Response to Requested Information GL 2006-02, July 21, 2006 Question 4 sections, the final safety includes examples of, but does not include all procedural guidance associated with this analysis report, or plant question.

procedures regarding

• 345kV BUS VOLTAGE LOW/HIGH; situations in which the condition of plant-controlled

• 115kV BUS VOLTAGE LOW/HIGH; or -monitored equipment

• 345kV & 115kV YARD TROUBLE; (e.g., voltage regulators, auto tap changing transformers,

• 1 GEN U.F. RELAY OPERATION; capacitors, static VAR

• NO. 1 GEN MAX EXC TRIP; compensators, main generator voltage regulators)

• 1-BUS 345kV LOW FREQUENCY; can adversely affect the

• NO. 2R XFMR TROUBLE; operability of the NPP offsite power system? If so,

• 1AR TRANS TROUBLE; describe how the operators

• 1AR TRANS GROUND; are trained and tested on the guidance and procedures.

• NO. 1 RES TRANS TROUBLE;

• Removal of Automatic Voltage Regulator While on Line;

• Restoration of the Automatic Voltage Regulator While on Line;

• Faulty Voltage Regulator;

• Loss of Gen Field Current;

• 115kV System Contingency Voltage Notification;

• 345kV System Contingency Voltage Notification;

• Loss or Partial loss of 10 Transformer Cooling;

• 345kV System Contingency Voltage Notification;

• Loss of 10 Transformer; 15 of 32 MNGP Response to Requested Information GL 2006-02, July 21, 2006 Question 4

• Voltage Outside Operating Action Levels for Standby Power Sources;

• Voltage Outside Operating Action Levels With Power Supplied From 1R Transformer; and

• Voltage Outside Operating Action Levels With Essential Buses Supplied Power From 1AR Transformer.

Licensed Operator Training for these conditions is encompassed in the response to question 1(d).

(b) If your TS bases sections, Not applicable. MNGP does have procedural guidance that provides the operator with written the final safety analysis direction for responding to equipment malfunctions and manipulation of controls that can report, and plant procedures adversely affect the operability of the MNGP offsite power system.

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.

16 of 32 MNGP Response to Requested Information GL 2006-02, July 21, 2006 Use of NPP licensee/TSO 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.

Question 5

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 Yes. The MNGP scheduling group ensures that all maintenance activities for the plant and qualitative grid reliability MNGP substation affecting grid reliability or equipment designed to mitigate loss of offsite evaluation performed at your power scenarios are assessed for their impact on risk before those activities are performed.

NPP as part of the As part of this assessment, grid reliability is considered and adjustments to the work schedule maintenance risk assessment are made if appropriate (severe weather or grid instability is significant).

required by 10 CFR Many routine maintenance activities associated with equipment supporting offsite power 50.65(a)(4) before performing supply have been reviewed and qualitatively determined to have a relatively small risk impact grid-risk-sensitive and are noted as having been qualitatively assessed. In such cases the online risk model maintenance activities? This does not quantitatively assess this impact. Other maintenance activities associated with includes surveillances, post- equipment supporting offsite power, such as removing a transformer, power supply line, or maintenance testing, and substation breaker from service, have been determined to be significant and are quantitatively preventive and corrective incorporated into online risk assessment calculations. The scheduling group contacts the risk maintenance that could analysis group for support when a condition arises that requires a detailed assessment increase the probability of a beyond the capability of the normal online assessment tool (EOOS, EPRI software program plant trip or LOOP or impact Equipment Out Of Service that is used to provide risk analysis for maintenance activities).

LOOP or SBO coping capability, for example, before taking a risk-significant piece of equipment (such as an EDG, a battery, a steam-17 of 32 MNGP Response to Requested Information GL 2006-02, July 21, 2006 Question 5 driven pump, an alternate AC power source) out-of-service?

(b) Is grid status monitored by The TSO notifies the MNGP control room if grid stability degrades. The MNGP operations some means for the duration group is responsible for ensuring that risk is assessed for applicable plant conditions, including of the grid-risk-sensitive degraded grid stability. The schedule reflects that maintenance activities are being performed, maintenance to confirm the and indicates corresponding risk values. If conditions change unexpectedly, risk is re-continued validity of the risk assessed with assistance from the scheduling group or the risk analysis group, as necessary.

assessment and is risk reassessed when warranted?

If not, how is the risk assessed during grid-risk-sensitive maintenance?

(c) Is there a significant Typically the grid carries more power during summer months due to heavier loading. However variation in the stress on the the stress on the grid is a function of what equipment is in service and the ability of the grid to grid in the vicinity of your handle the increased loading with respect to winter months. Existing procedures and NPP site caused by seasonal protocols used by the TSO provide guidance on the grid operations to maintain grid reliability loads or maintenance and stability. These guidelines include direction on adjustments of real and reactive power activities associated with generation, load shedding, etc. to maintain a stable grid and reliable power to the MNGP.

critical transmission The overriding concern of the TSO is to maintain continued grid reliability/stability. To protect elements? the grid, TSO procedures require that service to residential and commercial customers be Is there a seasonal variation reduced by first reducing voltage at the distribution level and if required, shedding load. The (or the potential for a residential and commercial customers may experience electrical outages at the distribution seasonal variation) in the level while the grid is unaffected. Hence, offsite power would continue to be available to LOOP frequency in the local MNGP.

transmission region? Offsite power to MNGP is provided via a substation located on site. The substation consists of If the answer to either four incoming 345 kV transmission lines and three 115 kV transmission lines. There are three 18 of 32 MNGP Response to Requested Information GL 2006-02, July 21, 2006 Question 5 question is yes, discuss the large coal-fired units nearby that each delivers more power (between 678 MW and 877 MW) to time of year when the the grid than does MNGP. With the number of lines providing access to the grid and the variations occur and their number of large generating units in the vicinity, removal of a transmission line from service magnitude. either within the MNGP Substation or elsewhere in the system does not result in a significant increase in grid stress near MNGP.

Current industry data is inconclusive relative to the degree of seasonal variation in LOOP frequency. EPRI TR-1011759, dated December 2005, has shown that there is no statistically significant seasonal-regional variation in recorded LOOP events from 1997 to 2004. In addition, MNGP is not aware of a seasonal variation in LOOP frequency in the local transmission region.

(d) Are known time-related The estimated likelihood of losing offsite power to MNGP is adjusted for certain conditions, variations in the probability of such as degraded grid stability, severe weather, and maintenance activities that impact offsite a LOOP at your plant site power reliability, and this adjusted offsite power reliability information is factored into the online considered in the grid-risk- risk monitoring tool for quantitative risk assessments. The thresholds for implementing sensitive maintenance quantitative adjustments to the online risk assessments are well established, but some evaluation? If not, what is conditions may arise that need to be addressed on a case by case basis.

your basis for not considering MNGP adjusts the loss of offsite power frequency when grid stability degrades to an orange or them? red level, as defined by the TSO. Nominal values are used when grid stability is green or yellow.

The frequency of LOOP is adjusted (quantitatively assessed in the online risk monitoring model) for tornado warnings, winds in excess of 60 mph, or icing conditions when reported by the TSO.

The online risk analysis model incorporates maintenance activities that remove any of the offsite power supplies from service, remove substation components such as transformers, or isolate breakers. Passive activities such as working in the substation area are qualitatively assessed and generally determined to have a negligible impact on risk.

19 of 32 MNGP Response to Requested Information GL 2006-02, July 21, 2006 Question 5 MNGP makes no adjustments to the LOOP estimates as a function of time of day, day of week, or season.

(e) Do you have contacts with Yes. MNGP has procedural guidance that requires direct notification of the TSO when work is the TSO to determine current planned on equipment such as load tap changers, generator voltage regulator, diesel and anticipated grid generator testing and removal of transformers from service.

conditions as part of the grid Balance of plant activities such as half-scram testing and equipment maintenance activities reliability evaluation internal to the plant that could result in a MNGP trip or grid instabilities are not directly performed before conducting coordinated with the TSO. However, these activities are evaluated against current system grid-risk-sensitive conditions per the written responsibilities outlined in the response to question 6(d) below.

maintenance activities?

MNGP specific guidance is provided by procedure. This procedure provides MNGP operators with written guidance to evaluate and make decisions accordingly, for all in progress or planned work, based on Xcels Grid System Condition Color Codes.

(f) Describe any formal The TSO will notify MNGP in accordance with the agreement discussed in response to agreement or protocol that question 1(a) based upon grid conditions described in the response to question 1(b) above.

you have with your TSO to These notifications would be provided to MNGP whether or not maintenance is on-going.

assure that you are promptly alerted to a worsening grid condition that may emerge during a maintenance activity.

(g) Do you contact your TSO No. MNGP relies on the TSO to contact control room operators when any grid instabilities are periodically for the duration of occurring or predicted. At that time MNGP assesses all on-going work and determines the the grid-risk-sensitive most appropriate action(s) to take per MNGP procedures. MNGP does followup with the TSO maintenance activities? to understand the expected duration for any grid condition that results in a color coded yellow 20 of 32 MNGP Response to Requested Information GL 2006-02, July 21, 2006 Question 5 or higher.

(h) If you have a formal There is no formal training provided to the plant operators and maintenance personnel on the agreement or protocol with details of the formal agreement between MNGP and the TSO and/or MISO. Portions of the your TSO, describe how NPP formal agreement which impact operations and/or maintenance have, however, been operators and maintenance extracted from the agreement and incorporated into plant procedures. Training on this personnel are trained and procedural material is provided as discussed below.

tested on this formal Licensed Operator training for the protocol is contained within the response to question 1(d).

agreement or protocol.

Maintenance personnel are not involved or trained in the protocol.

(i) If your grid reliability A formal agreement for communication exists which would result in notification of grid evaluation, performed as part conditions that would be considered as part of maintenance risk assessment. Therefore, this of the maintenance risk question is not applicable.

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 Not applicable to MNGP. The TSO communicates grid conditions to the plant shift supervision (when warranted) based on and that information is incorporated into online risk assessments as described above (see continuing communication answer to question 5(d)).

with the TSO throughout the duration of grid-risk-sensitive 21 of 32 MNGP Response to Requested Information GL 2006-02, July 21, 2006 Question 5 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 No alternative actions to be taken.

5(i) and 5(j), you 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.

Question 6

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 Yes. The TSOs "Transmission Work Request" (TWR) process and NMCs Fleet Tagging 22 of 32 MNGP Response to Requested Information GL 2006-02, July 21, 2006 Question 6 transmission system Switchyard Tagging Practices control work and maintenance activities within the substations maintenance activities that and are the processes used to communicate information regarding substation work activities in can have an impact on the the grid area between the plants and the grid operators. In addition, there are policies and NPP operation with the NPP procedures that address these interface issues between the nuclear plants and the system operator? operations department, which govern work activities in the nuclear plant substations. Plant level work instructions reference nuclear and generation policies and procedures, which provide the administrative and control requirements for all activities involving the nuclear generating plant substations. They apply to all Generation organizations performing work in or which could affect a nuclear generating plant substation. The type of work activities covered by these directives includes:

• Switching of breakers, switches, relays, or communication equipment in a plant substation;

• Routine relay, breaker, transformer, battery, meter and structural maintenance; and

• Testing.

TWRs associated with substation equipment under the jurisdiction of Delivery System Operations, is processed in accordance with the requirements of the Interface Agreement.

(b) Do you coordinate NPP Yes, refer to response to question 5(e).

maintenance activities that MNGP informs the NSP TSO of planned maintenance through NSP's TWR process. It should can have an impact on the be noted that this would apply to maintenance of substation transformers, breakers and other transmission system with the equipment in the substation that is owned and maintained by Xcel, the parent utility that also TSO? operates the transmission system.

(c) Do you consider and Yes. The current grid condition is posted in the MNGP Work Control Center (WCC) and Main implement, if warranted, the Control Room. In addition, contingency voltages are continuously monitored, and the plant rescheduling of grid-risk- shift supervision is notified if contingency voltages are predicted to be inadequate. This sensitive maintenance information is taken into account, as applicable, prior to performing maintenance or testing on 23 of 32 MNGP Response to Requested Information GL 2006-02, July 21, 2006 Question 6 activities (activities that could risk significant equipment. MNGP work instructions provide guidance on approval for work to (i) increase the likelihood of a commence. This written direction requires shift supervision to take into account the condition plant trip, (ii) increase LOOP of the electrical grid as appropriate for the activity under consideration. If warranted, grid-risk-probability, or (iii) reduce sensitivity activities are rescheduled.

LOOP or SBO coping capability) under existing, imminent, or worsening degraded grid reliability conditions?

(d) If there is an overriding Yes. All grid-risk-sensitive maintenance activities are subject to a rigorous review prior to work need to perform grid-risk- start as outlined in various MNGP and TSO procedures and guidance documents per the sensitive maintenance interface agreement.

activities under existing or Xcel grid (transmission/generation) system status color codes provide an indication of grid imminent conditions of status. This code is based on the combination of: 1) system generation availability versus degraded grid reliability, or demand; and 2) transmission system load versus operating limits. A color code of green continue grid-risk-sensitive indicates normal system status. Yellow is a warning status. Orange is a danger status. Red maintenance when grid is an emergency status.

conditions worsen, do you implement appropriate risk MNGPs PRA group has developed a computer model to determine the probability of a core management actions? If so, damaging event based on plant configuration. The small probability of the loss of the grid describe the actions that you system when the status changes from green to yellow has been determined to be negligible.

would take. (These actions However; the likelihood of a loss of offsite power is assessed to be significantly higher when could include alternate the grid system status is changed to orange or red.

equipment protection and If there is an overriding need to perform or continue in progress work during imminent or compensatory measures to degraded grid conditions, then, written guidance would direct the necessary actions to be limit or minimize risk.) taken for the given system condition code.

The system condition color code is displayed in the Work Control Center (WCC) and Main 24 of 32 MNGP Response to Requested Information GL 2006-02, July 21, 2006 Question 6 Control Room.

The Control Room Supervisor is responsible for ensuring the Main Control Room and WCC system condition color code indicators reflect any changes indicated by System Operations in a timely manner and also match each other.

(e) Describe the actions Actions to be taken are addressed within each of the responses to questions 6(a) through 6(c) associated with questions above. The procedures that govern these actions are also discussed in the same responses.

6(a) through 6(d) above that Strict procedure adherence is an expectation of both NMC and Xcel management.

would be taken, state For 6(d), the MNGP and NMC Fleet risk management procedures direct that additional risk whether each action is evaluations be performed taking into account elevated grid conditions (described as yellow, governed by documented orange or red) as provided by the TSO to assess the core damage frequency (CDF) procedures and identify the associated with the proposed maintenance activity. A similar maintenance risk color identifier procedures, and explain why is assigned (per the EOOS evaluation) to the unit for equipment out-of-service configuration these actions are effective based on the configurations of both plant and grid to establish a specific CDF. A maintenance and will be consistently risk color category of red indicates that the risk rate is too high, and must be reduced accomplished. immediately by placing equipment back in service or by implementing contingency or compensatory measures. The color category actions are assigned based on the length of the risk-informed allowable out-of-service time, as follows:

• Red - Do not voluntarily enter these configurations. Plant Operations Review Committee must authorize operation for any length of time in this condition.

Immediately restore equipment to service, or implement risk management actions to restore at least an ORANGE color category.

• Orange - Plant Manager approval required to commence planned activity.

• Yellow - Shift Manager approval required to commence planned activity.

• Green - Normal work control procedures apply.

Maintenance activities performed by Xcel on grid reliability sensitive equipment are also 25 of 32 MNGP Response to Requested Information GL 2006-02, July 21, 2006 Question 6 governed by similar restrictions based on the system condition color code and are coordinated with plant maintenance or curtailed appropriately, and specific elevated grid condition operating procedures are initiated depending on the severity of the system code.

By maintaining the lowest out-of-service times and the lowest CDF risk with appropriate risk informed decisions, reasonable assurance is provided that grid sensitive maintenance activities will be effectively managed.

(f) Describe how NPP Licensed Operators are trained on and process several TWRs which affect the MNGP operators and maintenance substation during the initial training.

personnel are trained and Classroom training is provided on MNGP Administrative Work Instructions that specify tested to assure they can compensatory measures to be applied under the conditions described in response to question accomplish the actions 6(e) above. On the Job Training / Task Performance Evaluation (OJT/TPE) is then performed described in your answers to on-shift.

question 6(e).

MNGP maintenance personnel do not perform maintenance on substation equipment.

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

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

26 of 32 MNGP Response to Requested Information GL 2006-02, July 21, 2006 Question 6 (h) If you do not consider and As discussed in response to questions 6(a) through 6(d), MNGP effectively implements effectively implement appropriate risk management actions.

appropriate risk 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 No alternative actions to be taken.

to questions 6(g) 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).

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.

27 of 32 MNGP Response to Requested Information GL 2006-02, July 21, 2006 Question 7

7. Procedures for identifying local power sources 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 (a) Briefly describe any MNGP is also owned by the parent owner of the grid TSO, therefore no formal agreements agreement made with the exist other than the agreements identified in response to question 1(a). The Xcel Corporate TSO to identify local power System Restoration Plan states in Section 7.2 that, The nuclear plants could receive auxiliary sources that could be made power as soon as the system and frequency stabilize. However, if either or both nuclear sites available to re-supply power were to request power because of failures or problems with their emergency station to your plant following a generators, power would be routed to their respective substations.

LOOP event. The plant would get top priority for restoration of offsite power if the emergency diesel generators were not operable. The priority would not be for re-starting the plant, but rather to restore power to the safe shutdown equipment. Procedures allow back feeding from the Elk River - Great River Energy 230 kV line through 7N2 to accomplish this. The nuclear plants would not necessarily be the first to have offsite power restored (providing the emergency diesel generators were functional), because it is much easier, faster, and safer, from a reactor safety perspective, to restart the fossil units first.

(b) Are your NPP operators The TSO is responsible for restoration of power to the Monticello Substation in the event of a trained and tested on 28 of 32 MNGP Response to Requested Information GL 2006-02, July 21, 2006 Question 7 identifying and using local LOOP.

power sources to resupply Operators are trained on the station blackout (SBO) AOP, which gives direction for your plant following a LOOP communication with the TSO on plant conditions and also directs actions for restoration per event? If so, describe how. MNGP procedures. This is comprised of classroom training on the abnormal procedures and training in the Simulator.

(c) If you have not MNGP is an asset owned by the same company that owns and operates the Transmission established an agreement System and has established agreements to maintain adequate voltage and current support as with your plants TSO to described in response to question 1(a).

identify local power sources The requirement for procedures to restore AC power to MNGP is met by providing instructions that could be made available to the system dispatcher to give the highest possible priority for restoring offsite power to to resupply power to your MNGP in the event of a grid collapse and a simultaneous loss of emergency diesel generators plant following a LOOP event, at the site. The TSO System restoration and blackout procedures also contain this guidance explain why you believe you and identify initial power sources for restoration.

comply with the provisions of 10 CFR 50.63, or describe The TSO is required by the North American Electric Reliability Council (NERC) standards to what actions you intend to maintain a system restoration plan. The plan provides for priority restoration of power to take to establish compliance. nuclear units in the event of a system blackout. MNGPs SBO and LONOP AOPs provide for communication between the system operator and MNGP Operations with regard to efficient restoration of AC power from the grid. Load restoration at the plant level is also addressed within the SBO and LONOP AOPs.

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 29 of 32 MNGP Response to Requested Information GL 2006-02, July 21, 2006 with 10 CFR 50.63.

Question 8

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

(a) Has your NPP No. The site has not experienced a LOOP event since the implementation of the Station experienced a total LOOP Blackout rule.

caused by grid failure since the plants coping duration was initially determined under 10 CFR 50.63?

(b) If so, have you Not applicable.

reevaluated the NPP using the 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 Not applicable.

