Text

License Amendment Request; Changes to 10CFR50.63 Licensing Basis
	ML12362A041
Person / Time
Site:	Vermont Yankee
Issue date:	12/21/2012
From:	Wamser C; Entergy Nuclear Operations
To:	; Document Control Desk, Office of Nuclear Reactor Regulation
References
	BVY 12-084
	Download: ML12362A041 (38)
	v • d • e

.5k Entergy Nuclear Operations, Inc.

Vermont Yankee Vernon, VT 05354

%-w~ff~n ffgyTel 802 257 7711 Christopher J. Wamser Site Vice President BVY 12-084 December 21, 2012 ATTN: Document Control Desk U.S. Nuclear Regulatory Commission Washington, DC 20555

SUBJECT:

License Amendment Request; Changes to 10CFR50.63 Licensing Basis Vermont Yankee Nuclear Power Station Docket No. 50-271 License No. DPR-28

Dear Sir or Madam:

In accordance with 10CFR50.90, Vermont Yankee (VY) is proposing to revise the licensing basis relative to how the station satisfies the requirements of 10 CFR 50.63, "Loss of all alternating current power." VY currently relies on the Vernon Hydroelectric Station (VHS) as the alternate ac (AAC) power source providing acceptable capability to withstand station blackout under 10 CFR 50.63(c)(2). VY proposes to replace the VHS with an onsite diesel generator as the AAC power source providing this capability. Replacing the AAC power source involves changes to the facility and procedures described in the Updated Final Safety Analysis Report (UFSAR), requiring approval by license amendment.

VY has reviewed the proposed amendment in accordance with 10 CFR 50.92 and concludes it does not involve a significant hazards consideration. In accordance with 10 CFR 50.91, a copy of this application, with attachments, is being provided to the State of Vermont, Department of Public Service.

Attachment 1 to this letter provides a detailed description and evaluation of the proposed change.

Attachment 2 contains a markup of the applicable current UFSAR pages. Attachment 3 contains a markup of the applicable current VY Technical Specifications Bases page. The UFSAR and Bases pages are provided for information only.

As a result of a forthcoming change to the Independent System Operator - New England (ISO-NE) system restoration strategy, the contract between ISO-NE and the owner-operator of the VHS for black-start of the VHS will expire on September 1, 2013 and will not be renewed. Additionally, the owner-operator of the VHS has declined to enter into a contractual agreement with Entergy to supply black-start power to allow VY to meet the requirements of 10 CFR 50.63. Therefore, the VHS will not be able to be credited by VY for compliance with 10 CFR 50.63 as of September 1, 2013. Accordingly, VY requests review and approval of the proposed license amendment by August 1, 2013 and a 30 day implementation period from the date of the amendment approval.

Attachment 4 contains new regulatory commitments.

BVY 12-084 / Page 2 of 2 If you have any questions on this transmittal, please contact Mr. Robert Wanczyk at 802-451-31"66.

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

Executed on December 21, 2012.

Sincerely, CJW/plc Attachments: 1. Description and Evaluation-of the Proposed Change

2. Markup of Current UFSAR Pages

3. Markup of Current TS Bases Page

4. List of Regulatory Commitments cc: Mr. William M. Dean Regional Administrator, Region 1 U.S. Nuclear Regulatory Commission 2100 Renaissance Blvd, Suite 100 King of Prussia, PA 19406-2713 Mr. Richard V. Guzman, Project Manager Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Mail Stop 08C2A Washington, DC 20555 USNRC Resident Inspector Entergy Nuclear Vermont Yankee, LLC 320 Governor Hunt Rd Vernon, Vermont 05354 Ms. Elizabeth Miller, Commissioner VT Department of Public Service 112 State Street - Drawer 20 Montpelier, Vermont 05620-2601

BVY 12-084 Docket No. 50-271 Attachment 1 Vermont Yankee Nuclear Power Station Description, and Evaluation of Proposed Change

BVY 12-084 / Attachment 1 / Page 1 of 22

1.

SUMMARY

DESCRIPTION In accordance with 10 CFR 50.90, Vermont Yankee (VY) is proposing to revise the licensing basis for satisfying the requirements of 10 CFR 50.63 "Loss of all alternating current power." VY currently relies on the Vernon Hydroelectric Station (VHS) asthe alternate ac (AAC) power source providing acceptable capability to withstand station blackout under 10 CFR 50.63(c)(2). VY proposes to replace the VHS with an onsite diesel generator as the AAC power source providing this capability. Replacing the AAC power source involves changes to the facility and procedures described in the Updated Final Safety Analysis Report (UFSAR), requiring approval by license amendment.

