BVY 06-032, 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.

ML061000310
Person / Time
Site:	Vermont Yankee
Issue date:	04/03/2006
From:	Thayer J Entergy Nuclear Northeast, Entergy Nuclear Operations
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
BVY 06-032, GL-06-002
Download: ML061000310 (34)

Text

Entergy Nuclear Northeast Entergy Nuclear Operations, Inc.

Vermont Yankee

- -P.O. Box 0500 E1 tergy 1185 Old Ferry Road Brattleboro, Vr 05302-0500 Tel 802 257 5271 April 3, 2006 BVY 06-032 Attrl: Document Control Desk U.S. Nuclear Regulatory Commission Washington, DC 20555

Reference:

1) NRC Generic Letter 2006-02, Grid Reliability and the Impact on Plant Risk and the Operability of Offsite Power, dated February 1, 2006.

Subject:

Vermont Yankee Nuclear Power Station License No. DPR-28 (Docket No. 50-271)

Response to Generic Letter 2006-02, Grid Reliability and the Impact on Plant Risk and the Operability of Offsite Power The NRC issued Generic Letter 2006-02 (Reference 1) to request information for determining compliance with regulatory requirements governing electric power sources.

Specifically, the NRC is requesting information regarding (1) use of protocols between the nuclear power plant (NPP) and the transmission system operator (TSO),

independent system operator (ISO), or reliability coordinator/authority (RC/RA) including transmission load flow analysis tools (analysis tools) by TSOs to assist NPPs in monitoring grid conditions to determine the operability of offsite power systems under plant Technical Specification (TS); (2) use of NPP/TSO protocols and analysis tools by TSCs to assist NPPs in monitoring grid conditions for consideration in maintenance risk assessments; (3) offsite power restoration procedures in accordance with Section 2 0o:

NRC( Regulatory Guide (RG) 1.155, "Station Blackout;" and, (4) losses of offsite power caused by grid failures at a frequency equal to or greater than once in 20 site-years in accordance with RG 1.155. The requested information is being provided pursuant to 10CFR50.54(f).

Attachment 1 to this letter provides the Vermont Yankee Nuclear Power Station (Vermont Yankee) response to Generic Letter 2006-02. Generic Letter 2006-0,2 discusses compliance with General Design Criterion (GDC) 17 in several locations. It should be noted that Vermont Yankee was designed and constructed based on the 1967 draft GDC.

Some of the questions in Generic Letter 2006-02 seek information, procedures and activities concerning grid reliability for which Vermont Yankee does not have first-hand knowledge. Vermont Yankee has not independently verified all information provided by:

Independent System Operator of New England

" Vermont Electric Power Company

.0)C3

BVY 06-032 / Page 2 Vermont Yankee's enclosed response is a partial response. Certain information regarding the site's interaction with the ISO, TSO and other outside entities is provided in Attachment 1. The plant-specific information will be provided by June 2, 2006.

Vermont Yankee plant resources, at the time Generic Letter 2006-02 was published, were dedicated to ensuring that the plant was ready to implement the Extended Power Uprate (EPU) License Amendment. Currently, the plant engineering and operations resources are focused on power ascension and testing. Vermont Yankee believes that the additional two months to fully respond to Generic Letter 2006-02 are warranted to effic:iently coordinate the appropriate plant personnel needed for each response subsequent to the completion of their EPU tasks. Therefore, Vermont Yankee requests an extension, to fully respond to Generic Letter 2006-02, until June 2, 2006.

Commitments made by Vermont Yankee in this letter are listed in Attachment 2.

If you should have any questions concerning this submittal, please contact Mr. James M.

DeVincentis at (802)258-4236.

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

Executed on April 3 , 2006.