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

30 of 32 MNGP Response to Requested Information GL 2006-02, July 21, 2006 Question 8 (d) If your NPP has Not applicable.

experienced a total LOOP caused by grid failure since the plants 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 Based on the responses provided above, NMC considers that operation and maintenance of any action is warranted to the MNGP is in compliance with the noted regulatory requirements to the extent described in bring your NPP into the plants licensing basis.

compliance with NRC regulatory requirements, including TSs, GDC 17, 10 31 of 32 MNGP Response to Requested Information GL 2006-02, July 21, 2006 CFR 50.65(a)(4),

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

32 of 32

Text

Nuclear Management Company, LLC L-HU-06-030 July 21, 2006 10 CFR 50.54(f)

U. S. Nuclear Regulatory Commission ATTN: Document Control Desk 11555 Rockville Pike Rockville, Maryland 20852 Point Beach Nuclear Plant Units 1 and 2 Palisades Nuclear Plant Dockets 50-266 and 50-301 Docket 50-255 Renewed License Nos. DPR-24 and DPR-27 License No. DPR-20 Prairie Island Nuclear Generating Plant Monticello Nuclear Generating Plant Units 1 and 2 Docket 50-263 Dockets 50-282 and 50-306 License No. DPR-22 License Nos. DPR-42 and DPR-60 Response to Generic Letter 2006-02, Grid Reliability and the Impact on Plant Risk and the Operability of Offsite Power By letter dated February 1, 2006, the Nuclear Regulatory Commission (NRC) issued Generic Letter (GL) 2006-02, Grid Reliability and the Impact on Plant Risk and the Operability of Offsite Power. The NRC requested that specific information be provided within 60 days of the date of this GL. The Nuclear Management Company, LLC (NMC) submitted the requested information by letter L-HU-06-010 dated April 3, 2006.

In response to an NRC request, NMC submits this letter and enclosures which replace NMC letter L-HU-06-010 dated April 3, 2006 and its enclosures in their entirety.

Enclosures 1 through 4 provide the requested information for the Point Beach Nuclear Plant, Palisades Nuclear Plant, Prairie Island Nuclear Plant and Monticello Nuclear Plant, respectively.

Some of the questions in GL 2006-02 seek information about analyses, procedures, and activities concerning grid operation of which the Nuclear Management Company, LLC (NMC) does not have first-hand knowledge and of which are beyond the control of NMC. In providing information responsive to such questions, NMC makes no representation as to their accuracy or completeness.

Some GL 2006-02 questions are directed toward compliance with 10CFR Part 50, Appendix A, General Design Criteria, (GDC) Criterion 17. The NMC-operated plants were licensed prior to the formal publication of the GDC. As noted in SECY-92-223, all plants with Construction Permits issued prior to May 21, 1971 are not subject to these provisions and each licensee has its own licensing basis. As a Systematic Evaluation 700 First Street Hudson, Wisconsin 54016 Telephone: 715-377-3300

Document Control Desk Page 2 Program (SEP) plant, the Palisades Nuclear Plant complies with GDC 17 to the extent described in the Technical Specification Bases and the Final Safety Analysis Report.

Generally, the NMC-operated plants were licensed to comply with the Atomic Energy Commission General Design Criteria as proposed on July 10, 1967 (AEC GDC) as described in the plant Final (Updated) Safety Analysis Report. AEC GDC proposed Criterion 39, which provides guidance applicable to the design of the AC electrical power system supplies to the engineered safety features, states:

Alternate power systems shall be provided and designed with adequatle independency, redundancy, capacity, and testability to permit the functioning required of the engineered safety features. As a minimum, the onsite power system and the offsite power system shall each, independently, provide this capacity assuming a failure of a single active component in each power system.

Thus, many of the provisions of GDC Criterion 17 are not applicable to the NFJC-operated plants, the responses to the questions reflect that the plants are not committed to GDC Criterion 17, and the responses do not in any manner commit to or imply compliance with GDC Criterion 17 for the NMC-operated plants.

Summary of Commitments This letter contains no new commitments and no revisions to existing commitments.

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

Executed on 21 ~ulG2006.

&r$.~. Wdkam Director, Nuc ear Licensing and Regulatory Services Nuclear Management Company, LLC Enclosures (4) cc: Administrator, Region Ill, USNRC Project Manager, Point Beach Nuclear Plant, Palisades Nuclear Plant, Prairie Island Nuclear Generating Plant, and Monticello Nuclear Generating Plant, USNRC Senior Resident Inspector, Point Beach Nuclear Plant, Palisades Nuclear Plant, Prairie Island Nuclear Generating Plant, and Monticello Nuclear Generating Plant, USNRC PBNP Response to Requested Information GL 2006-02, July 21, 2006 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).

Question 1

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 Yes. The Transmission System Operator (TSO) to which the Point Beach Nuclear Plant agreement or protocol with (PBNP) supplies power is the American Transmission Company (ATC, referred to as the TSO your TSO? in this response). The PBNP is owned by We Energies and operated by Nuclear Management Company, LLC (NMC). Although NMC is the plant operating entity, references to management actions on behalf of PBNP in the remainder of this document are referred to as PBNP.

PBNP does have a formal agreement with We Energies and ATC. In addition, PBNP and the TSO follow the approved Midwest Independent System Operator (MISO) communication and mitigation protocols for nuclear plant/electric system interfaces that describe the notification requirements.

(b) Describe any grid The TSO is required to notify PBNP immediately whenever the real time voltage on the PBNP conditions that would trigger 345 kV bus goes outside of specified voltage limits (high or low). These limits are intended to a notification from the TSO to ensure that adequate voltage is present to supply safety related equipment and prevent the NPP licensee and if there actuation of the degraded grid voltage relays. Specific examples of known potentially is a time period required for degrading conditions identified in the agreement include:

1 of 29 PBNP Response to Requested Information GL 2006-02, July 21, 2006 Question 1 the notification 1. The TSO will notify PBNP within 15 minutes after verification, if it is determined that the loss of any single transmission element or generator connected to the TSO transmission system would cause the PBNP 345 kV bus voltage to go outside of the specified limits. If the condition triggering the notification is resolved within the notification time requirement, then notification is not required.

2. The TSO will notify PBNP of forced outages on either end of any 345 kV transmission line connected to the PBNP switchyard as well as other critical transmission lines.

3. Notifications for VAR adjustments are routinely made by the TSO through We Energies Power System Supervisors (WEPSS) to PBNP. In an emergency the TSO may communicate directly to PBNP.

(c) Describe any grid Grid conditions and status are the primary responsibility of the TSO and Reliability Coordinator conditions that would cause (MISO). PBNP does not typically initiate communication with the TSO based upon grid the NPP licensee to contact conditions. PBNP relies upon the agreements and protocols to be notified of grid conditions the TSO. as described in the response to question 1(b) above. PBNP procedures address conditions that could affect the grid and that require communication with the TSO. These Describe the procedures communications are normally through WEPSS. Reasons for notifications include: removal associated with such a from service or testing of emergency diesel generators or the gas turbine generator, either unit communication. If you do not voltage regulator placed in manual, or power system stabilizer out of service on either unit.

have procedures, describe how you assess grid conditions that may cause the NPP licensee to contact the TSO.

(d) Describe how NPP Review of the procedure for electrical communications, switchyard access and work planning operators are trained and is typically performed in initial license operator training as a result of an association to the task tested on the use of the that is being trained. Senior Reactor Operators (SROs) are trained and evaluated via the On-2 of 29 PBNP Response to Requested Information GL 2006-02, July 21, 2006 Question 1 procedures or assessing grid the-Job Training (OJT) and Task Performance Evaluation (TPE) process on coordinating with conditions in question 1(c). TSO/WEPSS for load changes.

Control Operators (and instant SROs) are trained and evaluated via the OJT and TPE process on performing a Technical Specification (TS) Test of the Emergency Diesel Generators (EDG).

Contained within the TS procedures are Initial Conditions and a procedural step requiring notifications to TSO and WEPSS of testing EDGs.

Control Operators (and instant SROs) are trained and evaluated via the OJT and TPE process on performing a start of the gas turbine. Contained within the Operating Instructions are Precautions and Limitations and a procedural step directing notification to WEPSS of operating the gas turbine generator.

During classroom training on the 345 kV sstem, operators are presented an overview of the procedure for electrical communications, switchyard access and work planning.

During classroom training on normal power operations, operators discuss the responsibilities of the WEPSS regarding 345 kV voltage control as listed in plant procedures.

Selected procedural topics may also be reviewed as part of task-based training in the classroom or simulator. Recent examples of training as part of a task review are:

During licensed operator continuing training on Loss of Offsite Power and Significant Operating Event Report (SOER) 99-01, Loss of Grid, in 2006: a review of the procedural communication responsibilities for the TSO, PBNP Production Planning Group, and PBNP Shift Supervision was conducted as part of a discussion on the lessons learned from the August 2003 Loss of Grid event outlined in SOER 99-01 addendum.

During licensed operator continuing training on Post Trip Stabilization in 2004: operators implemented the procedural steps requiring them to notify the TSO when the main generator disconnects are opened.

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

formal agreement or protocol 3 of 29 PBNP Response to Requested Information GL 2006-02, July 21, 2006 Question 1 with your TSO, describe why 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.

(f) If you have an existing As previously stated in response to question 1(a), PBNP does have a formal TSO agreement.

formal interconnection Grid conditions in which the TSO will notify PBNP are described in the response to question agreement or protocol that 1(b) above. This includes conditions in which real-time voltage or the contingent loss of any ensures adequate single transmission element or generator connected to the TSO transmission system would communication and result in PBNP 345 kV bus voltage above or below the specified limits.

coordination between the NPP licensee and the TSO, describe whether this agreement or protocol requires that you be promptly 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 At PBNP, degraded voltage is not sensed in the switchyard. The degraded voltage protection 4 of 29 PBNP Response to Requested Information GL 2006-02, July 21, 2006 Question 1 switchyard voltage conditions scheme senses voltage at the 4.16 kV safety related buses. Initiation of the degraded voltage that would initiate operation protection would occur if the 345 kV system (switchyard) voltage would drop to a point where of plant degraded voltage safety related 4.16 kV bus voltage would reach the degraded voltage relay dropout setpoint.

protection. Current PBNP Technical Specification degraded voltage allowable values are: Greater than or equal to 3937 Volts; time delay of less than 6.47 seconds with a Safety Injection (SI) signal present; time delay of less than 54 seconds without an SI signal present. Therefore, if switchyard voltage was at or below minimum per operating procedures, the degraded voltage protection scheme may initiate depending upon plant operating conditions (normal operation, loss of coolant accident (LOCA), unit trip, etc.). The degraded voltage protection scheme ensures that the safety related equipment will have sufficient voltage to perform their designated safety functions while supplied from offsite power, or the equipment will be separated from offsite power and supplied from the onsite emergency power system.

Question 2

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 NPPs TSO Yes. The TSO makes use of analysis tools to predict grid conditions that would make the use any analysis tools, an PBNP offsite power system non-functional. These tools are not available to the PBNP.

online analytical transmission The TSO currently uses both offline (PSSE, Areva, POM/OPM, VSAT, etc.) and online (Areva system studies program, or energy management system) analytical tools to determine grid conditions under a variety of other equivalent predictive situations. The online analysis is performed approximately once every 5 minutes while the methods to determine the offline analysis is performed on an as needed basis. Note that the TSO can change the grid conditions that would selection and use of the analytical tools, provided they perform the functions required to make the NPP offsite power support the agreements and protocols.

system inoperable during 5 of 29 PBNP Response to Requested Information GL 2006-02, July 21, 2006 Question 2 various contingencies?

If available to you, please provide a brief description of the analysis tool that is used by the TSO.

(b) Does your NPPs TSO Yes. The TSO uses the above analysis tools, in conjunction with procedures, as the basis for use an analysis tool as the determining when conditions warrant PBNP notification. Notifications are made based on grid basis for notifying the NPP configurations being outside of predefined procedure requirements or based on unsatisfactory licensee when such a monitoring and predictive analysis computer program tool results. Refer to the response to condition is identified? If not, question 1(b) above.

how does the TSO determine if conditions on the grid warrant NPP licensee notification?

(c) If your TSO uses an The analysis tools identify when a trip of either PBNP unit would result in switchyard voltages analysis tool, would the falling below the specified limit. The analysis tools determine grid voltages that would occur analysis tool identify a immediately as the result of the unit trip, based upon the current grid configuration.

condition in which a trip of the Following a unit trip, the analysis tools would continue to monitor grid configuration and would NPP would result in identify N-1 contingencies that would result in switchyard voltages falling below the specified switchyard voltages limit.

(immediate and/or long-term) falling below TS nominal trip setpoint value requirements (including NPP licensees using allowable value in its TSs) and consequent 6 of 29 PBNP Response to Requested Information GL 2006-02, July 21, 2006 Question 2 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 The TSOs current online analysis tool updates approximately every 5 minutes. It will analysis tool, how frequently immediately update following the operation of any breaker 100 kV or greater, or as initiated by does the analysis tool the system operator. The TSO completes off-line studies on an as needed basis. Note that program update? the TSO can change the selection and use of the analytical tools, provided they perform the functions required to support the agreements and protocols.

(e) Provide details of analysis The contingencies that are modeled and studied include the loss of any single TSO tool-identified contingency transmission line or transformer as well as any generator connected to the TSOs system.

conditions that would trigger The contingency definition for the loss of either PBNP unit includes the transfer of its auxiliary an NPP licensee notification load from the main auxiliary transformer to the associated reserve auxiliary transformer.

from the TSO. PBNP is notified whenever any N-1 contingency results in voltages outside of predefined limits.

(f) If an interface agreement Yes. If the TSO loses the ability to monitor and predict the operation of the transmission exists between the TSO and system, they would validate that MISO maintained this ability and would also notify PBNP. If the NPP licensee, does it MISO also lost this ability, the TSO would continue to monitor the grid and would perform require that the NPP licensee offline studies or would confirm that the real-time conditions were within the existing study be notified of periods when assumptions. Therefore, if the on-line analysis tools were out-of-service, operability would the TSO is unable to continue to be evaluated.

determine if offsite power 7 of 29 PBNP Response to Requested Information GL 2006-02, July 21, 2006 Question 2 voltage and capacity could be inadequate?

If so, how does the NPP licensee determine that the offsite power would remain operable when such a notification is received?

(g) After an unscheduled No. For post event analysis, the TSO does not verify by procedure the switchyard voltages inadvertent trip of the NPP, are bounded by the analysis tools. Following an inadvertent trip of one or both PBNP units, are the resultant switchyard any unexpected actuations or equipment operation associated with supply voltage would be voltages verified by documented and evaluated in accordance with the corrective action process.

procedure to be bounded by the voltages predicted by the analysis tool?

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

available to the NPP licensees TSO, do you know if there are any plans for the TSO to obtain one? If so, when?

(i) If an analysis tool is not Not applicable to PBNP since the TSO analysis tools are presently in use.

available, does your TSO perform periodic studies to verify that adequate offsite 8 of 29 PBNP Response to Requested Information GL 2006-02, July 21, 2006 Question 2 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 provisions discussed in question 1 above?

(j) If your TSO does not use, Not applicable to PBNP since the TSO utilizes analysis tools and communicates the applicable or you do not have access to results to PBNP.

the results of an analysis tool, or your TSO does not perform and make available to you periodic studies that determine the adequacy of offsite power capability, 9 of 29 PBNP Response to Requested Information GL 2006-02, July 21, 2006 Question 2 please describe why you believe you comply 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.

Question 3

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

(a) If the TSO notifies the By procedure, PBNP will declare the associated offsite power circuits inoperable and enter the NPP operator that a trip of associated Technical Specification Action Condition (TSAC) when the TSO notifies PBNP that the NPP, or the loss of the a single element (most limiting) failure can cause the 345 kV system to drop below the most critical transmission line specified minimum voltage. This procedural control, which enters the TSAC based on a or the largest supply to the postulated single element failure, is more restrictive than the plant licensing basis which states grid would result in that the sudden loss of any single generating unit will not affect the ability of the transmission switchyard voltages system to supply power to the PBNP auxiliary systems.

(immediate and/or long-term) below TS nominal trip setpoint value requirements 10 of 29 PBNP Response to Requested Information GL 2006-02, July 21, 2006 Question 3 (including NPP licensees using allowable value in its TSs) and would actuate plant degraded voltage protection, is the NPP offsite power system declared inoperable under the plant TSs? If not, why not?

(b) If onsite safety-related The plant accident analyses evaluate a loss of offsite power (LOOP) occurring coincident with equipment (e.g., emergency various accidents. A postulated double sequencing event is outside the plants licensing basis diesel generators or safety- and has not been evaluated. Equipment operability is based on performance of safety related motors) is lost when functions and safety support functions required within the plant licensing basis.

subjected to a double sequencing (LOCA with delayed LOOP event) as a result of the anticipated system performance 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?

(c) Describe your evaluation Double sequencing is not in the PBNP licensing basis and PBNP is not designed or analyzed of onsite safety-related for double sequencing scenarios.

equipment to determine 11 of 29 PBNP Response to Requested Information GL 2006-02, July 21, 2006 Question 3 whether it will operate as designed during the condition described in question 3(b).

(d) If the NPP licensee is No. Technical Specification Conditions are not entered for grid conditions other than those notified by the TSO of other mentioned above.

grid conditions that may impair the capability or availability of offsite power, are any plant TS action statements entered? If so, please identify them.

(e) If you believe your plant Not applicable to PBNP since offsite power sources will be declared inoperable as described TSs do not require you to in the response to question 3(a) above in accordance with the plant licensing basis and declare your offsite power Technical Specifications.

system or safety-related equipment inoperable in any of these circumstances, explain why you believe you comply with the provisions of GDC 17 and 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 12 of 29 PBNP Response to Requested Information GL 2006-02, July 21, 2006 Question 3 inadequate.

(f) Describe if and how NPP The compensatory actions discussed in response to questions 3(a) through 3(e) involve operators are trained and entering Technical Specification Conditions. PBNP operators are trained in the interpretation tested on the compensatory and use of plant Technical Specifications and associated compensatory measures.

actions mentioned in your answers to questions 3(a) through (e).

Question 4

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 Yes. Procedural guidance is provided to the PBNP operators. Guidance is provided in the have any guidance or PBNP normal power operation procedure for controlling the generator voltage regulators and procedures in plant TS bases the power system stabilizers and notifying the TSO through WEPSS when the voltage sections, the final safety regulators are placed in manual or the power system stabilizers are disabled.

analysis report, or plant PBNP does not have tap changing transformers, capacitor banks or VAR compensators.

procedures regarding situations in which the Operator training on electrical communications, switchyard access and work planning occurs condition of plant-controlled as indicated in the response to question 1(d). The power system stabilizers are relatively new or -monitored equipment pieces of equipment at PBNP. Operators were trained on the power system stabilizers after (e.g., voltage regulators, auto their installation.

tap changing transformers, capacitors, static VAR 13 of 29 PBNP Response to Requested Information GL 2006-02, July 21, 2006 Question 4 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, Not applicable. PBNP does have procedural guidance that provides the operator with written the final safety analysis direction for responding to equipment malfunctions and manipulation of controls that can report, and plant procedures adversely affect the operability of the PBNP offsite power system.

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.

14 of 29 PBNP Response to Requested Information GL 2006-02, July 21, 2006 Use of NPP licensee/TSO 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.

Question 5

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 Yes. The effect on the maintenance risk assessment of plant activities, environmental qualitative grid reliability conditions, or grid conditions that affect offsite power reliability at PBNP is included evaluation performed at your quantitatively, but this is done by using a qualitatively-derived multiplier for the LOOP NPP as part of the frequency in the calculation. PBNP utilizes a software tool to perform on-line risk maintenance risk assessment management. The safety monitor tool calculates the risk of a particular plant configuration required by 10 CFR using the probabilistic risk assessment (PRA) model for the appropriate unit. The complete 50.65(a)(4) before performing plant configuration includes which equipment is unavailable, the alignment of running and grid-risk-sensitive standby plant equipment, and any environmental/test factors in effect. Four of the maintenance activities? This environmental/test factors in Safety Monitor increase the LOOP frequency in the PRA includes surveillances, post- calculation above the base value by using either one of two multipliers. The intent of these maintenance testing, and multipliers is to move the LOOP frequency to the upper end of the statistical distribution while preventive and corrective the associated testing, grid condition or environmental condition is in effect. By including the maintenance that could impact this way, the PRA results are made more sensitive to those other activities that affect increase the probability of a the ability of PBNP to mitigate the impact of a loss of offsite power, such as maintenance on plant trip or LOOP or impact an emergency diesel generator or on a turbine driven auxiliary feedwater pump.

LOOP or SBO coping capability, for example, before taking a risk-significant piece of equipment (such as an EDG, a battery, a steam-15 of 29 PBNP Response to Requested Information GL 2006-02, July 21, 2006 Question 5 driven pump, an alternate AC power source) out-of-service?

(b) Is grid status monitored by Notifications of operating criteria violations are made as described above in the response to some means for the duration question 1(b) above. Risk would be reassessed upon this notification. In addition the online of the grid-risk-sensitive risk management tool contains factors that can be applied for onsite switchyard work, some maintenance to confirm the types of grid work, peak demand, severe weather, and severe cold. Online risk is monitored continued validity of the risk on a real time basis by the shift technical advisors to validate the planned risk assessment.

assessment and is risk reassessed when warranted?