2. DETAILED DESCRIPTION Station blackout (SBO) refers to a complete loss of AC electric power to the essential and nonessential switchgear buses in a nuclear power plant. SBO involves a loss of offsite power concurrent with a turbine trip and unavailability of the onsite emergency AC power sources.

The Station Blackout Rule (10 CFR 50.63) required all nuclear plants to ensure that their plants could withstand and recover from a loss of all off-site power in conjunction with a turbine trip and the unavailability of the emergency diesel generators (EDG).

The VHS is the AAC power source that is credited for compliance with 10 CFR 50.63 following the loss of all AC power to VY. The VHS is designated as a black-start facility under arrangements with Independent System Operator-New England (ISO-NE), the regional grid operator, which requires that the facility be capable of being black-started within 90 minutes after the operator of the facility is notified.

VY is categorized as an 8 hour9.259259e-5 days 0.00222 hours 1.322751e-5 weeks 3.044e-6 months SBO coping duration plant. The VHS is currently credited as an AAC power source available at the station safety buses within 2 hours2.314815e-5 days 5.555556e-4 hours 3.306878e-6 weeks 7.61e-7 months of losing all offsite, and onsite emergency ac power, and coping analysis demonstrates that VY can cope with the station blackout during the initial 2 hour2.314815e-5 days 5.555556e-4 hours 3.306878e-6 weeks 7.61e-7 months interval.

As a result of a forthcoming change to the ISO-NE system restoration strategy, the contract between ISO-NE and the owner-operator of the VHS for black-start of the VHS will expire on September 1, 2013 and will not be renewed. Additionally, the owner-operator of the VHS has declined to enter into a contractual agreement with Entergy to supply black-start power to allow VY to meet the requirements of 10 CFR 50.63. Therefore, the VHS will not be able to be credited as an AAC power source as of September 1, 2013.

VY is planning to install a new onsite Station Blackout Diesel Generator (SBO DG) unit and associated equipment. This proposed amendment would approve replacing the VHS with the SBO DG as the AAC power source providing the capability to withstand a station blackout as provided in10 CFR 50.63(c)(2).

3. TECHNICAL EVALUATION Current and Proposed AAC Power Source Configuration As described in UFSAR Section 8.5.5.1, VY uses an AAC power source approach to provide the capability to withstand an SBO using the methodology of Regulatory Guide 1.155, "Station Blackout," dated August 1988. VY relies on the VHS to provide power to a safety bus until offsite or onsite AC power is available. The VY licensing basis with respect to coping duration is 8 hours9.259259e-5 days 0.00222 hours 1.322751e-5 weeks 3.044e-6 months .

BVY 12-084 / Attachment 1 / Page 2 of 22 Power from the VHS is provided via a 13.2kV underground feeder cable (VHS tie line) from the VHS switchyard that is connected to a 13.2kV / 4.16kV transformer located near the VY cooling towers. The transformer secondary is connected by underground cable to breaker 3V4 located in safety bus 3. Breaker 3V4, in turn, is connected to breaker 3V, located in safety bus 3, and breaker 4V, located in safety bus 4. This allows the VHS feed to be connected to either safety bus.

Although the VHS will no longer be credited as the VY AAC power source, the VHS tie line will remain normally energized from the Vernon 69kV and 13.2 kV switchyards and will be available to provide power to VY whenever it is energized. The VHS tie line will normally be aligned to provide power to a new 4,160VAC bus being installed along with the~new SBO DG unit. The new 4,160VAC bus will normally provide power to the SBO DG system auxiliaries (such as battery chargers and heaters) that maintain the readiness of SBO DG, but this AC power is not required to start or operate the SBO DG in the event of an SBO. The proposed configuration of the new SBO DG system is shown in Figure 1. Additional technical details of the new SBO DG are provided in the regulatory evaluation section of this attachment.

Current Licensinq Basis and Proposed Changes to the Licensing Basis In Reference 7.a, the NRC accepted the determination that VY is categorized as an 8 hour9.259259e-5 days 0.00222 hours 1.322751e-5 weeks 3.044e-6 months coping plant with a target EDG reliability of 0.95. No changes to the station coping duration or credited EDG reliability are proposed in the amendment.