Sincerely, Jay K. Thayer Site Vice President Vermont Yankee Nuclear Power Station cc: Next page Attachments: (2)

BV'Y 06-032 / Page 3 cc: Mr. Samuel J. Collins Regional Administrator, Region 1 U.S. Nuclear Regulatory Commission 475 Allendale Road King of Prussia, PA 19406-1415 Mr. James J. Shea, Project Manager Project Directorate I Division of Licensing Project Management Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Washington, D.C. 20555-0001 NRC Resident Inspector U.S. Nuclear Regulatory Commission Vermont Yankee Nuclear Power Station 320 Governor Hunt Road P.O. Box 157 Vernon, Vermont 05354 Mr. David O'Brien Commissioner Department of Public Service 112 State Street, Drawer 20 Montpelier, Vermont 05620-2601

BVY 06-032 Docket No. 50-271 ATTACHMENT 1 - --

Vermont Yankee Nuclear Power Station Partial Response to NRC Generic Letter 2006-02

Attachment 1 Docket No. 50-271 BVY 06-032 Page 1 of 29 IUse 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 TS.

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).

Vermont Yankee (VY) Offsite Power Sources

Description:

Three 345 KV transmission lines and one 115 kV transmission line connect to various transmission systems operated by Independent System Operator-New England (ISO-NE) and its Local Control Centers (LCCs). The TSO is ISO-NE, the regional transmission operator. ISO-NE and its LCC's employ contingency monitoring programs (Real-Time Contingency Analysis Programs) for these connecting transmission lines.

VY has two qualified offsite power sources, as described in VY's TS. VY's UFSAR describes to what extent the offsite power sources were reviewed to the draft GDCs. These power sources are described as follows:

Immediate Access Source: The 345 kV transmission source, via the autotransformer, 115 kV bus, and the startup transformers, that is capable of powering from the offsite transmission network to the onsite emergency safeguard buses (4 kV buses 3 and 4).

ISO-NE and the VY associated LCC employ real-time contingency analysis programs for the VY 115 kV bus, which powers, via the startup transformers, the onsite emergency safeguard buses.

Delayed Access Source: The 345 kV transmission source, via the main transformer and the auxiliary transformer, that is capable of powering from the offsite transmission network to the onsite emergency safeguard buses. Because this source is normally unconnected and manually aligned per operating procedures with the VY associated LCC's permission by isolating the generator and back-feeding the main transformer from the 345 kV system, the real-time contingency monitor programs are not applicable to determine inoperability for contingencies.

Attachment 1 Docket No. 50-271 BVY 06-032 Page 2 of 29

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 TS.

1(a). Do you have a formal Response:

agreement or protocol with your TSO? Yes. VY has formal agreements with the Transmission Owner (Interconnection Agreement) and the TSO (Market Participant Service Agreement). The Transmission Owner and TSO agreements require all parties to operate per ISO-NE procedures and documents, therefore the ISO-NE procedures and documents are considered part of the formal agreements.

For VY, the TSO and its LCCs provide for the monitoring of grid conditions to determine the operability of the immediate access source.

+

1(b). Describe any grid Response:

conditions that would trigger a notification from the TSO TSO makes notifications as soon as practical per good utility practice upon identification of any of to the NPP licensee and if the following:

there is a time period required for the notification 1) Overall system wide warning or alert conditions.

2) If the computerized contingency monitoring program (Real-Time Contingency Analysis) determines that the immediate access source could degrade below a value specified by VY.

3) In the event that LCC's and ISO-NE's control center's Real-time On-line AC Contingency Monitor Programs become unavailable.

4) A local system configuration, which would cause VY to become unstable in the event of a potential transmission system contingency.

5) Predetermined line outages, which require VY or the TSO to take action to ensure unit stability in the event of an N-2 system contingency (loss of another line plus a stuck breaker).

Attachment 1 Docket No. 50-271 BVY 06-032 Page 3 of 29 I-.-- WT UJTT

_Vj-M -V*'.UMMM 1(c). Describe any grid Response:

conditions that would cause the NPP licensee to contact LATER the TSO.

Describe the procedures associated with such a communication. If you do not have procedures, describe how you assess grid conditions that may cause the NPP licensee to contact the TSO.

1(d). Describe how NPP Response:

operators are trained and tested on the use of the LATER procedures or assessing grid conditions in question 1(c).

1(e). If you do not have a Response:

formal agreement or protocol with your TSO, describe why Not Applicable. As previously stated, W has a formal agreement with ISO-NE. VY's UFSAR you believe you continue to describes to what extent the offsite power sources were reviewed to the draft GDCs.