If not, how is the risk assessed during grid-risk-sensitive maintenance?

(c) Is there a significant Typically the grid carries more power during summer months due to heavier loading. However variation in the stress on the the stress on the grid is a function of what equipment is in service and the ability of the grid to grid in the vicinity of your handle the increased loading. Grid stress varies and can be affected by weather-related or NPP site caused by seasonal other equipment failures, planned outages, or periods of high demand. Planned outages and loads or maintenance maintenance consider grid conditions and seasonal demand to manage overall grid stress.

activities associated with Existing procedures and protocols used by the TSO provide guidance on the grid operations critical transmission to maintain grid reliability and stability.

elements? Current industry data is inconclusive relative to the degree of seasonal variation in LOOP Is there a seasonal variation frequency. Because LOOP frequency for PBNP is very low and because outages and (or the potential for a maintenance are effectively managed, there is no identified seasonal variation in LOOP seasonal variation) in the frequency.

LOOP frequency in the local transmission region?

If the answer to either 16 of 29 PBNP Response to Requested Information GL 2006-02, July 21, 2006 Question 5 question is yes, discuss the time of year when the variations occur and their magnitude.

(d) Are known time-related Seasonal variations in the LOOP probability are not significant at PBNP and therefore do not variations in the probability of provide a usable basis for an adjustment in the safety monitor LOOP frequency determined a LOOP at your plant site solely from those variations. The safety monitor tool has environmental/test factors for grid considered in the grid-risk- work, switchyard work, peak demand, and severe weather to account for other variations in sensitive maintenance LOOP probability. Criteria for when to include these factors are contained in the on-line safety evaluation? If not, what is assessment procedure.

your basis for not considering them?

Yes. PBNP coordinates with the TSO to schedule and implement major work in the PBNP (e) Do you have contacts with switchyard. PBNP will contact the TSO when scheduling work activities that remove the G-05 the TSO to determine current gas turbine or an EDG from service to verify that line outages and other work which may and anticipated grid reduce reliability of the offsite power supplies is not scheduled concurrently.

conditions as part of the grid reliability evaluation performed before conducting grid-risk-sensitive maintenance activities?

(f) Describe any formal The TSO will notify PBNP in accordance with the agreement discussed in response to agreement or protocol that question 1(a) based upon grid conditions described in the response to question 1(b) above.

you have with your TSO to These notifications would be provided to PBNP whether or not maintenance is on-going.

assure that you are promptly alerted to a worsening grid 17 of 29 PBNP Response to Requested Information GL 2006-02, July 21, 2006 Question 5 condition that may emerge during a maintenance activity.

(g) Do you contact your TSO PBNP does not routinely contact the TSO during grid-risk-sensitive maintenance activities.

periodically for the duration of PBNP would be notified of grid conditions described in the response to question 1(b) above the grid-risk-sensitive and would follow procedures to reassess risk or take required actions.

maintenance activities?

(h) If you have a formal There is no formal training provided to the plant operators and maintenance personnel on the agreement or protocol with details of the formal agreement between PBNP and the TSO and/or MISO. Portions of the your TSO, describe how NPP formal agreement which impact operations and/or maintenance have, however, been operators and maintenance extracted from the agreement and incorporated into plant procedures. Training on this personnel are trained and procedural material is provided as discussed below.

tested on this formal Operations personnel receive training on the communication requirements outlined in the agreement or protocol. PBNP procedures for electrical communications, switchyard access, work planning and normal power operations. These procedures include the requirements for PBNP to communicate with the TSO and WEPSS for notifications from the TSO concerning operability of offsite power. Refer to the responses to questions 1(d) and 3(f) for descriptions of the training provided.

No training is provided to maintenance personnel.

(i) If your grid reliability A formal agreement for communication exists which would result in notification of grid evaluation, performed as part conditions that would be considered as part of maintenance risk assessment. Therefore, this of the maintenance risk question is not applicable.

assessment required by 10 CFR 50.65(a)(4), does not 18 of 29 PBNP Response to Requested Information GL 2006-02, July 21, 2006 Question 5 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 Not applicable to PBNP. The TSO communicates grid conditions to the plant shift supervision (when warranted) based on and that information is incorporated into online risk assessments as described above (see continuing communication answer to question 5(d)).

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 No alternative actions to be taken.

5(i) and 5(j), you 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 19 of 29 PBNP Response to Requested Information GL 2006-02, July 21, 2006 Question 5 maintenance activities, respectively.

Question 6

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 Yes. The TSO communicates with PBNP to schedule online work; including switching and transmission system grounding activities that may affect the diversity of the power feed to PBNP, and work on the maintenance activities that transmission elements that affect PBNP.

can have an impact on the NPP operation with the NPP operator?

(b) Do you coordinate NPP Work at PBNP is coordinated through WEPSS for activities involving the 345 kV switchyard, maintenance activities that Unit load changes, operation or removal from service of the gas turbine, or loading an EDG.

can have an impact on the WEPSS coordinates with the TSO. The PBNP production planning group also communicates transmission system with the with the TSO to schedule online work involving switchyard equipment owned by the TSO.

TSO?

(c) Do you consider and Yes. The online safety assessment process would reevaluate in-progress and scheduled grid-implement, if warranted, the risk-sensitive maintenance activities following notification of grid conditions as described in the rescheduling of grid-risk- response to question 1(b) above. Risk management actions are taken such as limiting sensitive maintenance voluntary TSAC entries, trip transient evolutions, or work on or near components that could 20 of 29 PBNP Response to Requested Information GL 2006-02, July 21, 2006 Question 6 activities (activities that could affect generation or offsite power.

(i) increase the likelihood of a plant trip, (ii) 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 The PBNP online safety assessment procedure contains guidance for risk assessment, need to perform grid-risk- contingency actions and compensatory measures to take if the plant is in an elevated risk sensitive maintenance condition. Alternate power sources such as the EDG and gas turbine generator would be activities under existing or verified to be available. Critical equipment would be posted as protected. Additional risk imminent conditions of mitigation strategies would be used to address human error probability such as pre-job briefs, degraded grid reliability, or supervisory oversight, and peer checks.

continue grid-risk-sensitive 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 PBNP has procedures that address coordination of maintenance activities with the TSO, risk 21 of 29 PBNP Response to Requested Information GL 2006-02, July 21, 2006 Question 6 associated with questions assessment and associated risk mitigation strategies for both online and shutdown unit work, 6(a) through 6(d) above that protecting critical equipment, and managing human performance risk. Communication occurs would be taken, state between PBNP and the TSO when PBNP or the TSO schedules maintenance activities whether each action is affecting the transmission system, as required in the procedures. Risk assessment is governed by documented performed for scheduled and emergent work, which includes assessment of grid conditions.

procedures and identify the Actions would be taken to assess and mitigate risk for changes in grid conditions included in procedures, and explain why the communication protocols. These actions would be effective and consistently these actions are effective accomplished because they are part of the existing work management process and are and will be consistently implemented effectively for online and outage work.

accomplished.

(f) Describe how NPP Reference the answer to question 1(d) for operations training on the procedure for electrical operators and maintenance communications, switchyard access and work planning.

personnel are trained and The ILT course on Transient Accident Analysis and Mitigating Core Damage contains a tested to assure they can classroom lesson plan on Shutdown Safety Assessment, which includes a review of the accomplish the actions procedure for protected critical equipment. The course also includes a classroom lesson on described in your answers to probabilistic safety assessment and on-line safety monitoring per associated procedures.

question 6(e).

In ILT, shutdown safety assessment and on-line safety assessment are trained and evaluated by trainee completion of the OJT/TPE qualification card for SROs, Licensed Shift Technical Advisors (STAs), and Non-Licensed STAs.

SRO, Authorize performance of maintenance STA, Perform On-Line Safety Monitoring STA, Perform Shutdown Safety Assessments Licensed Operator Continuing Training:

The procedure for managing work activity risk is among the administrative topics listed in the Licensed Operator Continuing program that are selected for training by the Operations Manager. A training review of the procedure for managing work activity risk occurred most 22 of 29 PBNP Response to Requested Information GL 2006-02, July 21, 2006 Question 6 recently in Administrative Procedure Review for SROs in 2005.

The shutdown safety assessment procedure was last reviewed by Licensed Operator Continuing training in SRO/STA Task Review during 2005.

The requirements of the procedure for protected critical equipment are customarily reinforced during cycle training and evaluations by identifying protected critical equipment with placards per the plant procedure when equipment is removed from service for training or evaluation scenarios in the simulator.

The procedure for on-line safety monitoring was last reviewed with licensed operators during 2001.

No training is provided to maintenance personnel related to this question.

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

regarding transmission system maintenance or NPP maintenance 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 As discussed in response to questions 6(a) through 6(d), PBNP effectively implements effectively implement appropriate risk management actions.

appropriate risk management actions during the conditions described above, explain why 23 of 29 PBNP Response to Requested Information GL 2006-02, July 21, 2006 Question 6 you believe you effectively addressed the relevant provisions of the associated NRC-endorsed industry guidance.

(i) You may, as an alternative No alternative actions to be taken.

to questions 6(g) 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).

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.

Question 7

7. Procedures for identifying local power sources that could be made available to resupply your plant following a LOOP 24 of 29 PBNP Response to Requested Information GL 2006-02, July 21, 2006 Question 7 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 (a) Briefly describe any We Energies has an agreement with PBNP to ensure that PBNP is provided with an assured agreement made with the source of off-site power, sufficient to meet the requirements of the Operating License and TSO to identify local power NRC regulations.

sources that could be made The TSO participates in the development and implementation of the black start and system available to re-supply power restoration plan established for the loss of all or part of the transmission system with the MISO to your plant following a Power System Restoration Working Group (PSRWG) to re-supply PBNP Switchyard following LOOP event. a LOOP event. The MISO PSRWG includes the TSO and We Energies (owner of PBNP) as well as MISO and other utilities in the TSO footprint.

(b) Are your NPP operators The TSO is responsible for restoration of power to the Point Beach Switchyard in the event of trained and tested on a LOOP. PBNP operators are not trained on the specifics of restoring power to the identifying and using local switchyard.

power sources to resupply PBNP procedures identify available power sources and provide guidance for re-supplying your plant following a LOOP needed on-site buses from the available power sources. Among the sources are EDGs, unit event? If so, describe how. cross-tie lines, and the G-05 Gas Turbine Generator. Operators are trained and tested on the use and alignments of these power sources for restoration following a LOOP or Station Blackout. Specific procedures include:

25 of 29 PBNP Response to Requested Information GL 2006-02, July 21, 2006 Question 7 In initial licensed operator training:

In the Integrated Operations training course associated with applying the procedure for declining grid frequency, trainees respond in a training scenario to a declining grid frequency. Their response is limited to pre-trip actions since the trainees have not yet been introduced to emergency operating procedures.

During the Emergency Operating Procedures course, trainees respond to a unit blackout and restore safeguards power from the G-05 Gas Turbine Generator per the procedure for Loss of All AC Power.

In licensed operator continuing training:

In 2006, a dual unit training scenario on a complete loss of the offsite power grid required operators to manually restore both trains of safeguards power to Unit 2 from the emergency diesel generators. In addition, due to an extended loss of offsite power, operators had to start the G-05 Gas Turbine Generator, restore important non-safeguards buses for both units per the abnormal operating procedure, and then parallel with offsite power after it was restored.

In 2005 operating crews were tested on their ability to respond to a complete loss of the offsite power grid and dual unit station blackout. Crews were timed on their ability to meet the sites one hour coping strategy by implementing the procedures to restore safeguards buses to both units and safety-related DC battery chargers from the G-05 Gas Turbine Generator.

(c) If you have not PBNP has established agreements as described in the response to question 7(a) above.

established an agreement Therefore this question is not applicable to PBNP.

with your plants TSO to identify local power sources that could be made available to resupply power to your 26 of 29 PBNP Response to Requested Information GL 2006-02, July 21, 2006 Question 7 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.

Question 8

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

(a) Has your NPP No. No total Loss of Offsite Power events caused by grid failure have occurred since the experienced a total LOOP plants coping duration was initially determined in an April 17, 1989 letter and subsequently caused by grid failure since revised in later correspondence.

the plants coping duration was initially determined under 10 CFR 50.63?

27 of 29 PBNP Response to Requested Information GL 2006-02, July 21, 2006 Question 8 (b) If so, have you Not applicable.

reevaluated the NPP using the 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 Not applicable.

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

(d) If your NPP has Not applicable.

experienced a total LOOP caused by grid failure since the plants 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 28 of 29 PBNP Response to Requested Information GL 2006-02, July 21, 2006 Question 8 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 Based on the responses provided above, NMC considers that operation and maintenance of any action is warranted to the PBNP is in compliance with the noted regulatory requirements to the extent described in bring your NPP into the plants licensing basis.

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.

29 of 29 PNP Response to Requested Information GL 2006-02, July 21, 2006 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).

Question 1

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 Yes. The Transmission System Operator (TSO) to which the Palisades Nuclear Plant (PNP) agreement or protocol with supplies power is owned by the Michigan Electric Transmission Company (METC) and your TSO? operated and maintained by the Consumer Energy Company. The PNP is owned by Consumers Energy Company and operated by Nuclear Management Company, LLC (NMC).

Although NMC is the plant operating entity, references to management actions on behalf of PNP in the remainder of this document are referred to as PNP.

PNP does have a formal agreement with METC, the owner of the transmission system to which PNP is connected. The agreement is documented in Amendment and Restatement of the April 1, 2001 Generator Interconnection Agreement, between Michigan Electric Transmission Company and Consumers Energy Company.

In addition, Midwest Independent System Operator (MISO) and the MISO interconnected nuclear power plants and their associated Transmission Owners (TOs) have developed a generic communication protocol, Communication and Mitigation Protocols for Nuclear Plant/Electric System Interfaces, to address roles and responsibilities in grid monitoring and communication The TOs are signatories to the MISO Transmission Owners Agreement. Appendix E Section 1 of 31 PNP Response to Requested Information GL 2006-02, July 21, 2006 Question 1 C, states, For Members and Users who are operators of nuclear generating facilities, the MISO shall enter into written agreements, which define scheduling protocols, limitations, and restrictions necessary to ensure the safety and reliability of such facilities. Efforts to develop these agreements with each nuclear plant are in progress.

(b) Describe any grid The TSO is required by the agreement to immediately notify PNP whenever an impaired or conditions that would trigger potentially degraded grid condition is recognized by the TSO. Specific examples of known a notification from the TSO to potentially degrading conditions identified in the agreement include:

the NPP licensee and if there 1. Voltage calculated to be less than a specified value following a trip of the PNP unit; and is a time period required for the notification 2. Deficient operating reserve requiring canceling maintenance activities which could jeopardize generating equipment.

In addition, The MISO Communication Protocol states MISO will monitor the appropriate system conditions and notify the nuclear plants operating personnel via the transmission operator when operating conditions are outside of established limits, as well as, when they are restored to within acceptable criteria.

(c) Describe any grid Grid conditions and status are the primary responsibility of the TSO and Reliability Coordinator conditions that would cause (MISO). The observable parameters of the PNP operator include only voltage and frequency, the NPP licensee to contact generator reactive output, breaker status, line status, and certain switchyard alarm points.

the TSO. Relative to this question, grid conditions is assumed to be changes that impact the TSOs Describe the procedures analysis of the grid interface. PNP notifies the TSO for changes in the following plant or grid associated with such a conditions:

communication. If you do not

• Inability to maintain voltage schedule; have procedures, describe how you assess grid

• Operation with the controls for the main generator or turbine in manual; conditions that may cause the

• Removal of generator protective relaying from service; and NPP licensee to contact the 2 of 31 PNP Response to Requested Information GL 2006-02, July 21, 2006 Question 1 TSO.

• Voltage approaching the value where trip of the unit could result in low grid voltage.

Requirements for these communications are included in PNP procedures associated with Main Turbine and Generating Systems and Station Power.

(d) Describe how NPP As part of their initial training, Licensed Operators are instructed on the requirements operators are trained and associated with grid voltage. Training related to these requirements is provided in association tested on the use of the with training on the appropriate procedures which specify the requirements. This training is procedures or assessing grid provided in the following lesson plans:

conditions in question 1(c).

• Station Power; and

• Main Generator.

Additionally, annual training is provided in Summer Readiness training as required by a Nuclear Management Fleet Policy on Seasonal Readiness. This training contains instruction on the following applicable items:

• Review of switchyard components and operation;

• Review of symptoms of grid disturbance, and the potential affect on generator and generator auxiliaries; and

• Review of station procedures for response to grid anomalies.

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

formal agreement or protocol with your TSO, describe why you believe you continue to comply with the provisions of GDC 17 as stated above, or describe what actions you 3 of 31 PNP Response to Requested Information GL 2006-02, July 21, 2006 Question 1 intend to take to assure compliance with GDC 17.

(f) If you have an existing As previously stated in response to question 1(a), PNP does have a formal TSO agreement.

formal interconnection The agreement requires that the TSO promptly notify PNP when grid conditions are such that agreement or protocol that a trip of PNP unit would result in an unacceptable voltage in the switchyard.

ensures adequate These communication requirements are included in the plant procedure addressing station communication and power.

coordination between the NPP licensee and the TSO, Additionally, The MISO Communication Protocol states, "the MISO or the Transmission describe whether this Operator will initiate communication with each other to verify study results that indicate a post-agreement or protocol contingent violation of operating criteria." Upon verification, the Transmission Operator and requires that you be promptly the MISO will immediately initiate steps to mitigate the pre and post contingent operating notified when the conditions criteria violation.

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 At PNP, degraded voltage is not sensed in the switchyard. The degraded voltage protection switchyard voltage conditions scheme senses voltage at the 2400 V safety related buses. The nominal setting for the relays that would initiate operation is 93% of rated voltage. When bus voltage decreases below the setpoint, and following a 0.65 of plant degraded voltage second delay, the emergency diesel generators are started and a timer is initiated. If voltage protection. does not recover above the degraded voltage reset value (nominally 93.5%) within 6 seconds, 4 of 31 PNP Response to Requested Information GL 2006-02, July 21, 2006 Question 1 load shed is actuated, the emergency diesel generator (EDG) breaker is closed and safety related loads are sequenced onto the safety related buses.

Question 2

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 NPPs TSO Yes. The TSO makes use of analysis tools to predict grid conditions that would make a PNP use any analysis tools, an offsite power circuit inoperable. These tools are not available to the PNP.

online analytical transmission The following description is based on conversations with and a demonstration of the real time system studies program, or system analysis tool.

other equivalent predictive methods to determine the The TSO maintains a computer simulation of the METC transmission system. The computer grid conditions that would model evaluates real time system conditions obtained from the Supervisory Control and Data make the NPP offsite power Acquisition (SCADA) system and predicts post contingency voltages and load flows for system inoperable during approximately 650 contingencies. These contingencies include transmission system element various contingencies? failures including a trip of the PNP main generator. The real-time analysis, referred to as the Security Analysis, is run every 15 minutes. For the contingency of the PNP main generator If available to you, please tripping, an alarm is provided to the System Control Operator if the case indicates that the provide a brief description of Palisades Switchyard voltage would decrease below a specified value.

the analysis tool that is used by the TSO. Additionally, MISO Energy Management System (EMS) includes a State Estimator (SE) that currently runs every 90 seconds and Real-Time Contingency Analysis (RTCA) program that runs every 5 minutes. The Contingency Analysis analyzes over 7000 contingencies based on the transmission owners criteria. One of the contingencies analyzed by the MISO EMS is the trip of PNP. The analysis provides results with respect to thermal, voltage, and voltage drop 5 of 31 PNP Response to Requested Information GL 2006-02, July 21, 2006 Question 2 limit violations.

(b) Does your NPPs TSO Yes. The TSO uses the above analysis tools, in conjunction with procedures, as the basis for use an analysis tool as the determining when conditions warrant PNP notification. The Security Analysis, described in basis for notifying the NPP response to question 2(a) above, generates a critical alarm if the PNP trip results in a post licensee when such a contingency voltage less than a specified value. The TSO is required by procedure to notify condition is identified? If not, PNP promptly if this alarm is received, while MISO is required to promptly notify the TSO if how does the TSO determine their alarm is received.

if conditions on the grid warrant NPP licensee notification?