VY performed an SBO coping analysis assuming Extended Power Uprate (EPU) conditions that demonstrates that the station can cope for two hours to allow for placing the AAC power source into service and energizing one of the safety related 4kV buses following a SBO. The VHS is capable of being black-started in the event of a grid-wide blackout and agreements are currently in place to ensure that the VHS power is available to VY when needed. The NRC reviewed the current SBO licensing basis and coping analysis during the EPU application review as documented in Reference 7.b. The proposed amendment does not require any changes to the existing coping analysis because the new AAC power source (SBO DG) will be available within 1 hour1.157407e-5 days 2.777778e-4 hours 1.653439e-6 weeks 3.805e-7 months following a SBO, and the existing coping analysis thus bounds the interval from onset of an SBO until the AAC power source is started and aligned. No changes to the method of operation of systems or operating parameters used in the coping analysis are being made with this proposed change.

Upon approval of this proposed amendment, VY will revise UFSAR Sections 8.1.1, 8.3.3, 8.3.4, 8.4.5.1, 8.5.5 and 8.5.5.1 to replace the VHS with an onsite SBO DG as the source of AAC power credited for compliance with 10 CFR 50.63. Markups of the affected UFSAR sections are provided in Attachment 2 for information only.

TS Bases 3.1 0.A will also need to be revised upon approval of the amendment to reflect that the SBO DG is credited for compliance with 10 CFR 50.63. Markup of TS Bases 3.10.A is provided in for information only.

The renewed facility operating license is not affected by this proposed change. There are no TS affected, by this proposed change.

The VHS tie line is also credited for compliance with 10 CFR 50 Appendix R and for allowable Technical Specification (TS) configurations in TS 3.7.B.1 .b. These functions are not affected by this proposed change.

As described in UFSAR Section 8.3.3, VY has a commitment to perform a timed startup, alignment and load capacity test of the AAC power source once every third refueling outage.

BVY 12-084 / Attachment 1 / Page 3 of 22 4160V Bus 3 STA. SERVICE TRANSF T-8-1A DIESEL DRIVEN GEN DOG- 1-11 3000KW. 3750KVA. 0.8 PF 4160V, 3 0, 60 Hz, 900 RPh Xd-1.41. Xq-0.83, Xd-030, X"d0.18.X2 =0.18. Xo=.034 FAIRBANKS MORSE FOR RELAYING &

INSTRUMENTATION SEE MAIN ONELINE DIAGRAM DWO 0-191298 SH.5 SBO 4160V Bus 13

-L.

Figure 1 - Proposed AAC Power Source Configuration .

BVY 12-084 / Attachment 1 / Page 4 of 22

4. REGULATORY EVALUATION The SBO DG will satisfy the criteria contained in Appendix B of Nuclear Management and Resources Council (NUMARC) 87-00, Revision 1 (Reference 7.c), Section 3.3.5 and Appendices A and B of Regulatory Guide 1.155 (Reference 7.d), portions of Standard Review Plan (SRP) Section 8.4 (Reference 7.e) related to operator interface, operating procedures and training and 10 CFR 50.2 as discussed in the regulatory evaluation below.

NUMARC 87-00, Revision 1 provides generic guidance developed for meeting the requirements of the Station Blackout Rule. Appendix B of NUMARC 87-00 describes the criteria that must be met by a power supply in order to be classified as an AAC power source.

Regulatory Guide 1.155 provides methods acceptable to the NRC for complying with the regulatory requirements for nuclear plants to withstand and recover from a station blackout. This includes assuring that the systems have the availability, adequacy and capability to achieve and maintain a safe shutdown and recovery from an SBO.

SRP Section 8.4 provides criteria for NRC review of applications related to establishing or maintaining compliance with the Station Blackout Rule to use in evaluating whether an applicant/licensee meets the NRC regulation (10 CFR 50.63). Section 111.3.C contains review criteria for control room monitoring of the AAC power source and Section 111.4 contains review criteria for establishing procedures and training.