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

I _ _ _ _ _ _ l

Attachment 1 Docket No. 50-271 BVY 06-032 Page 4 of 29 I- _1 _-" W 1F-V'N _

1(f). If you have an existing Response:

formal interconnection agreement or protocol that As previously stated, VY has a formal agreement with ISO-NE. These agreements require the TSO ensures adequate to notify VY as soon as practicable per good utility practice, upon receipt of a potential 11 5kV post-communication and VY-trip degraded voltage alarm.

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).

1(g). Describe the low Response:

switchyard voltage conditions that would initiate LATER operation of plant degraded voltage protection.

Attachment 1 Docket No. 50-271 BVY 06-032 Page 5 of 29 NO S...to - i*~~-0 -aI

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.

2(a). Does your NPP's TSO Response:

use any analysis tools, an online analytical Yes. LCCs employ Real-Time Contingency Analysis Programs for the VY immediate access source.

transmission system studies The program and related actions are summarized as follows. The Program utilizes real-time program, or other equivalent transmission system information and VY unit specific shutdown loads and minimum voltage predictive methods to requirements. The program creates a real-time network model starting with bus/branch connectivity, determine the grid conditions branch impedances and ratings, and steady state generator models. The program then that would make the NPP superimposes real-time switch and breaker status to determine network topology. Real-time offsite power system generation and bus loads are also applied to this model. Statistical techniques are used to resolve inoperable during various tele-metering inconsistencies. The result forms the basis upon which contingent events contingencies? (contingencies) are tested. A pre-defined list of contingencies includes loss of each generator (including VY) and transmission events. Results of the VY contingency are automatically compared If available to you, please to VY 115 kV system post-trip voltage limit. If the VY trip contingency violates the VY's 115 kV post-provide a brief description of trip voltage limit, alarms are generated and VY would be notified. The ISO-NE Real-Time the analysis tool that is used Contingency Analysis Program would be used upon loss of the VY associated LCC capability. The by the TSO. ISO-NE program operates similar to the LCC except the VY contingency is the trip of the unit only.

2(b). Does your NPP's TSO Response:

use an analysis tool as the basis for notifying the NPP Yes. As discussed above, TSO uses a real-time analysis tool to notify VY of abnormal transmission licensee when such a system conditions that would impact the immediate access source.

condition is identified?

If not, how does the TSO determine if conditions on the grid warrant NPP licensee notification?

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II Attachment 1 Docket No. 50-271 BVY 06-032 Page 6 of 29

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2(c). If your TSO uses an Response:

analysis tool, would the analysis tool identify a Yes. The TSO real-time analysis tool, in conjunction with VY load flow studies, has the capability to condition in which a trip of determine if the trip of VY would result in a 115 kV system post-VY-trip offsite voltage, which would the NPP would result in actuate the VY degraded voltage protection logic and initiate separation from an offsite power source switchyard voltages upon a VY trip.

(immediate and/or long-term) 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 on the grid.

2(d). If your TSO uses an Response:

analysis tool, how frequently does the analysis tool The TSO real-time analysis tool calculations are performed for the connecting 345kV and 115 kV program update? transmission lines every 5 minutes at ISO-NE and the VY associated LCC. In addition, real-time system interface limit calculations for the connecting 345kV and 115 kV transmission lines are performed every 30 seconds by ISO-NE.

_ _ __ _ __ _ __ __ __ _ _ __ _ _ __ __ __ __ _ I

Attachment 1 Docket No. 50-271 BVY 06-032 Page 7 of 29

_ I 2(e). Provide details of Response:

analysis tool-identified contingency conditions that See response to item 2(a).

would trigger an NPP licensee notification from the TSO.

2(f). If an interface Response:

agreement exists between the TSO and the NPP LATER licensee, does it require that the NPP licensee be notified of periods when the TSO is unable to determine if offsite power 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?

2(g). After an unscheduled Response:

inadvertent trip of the NPP, are the resultant switchyard No. Neither VY nor the TSO validate the real-time analysis tool predicted post-VY-trip voltage value voltages verified by against the actual voltage.