(c) If your TSO uses an Yes. Both the TSO and MISO analysis tools, in conjunction with PNPs analysis, identifies analysis tool, would the conditions which would potentially actuate the degraded voltage protection logic and initiate analysis tool identify a separation from an offsite power source upon a PNP trip concurrent with a loss of coolant condition in which a trip of the accident (LOCA).

NPP would result in Following a trip of the PNP unit, the TSO would typically increase generation elsewhere to switchyard voltages restore the system to near nominal operating conditions precluding further long-term decrease (immediate and/or long-term) in voltage. Such actions are under the control of the TSO.

falling below TS nominal trip setpoint value 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 6 of 31 PNP Response to Requested Information GL 2006-02, July 21, 2006 Question 2 on the grid.

(d) If your TSO uses an Based on discussions with the TSO, the Security Analysis program presently updates the PNP analysis tool, how frequently trip contingency on a 15 minute time interval. The analysis can also be initiated on demand.

does the analysis tool The MISO RTCA runs every 5 minutes.

program update?

(e) Provide details of analysis The only analysis-tool identified contingency which would trigger notification from the TSO or tool-identified contingency MISO is the voltage alarm generated by the PNP trip contingency.

conditions that would trigger an NPP licensee notification from the TSO.

(f) If an interface agreement The agreement does not specifically require notification for periods of time when grid exists between the TSO and conditions are indeterminate. However, procedurally the TSO is required to notify PNP if the the NPP licensee, does it Security Analysis is not operating or considered unreliable.

require that the NPP licensee If informed by the TSO that the Security Analysis is unreliable, PNP defaults to grid system be notified of periods when studies which identify the maximum expected voltage drop following a plant trip. This voltage the TSO is unable to is then used to determine operability of offsite power sources.

determine if offsite power voltage and capacity could be The TSO can also call on the support of MISO to evaluate conditions and re-dispatch inadequate? generation as required to support PNPs voltage. MISO actions to support PNP voltage requirements are provided in MISO Standard Operating Guide, Palisades 345 kV Bus If so, how does the NPP Voltage.

licensee determine that the offsite power would remain Per the MISO Nuclear Plant Communication protocol, should the TO lose its ability to monitor operable when such a or predict the operation of the transmission system affecting off-site power to the nuclear plant, notification is received? the TO shall notify the MISO, validate MISOs ability to monitor and predict the operation of the 7 of 31 PNP Response to Requested Information GL 2006-02, July 21, 2006 Question 2 transmission system and then communicate to the nuclear plant. TO will communicate to the nuclear plant and MISO when this capability is restored. This communication should be as soon as practicable or per established agreements with the TO. Should MISO lose its ability to monitor or predict the operation of the transmission system affecting off-site power to the nuclear plant, MISO shall notify the TO.

The MISO has developed Abnormal Operating Procedures (AOPs) to guide its transmission system operation for failures of different components of analytical and communication tools.

For loss of the MISO RTCA, MISO will consider the results of the local transmission operators analytical tools. For loss of both sets of tools, MISO Operating Engineers will attempt to use off-line power flow tools to replicate operating conditions and predict contingent operation.

(g) After an unscheduled No. For post event analysis, the TSO does not verify by procedure the switchyard voltages inadvertent trip of the NPP, are bounded by the analysis tools.

are the resultant switchyard There is no formal process for comparing the actual post-trip voltages to the post-trip voltages verified by contingency voltage results calculated by the MISO RTCA program. Because many of the procedure to be bounded by MISO transmission owning member companies have similar RTCA programs, there are many the voltages predicted by the opportunities to compare the results. This results in a high confidence that the RTCA results analysis tool? are accurate. However, if the resultant voltages are outside of the criteria, when they are predicted to be within, MISO would be initiating an investigation.

(h) If an analysis tool is not Not applicable to PNP since TSO analysis tools are presently in use.

available to the NPP licensees TSO, do you know if there are any plans for the TSO to obtain one? If so, when?

8 of 31 PNP Response to Requested Information GL 2006-02, July 21, 2006 Question 2 (i) If an analysis tool is not Not applicable to PNP since TSO analysis tools are presently in use.

available, does your 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 provisions discussed in question 1 above?

(j) If your TSO does not use, Not applicable to PNP since the TSO utilizes analysis tools, performs periodic studies and or you do not have access to communicates the applicable results to PNP.

the results of an analysis tool, 9 of 31 PNP Response to Requested Information GL 2006-02, July 21, 2006 Question 2 or your TSO does not perform and make available to you periodic studies that determine the adequacy of offsite power capability, please describe why you believe you comply 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.

Question 3

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

(a) If the TSO notifies the In accordance with the requirements of PNP operating procedures related to station power, NPP operator that a trip of control room operators would declare the appropriate offsite power source inoperable if the NPP, or the loss of the notified by the TSO that switchyard voltage, following a contingent trip of the PNP unit, would most critical transmission line be inadequate to support LOCA loads concurrent with the unit trip.

or the largest supply to the 10 of 31 PNP Response to Requested Information GL 2006-02, July 21, 2006 Question 3 grid would result in The PNP operator is not notified by the TSO and would not declare the appropriate offsite switchyard voltages power sources inoperable for a contingent loss of a transmission line or contingent loss of (immediate and/or long-term) another generating facility.

below TS nominal trip System studies performed by the TSO conclude that the system will remain stable following a setpoint value requirements trip of the largest generator, loss of a transmission line, or drop of the largest load. If any of (including NPP licensees these events were to occur in real time, the next running of the TSO Security Analysis or using allowable value in its MISO RTCA would indicate if PNPs voltage would be impacted such that substation voltage TSs) and would actuate plant would be unacceptable.

degraded voltage protection, is the NPP offsite power system declared inoperable under the plant TSs? If not, why not?

(b) If onsite safety-related No. The plant accident analyses evaluate a loss of offsite power (LOOP) occurring coincident equipment (e.g., emergency with various accidents. A postulated double sequencing event is outside the plants licensing diesel generators or safety- basis and has not been evaluated. Equipment operability is based on performance of safety related motors) is lost when functions and safety support functions required within the plant licensing basis.

subjected to a double sequencing (LOCA with delayed LOOP event) as a result of the anticipated system performance 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?

11 of 31 PNP Response to Requested Information GL 2006-02, July 21, 2006 Question 3 If not, why not?

(c) Describe your evaluation Double sequencing is not in the PNPs licensing basis and PNP is not designed or analyzed of onsite safety-related for double sequencing scenarios equipment to determine whether it will operate as designed during the condition described in question 3(b).

(d) If the NPP licensee is No. Technical Specification Conditions are not entered for grid conditions that might occur.

notified by the TSO of other The PNP operator only declares offsite power sources inoperable when the predicted voltage grid conditions that may following a unit trip is low enough to preclude initiation of LOCA loads concurrent with a unit impair the capability or trip.

availability of offsite power, are any plant TS action statements entered? If so, please identify them.

(e) If you believe your plant Not applicable to PNP since offsite power sources will be declared inoperable as described in TSs do not require you to the response to question 3(a) above in accordance with the plant licensing basis and declare your offsite power Technical Specifications.

system or safety-related equipment inoperable in any of these circumstances, explain why you believe you comply with the provisions of GDC 17 and your plant TSs, or describe what 12 of 31 PNP Response to Requested Information GL 2006-02, July 21, 2006 Question 3 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.

(f) Describe if and how NPP The compensatory actions discussed in response to questions 3(a) through 3(e) involve operators are trained and entering Technical Specification Conditions. PNP operators are trained in the interpretation tested on the compensatory and use of plant Technical Specifications and associated compensatory measures.

actions mentioned in your answers to questions 3(a) through (e).

Question 4

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 Yes. Procedural guidance is available to PNP operators.

have any guidance or PNP does not have voltage regulators, capacitors or static VAR compensators.

procedures in plant TS bases sections, the final safety As discussed in response to question 1(g), one source of offsite power is provided via a load analysis report, or plant tap changing transformer. Although procedures do not explicitly state that this source of procedures regarding offsite power is inoperable if the load tap changer is in manual, the procedure on station power 13 of 31 PNP Response to Requested Information GL 2006-02, July 21, 2006 Question 4 situations in which the requires that the voltage on the bus be maintained within required limits. If the tap changer condition of plant-controlled cannot maintain these voltage requirements, due to either the regulator being in manual or the or -monitored equipment tap changer being stuck, the source of offsite power would be declared inoperable.

(e.g., voltage regulators, auto The North American Electric Reliability Council (NERC) requires that the TSO be notified if the tap changing transformers, main generator voltage regulator is placed in manual. Operation in this mode can result in the capacitors, static VAR plant output not responding as assumed in the grid system planning analysis potentially compensators, main resulting in decreased reliability of the grid. The NERC requirement assures that the TSO is generator voltage regulators) aware of the potential for an unexpected response of the unit to grid upsets. The requirement can adversely affect the to inform the TSO of the status of the voltage regulator is specified in the plant procedure on operability of the NPP offsite the main turbine and generating systems.

power system? If so, describe how the operators Training on the guidance and procedures described above are discussed in response to are trained and tested on the question 1(d).

guidance and procedures.

(b) If your TS bases sections, Not applicable. PNP does have procedural guidance that provides the operator with written the final safety analysis direction for responding to equipment malfunctions and manipulation of controls that can report, and plant procedures adversely affect the operability of the PNP offsite power system.

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 14 of 31 PNP Response to Requested Information GL 2006-02, July 21, 2006 Question 4 intend to take to provide such guidance or procedures.

Use of NPP licensee/TSO 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.

Question 5

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 Yes a qualitative evaluation is performed. 10CFR 50.65(a)(4) requires performance of a risk qualitative grid reliability assessment prior to maintenance activities. Procedural requirements for performing the evaluation performed at your required risk assessment at PNP are included in a procedure regarding risk management and NPP as part of the risk monitoring. This information is associated with the plant procedure specifying maintenance risk assessment requirements for control of equipment. As regards grid risk sensitive maintenance, the required by 10 CFR procedure specifies that maintenance or testing on sensitive or critical equipment during 50.65(a)(4) before performing periods of severe weather forecasts, grid voltage degradation, or system generation alert grid-risk-sensitive conditions should be avoided. This guidance would be considered prior to taking a risk-maintenance activities? This significant piece of equipment (such as an EDG, a battery, a steam-driven pump, or an includes surveillances, post- alternate AC power source) out-of-service.

maintenance testing, and preventive and corrective 15 of 31 PNP Response to Requested Information GL 2006-02, July 21, 2006 Question 5 maintenance that could increase the probability of a plant trip or LOOP or impact LOOP or SBO coping capability, for example, before taking a risk-significant piece of equipment (such as an EDG, a battery, a steam-driven pump, an alternate AC power source) out-of-service?

(b) Is grid status monitored by Yes. As discussed in the response to question 2(a), the TSO and MISO, through use of real some means for the duration time analysis, continuously monitor the status of the voltage within the PNP switchyard and of the grid-risk-sensitive notifies the plant if post plant trip contingency voltages would be below acceptable values.

maintenance to confirm the Such a notification would be considered an emergent condition. For emergent conditions, the continued validity of the risk PNP risk management guidelines discussed in response to the previous question requires that assessment and is risk the risk impact be reassessed.

reassessed when warranted?

If not, how is the risk assessed during grid-risk-sensitive maintenance?

(c) Is there a significant No. Typically the grid carries more power during summer months due to heavier loading.

variation in the stress on the However the stress on the grid is a function of what equipment is in service and the ability of grid in the vicinity of your the grid to handle the increased loading with respect to winter months. Existing procedures NPP site caused by seasonal and protocols used by the TSO provide guidance on the grid operations to maintain grid loads or maintenance reliability and stability.

activities associated with Offsite power to PNP is provided from a major METC 345KV switchyard located approximately critical transmission 16 of 31 PNP Response to Requested Information GL 2006-02, July 21, 2006 Question 5 elements? one-half mile from the plant. The switchyard consists of six incoming transmission lines, 2 Is there a seasonal variation each from the east, north and south. In addition, there is an incoming line from a 1350 MW gas fired plant. These incoming lines and the PNP generator output are connected in a (or the potential for a seasonal variation) in the breaker and a half scheme powering two buses identified as Front (F) and Rear (R) bus.

LOOP frequency in the local The two transmission lines from the south are the METC interconnection with American transmission region? Electric Power (AEP). With the number of lines providing access to the grid, removal of a transmission line from service either within the Palisades Switchyard or elsewhere in the If the answer to either system does not result in a significant increase in grid stress near PNP. Prior to removal of question is yes, discuss the lines from service, the impact on the grid, including PNP operating criteria, would be evaluated time of year when the and approved by the MISO as discussed in the response to question 6(a).

variations occur and their The overriding concern of the TSO is to maintain continued grid reliability/stability. To protect magnitude.

the grid, TSO procedures require that service to residential and commercial customers be reduced by first reducing voltage at the distribution level and if required, shedding load. The residential and commercial customers may experience electrical outages at the distribution level while the grid is unaffected. Hence, offsite power would continue to be available to PNP.

Current industry data is inconclusive relative to the degree of seasonal variation in LOOP frequency. Because LOOP frequency for PNP is very low and because outages and maintenance are effectively managed, there is no identified seasonal variation in LOOP frequency.

In response to this question, MISO performed a review of Energy Emergency Alerts, as defined in NERC Standard EOP-002-0, which have occurred within the MISO Reliability footprint. This review determined that there is no correlation between grid stress and seasonal load or maintenance activities.

Seasonal variations in the LOOP probability are not significant at PNP and therefore do not (d) Are known time-related provide a useable basis for determination of risk based solely on the season. Other time variations in the probability of related variations such as system generation alert conditions, grid voltage degradation and a LOOP at your plant site severe weather are considered as part of risk management. For these conditions, procedural considered in the grid-risk-guidance is provided to the operators regarding actions to be taken to minimize risk.

17 of 31 PNP Response to Requested Information GL 2006-02, July 21, 2006 Question 5 sensitive maintenance evaluation? If not, what is your basis for not considering them?

(e) Do you have contacts with Yes. Switchyard activities are administratively controlled by procedure. This procedure the TSO to determine current identifies the interface arrangements between PNP and the various TSO operations, and anticipated grid maintenance and test organizations. PNP maintains contacts with these various TSO conditions as part of the grid organizations to coordinate maintenance and testing activities and to determine grid status.

reliability evaluation These organizations are specifically called upon when performing switchyard maintenance.

performed before conducting Taking lines out of service in the switchyard always involves the coordination and direction of grid-risk-sensitive the TSOs System Control. System Control is the organization most knowledgeable of current maintenance activities? system conditions.

As regards maintenance of plant installed critical equipment, the need to request input from System Control as to current or projected grid conditions prior to performing risk sensitive maintenance activities would be dependent on grid conditions at the time. There are specific procedural requirements for times when PNP control room operators are required to contact the TSO System Control. These occur when the unit is unable to maintain their voltage schedule, or when voltage lowers to a trigger point where loss of the unit could potentially reduce voltage below the required minimum.

As a result of the dynamic nature of loads and active generation on the power-grid, the TSO is only able to comment on the grid conditions shortly before (on the order of hours) maintenance tasks commence. The TSO can provide commentaries on grid conditions at any time maintenance tasks are underway. The same dynamic nature of loads and active generation make prediction of grid conditions days or weeks ahead of time highly uncertain.

(f) Describe any formal The TSO will notify PNP in accordance with the agreement discussed in response to question agreement or protocol that 18 of 31 PNP Response to Requested Information GL 2006-02, July 21, 2006 Question 5 you have with your TSO to 1(a) based upon grid conditions described in the response to question 1(b) above.

assure that you are promptly Additionally, MISO has established a communication protocol for nuclear power plants that alerted to a worsening grid requires the MISO to communicate to the local transmission owner (TSO) whenever the MISO condition that may emerge has determined that the pre and/or post contingent voltage for the nuclear power plants is during a maintenance activity. outside of the acceptable voltage range.

These notifications would be provided to PNP whether or not maintenance is on-going.

(g) Do you contact your TSO PNP does not contact the TSO solely based on the type of plant maintenance being periodically for the duration of performed. As described earlier, there are specific procedural requirements for times when the grid-risk-sensitive PNP control room operators are required to contact the TSO System Control. These occur maintenance activities? when the unit is unable to maintain their voltage schedule, or when voltage lowers to a point where loss of the unit could potentially reduce voltage below the required minimum.

(h) If you have a formal There is no formal training provided to the plant operators and maintenance personnel on the agreement or protocol with details of the formal agreement between PNP and the TSO and/or MISO. Portions of the your TSO, describe how NPP formal agreement which impact operations and/or maintenance have, however, been operators and maintenance extracted from the agreement and incorporated into plant procedures. Training on this personnel are trained and procedural material is provided as discussed below.

tested on this formal Training on the maintenance rule, risk management and probabilistic safety assessment agreement or protocol. (PSA) is provided to plant operators as part of initial license training. This training is encompassed within the lesson plan entitled Equipment Out of Service Overview. This lesson plan provides the operators training on the EPRI developed Equipment Out of Service (EOOS) monitor. This monitor provides the operators with a risk score based on the PSA model. The EOOS system is provided with the capability to input grid conditions manually to account for potentially degraded grid conditions. Additional training is provided periodically as part of Licensed Operator News training. Recent training in this area was provided which addressed risk management.

19 of 31 PNP Response to Requested Information GL 2006-02, July 21, 2006 Question 5 Additionally, as part of summer readiness training, the following topics are addressed:

• Review of switchyard components and operation;

• Review of symptoms of grid disturbance, and the potential affect on generator and generator auxiliaries; and

• Review of station procedures for response to grid anomalies.

No training is provided to maintenance personnel.

(i) If your grid reliability A formal agreement for communication exists which would result in notification of grid evaluation, performed as part conditions that would be considered as part of maintenance risk assessment. Therefore, this of the maintenance risk question is not applicable.

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 Not applicable to PNP. The TSO communicates grid conditions to the plant shift supervision (when warranted) based on and that information is incorporated into online risk assessments as described above (see continuing communication answer to question 5(d)).

with the TSO throughout the duration of grid-risk-sensitive maintenance activities, explain why you believe you have effectively implemented 20 of 31 PNP Response to Requested Information GL 2006-02, July 21, 2006 Question 5 the relevant provisions of the endorsed industry guidance associated with the maintenance rule.

(k) With respect to questions No alternative actions to be taken.

5(i) and 5(j), you 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.

Question 6

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 Yes. PNP coordinates maintenance in the PNP switchyard with the TSO. Maintenance transmission system activities in the switchyard are controlled in accordance with PNP procedure on control of maintenance activities that switchyard activities. The procedure outlines the planning and communication required for can have an impact on the work to be performed to assure that the PNP Technical Specifications and operating 21 of 31 PNP Response to Requested Information GL 2006-02, July 21, 2006 Question 6 NPP operation with the NPP requirements for switchyard equipment are met. The procedure requires that the TSO inform operator? PNP of schedules for performing work in the switchyard, and that the maintenance personnel contact PNP prior to removing equipment from service.

With respect to transmission system maintenance beyond the PNP switchyard, MISO is responsible for approving the maintenance schedule of transmission facilities and coordinating the scheduling of generation facilities. The decision to approve transmission and generation facility maintenance schedules is based on the ability of the MISO to operate the system within the criteria set forth by the transmission owner, NERC and the applicable regional reliability coordinator.

The outage scheduling process analyzes the outages under expected grid operating conditions. One day prior and on the outage day, the system is analyzed by MISO before permitting the equipment to be switched out of service. Once the equipment is switched out of service, grid status is automatically captured by the MISO SE and continually evaluated by the MISO RTCA program.

(b) Do you coordinate NPP Short of inducing a trip of the main generator, no work at PNP is able to make a significant maintenance activities that change to the status of the grid in the vicinity of the plant or the grid at-large. For activities can have an impact on the that may result in a change in plant power output or have a higher risk of a plant trip, such as transmission system with the turbine valve testing, the TSO System Control would be notified prior to performing the activity.

TSO?

(c) Do you consider and Yes. The PNP procedure on control of plant equipment identifies the actions to be taken implement, if warranted, the when notified by Electric Source and Trading or the (TSO) System Control of a System rescheduling of grid-risk- Critical status due to generation or transmission availability constraints. When notified of this sensitive maintenance status, the procedure requires that maintenance on batteries, emergency diesel generators, activities (activities that could and the auxiliary feedwater system be rescheduled. Additionally the procedure requires (i) increase the likelihood of a rescheduling activities that have the potential of causing a reactor trip such as reactor plant trip, (ii) increase LOOP protective system testing, switchyard manipulations, turbine valve testing or feedwater heater 22 of 31 PNP Response to Requested Information GL 2006-02, July 21, 2006 Question 6 probability, or (iii) reduce level control manipulations.