10 CFR 50.2 contains a definition of an AAC source.

Comparison of Proposed Design to Applicable AAC Power Source Design Criteria (Appendix B of NUMARC 87-00, Rev. 1)

B.3 Components and subsystems shall be protected against the effects of likely weather-related events that may initiate the loss of off-site power event. Protection may be provided by enclosing AAC components within structures that conform with the Uniform Building Code, and burying exposed electrical cable run between buildings (i.e., connections between the AAC power source and the shutdown buses).

The SBO DG and its auxiliary equipment will be located within enclosures that conform to the International Building Code, which superseded the Uniform Building Code. The electrical cables that connect the SBO DG to the shutdown buses will be located within buried conduit or duct banks to provide protection against events that may initiate the loss of off-site power event. These cables will be included in the License Renewal Non-EQ Inaccessible Medium Voltage Cable Program and subject to periodic inspection and testing in accordance with that program. Additionally, the manholes through which these cables are routed are subject to periodic inspection in accordance with the Non-EQ Inaccessible Medium Voltage Cable Program.

The enclosures will. be physically located a considerable distance (at least 800 feet) from the high-voltage switchyard, which, in conjunction with the features described above, provides reasonable protection against the effects of likely weather-related events that may initiate the loss of off-site power event to VY.

BVY 12-084 / Attachment 1 / Page 5 of 22.

B.4 Physical separation of AAC components from safety related components or equipment shall conform with the separation criteria applicable for the unit's licensing basis.

The SBO DG and its auxiliary equipment will be physically separated from safety-related components. The equipment will be installed within dedicated enclosures located away from plant structures containing safety-related equipment. Additionally, the power and control cables for the SBO DG and its auxiliary equipment will be installed to meet VY's electrical separation requirements.

B.5 Failure of AAC components shall not adversely affect Class 1E AC power systems.

A failure of the SBO DG or its auxiliary equipment will not adversely affect Class 1 E AC power systems. The SBO DG system will be physically separated from Class 1 E AC power systems by a considerable distance, so mechanical failure of the SBO DG system will not impact the Class 1 E AC power systems. The SBO DG is not connected to the Class 1 EAC power system except during an actual SBO or for periodic testing to demonstrate the ability to supply power to a single emergency bus (once per cycle). Additionally, protective relaying will be provided to automatically isolate the SBO DG electrical system upon failure of the SBO DG such that an electrical fault will not, propagate to the Class 1 E AC power systems. The same interlocks that exist for the connection of the VHS tie line to the Class 1E power system will be used to control the connection of the SBO DG to the Class 1 E power system. These interlocks permit connection of the VHS tie line to only one Class 1 E bus at a time and the interlocks prevent connection of the tie to the bus unless all sources of power (normal bus feed and emergency diesel generator) are disconnected. These interlocks assure failure of AAC components do not adversely affect the Class 1 E AC

.power systems.

An operator interface panel (0IP) will be installed in the VY Control Room to provide monitoring and control capability for the AAC power system when it is in service. The OIP is non-safety related and will be located in Control Room Panel 9-8. It will be supplied by a power supply located within the panel which will be protected by a5 ampere Class 1E fuse located within panel 9-8. The power supply is, in turn, supplied by a 15 ampere Class 1 E circuit breaker located in 120 VAC Vital Distribution Panel VAC-A. The design of Vermont Yankee permits a single Class 1 E fuse or circuit breaker to protect Class 1E circuits or equipment from failure of non.safety related loads. The single Class 1 E 5 ampere fuse will provide this required protection and isolation.

B.6 Electrical isolation of AAC power shall be provided through an appropriate isolation device. If the AAC source is connected to Class 1 E buses, isolation shall be provided by two circuit breakers in series (one Class 1 E breaker at the Class 1 E bus and one non-Class 1 E breaker to protect the source).

The SBO DG will be electrically connected to a new non-Class 1 E 4,160VAC bus located in an enclosure installed adjacent to the SBO DG enclosure and will not be directly connected to a Class 1 E bus. A circuit breaker isolation device located within the new bus will provide protection for the SBO DG and the bus. The new bus, in turn, will be connected to an existing non-Class 1 E circuit breaker (breaker 3V4) installed in safety-related 4,160VAC Bus 3. Additional Class-1 E breakers' (3V and 4V) allow the SBO DG to be aligned to either Bus 3 or Bus 4. This configuration provides the electrical isolation required by section B.6.