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

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Attachment 1 Docket No. 50-271 BVY 06-032 Page 8 of 29 2(h). If an analysis tool is Response:

not available to the NPP licensee's TSO, do you Not applicable for the immediate access source. The TSO has real-time analysis tool presently in know if there are any plans use for the connecting 345 kV and 115 kV transmission lines as discussed above.

for the TSO to obtain one?

If so, when?

2.(i). If an analysis tool is Response:

not available, does your TSO perform periodic Not applicable for the immediate access source. TSO uses a real-time analysis tool as discussed studies to verify that above.

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?

2(i)(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?

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Attachment 1 Docket No. 50-271 BVY 06-032 Page 9 of 29 W04TMTAT-NWATAM - W.-MM".

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

4 20). If your TSO does not Response:

use, or you do not have access to the results of an Not applicable. The TSO has a real-time analysis tool for the connecting 345 kV and 115 kV analysis tool, or your TSO transmission lines and provides results that verify post-VY-trip operability of the immediate access does not perform and make source.

available to you periodic studies that determine the The 345 kV delayed back-feed source will be provided LATER.

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.

Attachment 1 Docket No. 50-271 BVY 06-032 Page 10 of 29 W

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3. Use of criteria and methodologies to assess whether the NPP's offsite power system and safety-related components will

remain operable when switchyard voltages are inadequate.-- -7 7.

3(a). If the TSO notifies the Response:

NPP operator that

• a trip of the NPP, or Yes. VY would declare the immediate access source "inoperable". The TSO has real-time monitor

• the loss of the most capability for the connecting 345 kV and 115 kV transmission lines and VY is notified by the TSO if critical transmission the loss of the unit would result in an unacceptable offsite post-VY-trip voltage.

line or

• the largest supply to There are a number of predetermined outage conditions for the connecting 345 kV and 115 kV transmission lines, which could result in the trip of VY for an N-2 system contingency. If one of these the grid line outages was scheduled or occurred, VY is notified by ISO-NE or the VY associated LCC and a would result in switchyard pre-determined corrective action would be implemented by VY and/or the TSO to resolve the voltages (immediate and/or stability issue per direction from the ISO-NE.

long-term) below TS nominal trip setpoint value requirements (including NPP licensees using allowable value in its TSs) and would actuate plant degraded voltage protection, is the NPP off site power system declared inoperable under the plant TSs? If not, why not?

3(b). If onsite safety-related Response:

equipment (e.g., emergency diesel generators or safety- LATER related motors) is lost when subjected to a double I

Attachment 1 Docket No. 50-271 BVY 06-032 Page 11 of 29 ffaa_ _ _ _ _ _ _ _ _ _ _ _ - -".

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?

3(c). Describe your Response:

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

3(d). If the NPP licensee is Response:

notified by the TSO of other grid conditions that may LATER impair the capability or availability of offsite power, are any plant TS action statements entered?

If so, please identify them.

l___________________________________________ l

Attachment 1 Docket No. 50-271 BVY 06-032 Page 12 of 29 WIW.WhWk*MUF I --.. -

3(e). If you believe your Response:

plant TSs do not require you to declare your offsite power LATER 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 inadequate.

3(f). Describe if and how Response:

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

Attachment 1 Docket No. 50-271 BVY 06-032 Page 13 of 29 gelOWM, y- - ff-S. -_

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

4(a). Do the NPP operators Response:

have any guidance or procedures in plant TS LATER bases sections, the final safety analysis report, or plant procedures regarding situations in which the condition of plant-controlled or -monitored equipment (e.g., 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.

Attachment 1 Docket No. 50-271 BVY 06-032 Page 14 of 29 WI~ Vv~-

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4(b). If your TS bases Response:

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

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Attachment 1 Docket No. 50-271 BVY 06-032 Page 15 of 29 gee, effly - S -- ST. in Use of NPP licensee/TSO protocols and analysis tool by TSOs to assist NPP licensees in monitoring grid conditions for I

consideration in maintenance risk assessments The Maintenance Rule (10 CFR 50.65(a)(4)) requires that licensees assess and manage the increase in risk that may result from proposed maintenance activities before performing them.