LOOP or SBO coping capability) under existing, imminent, or worsening degraded grid reliability conditions?

(d) If there is an overriding Yes. Risk management compensatory actions for higher risk activities are provided in Risk need to perform grid-risk- Management and Risk Monitoring, guidelines. The actions identified within these guidelines sensitive maintenance include:

activities under existing or 1. Actions to provide increased risk awareness and control:

imminent conditions of degraded grid reliability, or

• Discuss planned maintenance activity with operating shift and obtain operator continue grid-risk-sensitive awareness and approval of planned evolution; maintenance when grid

• Conduct pre-job briefing of maintenance personnel, emphasizing risk aspects of conditions worsen, do you planned maintenance evolution; implement appropriate risk management actions? If so,

• Request the system engineer or subject matter expert (SME) to be present for the describe the actions that you maintenance activity, or applicable portions of the activity, and would take. (These actions

• Obtain plant management approval for the proposed activity.

could include alternate equipment protection and 2. Actions to reduce duration of maintenance activity:

compensatory measures to

• Pre-stage parts and materials; limit or minimize risk.)

• Walk-down tagout and maintenance activity prior to conducting maintenance;

• Conduct training on mock-ups to familiarize maintenance personnel with the activity.

• Perform maintenance around the clock; and

• Establish contingency plans to restore out-of-service equipment rapidly.

23 of 31 PNP Response to Requested Information GL 2006-02, July 21, 2006 Question 6

3. Actions to minimize magnitude of risk increase:

• Minimize work in areas that could cause a plant trip or transient, or a loss of power (sub-station, switchgear rooms, or EDG rooms) to lower the frequency of initiating events that are mitigated by the safety function served by the out-of-service equipment;

• Minimize other work in areas that could affect the redundant systems (place protected train boundaries);

• Walk-downs of key safety systems by on-shift Senior Reactor Operator (SRO) personnel and management before and during higher risk evolutions: and

• Increased surveillance frequencies of key safety functions by testing alternate equipment prior to the planned work or frequent inspections of standby equipment during work.

(e) Describe the actions Actions to be taken are addressed within each of the responses to questions 6(a) through 6(d) associated with questions above. The PNP procedures which control these activities are:

6(a) through 6(d) above that Control of Plant Equipment; and would be taken, state whether each action is Control of Switchyard Maintenance.

governed by documented NMCs management expectation is that procedural requirements be strictly adhered to.

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

(f) Describe how NPP Training on the maintenance rule, risk management and PSA is provided to plant operators as operators and maintenance part of initial license training. This training is encompassed within the lesson plan entitled personnel are trained and Equipment Out of Service Overview. This lesson plan provides the operators training on the 24 of 31 PNP Response to Requested Information GL 2006-02, July 21, 2006 Question 6 tested to assure they can EPRI EOOS monitor. This monitor provides the operators with a risk score based on the PSA accomplish the actions model. The EOOS system is provided with the capability to input grid conditions manually to described in your answers to account for potentially degraded grid conditions. Additional training is provided periodically as question 6(e). part of Licensed Operator News training. Recent training in this area was provided which addressed risk management.

Additionally, as part of summer readiness training, the following topics are addressed:

• Review of switchyard components and operation;

• Review of symptoms of grid disturbance, and the potential affect on generator and generator auxiliaries; and

• Review of station procedures for response to grid anomalies.

No training is provided to maintenance personnel on risk management.

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

regarding transmission system maintenance or NPP maintenance 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 As discussed in response to questions 6(a) through 6(d), PNP effectively implements effectively implement appropriate risk management actions.

appropriate risk management 25 of 31 PNP Response to Requested Information GL 2006-02, July 21, 2006 Question 6 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 No alternative actions to be taken.

to questions 6(g) 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).

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.

26 of 31 PNP Response to Requested Information GL 2006-02, July 21, 2006 Question 7

7. Procedures for identifying local power sources 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 (a) Briefly describe any PNP has a formal agreement with METC as discussed in response to question 1(a) above.

agreement made with the The agreement requires that METC provide PNP the highest possible priority during Black TSO to identify local power Light Procedures for restoration of the Palisades Substation. Following a total system sources that could be made collapse (Black Light), the TSO System Restoration Manual provides for the use of a nearby available to re-supply power black start capable pumped storage facility to provide power to the PNP switchyard.

to your plant following a The following discussion of the region wide restoration process was provided by MISO:

LOOP event.

The MISO restoration process will provide the development of individual TSO Restoration Plans. MISO conducts reviews, workshops and drills to ensure the effectiveness of the restoration plan.

The MISO restoration process will provide updates to the TO and PNP on transmission system status during emergency restoration, and will give the highest priority to restoring power to affected nuclear facilities per NERC standard EOP-005-0.

However, due to the myriad of possible restoration scenarios, no specific power sources to re-supply PNP will be identified. The MISO restoration process allows for the fact that the blacked out area may or may not be separated from the remainder of the system. The MISO restoration process allows the use of black start unit or cranking path from the non-blacked out 27 of 31 PNP Response to Requested Information GL 2006-02, July 21, 2006 Question 7 areas. Regardless of the scenario, there is a clear recognition of the importance of expeditious restoration of a nuclear power plant offsite power source.

(b) Are your NPP operators The TSO is responsible for restoration of power to the Palisades Switchyard in the event of a trained and tested on LOOP. PNP operators are not trained on the specifics of restoring power to the switchyard.

identifying and using local The operators are trained and tested on the use of the Emergency Operating Procedure power sources to resupply (EOP) on Station Blackout Recovery. This training includes a simulator exercise on Station your plant following a LOOP Blackout Recovery.

event? If so, describe how.

(c) If you have not PNP has an established agreement with the TSO related to restoration of power to the PNP established an agreement switchyard. Thus this item is not applicable.

with your plants 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 28 of 31 PNP Response to Requested Information GL 2006-02, July 21, 2006 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.

Question 8

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

(a) Has your NPP There have been no grid related losses of offsite power at PNP since the NRC Safety experienced a total LOOP Evaluation Report on Station Blackout was issued on June 25,1992. (Reference Table A.1 caused by grid failure since NUREG/CR-6890, December 2005) the plants coping duration was initially determined under 10 CFR 50.63?

(b) If so, have you Not applicable.

reevaluated the NPP using the 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 Not applicable.

results of this reevaluation, and did the initially determined coping duration for the NPP need to be 29 of 31 PNP Response to Requested Information GL 2006-02, July 21, 2006 Question 8 adjusted?

(d) If your NPP has Not applicable.

experienced a total LOOP caused by grid failure since the plants 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 Based on the responses provided above, NMC considers that operation and maintenance of any action is warranted to the PNP is in compliance with the noted regulatory requirements to the extent described in the bring your NPP into plants licensing basis.

compliance with NRC 30 of 31 PNP Response to Requested Information GL 2006-02, July 21, 2006 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.

31 of 31 PINGP Response to Requested Information GL 2006-02, July 21, 2006 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).

Question 1

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 Yes. The Transmission System Operator (TSO) to which the Prairie Island Nuclear agreement or protocol with Generating Plant (PINGP) supplies power is owned and operated by Xcel Energy, Inc. PINGP your TSO? is owned by Northern States Power Company (NSP), a wholly owned subsidiary of Xcel Energy, Inc. (Xcel), and operated by Nuclear Management Company, LLC (NMC). Although NMC is the plant operating entity, references to management actions on behalf of PINGP in the remainder of this document are referred to as PINGP.

PINGP does have a formal agreement with the TSO (all references to TSO, ISO, Reliability Controller or Control Center, or Balancing Authority etc. throughout this document refer to Excel Energys Northern States Power System Control Center). The agreement is documented in the Voltage Support Agreement, June 12, 1990 and NMC - Xcel Nuclear Power Plant Operating Services Agreement, November 23, 1999.

(b) Describe any grid The TSO is required to notify PINGP whenever an impaired or potentially degraded grid conditions that would trigger condition is recognized by the TSO. Specific examples of known potentially degrading a notification from the TSO to conditions identified in the agreement include:

the NPP licensee and if there 1 of 31 PINGP Response to Requested Information GL 2006-02, July 21, 2006 Question 1 is a time period required for 1. If a Real Time Contingency Analysis (RTCA) post contingent alarm is received the notification indicating that the post-trip grid voltage at the Prairie Island Substation will be below the calculated minimum voltage for the present plant substation lineup; and

2. If grid conditions, as established by Energy Supply (Energy Supply is the power marketing arm of NSP), enters into or leaves a system condition designated as orange or red. (These are the two most stressed grid conditions)

The occurrence of a grid contingency that impacts PINGP requires immediate notification.

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

Describe the procedures The TSO is contacted per procedure for response to any grid conditions that result in associated with such a substation alarms. Plant Abnormal Operating Procedures (AOP) direct communication with communication. If you do not the TSO in response to loss of major substation components.

have procedures, describe Relative to this question, grid conditions is assumed to be any changes within the jurisdiction how you assess grid of PINGP that impact the TSO analysis of the grid interface. The PINGP Shift Supervisor also conditions that may cause the notifies the TSO for changes in the following grid conditions:

NPP licensee to contact the TSO.

• Changes to switchyard voltage, switchyard breaker alignment that affects the RTCA setpoint as per operating procedure;

• If generator real and reactive power loading must be changed due to generator limitations or plant maintenance;

• Change in status of the 10 Bank Transformer offsite power voltage regulating devices (such as load tap changers (LTCs) in manual versus auto.);

• Modifications resulting in changes to generator electrical characteristics or substation 2 of 31 PINGP Response to Requested Information GL 2006-02, July 21, 2006 Question 1 operating characteristics; and

• Transfer of the generator voltage regulator to manual.

(d) Describe how NPP Since 1996, PINGP has trained the operators annually on loss of offsite power on the operators are trained and simulator. PINGP has also taught on loss of all safeguards AC power recovery with and tested on the use of the without safety injection, but this was on a 3-year frequency and was last discussed in 2004.

procedures or assessing grid The Loss of Grid INPO Significant Operating Event Report (SOER) was discussed by conditions in question 1(c). operations in 2002, 2003, and 2005 In 2005, classroom and simulator training included:

• discussion of SOER 99-1, loss of grid events, and, SOER 02-3, transformer reliability;

• virtual tour of the NSP System Control Center and the Mid-Continent Area Power Pool (MAPP) system. Plant operators interviewed TSO operators and asked what information the TSO operators like to hear from the plant control room during upset conditions;

• reviewed work procedures for substation work;

• discussed the plant response to degrading grid conditions and reviewed the system operating codes and the procedure for responding to degraded grid conditions using the plant station load reduction procedure;

• during two simulator sessions in that same cycle, training focused on degraded grid conditions entering the system operating code procedure and the plant station load reduction procedure. This was followed by a loss of offsite power and other electrical switching operations. The crews had practice in implementing various plant electrical AOPs;

• Switchyard distribution is taught on a 3 year frequency and was last taught in January of 2005; 3 of 31 PINGP Response to Requested Information GL 2006-02, July 21, 2006 Question 1

• Operators were evaluated on the simulator during a simulated loss of offsite power condition;

• Training was conducted on motor and transformer theory; and

• Transformer reliability was taught based on SOER 02-3 in 2002 which has been incorporated into the transformer lesson plan.

Examples of training in 2004 include multiple simulator scenarios that used electrical switching as their base operation: (Listed are tasks trained on the simulator)

• Loss of Offsite and Onsite Power; Response To Faulty Generator Voltage Regulator; Op Restrictions/Limitations Loss of 345 kV Bus 1 and 2; Loss of Offsite Power; Loss of All AC. Power Recovery w/o SI Required; Restart DG With Automatic Start Signal Present;

• Reenergize a Dead 4.16 KV Bus; Response To Instrument Inverter Bypass; Response To Loss of an Instrument Bus; Op Restrictions/Limitations Loss of CT1/CT11/CT12 Transformers;

• Response To System Underfrequency Disturbance: Operating Restrictions/Limitations Loss of 10 Bank Transformer; Response to a Loss of 1R/2RX/2RY; and

• Rapid Load Reduction.

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

formal agreement or protocol with your TSO, describe why 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 4 of 31 PINGP Response to Requested Information GL 2006-02, July 21, 2006 Question 1 compliance with GDC 17.

(f) If you have an existing As previously stated in response to question 1(a), PINGP does have a formal TSO agreement formal interconnection which ensures prompt communications between the TSO and the Shift Supervisor in the event agreement or protocol that of changes in the grid alignment that may affect the post contingent setpoint or result.

ensures adequate Although the notification time is not specifically called out in the operating procedure, past communication and practice has been to immediately notify the PINGP control room in the event of a post coordination between the contingent voltage violation. An event notification (i.e., failure to meet minimum post NPP licensee and the TSO, contingent voltages) includes predicted post-trip voltage at the Prairie Island Substation. The describe whether this TSO will also promptly notify PINGP when grid conditions become more stressed agreement or protocol necessitating changes to the grid condition system operating code.

requires that you be promptly 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 At PINGP, degraded voltage is not sensed in the switchyard. The degraded voltage protection switchyard voltage conditions scheme senses voltage at the 4.16 kV safety related buses. The two conditions at PINGP will that would initiate operation initiate a degraded voltage logic initiation on the plant 4.16 kV Safeguards Buses are:

of plant degraded voltage

• Bus undervoltage nominal allowable value: 75% with a fixed nominal time delay of 4 protection. seconds.

• Bus degraded voltage nominal allowable value: 95.5% with a nominal conditional time 5 of 31 PINGP Response to Requested Information GL 2006-02, July 21, 2006 Question 1 delay of 8 seconds (Safety Injection (SI) signal present) or 60 seconds (no SI signal present).

Question 2

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 NPPs TSO Yes. The TSO makes use of analysis tools to predict grid conditions that would make the use any analysis tools, an PINGP offsite power system non-functional. These tools are not available to the PINGP.

online analytical transmission The tools presently used by the TSO to manage the grid programs, control the transmission system studies program, or related activities, and monitor grid actions that are outside the control of the PINGP include other equivalent predictive the following:

methods to determine the grid conditions that would

• a fully commissioned RTCA program; make the NPP offsite power

• a grid state estimator and System Control and Data Acquisition (SCADA) system in system inoperable during conjunction with periodic studies of a reasonable number of contingencies; and various contingencies?

• bounding analyses.

If available to you, please provide a brief description of The following is a brief description of the RTCA operation:

the analysis tool that is used The Security Analysis (SA) is a real time load flow program that takes data from the SCADA by the TSO. network to establish the various state variable parameters required to analyze the network.

Once all the state input data is set, the program calculates the voltages at all of the nodes in the network. As in any load flow analysis, the program may take a few iterations to reach a solution. For purposes of this explanation, this is referred to as the Base Real Time Analysis.

Upon reaching the base solution the program then sequentially steps through a sequence of 6 of 31 PINGP Response to Requested Information GL 2006-02, July 21, 2006 Question 2 N contingencies to recalculate resultant node voltages for a series of what if scenarios.

Each contingency calculation considers the loss of one of the major components in the base analysis at a time, hence the term N-1 Contingency Analysis. It calculates the resultant voltage at each node based on the loss of one of the components from the base real time solution. This list of contingencies may be several hundred elements long and runs immediately after the base solution is calculated. The contingency of primary concern to the nuclear plant is the trip of the plant and the effect on the resultant voltage at the plants substation. For the purpose of this discussion this will be referred to as the Primary Contingency. For each of the N-1 contingencies, the resultant voltage at each of the nodes of concern is compared to pre-established voltage limits and if any voltage falls out of that range, the system operator receives an alarm. If an alarm is received upon running of the primary contingency the system operator is instructed to contact the nuclear plant in accordance with established protocols.

(b) Does your NPPs TSO Yes. The TSO uses the above analysis tools, in conjunction with procedures, as the basis for use an analysis tool as the determining when conditions warrant PINGP notification.

basis for notifying the NPP Refer to the response to question 1(b).

licensee when such a condition is identified? If not, how does the TSO determine if conditions on the grid warrant NPP licensee notification?

(c) If your TSO uses an Yes. The TSO analysis tool, in conjunction with PINGP plant analysis, identifies contingent analysis tool, would the conditions which would actuate the PINGP degraded voltage protection logic and initiate analysis tool identify a separation from an offsite power source upon a postulated dual-unit PINGP trip. The RTCA condition in which a trip of the predicts the loss of both units generation and the immediate assumption of offsite support of NPP would result in auxiliary station loads. This is a static analysis that calculates a postulated post trip steady 7 of 31 PINGP Response to Requested Information GL 2006-02, July 21, 2006 Question 2 switchyard voltages state voltage that is assumed constant.

(immediate and/or long-term) The brief description of how the RTCA functions provides insights that the analysis is valid falling below TS nominal trip only for a few minutes (on the order of 8 or 9 minutes) until the next data update and setpoint value requirements recalculation is run. The RTCA does not perform a look ahead calculation to determine post (including NPP licensees contingent voltages for projected grid conditions hours or days in advance. System wide using allowable value in its studies that take into account projected plant outages, major transmission line maintenance, TSs) and consequent etc. are performed for market planning and for establishing a daily system condition. These actuation of plant degraded studies are independent of the RTCA analysis.

voltage protection?

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

(d) If your TSO uses an The TSO RTCA program presently updates and recalculates the PINGP dual unit trip analysis tool, how frequently contingency on a time interval of approximately 7 to 8 minutes.

does the analysis tool The TSO SCADA information available as an input to the RTCA is essentially real time and program update? provides updates to the RTCA each time it runs.

(e) Provide details of analysis The notification from the TSO is based upon the predicted post-trip switchyard voltage falling tool-identified contingency below the required voltage identified in plant operating procedures.

conditions that would trigger PINGP operating procedures provide previously calculated setpoints dependent on plant an NPP licensee notification internal load configuration.

from the TSO.

(f) If an interface agreement Yes. The agreement does specifically require PINGP notification for periods of time when the exists between the TSO and RTCA is out of service or grid conditions are indeterminate.

the NPP licensee, does it 8 of 31 PINGP Response to Requested Information GL 2006-02, July 21, 2006 Question 2 require that the NPP licensee PINGP follows plant abnormal operating procedure requirements when notified by the TSO be notified of periods when that the RTCA is out of service or grid conditions are indeterminate. The abnormal operating the TSO is unable to procedures provide acceptable operating parameter guidelines to conservatively predict that determine if offsite power post trip substation voltages, based on current real and reactive power conditions will remain voltage and capacity could be above degraded voltage relay setpoints.

inadequate?

If so, how does the NPP licensee determine that the offsite power would remain operable when such a notification is received?

(g) After an unscheduled No. For post event analysis, the TSO does not verify by procedure the switchyard voltages inadvertent trip of the NPP, are bounded by the analysis tools. However, post trip voltages are verified as being adequate are the resultant switchyard as part of the plant emergency procedures for trip recovery and any low voltage conditions voltages verified by existing on the safeguards buses would be alarmed and the appropriate alarm response procedure to be bounded by would be followed. Following an inadvertent trip of one or both PINGP units, any unexpected the voltages predicted by the actuations or equipment operation associated with supply voltage would be documented and analysis tool? evaluated in accordance with the corrective action process.

(h) If an analysis tool is not Not applicable to PINGP since TSO analysis tools are presently in use.

available to the NPP licensees TSO, do you know if there are any plans for the TSO to obtain one? If so, when?

9 of 31 PINGP Response to Requested Information GL 2006-02, July 21, 2006 Question 2 (i) If an analysis tool is not Not applicable to PINGP since TSO analysis tools are presently in use.

available, does your 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 provisions discussed in question 1 above?

(j) If your TSO does not use, Not applicable to PINGP since the TSO utilizes analysis tools and communicates the or you do not have access to applicable results to PINGP.

the results of an analysis tool, 10 of 31 PINGP Response to Requested Information GL 2006-02, July 21, 2006 Question 2 or your TSO does not perform and make available to you periodic studies that determine the adequacy of offsite power capability, please describe why you believe you comply 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.