B.7 The AAC power source shall not normally be directly connected to the preferred or onsite emergency AC power system for the unit affected by the blackout. In addition,

BVY 12-084 / Attachment 1 / Page 6 of 22 the AAC system shall not be capable of automatic loading of shutdown equipment from the blacked-out unit unless licensed with such capability.

The SBO DG will normally be isolated from the 4,160VAC preferred and onsite emergency AC power systems by at least two circuit breakers installed in series, including non-Class 1 E breaker 3V4 installed in safety-related 4,160VAC Bus 3, a new non-Class 1 E breaker installed in the new SBO DG bus, and Class-1 E breakers 3V and 4V. The 3V and 4V breakers are each electrically interlocked to prevent closure when the corresponding normal bus feeder breaker or EDG output breaker is closed. This prevents direct connection of the AAC power source to the preferred or onsite emergency AC power systems.

The auxiliary equipment needed to start and operate the SBO DG (e.g. battery chargers, DG heaters, etc.) will normally be powered from the 4,160VAC SBO DG bus, which will normally be energized via the VHS tie line connection from the Vernon Hydro Station switchyard. The VHS tie line is not classified as a preferred, Class 1 E, or onsite emergency AC power system. A manually-operated transfer switch will be installed to allow the auxiliary equipment to be energized from the non-safety-related portion of the VY station auxiliary AC power system during those times that the normal AC power source (VHS tie line) is unavailable due to a planned or unplanned outage. The intent of this secondary feed is to maximize the availability of the AAC power source when the VHS tie line is unavailable by maintaining the SBO DG in a standby state. The use of the transfer switch will be procedurally controlled, and requires manual operator actions to initiate the transfer.

The SBO DG will not be capable of automatic loading of shutdown equipment. Manual operator actions will be required to align the SBO DG to Class 1 E Bus 3 or Bus 4.

B.8 There shall be minimal potential for common cause failure of the AAC power source(s).

The following system features provide assurance that the minimal potential for common cause failure has been adequately addressed.

(a) The AAC power system shall be equipped with a DC power source that is electrically independent from the blacked-out unit's preferred and Class 1 E power system.

The SBO DG system will be equipped with independent DC battery systems for operation of the DG and associated 4,160VAC circuit breakers in the SBO DG bus.

AC power to the DC system battery chargers will normally be provided from the 4,160VAC SBO DG bus, which will normally be energized via the VHS tie line connection from the Vernon Hydro Station switchyard. The VHS tie line is not classified as a preferred, Class 1 E, or onsite emergency AC power system.

As discussed in section B.7, a manually-operated transfer switch will be installed to allow the DC system battery chargers to be energized from the non-safety-related portion of the VY station auxiliary AC power system during those times that the normal AC power source (VHS tie line) is unavailable. The useof the transfer switch will be procedurally controlled.

BVY 12-084 / Attachment 1 / Page 7 of 22 (b) The AAC power system shall be equipped with an air start system, as applicable, that is independent of the preferred and the blacked-out unit's preferred and Class 1 E power supply. (NOTE: SRP Section 8.4 contains the following wording: The AAC power system is equipped with a starting,system (andmotive energy source for starting)that is independent from the blacked-out unit's preferredand Class 1E ac power systems.")

The SBO DG will not include an air start system, but does include redundant electric starting motors (DC). As discussed above, the SBO DG system will be equipped with independent DC battery systems for operation, of the. DG and the 4,160VAC circuit breakers in the SBO DG bus. AC power to the DC system battery chargers will normally be provided from a source that is independent of the preferred and Class 1 E power system. AC power is not required to be available to start the SBO DG or operate the SBO DG bus breakers necessary to align the AAC power source to the plant shutdown buses; the DC battery systems provide power to start and operate the SBO DG and to operate the SBO DG bus breakers.

(c) The AAC power system shall be provided with a fuel oil supply, as applicable, that is separate from the fuel oil supply for the onsite emergency AC power system. A separate day tank supplied from a common storage tank is acceptable provided the fuel oil is sampled and analyzed consistent with applicable standards prior to transfer to the day tank.

The SBO DG will include a dedicated fuel oil storage tank with a capacity sufficient for operation of the DG at 100% rated load for at least 36 hours4.166667e-4 days 0.01 hours 5.952381e-5 weeks 1.3698e-5 months , which provides significant margin over the existing design basis eight hours coping time. This dedicated fuel oil storage tank will be separate from the fuel oil supply for the onsite emergency AC power system. Capability to refill the SBO DG fuel oil storage tank from the onsite EDG fuel oil storage tank will be available using a portable tank or a temporary connection between the tanks, but there will be no permanent connections between the two storage tanks.