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

O. - -.... I _ = ~ = = = = II . _ I-. . -- _ . . I = ,= - , - .. .- . r 11 . - .. . . ,. . L . . . . . I 5(a). Is a quantitative or Response:

qualitative grid reliability evaluation performed at your LATER NPP as part of the maintenance risk assessment required by 10 CFR 50.65(a)(4) before performing grid-risk-sensitive maintenance activities? This includes surveillances, post-maintenance testing, and preventive and corrective 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?

Attachment 1 Docket No. 50-271 BVY 06-032 Page 16 of 29 AAV-l. I 4......... ~ sV 5(b). Is grid status Response:

monitored by some means for the duration of the grid- Yes. The connecting 345 kV and 115 kV transmission line status is continuously monitored by the risk-sensitive maintenance TSO and LCCs. If conditions occur that impact VY's operation or its immediate access source, such to confirm the continued as grid-risk-sensitive maintenance, the TSO or appropriate LCC would notify VY operations.

validity of the risk assessment and is risk reassessed when warranted?

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

5(c). Is there a significant Response:

variation in the stress on the grid in the vicinity of your Yes. For the 345 kV and 115 kV systems, based on a review of the number of times the TSO NPP site caused by entered specific off-normal system notifications over the past 19 years, it has been determined there seasonal loads or are seasonal and maintenance variations in grid stress maintenance activities associated with critical transmission elements?

Is there a seasonal variation No. Based on the limited number of LOOP occurrences in the ISO-NE region over the past 10 years (or the potential for a no seasonal variation can be established. During the last twenty years, VY has not experienced the seasonal variation) in the loss of both the immediate access and the delayed access sources.

LOOP frequency in the local transmission region?

Attachment 1 Docket No. 50-271 BVY 06-032 Page 17 of 29 I M-fl " . - m - __ _ _ _ _ _ _ _ _ _ _ _ _ _ __ _ _ _ _ _ _ _ _ _ _ _ _ _ __ _ _ _ _ _ _ _ _ _

If the answer to either Yes. Based on the number of times TSO had made off-normal system notifications over the past 19 question is yes, discuss the years, the summer months are the most stressed in New England. A practical means of determining time of year when the the magnitude of the variances cannot be provided.

variations occur and their magnitude.

5(d). Are known time- Response:

related variations in the probability of a LOOP at LATER your plant site considered in the grid-risk-sensitive maintenance evaluation?

If not, what is your basis for not considering them?

5(e). Do you have contacts Response:

with the TSO to determine current and anticipated grid LATER conditions as part of the grid reliability evaluation performed before conducting grid-risk-sensitive maintenance activities?

_____ l

Attachment 1 Docket No. 50-271 BVY 06-032 Page 18 of 29 5(f). Describe any formal Response:

agreement or protocol that you have with your TSO to The TSO has operating procedures which require TSO to notify VY if grid conditions degrade as assure that you are promptly described in response 1(b).

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

5(g). Do you contact your Response:

TSO periodically for the duration of the grid-risk- LATER sensitive maintenance activities?

5(h). If you have a formal Response:

agreement or protocol with your TSO, describe how LATER NPP operators and maintenance personnel are trained and tested on this formal agreement or protocol.

Attachment 1 Docket No. 50-271 BVY 06-032 Page 19 of 29 I1pI0 T~ .1 5(i). If your grid reliability Response:

evaluation, performed as part of the maintenance risk LATER 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).

5(). If risk is not assessed Response:

(when warranted) based on continuing communication LATER 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.

Attachment 1 Docket No. 50-271 BVY 06-032 Page 20 of 29 W04 TATMTNWATM V- 2 . . MT'.1 MLVL" Fr-'V-'U - - - -- I - -

5(k). With respect to Response:

questions 5(i) and 50), you may, as an alternative, LATER 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.

Attachment 1 Docket No. 50-271 BVY 06-032 Page 21 of 29 61.0 - 0 * ~ -

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).

6(a). Does the TSO Response:

coordinate transmission system maintenance Yes. The TSO coordinates the connecting 345 kV and 115 kV transmission system maintenance activities that can have an activities with VY in accordance with an ISO-NE procedure.

impact on the NPP operation with the NPP operator?