Question 3

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

(a) If the TSO notifies the If notified that a contingent PINGP trip would drive voltage below the degraded voltage NPP operator that a trip of protection setpoint, the PINGP operator declares one or both offsite paths inoperable for the NPP, or the loss of the postulated contingent dual unit trip per existing operating procedure and the PINGP operator most critical transmission line would enter the applicable TS 3.8.1 Condition.

or the largest supply to the 11 of 31 PINGP Response to Requested Information GL 2006-02, July 21, 2006 Question 3 grid would result in If a contingent line loss or the contingent loss of a remote generating unit would predict a post-switchyard voltages trip voltage PINGP below the degraded voltage protection setpoint (e.g. an N-2 contingency (immediate and/or long-term) evaluation), the PINGP operator would not enter any Technical Specification (TS) Conditions below TS nominal trip because Technical Specifications do not require entry into a TS Condition until an event setpoint value requirements actually happens.

(including NPP licensees using allowable value in its TSs) and would actuate plant degraded voltage protection, is the NPP offsite power system declared inoperable under the plant TSs? If not, why not?

(b) If onsite safety-related The plant accident analyses evaluate a LOOP occurring coincident with various accidents. A equipment (e.g., emergency postulated double sequencing event is outside the plants licensing basis and has not been diesel generators or safety- evaluated. Equipment operability is based on performance of safety functions and safety related motors) is lost when support functions required within the plant licensing basis subjected to a double sequencing (LOCA with delayed LOOP event) as a result of the anticipated system performance 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?

12 of 31 PINGP Response to Requested Information GL 2006-02, July 21, 2006 Question 3 If not, why not?

(c) Describe your evaluation Double sequencing is not in the PINGPs licensing basis and PINGP is not designed or of onsite safety-related analyzed for double sequencing scenarios equipment to determine whether it will operate as designed during the condition described in question 3(b).

(d) If the NPP licensee is No. Technical Specification Conditions are not entered for grid conditions that might occur.

notified by the TSO of other The PINGP operator only declares offsite path(s) inoperable when the RTCA predicted voltage grid conditions that may following a dual unit trip of PINGP is low enough to preclude initiation of loss of coolant impair the capability or accident (LOCA) loads concurrent with a dual unit trip.

availability of offsite power, are any plant TS action statements entered? If so, please identify them.

(e) If you believe your plant Not applicable to PINGP since offsite power sources will be declared inoperable as described TSs do not require you to in response to question 3(a) above in accordance with the plant licensing basis and Technical declare your offsite power Specifications.

system or safety-related equipment inoperable in any of these circumstances, explain why you believe you comply with the provisions of GDC 17 and your plant TSs, or describe what 13 of 31 PINGP Response to Requested Information GL 2006-02, July 21, 2006 Question 3 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.

(f) Describe if and how NPP The compensatory actions discussed in response to questions 3(a) through 3(e) involve operators are trained and entering Technical Specification Conditions. PINGP operators are trained in the interpretation tested on the compensatory and use of plant Technical Specifications and associated compensatory measures.

actions mentioned in your answers to questions 3(a) through (e).

Question 4

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 Yes. Procedural guidance is provided to the PINGP operators. The procedures require that have any guidance or the TSO be informed if the tap changer on 10 Bank Transformer is placed in manual and to do procedures in plant TS bases so only at the direction of the TSO so that the Security Analysis tool can be assessed for sections, the final safety accuracy. In addition, procedural guidance is provided for the abnormal operating condition of analysis report, or plant taking the generator voltage regulator to manual which includes requirements to contact the procedures regarding TSO in such an event.

situations in which the Operator training is provided within the context of general training on specific systems and condition of plant-controlled or 14 of 31 PINGP Response to Requested Information GL 2006-02, July 21, 2006 Question 4

-monitored equipment (e.g., operating procedures.

voltage regulators, auto tap changing 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, Not applicable. PINGP does have procedural guidance that provides the operator with written the final safety analysis report, direction for responding to equipment malfunctions and manipulation of controls that can and plant procedures do not adversely affect the operability of the PINGP offsite power system.

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.

15 of 31 PINGP Response to Requested Information GL 2006-02, July 21, 2006 Use of NPP licensee/TSO 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.

Question 5

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 Yes. The PINGP scheduling group ensures that all maintenance activities affecting grid qualitative grid reliability reliability or equipment designed to mitigate loss of offsite power scenarios are assessed for evaluation performed at your their impact on risk before those activities are performed. As part of this assessment, grid NPP as part of the reliability is considered and adjusted if appropriate (for severe weather, grid instability, or maintenance risk assessment offsite supply lines unavailable).

required by 10 CFR Maintenance activities associated with equipment supporting offsite power sources to the 50.65(a)(4) before performing safeguards buses, such as removing a transformer have been determined to be significant grid-risk-sensitive and are quantitatively incorporated into online risk assessment calculations. Removal from maintenance activities? This service of any of the four 345 kV lines to the substation is also quantitatively included in the includes surveillances, post- online risk assessment calculations. The scheduling group contacts the risk analysis group for maintenance testing, and support when a condition arises that requires a detailed assessment beyond the capability of preventive and corrective the normal online assessment tool (EOOS, EPRI software program Equipment Out Of maintenance that could Service that is used to provide risk analysis for maintenance activities).

increase the probability of a plant trip or LOOP or impact Plant procedures that provide guidance on the assessment and management of risk LOOP or SBO coping associated with maintenance activities include EOOS software to model equipment capability, for example, configurations. This includes equipment (transformers, breakers) that forms the paths from before taking a risk-significant the grid to the safety-related buses.

piece of equipment (such as When maintenance is being performed on one of the 345 kV lines, the EOOS variable an EDG, a battery, a steam-16 of 31 PINGP Response to Requested Information GL 2006-02, July 21, 2006 Question 5 driven pump, an alternate AC "Environmental Variances - Switchyard Maintenance" is set to a specific multiplier as called power source) out-of-service? out in the procedure. When maintenance is being performed on two of the 345 kV lines, the multiplier is set to a different value to account for the increased risk.

(b) Is grid status monitored by Yes. Per the responses provided in response to question 2, the grid status is continuously some means for the duration being monitored by the TSO with the operation of the RTCA. The TSO will inform the PINGP of the grid-risk-sensitive shift supervison if grid conditions significantly change that will place the grid into an elevated maintenance to confirm the system condition or that the minimum post contingent substation voltage is not met. Changes continued validity of the risk to the grid conditions are monitored internally by the work week manager and the risk assessment and is risk assessment would be revised accordingly in response to the changing or emergent grid reassessed when warranted? conditions as reported by the TSO.

If not, how is the risk assessed during grid-risk-sensitive maintenance?

(c) Is there a significant Typically the grid carries more power during summer months due to heavier loading. However variation in the stress on the the stress on the grid is a function of what equipment is in service and the ability of the grid to grid in the vicinity of your handle the increased loading with respect to winter months. Existing procedures and NPP site caused by seasonal protocols used by the TSO provide guidance on the grid operations to maintain grid reliability loads or maintenance and stability. These guidelines include direction on adjustments of real and reactive power activities associated with generation, load shedding, etc. to maintain a stable grid and reliable power to the PINGP.

critical transmission The overriding concern of the TSO is to maintain continued grid reliability/stability. To protect elements? the grid, TSO procedures require that service to residential and commercial customers be Is there a seasonal variation reduced by first reducing voltage at the distribution level and if required, shedding load. The (or the potential for a residential and commercial customers may experience electrical outages at the distribution seasonal variation) in the level while the grid is unaffected. Hence, offsite power would continue to be available to LOOP frequency in the local PINGP.

transmission region? Current industry data is inconclusive relative to the degree of seasonal variation in LOOP 17 of 31 PINGP Response to Requested Information GL 2006-02, July 21, 2006 Question 5 If the answer to either frequency. EPRI TR-1011759, dated December 2005 and EPRI TR-1009890, dated August question is yes, discuss the 2004, have shown that there is no statistically significant seasonal-regional variation in time of year when the recorded LOOP events from 1997 to 2004. Other recent documents and studies (i.e.,

variations occur and their NUREG/CR 6890) has indicated a statistical significant increase in frequency and associated magnitude. CDF during summer months. Current PINGP data from EPRI TR-1009889 does not breakdown or quantify a daily time dependent or seasonal variation in LOOP probability.

(d) Are known time-related The estimated likelihood of losing offsite power to PINGP is adjusted for certain conditions, variations in the probability of such as degraded grid stability, severe weather, and maintenance activities that impact offsite a LOOP at your plant site power reliability, and this adjusted offsite power reliability information is factored into the online considered in the grid-risk- risk monitoring tool for quantitative risk assessments. The thresholds for implementing sensitive maintenance quantitative adjustments to the online risk assessments are fairly well established, but some evaluation? If not, what is conditions may arise that need to be addressed on a case by case basis.

your basis for not considering PINGP adjusts the loss of offsite power (LOOP) frequency when grid stability degrades to a them? red level, as defined by the TSO. Nominal values are used when grid stability is green, yellow or orange.

The frequency of offsite power loss is adjusted (quantitatively assessed in the online risk monitoring model) for tornado, severe thunderstorm or high wind watches. Less severe conditions are treated on a case by case basis, and may be quantitatively assessed if conditions are determined to warrant an adjustment.

The online risk analysis model incorporates maintenance activities that remove the 345 kV lines to the substation from service or remove components such as transformers, or isolate breakers from offsite power lines that supply the safeguards buses. Passive activities such as working in the substation area are qualitatively assessed and generally determined to have a negligible impact on risk.

PINGP makes no adjustments to the loss of offsite power estimates as a function of time of day, day of week, or season.

18 of 31 PINGP Response to Requested Information GL 2006-02, July 21, 2006 Question 5 (e) Do you have contacts with Yes. The NSP TSO informs PINGP of planned maintenance through NSP's Transmission the TSO to determine current Work Request (TWR) process. If unplanned conditions take out a PINGP 345 kV transmission and anticipated grid line, the NSP TSO will also inform the PINGP control room.

conditions as part of the grid PINGP procedures require the NSP TSO to inform PINGP shift supervision if the N-1 reliability evaluation contingent voltage goes below the setpoint for a dual unit PINGP trip or if grid conditions performed before conducting change that may require suspension or postponement of maintenance and/or surveillance grid-risk-sensitive procedures affecting grid sensitive equipment.

maintenance activities?

Other maintenance activities that could result in a trip of PINGP or grid instabilities are not specifically coordinated with the TSO; however these activities are reviewed for risk sensitivity as described in 5(a) and 6(c).

(f) Describe any formal The TSO will notify PINGP in accordance with the agreement discussed in response to agreement or protocol that question 1(a) based upon grid conditions described in the response to question 1(b) above.

you have with your TSO to These notifications would be provided to PINGP whether or not maintenance is on-going.

assure that you are promptly The type of alerts provided to the PINGP conforms to the accepted practice promulgated by alerted to a worsening grid the North American Electric Reliability Council (NERC). Important alerts such as the one condition that may emerge suggested by this question would be made to all generators in the control area.

during a maintenance activity.

Changes to the grid operations, transmission lines out of service, generators taken off line, etc. are provided as real-time inputs to the RTCA via the SCADA system. Any change to the actual grid configuration that will cause a change in the grid system conditions codes or the dual unit post trip substation voltage to not meet degraded voltage requirements will trigger immediate notification to the Shift Supervisor from the TSO.

(g) Do you contact your TSO No, per the discussion in response to question 5(b). The TSO will inform the PINGP of any periodically for the duration of significant changes in the grid condition. Planned grid-risk sensitive maintenance activities the grid-risk-sensitive are identified beforehand to the TSO via the TWR notification as described in response to 19 of 31 PINGP Response to Requested Information GL 2006-02, July 21, 2006 Question 5 maintenance activities? question 5(e). Also plant surveillance and maintenance activities are reviewed when grid conditions may change as described in response to question 6(c).

(h) If you have a formal There is no formal training provided to the plant operators and maintenance personnel on the agreement or protocol with details of the formal agreement between PINGP and the TSO and/or MISO. Portions of the your TSO, describe how NPP formal agreement which impact operations and/or maintenance have, however, been operators and maintenance extracted from the agreement and incorporated into plant procedures. Training on this personnel are trained and procedural material is provided as discussed below.

tested on this formal Senior Rector Operators (SROs) have been trained in risk management and operability agreement or protocol. determination over the past few years at PINGP. This training has not been specific to the electrical grid, but has trained the SROs in the methodology that would be used when presented with the conditions stated above.

Operators were trained on the addition of switchyard maintenance to EOOS for doing a probabilistic risk assessment (PRA).

No training is provided to maintenance personnel.

(i) If your grid reliability A formal agreement for communication exists which would result in notification of grid evaluation, performed as part conditions that would be considered as part of maintenance risk assessment. Therefore, this of the maintenance risk question is not applicable.

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).

20 of 31 PINGP Response to Requested Information GL 2006-02, July 21, 2006 Question 5 (j) If risk is not assessed Not applicable to PINGP. The TSO communicates grid conditions to the plant shift (when warranted) based on supervision and that information is incorporated into online risk assessments as described continuing communication above (see answer to question 5(d)).

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 No alternative actions to be taken.

5(i) and 5(j), you 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.

21 of 31 PINGP Response to Requested Information GL 2006-02, July 21, 2006 Question 6

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 Yes. The NSP TSO informs PINGP of planned maintenance through NSP's TWR process. If transmission system unplanned conditions take out a PINGP 345 kV transmission line, the NSP TSO will also maintenance activities that inform the PINGP control room.

can have an impact on the PINGP procedures require the NSP Transmission System Operator (TSO) to inform the NPP operation with the NPP PINGP control room if the contingent voltage goes below the setpoint for a dual unit PINGP operator? trip. If this situation develops, PINGP declares the affected path from the grid (TS 3.8.1 Condition A) inoperable.

(b) Do you coordinate NPP Yes. See protocols as referenced in Question 1(a) and response to question 5(e).

maintenance activities that PINGP informs the NSP TSO of planned maintenance through NSP's TWR process. It should can have an impact on the be noted that this would apply to maintenance of substation transformers, breakers and other transmission system with the equipment in the substation that is owned and maintained by Xcel, the parent utility that also TSO?

operates the transmission system.

(c) Do you consider and Yes. Although rescheduling is not in the Maintenance Rule definitions, the risk informed implement, if warranted, the Maintenance Rule allows many choices.

rescheduling of grid-risk- Grid-risk sensitive maintenance is performed when the on-shift personnel conclude that the sensitive maintenance risk of the work is small compared to the safety benefit. When the maintenance work is done activities (activities that could in response to a Technical Specification, the risk assessment is informative for sequencing (i) increase the likelihood of a tasks, but not controlling.

plant trip, (ii) increase LOOP probability, or (iii) reduce Emergent issues with the grid are managed to maintain a high level of plant safety. When LOOP or SBO coping notified of elevated grid color code, appropriate management means rescheduling activities altogether, at other times the shift-supervisor will order the on-shift maintenance staff to back 22 of 31 PINGP Response to Requested Information GL 2006-02, July 21, 2006 Question 6 capability) under existing, out of the task and restore the safety-related function of the equipment until the grid imminent, or worsening awareness conditions have reduced.

degraded grid reliability As described in in response to questions 5(a) through 5(g) above, the risk assessment and the conditions? continuous monitoring of grid conditions will cause PINGP move activities into and out of the maintenance schedule as required to either minimize the risk or manage the risk with appropriate compensatory actions.

Yes. All grid-risk sensitive maintenance activities are subject to a rigorous review prior to work (d) If there is an overriding start as outlined in various PINGP and TSO procedures and guidance documents per the need to perform grid-risk-interface agreement.

sensitive maintenance activities under existing or Xcel grid (transmission/generation) system status color codes provide an indication of grid imminent conditions of status. This code is based on the combination of: 1) system generation availability versus degraded grid reliability, or demand; and 2) transmission system load versus operating limits. A color code of Green continue grid-risk-sensitive indicates normal system status. Yellow is a warning status. Orange is a danger status. Red maintenance when grid is an emergency status.

conditions worsen, do you implement appropriate risk PINGPs work management group utilizes the EOOS software program (described in response management actions? If so, to question 5) to determine the probability of a core damaging event based on plant and grid describe the actions that you configurations during the maintenance activities. The small probability of the loss of the grid would take. (These actions system when the status changes from green to yellow has been determined to be negligible.

could include alternate However; the likelihood of a loss of offsite power is assessed to be significantly higher when equipment protection and the grid system status is changed to orange or red.

compensatory measures to limit or minimize risk.) If there is an overriding need to perform or continue in progress work during imminent or degraded grid conditions, then, written guidance would direct the necessary actions to be taken for the given system condition code.

(e) Describe the actions Actions to be taken are addressed within each of the responses to questions 6(a) through 6(c) 23 of 31 PINGP Response to Requested Information GL 2006-02, July 21, 2006 Question 6 associated with questions above. The procedures that govern these actions are also discussed in the same responses.

6(a) through 6(d) above that Strict procedure adherence is an expectation of both NMC and Xcel management.

would be taken, state For 6(d), the risk management procedure at PINGP directs that additional risk evaluations be whether each action is performed taking into account elevated grid conditions (described as yellow, orange or red) as governed by documented provided by the TSO to assess the core damage frequency (CDF) associated with the procedures and identify the proposed maintenance activity. A similar maintenance risk color identifier is assigned (per the procedures, and explain why EOOS evaluation) to the unit for equipment out-of-service configuration based on the these actions are effective configurations of both plant and grid to establish a specific CDF. A maintenance risk color and will be consistently category of red indicates that the risk rate is too high, and must be reduced immediately by accomplished. placing equipment back in service or by implementing contingency or compensatory measures. The color category actions are assigned based on the length of the risk-informed allowable out-of-service time, as follows:

• Red - Do not voluntarily enter these configurations. Plant Operations Review Committee must authorize operation for any length of time in this condition.

Immediately restore equipment to service, or implement risk management actions to restore at least an orange color category.

• Orange - Plant Manager approval required to commence planned activity.

• Yellow - Shift Manager approval required to commence planned activity.

• Green - Normal work control procedures apply.

Maintenance activities performed by Xcel on grid reliability sensitive equipment are also governed by similar restrictions based on the system condition color code and are coordinated with plant maintenance or curtailed appropriately, and specific elevated grid condition operating procedures are initiated depending on the severity of the system code.

By maintaining the lowest out-of-service times and the lowest CDF risk with appropriate risk informed decisions, reasonable assurance is provided that grid sensitive maintenance activities will be effectively managed.

24 of 31 PINGP Response to Requested Information GL 2006-02, July 21, 2006 Question 6 (f) Describe how NPP SROs have been trained in risk management and operability determination over the past few operators and maintenance years at PINGP. This training has not been specific to the electrical grid, but has trained the personnel are trained and SROs in the methodology that would be used when presented with the conditions stated tested to assure they can above.

accomplish the actions Operators trained on the addition of switchyard maintenance to EOOS for doing PRA.

described in your answers to question 6(e). No training is provided to maintenance personnel related to this question.

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

regarding transmission system maintenance or NPP maintenance 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 As discussed in response to questions 6(a) through 6(d), PINGP effectively implements effectively implement appropriate risk management actions.

appropriate risk management actions during the conditions described above, explain why you believe you effectively addressed the relevant provisions of the associated NRC-endorsed industry 25 of 31 PINGP Response to Requested Information GL 2006-02, July 21, 2006 Question 6 guidance.

(i) You may, as an alternative No alternative actions to be taken.

to questions 6(g) 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).

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.

Question 7

7. Procedures for identifying local power sources 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 26 of 31 PINGP Response to Requested Information GL 2006-02, July 21, 2006 Question 7 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 PINGP is also owned by the parent owner of the grid TSO; therefore no formal agreements agreement made with the exist other than the agreements identified in response to question 1(a). The Xcel Corporate TSO to identify local power System Restoration Plan states in Section 7.2 that, The nuclear plants could receive auxiliary sources that could be made power as soon as the system and frequency stabilize. However, if either or both nuclear sites available to re-supply power were to request power because of failures or problems with their emergency station to your plant following a generators, power would be routed to their respective substations.

LOOP event. The plant would get top priority for restoration of offsite power if the emergency diesel generators were not operable. The priority would not be for re-starting the plant, but rather to restore power to the safe shutdown equipment. The TSO will utilize the best sources available for specific events to restore offsite power and to determine the specific 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 owner controlled local power sources.

It should be noted that due to the indeterminate nature of a LOOP, the actions that could take place in the event of a LOOP at PINGP are not prescriptively identified in any procedure.

(b) Are your NPP operators The TSO is responsible for restoration of power to the Prairie Island Substation in the event of trained and tested on a LOOP.

identifying and using local PINGP operators have been trained to use Emergency Operating Procedures (EOPs) and power sources to resupply AOPs to address issues related to the grid and to restoration of power to the essential buses your plant following a LOOP in the event of a LOOP. This is comprised of classroom training on the abnormal procedures 27 of 31 PINGP Response to Requested Information GL 2006-02, July 21, 2006 Question 7 event? If so, describe how. and training in the Simulator.

(c) If you have not PINGP is an asset owned by the same company that owns and operates the Transmission established an agreement System and has established agreements to maintain adequate voltage and current support as with your plants TSO to described in response to question 1(a).

identify local power sources The TSO has the responsibility to restore offsite power to PINGP as a priority as described in that could be made available response to question 7(a). Identifying local power sources that could be made available to to resupply power to your resupply power to PINGP following a LOOP is not part of the PINGP licensing basis.

plant following a LOOP event, explain why you believe you The requirement for procedures to restore AC power to PINGP is met by providing instructions comply with the provisions of to the system dispatcher to give the highest possible priority for restoring offsite power to 10 CFR 50.63, or describe PINGP in the event of a grid collapse and a simultaneous loss of emergency diesel generators what actions you intend to (EDGs) at the site. The TSO System restoration and blackout procedures also contain this take to establish compliance. guidance and identify initial power sources for restoration.

The TSO is required by NERC standards to maintain a system restoration plan. The plan provides for priority restoration of power to nuclear units in the event of a system blackout.

PINGPs SBO and LOOP Abnormal Operating Procedures provide for communication between the system operator and PINGP Operations with regard to efficient restoration of AC power from the grid. Load restoration at the plant level is also addressed within the SBO and LOOP AOPs.

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.

28 of 31 PINGP Response to Requested Information GL 2006-02, July 21, 2006 Question 8

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

(a) Has your NPP One, due to weather related conditions external to the plant. Refer to LER 1996012. It should experienced a total LOOP be noted, however, that one 345 kV line and one 161 kV line remained energized throughout caused by grid failure since the event maintaining some limited power to the non-safeguards buses throughout the event.

the plants coping duration was initially determined under 10 CFR 50.63?

(b) If so, have you No. Following the guidance of NUMARC 87-00 used in the original SBO classification, PINGP reevaluated the NPP using remains classified in Severe Weather (SW) Group 2 since the annual expectations for snow, the guidance in Table 4 of tornadoes and severe storms has not changed; therefore, no reevaluation was required.

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 No reevaluation was required since the annual expectations for snow, tornadoes and severe results of this reevaluation, storms have not changed.

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

(d) If your NPP has Per the guidance of NUMARC 87-00, PINGP remains classified as SW Group 2 since the 29 of 31 PINGP Response to Requested Information GL 2006-02, July 21, 2006 Question 8 experienced a total LOOP annual expectations for snow, tornadoes and severe storms have not changed; therefore, caused by grid failure since PINGP remains in compliance with the provisions of 10 CFR 50.63.

the plants 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 Based on the responses provided above, NMC considers that operation and maintenance of any action is warranted to the PNP is in compliance with the noted regulatory requirements to the extent described in the bring your NPP into plants licensing basis.

compliance with NRC regulatory requirements, including TSs, GDC 17, 10 CFR 50.65(a)(4),

10 CFR 50.63, 10 CFR 55.59 30 of 31 PINGP Response to Requested Information GL 2006-02, July 21, 2006 or 10 CFR 50.120, describe the schedule for implementing it.

31 of 31 MNGP Response to Requested Information GL 2006-02, July 21, 2006 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).

Question 1

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 Yes. The Transmission System Operator (TSO) to which the Monticello Nuclear Generating agreement or protocol with Plant (MNGP) supplies power is owned and operated by Xcel Energy, Inc. (Xcel). MNGP is your TSO? owned by Northern States Power Company (NSP), a wholly owned subsidiary of Xcel Energy, Inc. (Xcel), and operated by Nuclear Management Company, LLC (NMC). Although NMC is the plant operating entity, references to management actions on behalf of MNGP in the remainder of this document are referred to as MNGP.

The MNGP formal agreement with the TSO (all references to TSO, ISO, Reliability Controller or Control Center, System Operation, Delivery System Operations, Energy Supply, Balancing Authority, etc. throughout this document refer to Xcel Energys Northern States Power System Control Center) is documented in Nuclear Power Plant Operating Services Agreement between Northern States Power Company and Nuclear Management Company, LLC for the Monticello Nuclear Generating Plant.

(b) Describe any grid The TSO is required to notify MNGP in the event of changes in the transmission system lineup conditions that would trigger or conditions that could affect plant and offsite source reliability and availability.

a notification from the TSO to 1 of 32 MNGP Response to Requested Information GL 2006-02, July 21, 2006 Question 1 the NPP licensee and if there There are triggering conditions that cause the TSO to notify MNGP of potential or developing is a time period required for grid instabilities in the area of voltage control limits or voltage rate of change for their the notification transmission lines. Procedures direct the TSO to inform MNGP of tightening energy and capacity situations and put the facility on notice that the grid is being stressed or the potential for disturbances is imminent. An operating guide directs the TSO to notify MNGP shift supervision of a contingency condition that would result in MNGP degraded voltage conditions if it occurs. Specific examples of potentially degrading conditions identified in the agreement include:

1. If a Real Time Contingency Analysis (RTCA) post contingent alarm is received and cannot be cleared by system operator action indicating that the post-trip grid voltage at the MNGP substation will be below the calculated minimum voltage for the present plant substation lineup; and

2. If grid conditions, as established by Energy Supply, enters into or leaves a system condition designated as orange or red. (These are the two most stressed grid conditions).

(c) Describe any grid Grid conditions and status are the primary responsibility of the TSO and Reliability conditions that would cause Coordinator. The MNGP process computer continuously displays the 345 kV and 115 kV the NPP licensee to contact voltages, allowing for continuous monitoring by the plant operating staff. An alarm will the TSO. annunciate if the voltages approach unacceptable levels. In addition, the 345 kV frequency is monitored and a low frequency generates an alarm on a plant main control room panel.

Describe the procedures associated with such a The TSO is contacted per procedure for response to any grid conditions that result in communication. If you do not substation alarms. These procedures include computer alarm and annunciator response have procedures, describe procedures as well as Operations Manual procedures. In addition, Plant Abnormal Operating how you assess grid Procedures (AOP) direct communication with the TSO in response to loss of major substation conditions that may cause the components.

NPP licensee to contact the TSO.

2 of 32 MNGP Response to Requested Information GL 2006-02, July 21, 2006 Question 1 (d) Describe how NPP Licensed Operator Training includes the following:

operators are trained and Initial Training:

tested on the use of the procedures or assessing grid The following material is presented in the classroom and tested by written exam per program conditions in question 1(c). requirements:

• Main Generator: discuss the requirements for actions should transformer voltages (1R, 2R, or 1AR) be outside required action levels. Also discussed is MNGPs response to system underfrequency conditions and the actions that MNGP can take to increase plant reactive loading while remaining within the generator capacity curve;

• Substation: discuss the requirement for actions should MNGP be notified by the TSO of a 345 KV or a 115 KV System Contingency Voltage Notification, as described in 1(b) above;

• 4160 V system: discuss the requirements, precautions and actions for a system undervoltage situation; and

• Station Electrical Blackout (SEBO): discuss the bases and development of the Xcel response procedures to grid related problems.

The following are simulator sessions in the Initial Training Program that get evaluated in the simulator per program requirements:

• Degrading Grid (DG) Test, Degrading Grid and Loss of Offsite Power: This simulator session focuses on degrading grid conditions and operator actions required by these conditions. This simulator scenario degrades to the point of a complete loss of offsite power and interaction with the TSO; and

• Loss of Normal Offsite Power (LONOP) due to grid instability: This exercise simulates grid conditions present in the 2003 Northeast Blackout event and operator response.

Licensed Operator Requalification Training:

In 2005 the following training was presented:

3 of 32 MNGP Response to Requested Information GL 2006-02, July 21, 2006 Question 1 Both classroom training on the Northeast Blackout of 2003 and actions taken to prevent the same occurrence here included review of procedures for degrading transformer/grid voltages and the actions required at MNGP, and newly installed breakers in the switchyard including operation and alarms. Dynamic simulator training was conducted emphasizing degrading grid conditions. Training also included a discussion of voltage regulator and grid interaction, and loading capabilities of the turbine generator using the operating curves.

Plans for future continuing training include degraded voltage conditions.

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

formal agreement or protocol with your TSO, describe why 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.

(f) If you have an existing As previously stated in response to question 1(a), MNGP does have a formal TSO agreement.

formal interconnection Procedures exist that address the interface between the grid operator and MNGP. The TSO is agreement or protocol that required to promptly notify MNGP shift supervision in the event of changes in the transmission ensures adequate system lineup or conditions that could affect plant and offsite source reliability and availability.

communication and A procedure directs the TSO to inform MNGP of tightening energy and capacity situations coordination between the which will put the facilities on notice that the grid is being stressed or the potential for NPP licensee and the TSO, disturbances is imminent. This notification would come in advance of any MNGP substation describe whether this voltages approaching a value that would result in actuation of degraded voltage protection.

agreement or protocol requires that you be promptly In addition, the TSO continually monitors the grid for contingency conditions utilizing an RTCA 4 of 32 MNGP Response to Requested Information GL 2006-02, July 21, 2006 Question 1 notified when the conditions program. The TSO would inform MNGP if the contingency analysis results indicate the plant of the surrounding grid could would experience degraded voltage following a trip of MNGP, loss of MNGP Substation 10 result in degraded voltage Transformer, or other contingency, and the contingency condition voltages cannot be (i.e., below TS nominal trip corrected by system operator action.

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 At MNGP, degraded voltage is not sensed in the switchyard. The degraded voltage protection switchyard voltage conditions scheme senses voltage at the essential plant 4.16 kV buses. MNGP has maintained load flow that would initiate operation calculations to ensure that the Technical Specifications offsite power source minimum voltage of plant degraded voltage levels are adequate for station lineups under worst case loading and motor starting conditions:

protection.

Degraded voltage relay nominal set point: 3915 Volts on 4.16 kV nominal system voltage; and Nominal time delay: 9 seconds.

Degraded voltage protection will not initiate as long as switchyard voltages do not fall below the following values:

1. When supplied by the preferred source (2R Transformer):

115 kV system voltage < 114.7 kV or 345 kV system voltage < 342 kV; or

2. When supplied by the non-preferred source (1R Transformer):

115 kV system voltage < 116 kV or 345 kV system voltage < 342 kV.

Under the worst case loading on the plant auxiliary electrical system, these conditions would initiate operation of the plant degraded voltage protection.

5 of 32 MNGP Response to Requested Information GL 2006-02, July 21, 2006 Question 2

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 NPPs TSO Yes. The TSO makes use of analysis tools to predict grid conditions that would make the use any analysis tools, an MNGP offsite power system inoperable. These tools are not available to the MNGP.

online analytical transmission The tools presently used by the TSO to manage the grid programs, control the transmission system studies program, or related activities, and monitor grid actions include the following:

other equivalent predictive methods to determine the

• a fully commissioned RTCA program; grid conditions that would

• a grid state estimator and System Control and Data Acquisition (SCADA) system in make the NPP offsite power conjunction with periodic studies of a reasonable number of contingencies; and system inoperable during various contingencies?

• bounding analyses.

If available to you, please The following is a brief description of the RTCA operation:

provide a brief description of The Security Analysis (SA) is a real time load flow program that takes data from the SCADA the analysis tool that is used network to establish the various state variable parameters required to analyze the network.

by the TSO. Once all the state input data is set, the program calculates the voltages at all of the nodes in the network. As in any load flow analysis, the program may take a few iterations to reach a solution. For purposes of this explanation, this is referred to as the Base Real Time Analysis.

Upon reaching the base solution the program then sequentially steps through a sequence of N contingencies to recalculate resultant node voltages for a series of what if scenarios.

Each contingency calculation considers the loss of one of the major components in the base analysis at a time, hence the term N-1 Contingency Analysis. It calculates the resultant voltage at each node based on the loss of one of the components from the base real time solution. This list of contingencies may be several hundred elements long and runs immediately after the base solution is calculated. The contingency of primary concern to the nuclear plant is the trip of the plant and the effect on the resultant voltage at the plants 6 of 32 MNGP Response to Requested Information GL 2006-02, July 21, 2006 Question 2 substation. For the purpose of this discussion this will be referred to as the Primary Contingency. For each of the N-1 contingencies, the resultant voltage at each of the nodes of concern is compared to pre-established voltage limits and if any voltage falls out of that range, the system operator receives an alarm. If an alarm is received upon running of the primary contingency and cannot be cleared by system operator action, the system operator is instructed to contact the nuclear plant in accordance with established protocols.

(b) Does your NPPs TSO Yes. The TSO uses the above analysis tools, in conjunction with procedures, as the basis for use an analysis tool as the determining when conditions warrant MNGP notification.

basis for notifying the NPP licensee when such a condition is identified? If not, how does the TSO determine if conditions on the grid warrant NPP licensee notification?

(c) If your TSO uses an Yes. The TSO analysis tool, in conjunction with MNGP analysis, identifies conditions which analysis tool, would the may actuate the MNGP degraded voltage protection logic and initiate separation from an analysis tool identify a offsite power source upon a MNGP trip.

condition in which a trip of the The RTCA program used by the TSO analyzes the grid for the current real time conditions with NPP would result in one contingency condition and alarms if the MNGP switchyard voltage levels would be below switchyard voltages the thresholds established by MNGP (outlined in the response to question 1(g)) for one or (immediate and/or long-term) more contingencies. The established switchyard voltage thresholds are the levels at which falling below TS nominal trip the 4.16 kV essential bus voltage levels would dip within the analytical limits (3897 - 3933 V) setpoint value requirements of the degraded voltage set point. Two of the many contingencies used in the analysis are (1)

(including NPP licensees the loss of MNGP generation and (2) the loss of MNGP switchyard 345/115 kV transformer using allowable value in its (10 Transformer).

TSs) and consequent 7 of 32 MNGP Response to Requested Information GL 2006-02, July 21, 2006 Question 2 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 The TSO RTCA program presently updates and recalculates the MNGP trip contingency on a analysis tool, how frequently time interval of approximately 7 to 8 minutes.

does the analysis tool The TSO SCADA information available as an input to the RTCA is essentially real time and program update?

provides updates to the RTCA each time it runs.

(e) Provide details of analysis The notification from the TSO is based upon the predicted post-trip or other contingency tool-identified contingency switchyard voltage given actual (RTCA) grid conditions.

conditions that would trigger The RTCA tool applies the real time actual conditions of the grid to the analysis with one of the an NPP licensee notification major grid components (generating unit, transmission line, or transformer) removed. The tool from the TSO. will then generate an alarm if the resultant voltages at the MNGP substation 10 Transformer or MNGP generator do not meet the following thresholds:

• 342 kV on the 345 kV system;

• 114.7 kV on the 115 kV system when the plant is on its preferred source; and

• 116 kV on the 115 kV system when the plant is on its non-preferred source.

If an alarm is generated for a MNGP voltage threshold violation, the TSO operator procedurally attempts to restore the post-contingency predicted MNGP switchyard voltage levels. If the system changes do not restore the post-contingency predicted voltage levels, then the operator notifies the MNGP control room.

8 of 32 MNGP Response to Requested Information GL 2006-02, July 21, 2006 Question 2 (f) If an interface agreement Yes. The agreement specifically requires MNGP notification when grid conditions are exists between the TSO and indeterminate for 90 minutes or greater.

the NPP licensee, does it MNGP follows Technical Specifications requirements when notified by the TSO that grid require that the NPP licensee conditions are indeterminate. Operating procedures would be followed if this occurs. Voltage be notified of periods when is also monitored at the 4.16 KV buses and appropriate actions are defined in Plant the TSO is unable to Operations Manual procedures for operator action if voltage limits are not met at this system determine if offsite power level.

voltage and capacity could be inadequate?

If so, how does the NPP licensee determine that the offsite power would remain operable when such a notification is received?

(g) After an unscheduled No. For post event analysis, the TSO does not verify by procedure the switchyard voltages inadvertent trip of the NPP, are bounded by the analysis tools. Following an inadvertent trip of MNGP, any unexpected are the resultant switchyard actuations or equipment operation associated with supply voltage would be documented and voltages verified by evaluated in accordance with the corrective action process.

procedure to be bounded by the voltages predicted by the analysis tool?

(h) If an analysis tool is not Not applicable to MNGP since TSO analysis tools are presently in use.

available to the NPP licensees TSO, do you know if there are any plans for the TSO to obtain one? If so, 9 of 32 MNGP Response to Requested Information GL 2006-02, July 21, 2006 Question 2 when?

(i) If an analysis tool is not Not applicable to MNGP since TSO analysis tools are presently in use.

available, does your 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 provisions discussed in question 1 above?

(j) If your TSO does not use, Not applicable to MNGP, since the TSO utilizes analysis tools and communicates the 10 of 32 MNGP Response to Requested Information GL 2006-02, July 21, 2006 Question 2 or you do not have access to applicable results and alarms to MNGP.

the results of an analysis tool, or your TSO does not perform and make available to you periodic studies that determine the adequacy of offsite power capability, please describe why you believe you comply 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.

Question 3

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

(a) If the TSO notifies the Yes. MNGP Technical Specifications requirements are that at least two transmission lines, NPP operator that a trip of associated switchgear, and at least two offsite power sources (2R and 1R, or 1R and 1AR, or the NPP, or the loss of the 11 of 32 MNGP Response to Requested Information GL 2006-02, July 21, 2006 Question 3 most critical transmission line 2R and 1AR transformers) are fully operational and energized to carry the 4160 V AC buses.

or the largest supply to the If notified by the TSO of a contingency voltage alarm, the MNGP control room operator by grid would result in procedure declares offsite power sources inoperable for the following conditions:

switchyard voltages (immediate and/or long-term) For a 345 kV contingency voltage threshold violation, if the contingency is loss of MNGP below TS nominal trip generation, the 2R transformer is declared inoperable.

setpoint value requirements For a 115 kV contingency voltage threshold violation:

(including NPP licensees using allowable value in its

• If the contingency is loss of MNGP generation and the contingency voltage is less than or TSs) and would actuate plant equal to 114.7 kV, then the 1R transformer is declared inoperable; and degraded voltage protection,

• If the contingency is loss of 10 transformer, and the contingency voltage is less than or is the NPP offsite power equal to 114.7 kV, then the 1R transformer and 1AR transformers are not considered system declared inoperable redundant, and 1R or 1AR is declared inoperable.

under the plant TSs? If not, why not? MNGP Technical Specifications and procedures do not require declaring the offsite sources inoperable for other contingencies such as loss of a transmission line or a contingency loss of the largest supply to the grid.

(b) If onsite safety-related The plant accident analyses evaluate a loss of offsite power (LOOP) occurring coincident with equipment (e.g., emergency various accidents. A postulated double sequencing event is outside the plants licensing basis diesel generators or safety- and has not been evaluated. Equipment operability is based on performance of safety related motors) is lost when functions and safety support functions required within the plant licensing basis.

subjected to a double sequencing (LOCA with delayed LOOP event) as a result of the anticipated system performance and is incapable of performing its safety functions as a result of responding to an emergency 12 of 32 MNGP Response to Requested Information GL 2006-02, July 21, 2006 Question 3 actuation signal during this condition, is the equipment considered inoperable?

If not, why not?

(c) Describe your evaluation Double sequencing is not part of MNGPs licensing basis and MNGP is not designed or of onsite safety-related analyzed for double sequencing scenarios.

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

(d) If the NPP licensee is No. Technical Specification Conditions are not entered for grid conditions that might occur.

notified by the TSO of other The MNGP operator only declares offsite power sources inoperable when the predicted grid conditions that may voltage following a unit trip is low enough to preclude initiation of loss of coolant accident impair the capability or (LOCA) loads concurrent with a unit trip.

availability of offsite power, are any plant TS action statements entered? If so, please identify them.

(e) If you believe your plant Not applicable to MNGP since offsite power sources will be declared inoperable as described TSs do not require you to in 3(a) above in accordance with the plant licensing basis and Technical Specifications.

declare your offsite power system or safety-related equipment inoperable in any of these circumstances, explain why you believe you 13 of 32 MNGP Response to Requested Information GL 2006-02, July 21, 2006 Question 3 comply with the provisions of GDC 17 and 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.

(f) Describe if and how NPP Training on compensatory actions is encompassed within the response to question 1(d).

operators are trained and tested on the compensatory actions mentioned in your answers to questions 3(a) through (e).