6(b). Do you coordinate Response:

NPP maintenance activities that can have an impact on LATER the transmission system with the TSO?

6(c). Do you consider and Response:

implement, if warranted, the rescheduling of grid-risk- LATER sensitive maintenance activities (activities that could (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?

Attachment 1 Docket No. 50-271 BVY 06-032 Page 22 of 29 6(d). If there is an overriding Response:

need to perform grid-risk-sensitive maintenance LATER activities under existing or imminent conditions of degraded grid reliability, or 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.)

i.

6(e). Describe the actions Response:

associated with questions 6(a) through 6(d) above that LATER would be taken, state whether each action is governed by documented procedures and identify the procedures, and explain why these actions are effective and will be consistently accomplished.

Attachment 1 Docket No. 50-271 BVY 06-032 Page 23 of 29 6(f). Describe how NPP Response:

operators and maintenance personnel are trained and LATER tested to assure they can accomplish the actions described in your answers to question 6(e).

6(g). If there is no effective Response:

coordination between the NPP operator and the TSO LATER 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).

6(h). If you do not consider Response:

and effectively implement appropriate risk LATER management actions during the conditions described above, explain why you believe you effectively addressed the relevant provisions of the associated NRC-endorsed industry guidance._ _ __

Attachment 1 Docket No. 50-271 BVY 06-032 Page 24 of 29 6(i). You may, as an Response:

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

____________________________________________________________________I

Attachment 1 Docket No. 50-271 BVY 06-032 Page 25 of 29 I Offsite power restoration procedures in accordance with 10 CFR 50.63 as developed in Section 2 of RG 1.155 Pursuant to 10 CFR 50.63, the NRC requires that each NPP licensed to operate be able to withstand an SBO for a specified duration and recover from the SBO. NRC RG 1.155 gives licensees guidance on developing their approaches for complying with 10 CFR 50.63.

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

Note:. -Section 2, uOffsite Power," of RG 17.155 (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 7(a). Briefly describe any Response:

agreement made with the TSO to identify local power LATER sources that could be made available to re-supply power to your plant following a LOOP event.

Attachment 1 Docket No. 50-271 BVY 06-032 Page 26 of 29 7(b). Are your NPP Response:

operators trained and tested on identifying and using local LATER power sources to resupply your plant following a LOOP event? If so, describe how.

7(c). If you have not Response:

established an agreement with your plant's TSO to LATER 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.

Attachment 1 I Docket No. 50-271 BVY 06-032 Page 27 of 29 1115M .. ,-fe 0 I --

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

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

8(a). Has your NPP Response:

experienced a total LOOP caused by grid failure since LATER the plant's coping duration was initially determined under 10 CFR 50.63?

8(b). If so, have you Response:

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

Attachment 1 Docket No. 50-271 BVY 06-032 Page 28 of 29 8(c). If so, what were the Response:

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

8(d). If your NPP has Response:

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

Attachment 1 Docket No. 50-271 BVY 06-032 Page 29 of 29 p

MCI .MeSMW Actions to ensure compliance.

-- *I

9. If youxdetermine that any action is warranted to bring your NPP into compliance with NRC regulatory requirements, including

.TSs, GDC 17,10 CFR 50.65(a)(4), 10 CFR 50.63, 10 CFR 55.59 or 10 CFR 50.120, describe the schedule for implementing it.

Response

LATER

BVY 06-032 Docket No. 50-271 ATTACHMENT 2 Regulatory Commitments Table This table identifies actions discussed in this letter for which Entergy commits to perform. Any other actions discussed in this submittal are described for the NRC's information and are not commitments.

Letter Number/Title: BVY 06-032/ Response to Generic Letter 2006-02, Grid Reliability and the Im~ract on Plant Risk and the Ooerabilitv of Offsite Power TYPE SCHE1)ULED (Check one) COMPLETION COMMITMENT ______ one DATE ONE-TIME CONTINUING (If Required)

ACTION COMPLIANCE Submit to the NRC, remaining GL 2006-02 X June 2, 2006 responses for Vermont Yankee