Question 4

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 Yes. Procedural guidance is provided to the MNGP operators. The operators are provided have any guidance or with written direction for responding to equipment malfunctions and manipulation of controls procedures in plant TS bases that can adversely affect the operability of the MNGP offsite power system. The following list 14 of 32 MNGP Response to Requested Information GL 2006-02, July 21, 2006 Question 4 sections, the final safety includes examples of, but does not include all procedural guidance associated with this analysis report, or plant question.

procedures regarding

• 345kV BUS VOLTAGE LOW/HIGH; situations in which the condition of plant-controlled

• 115kV BUS VOLTAGE LOW/HIGH; or -monitored equipment

• 345kV & 115kV YARD TROUBLE; (e.g., voltage regulators, auto tap changing transformers,

• 1 GEN U.F. RELAY OPERATION; capacitors, static VAR

• NO. 1 GEN MAX EXC TRIP; compensators, main generator voltage regulators)

• 1-BUS 345kV LOW FREQUENCY; can adversely affect the

• NO. 2R XFMR TROUBLE; operability of the NPP offsite power system? If so,

• 1AR TRANS TROUBLE; describe how the operators

• 1AR TRANS GROUND; are trained and tested on the guidance and procedures.

• NO. 1 RES TRANS TROUBLE;

• Removal of Automatic Voltage Regulator While on Line;

• Restoration of the Automatic Voltage Regulator While on Line;

• Faulty Voltage Regulator;

• Loss of Gen Field Current;

• 115kV System Contingency Voltage Notification;

• 345kV System Contingency Voltage Notification;

• Loss or Partial loss of 10 Transformer Cooling;

• 345kV System Contingency Voltage Notification;

• Loss of 10 Transformer; 15 of 32 MNGP Response to Requested Information GL 2006-02, July 21, 2006 Question 4

• Voltage Outside Operating Action Levels for Standby Power Sources;

• Voltage Outside Operating Action Levels With Power Supplied From 1R Transformer; and

• Voltage Outside Operating Action Levels With Essential Buses Supplied Power From 1AR Transformer.

Licensed Operator Training for these conditions is encompassed in the response to question 1(d).

(b) If your TS bases sections, Not applicable. MNGP does have procedural guidance that provides the operator with written the final safety analysis direction for responding to equipment malfunctions and manipulation of controls that can report, and plant procedures adversely affect the operability of the MNGP offsite power system.

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.

16 of 32 MNGP Response to Requested Information GL 2006-02, July 21, 2006 Use of NPP licensee/TSO 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.

Question 5

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 Yes. The MNGP scheduling group ensures that all maintenance activities for the plant and qualitative grid reliability MNGP substation affecting grid reliability or equipment designed to mitigate loss of offsite evaluation performed at your power scenarios are assessed for their impact on risk before those activities are performed.

NPP as part of the As part of this assessment, grid reliability is considered and adjustments to the work schedule maintenance risk assessment are made if appropriate (severe weather or grid instability is significant).

required by 10 CFR Many routine maintenance activities associated with equipment supporting offsite power 50.65(a)(4) before performing supply have been reviewed and qualitatively determined to have a relatively small risk impact grid-risk-sensitive and are noted as having been qualitatively assessed. In such cases the online risk model maintenance activities? This does not quantitatively assess this impact. Other maintenance activities associated with includes surveillances, post- equipment supporting offsite power, such as removing a transformer, power supply line, or maintenance testing, and substation breaker from service, have been determined to be significant and are quantitatively preventive and corrective incorporated into online risk assessment calculations. The scheduling group contacts the risk maintenance that could analysis group for support when a condition arises that requires a detailed assessment increase the probability of a beyond the capability of the normal online assessment tool (EOOS, EPRI software program plant trip or LOOP or impact Equipment Out Of Service that is used to provide risk analysis for maintenance activities).

LOOP or SBO coping capability, for example, before taking a risk-significant piece of equipment (such as an EDG, a battery, a steam-17 of 32 MNGP Response to Requested Information GL 2006-02, July 21, 2006 Question 5 driven pump, an alternate AC power source) out-of-service?

(b) Is grid status monitored by The TSO notifies the MNGP control room if grid stability degrades. The MNGP operations some means for the duration group is responsible for ensuring that risk is assessed for applicable plant conditions, including of the grid-risk-sensitive degraded grid stability. The schedule reflects that maintenance activities are being performed, maintenance to confirm the and indicates corresponding risk values. If conditions change unexpectedly, risk is re-continued validity of the risk assessed with assistance from the scheduling group or the risk analysis group, as necessary.

assessment and is risk reassessed when warranted?

If not, how is the risk assessed during grid-risk-sensitive maintenance?

(c) Is there a significant Typically the grid carries more power during summer months due to heavier loading. However variation in the stress on the the stress on the grid is a function of what equipment is in service and the ability of the grid to grid in the vicinity of your handle the increased loading with respect to winter months. Existing procedures and NPP site caused by seasonal protocols used by the TSO provide guidance on the grid operations to maintain grid reliability loads or maintenance and stability. These guidelines include direction on adjustments of real and reactive power activities associated with generation, load shedding, etc. to maintain a stable grid and reliable power to the MNGP.

critical transmission The overriding concern of the TSO is to maintain continued grid reliability/stability. To protect elements? the grid, TSO procedures require that service to residential and commercial customers be Is there a seasonal variation reduced by first reducing voltage at the distribution level and if required, shedding load. The (or the potential for a residential and commercial customers may experience electrical outages at the distribution seasonal variation) in the level while the grid is unaffected. Hence, offsite power would continue to be available to LOOP frequency in the local MNGP.

transmission region? Offsite power to MNGP is provided via a substation located on site. The substation consists of If the answer to either four incoming 345 kV transmission lines and three 115 kV transmission lines. There are three 18 of 32 MNGP Response to Requested Information GL 2006-02, July 21, 2006 Question 5 question is yes, discuss the large coal-fired units nearby that each delivers more power (between 678 MW and 877 MW) to time of year when the the grid than does MNGP. With the number of lines providing access to the grid and the variations occur and their number of large generating units in the vicinity, removal of a transmission line from service magnitude. either within the MNGP Substation or elsewhere in the system does not result in a significant increase in grid stress near MNGP.

Current industry data is inconclusive relative to the degree of seasonal variation in LOOP frequency. EPRI TR-1011759, dated December 2005, has shown that there is no statistically significant seasonal-regional variation in recorded LOOP events from 1997 to 2004. In addition, MNGP is not aware of a seasonal variation in LOOP frequency in the local transmission region.

(d) Are known time-related The estimated likelihood of losing offsite power to MNGP is adjusted for certain conditions, variations in the probability of such as degraded grid stability, severe weather, and maintenance activities that impact offsite a LOOP at your plant site power reliability, and this adjusted offsite power reliability information is factored into the online considered in the grid-risk- risk monitoring tool for quantitative risk assessments. The thresholds for implementing sensitive maintenance quantitative adjustments to the online risk assessments are well established, but some evaluation? If not, what is conditions may arise that need to be addressed on a case by case basis.

your basis for not considering MNGP adjusts the loss of offsite power frequency when grid stability degrades to an orange or them? red level, as defined by the TSO. Nominal values are used when grid stability is green or yellow.

The frequency of LOOP is adjusted (quantitatively assessed in the online risk monitoring model) for tornado warnings, winds in excess of 60 mph, or icing conditions when reported by the TSO.

The online risk analysis model incorporates maintenance activities that remove any of the offsite power supplies from service, remove substation components such as transformers, or isolate breakers. Passive activities such as working in the substation area are qualitatively assessed and generally determined to have a negligible impact on risk.

19 of 32 MNGP Response to Requested Information GL 2006-02, July 21, 2006 Question 5 MNGP makes no adjustments to the LOOP estimates as a function of time of day, day of week, or season.

(e) Do you have contacts with Yes. MNGP has procedural guidance that requires direct notification of the TSO when work is the TSO to determine current planned on equipment such as load tap changers, generator voltage regulator, diesel and anticipated grid generator testing and removal of transformers from service.

conditions as part of the grid Balance of plant activities such as half-scram testing and equipment maintenance activities reliability evaluation internal to the plant that could result in a MNGP trip or grid instabilities are not directly performed before conducting coordinated with the TSO. However, these activities are evaluated against current system grid-risk-sensitive conditions per the written responsibilities outlined in the response to question 6(d) below.

maintenance activities?

MNGP specific guidance is provided by procedure. This procedure provides MNGP operators with written guidance to evaluate and make decisions accordingly, for all in progress or planned work, based on Xcels Grid System Condition Color Codes.

(f) Describe any formal The TSO will notify MNGP in accordance with the agreement discussed in response to agreement or protocol that question 1(a) based upon grid conditions described in the response to question 1(b) above.

you have with your TSO to These notifications would be provided to MNGP whether or not maintenance is on-going.

assure that you are promptly alerted to a worsening grid condition that may emerge during a maintenance activity.

(g) Do you contact your TSO No. MNGP relies on the TSO to contact control room operators when any grid instabilities are periodically for the duration of occurring or predicted. At that time MNGP assesses all on-going work and determines the the grid-risk-sensitive most appropriate action(s) to take per MNGP procedures. MNGP does followup with the TSO maintenance activities? to understand the expected duration for any grid condition that results in a color coded yellow 20 of 32 MNGP Response to Requested Information GL 2006-02, July 21, 2006 Question 5 or higher.

(h) If you have a formal There is no formal training provided to the plant operators and maintenance personnel on the agreement or protocol with details of the formal agreement between MNGP and the TSO and/or MISO. Portions of the your TSO, describe how NPP formal agreement which impact operations and/or maintenance have, however, been operators and maintenance extracted from the agreement and incorporated into plant procedures. Training on this personnel are trained and procedural material is provided as discussed below.

tested on this formal Licensed Operator training for the protocol is contained within the response to question 1(d).

agreement or protocol.

Maintenance personnel are not involved or trained in the protocol.

(i) If your grid reliability A formal agreement for communication exists which would result in notification of grid evaluation, performed as part conditions that would be considered as part of maintenance risk assessment. Therefore, this of the maintenance risk question is not applicable.

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 Not applicable to MNGP. The TSO communicates grid conditions to the plant shift supervision (when warranted) based on and that information is incorporated into online risk assessments as described above (see continuing communication answer to question 5(d)).

with the TSO throughout the duration of grid-risk-sensitive 21 of 32 MNGP Response to Requested Information GL 2006-02, July 21, 2006 Question 5 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 No alternative actions to be taken.

5(i) and 5(j), you 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.

Question 6

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 Yes. The TSOs "Transmission Work Request" (TWR) process and NMCs Fleet Tagging 22 of 32 MNGP Response to Requested Information GL 2006-02, July 21, 2006 Question 6 transmission system Switchyard Tagging Practices control work and maintenance activities within the substations maintenance activities that and are the processes used to communicate information regarding substation work activities in can have an impact on the the grid area between the plants and the grid operators. In addition, there are policies and NPP operation with the NPP procedures that address these interface issues between the nuclear plants and the system operator? operations department, which govern work activities in the nuclear plant substations. Plant level work instructions reference nuclear and generation policies and procedures, which provide the administrative and control requirements for all activities involving the nuclear generating plant substations. They apply to all Generation organizations performing work in or which could affect a nuclear generating plant substation. The type of work activities covered by these directives includes:

• Switching of breakers, switches, relays, or communication equipment in a plant substation;

• Routine relay, breaker, transformer, battery, meter and structural maintenance; and

• Testing.

TWRs associated with substation equipment under the jurisdiction of Delivery System Operations, is processed in accordance with the requirements of the Interface Agreement.

(b) Do you coordinate NPP Yes, refer to response to question 5(e).

maintenance activities that MNGP informs the NSP TSO of planned maintenance through NSP's TWR process. It should can have an impact on the be noted that this would apply to maintenance of substation transformers, breakers and other transmission system with the equipment in the substation that is owned and maintained by Xcel, the parent utility that also TSO? operates the transmission system.

(c) Do you consider and Yes. The current grid condition is posted in the MNGP Work Control Center (WCC) and Main implement, if warranted, the Control Room. In addition, contingency voltages are continuously monitored, and the plant rescheduling of grid-risk- shift supervision is notified if contingency voltages are predicted to be inadequate. This sensitive maintenance information is taken into account, as applicable, prior to performing maintenance or testing on 23 of 32 MNGP Response to Requested Information GL 2006-02, July 21, 2006 Question 6 activities (activities that could risk significant equipment. MNGP work instructions provide guidance on approval for work to (i) increase the likelihood of a commence. This written direction requires shift supervision to take into account the condition plant trip, (ii) increase LOOP of the electrical grid as appropriate for the activity under consideration. If warranted, grid-risk-probability, or (iii) reduce sensitivity activities are rescheduled.

LOOP or SBO coping capability) under existing, imminent, or worsening degraded grid reliability conditions?

(d) If there is an overriding Yes. All grid-risk-sensitive maintenance activities are subject to a rigorous review prior to work need to perform grid-risk- start as outlined in various MNGP and TSO procedures and guidance documents per the sensitive maintenance interface agreement.

activities under existing or Xcel grid (transmission/generation) system status color codes provide an indication of grid imminent conditions of status. This code is based on the combination of: 1) system generation availability versus degraded grid reliability, or demand; and 2) transmission system load versus operating limits. A color code of green continue grid-risk-sensitive indicates normal system status. Yellow is a warning status. Orange is a danger status. Red maintenance when grid is an emergency status.

conditions worsen, do you implement appropriate risk MNGPs PRA group has developed a computer model to determine the probability of a core management actions? If so, damaging event based on plant configuration. The small probability of the loss of the grid describe the actions that you system when the status changes from green to yellow has been determined to be negligible.

would take. (These actions However; the likelihood of a loss of offsite power is assessed to be significantly higher when could include alternate the grid system status is changed to orange or red.

equipment protection and If there is an overriding need to perform or continue in progress work during imminent or compensatory measures to degraded grid conditions, then, written guidance would direct the necessary actions to be limit or minimize risk.) taken for the given system condition code.

The system condition color code is displayed in the Work Control Center (WCC) and Main 24 of 32 MNGP Response to Requested Information GL 2006-02, July 21, 2006 Question 6 Control Room.

The Control Room Supervisor is responsible for ensuring the Main Control Room and WCC system condition color code indicators reflect any changes indicated by System Operations in a timely manner and also match each other.

(e) Describe the actions Actions to be taken are addressed within each of the responses to questions 6(a) through 6(c) associated with questions above. The procedures that govern these actions are also discussed in the same responses.

6(a) through 6(d) above that Strict procedure adherence is an expectation of both NMC and Xcel management.

would be taken, state For 6(d), the MNGP and NMC Fleet risk management procedures direct that additional risk whether each action is evaluations be performed taking into account elevated grid conditions (described as yellow, governed by documented orange or red) as provided by the TSO to assess the core damage frequency (CDF) procedures and identify the associated with the proposed maintenance activity. A similar maintenance risk color identifier procedures, and explain why is assigned (per the EOOS evaluation) to the unit for equipment out-of-service configuration these actions are effective based on the configurations of both plant and grid to establish a specific CDF. A maintenance and will be consistently risk color category of red indicates that the risk rate is too high, and must be reduced accomplished. immediately by placing equipment back in service or by implementing contingency or compensatory measures. The color category actions are assigned based on the length of the risk-informed allowable out-of-service time, as follows:

• Red - Do not voluntarily enter these configurations. Plant Operations Review Committee must authorize operation for any length of time in this condition.

Immediately restore equipment to service, or implement risk management actions to restore at least an ORANGE color category.

• Orange - Plant Manager approval required to commence planned activity.

• Yellow - Shift Manager approval required to commence planned activity.

• Green - Normal work control procedures apply.

Maintenance activities performed by Xcel on grid reliability sensitive equipment are also 25 of 32 MNGP Response to Requested Information GL 2006-02, July 21, 2006 Question 6 governed by similar restrictions based on the system condition color code and are coordinated with plant maintenance or curtailed appropriately, and specific elevated grid condition operating procedures are initiated depending on the severity of the system code.

By maintaining the lowest out-of-service times and the lowest CDF risk with appropriate risk informed decisions, reasonable assurance is provided that grid sensitive maintenance activities will be effectively managed.

(f) Describe how NPP Licensed Operators are trained on and process several TWRs which affect the MNGP operators and maintenance substation during the initial training.

personnel are trained and Classroom training is provided on MNGP Administrative Work Instructions that specify tested to assure they can compensatory measures to be applied under the conditions described in response to question accomplish the actions 6(e) above. On the Job Training / Task Performance Evaluation (OJT/TPE) is then performed described in your answers to on-shift.

question 6(e).

MNGP maintenance personnel do not perform maintenance on substation equipment.

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

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

26 of 32 MNGP Response to Requested Information GL 2006-02, July 21, 2006 Question 6 (h) If you do not consider and As discussed in response to questions 6(a) through 6(d), MNGP effectively implements effectively implement appropriate risk management actions.

appropriate risk 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 No alternative actions to be taken.

to questions 6(g) 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).

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.

27 of 32 MNGP Response to Requested Information GL 2006-02, July 21, 2006 Question 7

7. Procedures for identifying local power sources 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 (a) Briefly describe any MNGP is also owned by the parent owner of the grid TSO, therefore no formal agreements agreement made with the exist other than the agreements identified in response to question 1(a). The Xcel Corporate TSO to identify local power System Restoration Plan states in Section 7.2 that, The nuclear plants could receive auxiliary sources that could be made power as soon as the system and frequency stabilize. However, if either or both nuclear sites available to re-supply power were to request power because of failures or problems with their emergency station to your plant following a generators, power would be routed to their respective substations.

LOOP event. The plant would get top priority for restoration of offsite power if the emergency diesel generators were not operable. The priority would not be for re-starting the plant, but rather to restore power to the safe shutdown equipment. Procedures allow back feeding from the Elk River - Great River Energy 230 kV line through 7N2 to accomplish this. The nuclear plants would not necessarily be the first to have offsite power restored (providing the emergency diesel generators were functional), because it is much easier, faster, and safer, from a reactor safety perspective, to restart the fossil units first.

(b) Are your NPP operators The TSO is responsible for restoration of power to the Monticello Substation in the event of a trained and tested on 28 of 32 MNGP Response to Requested Information GL 2006-02, July 21, 2006 Question 7 identifying and using local LOOP.

power sources to resupply Operators are trained on the station blackout (SBO) AOP, which gives direction for your plant following a LOOP communication with the TSO on plant conditions and also directs actions for restoration per event? If so, describe how. MNGP procedures. This is comprised of classroom training on the abnormal procedures and training in the Simulator.

(c) If you have not MNGP is an asset owned by the same company that owns and operates the Transmission established an agreement System and has established agreements to maintain adequate voltage and current support as with your plants TSO to described in response to question 1(a).

identify local power sources The requirement for procedures to restore AC power to MNGP is met by providing instructions that could be made available to the system dispatcher to give the highest possible priority for restoring offsite power to to resupply power to your MNGP in the event of a grid collapse and a simultaneous loss of emergency diesel generators plant following a LOOP event, at the site. The TSO System restoration and blackout procedures also contain this guidance explain why you believe you and identify initial power sources for restoration.

comply with the provisions of 10 CFR 50.63, or describe The TSO is required by the North American Electric Reliability Council (NERC) standards to what actions you intend to maintain a system restoration plan. The plan provides for priority restoration of power to take to establish compliance. nuclear units in the event of a system blackout. MNGPs SBO and LONOP AOPs provide for communication between the system operator and MNGP Operations with regard to efficient restoration of AC power from the grid. Load restoration at the plant level is also addressed within the SBO and LONOP AOPs.

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 29 of 32 MNGP Response to Requested Information GL 2006-02, July 21, 2006 with 10 CFR 50.63.

Question 8

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

(a) Has your NPP No. The site has not experienced a LOOP event since the implementation of the Station experienced a total LOOP Blackout rule.

caused by grid failure since the plants coping duration was initially determined under 10 CFR 50.63?

(b) If so, have you Not applicable.

reevaluated the NPP using the 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 Not applicable.

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

30 of 32 MNGP Response to Requested Information GL 2006-02, July 21, 2006 Question 8 (d) If your NPP has Not applicable.

experienced a total LOOP caused by grid failure since the plants 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 Based on the responses provided above, NMC considers that operation and maintenance of any action is warranted to the MNGP is in compliance with the noted regulatory requirements to the extent described in bring your NPP into the plants licensing basis.

compliance with NRC regulatory requirements, including TSs, GDC 17, 10 31 of 32 MNGP Response to Requested Information GL 2006-02, July 21, 2006 CFR 50.65(a)(4),

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

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