The fuel oil for the SBO DG will be procured to the same procedurally-controlled quality requirements as the fuel oil for the onsite emergency diesel generators.

These fuel quality requirements were reviewed against the vendor's fuel quality requirements and the fuel oil was confirmed to be acceptable for use with the SBO DG. The SBO DG fuel oil storage tank will be subject to sampling at a frequency similar to that performed for the EDG fuel oil storage tank.

(d) If the AAC power source is an identical machine to the emergency onsite AC power source, active failures of the emergency AC power source shall be evaluated for applicability and corrective action taken to reduce subsequent failures.

The SBO DG will not be an identical machine to the emergency onsite AC power-source. The SBO DG will be a different manufacturer (Caterpillar) than the onsite EDG manufacturer (Fairbanks-Morse).

BVY 12-084 / Attachment 1 / Page 8 of 22 (e) No single point vulnerability shall exist whereby a likely weather-related event or single active failure could disable any portion of the onsite emergency AC power sources or the preferred power sources, and simultaneously fail the AAC power source(s).

The SBO DG and its auxiliary equipment will be located within enclosures that conform to the International Building Code, which superseded the Uniform Building Code. The electrical cables that connect the SBO DG to the shutdown buses are located within buried conduit or duct banks to provide protection against events that may initiate the loss of off-site power event. These cables will be included in the License Renewal Non-EQ Inaccessible Medium Voltage Cable Program and subject to periodic inspection and testing in accordance with that program.' Additionally, the manholes through which these cables are routed are subject to periodic inspection in accordance with the Non-EQ Inaccessible Medium Voltage Cable Program.

As discussed previously, the enclosures will be physically located a considerable distance (at least 800 feet) from the high-voltage switchyard, which, in conjunction with the features described above, provides reasonable protection against the effects of likely weather-related events that may initiate the loss of off-site power event to VY. The SBO DG will also be installed separate from the onsite emergency AC power sources (EDG units), so there is no postulated weather-related event that could disable the onsite EDG units concurrently with the SBO DG.

The SBO DG will be physically isolated from the onsite emergency AC and preferred power sources, so a single active failure will not disable the AAC power source concurrently with the onsite emergency AC or preferred power sources.

The SBO DG will normally be electrically isolated from the onsite emergency AC and preferred offsite power sources, so no single electrical failure will disable the SBO DG concurrently with the onsite emergency or the preferred power sources.

As discussed in'Section B.7, a manually-operated transfer switch will be installed to allow the auxiliary equipment to be energized from the non-safety-related portion of the VY station auxiliary AC power system during those times that the normal AC power source (VHS tie line) is unavailable due to a planned or unplanned outage. In this configuration, a single active failure will not disable the AAC power source concurrently with 'the onsite emergency AC or preferred power sources. An electrical failure initiated at the AAC power source, emergency AC power source, or preferred power sources will be isolated by tripping of circuit breakers prior to propagating to the other AC sources.

(f) The AAC power system shall be capable of operating during and after a station blackout without any support systems powered from the preferred power supply, or the blacked-out unit's Class 1 E power sources affected by the event.

The SBO DG will be designed to operate during and after a station blackout without any support systems powered from the preferred, Class 1 E, or emergency AC power sources.

The SBO DG system will be equipped with independent DC, battery systems for operation and control of the DG and bus equipment. AC power is not required to be available to start the SBO DG or operate the SBO DG bus breakers necessary to' align the AAC power source to the plant shutdown buses; the DC battery. systems

BVY 12-084 / Attachment 1 / Page 9 of 22 provide power to start and operate the SBO DG and to operate the SBO DG bus breakers.

The DC battery systems will normally be powered from the 4,160VAC SBO DG bus, which will normally be energized via the VHS tie line connection from the Vernon Hydro Station switchyard. The VHS tie line is not classified as a preferred, Class 1E, or onsite emergency AC power system. Once the SBO DG is started, AC power to the DC system battery chargers will be provided from the SBO DG, ensuring that the equipment can continue to operate during and after a station blackout.

(g) The portions of the AAC power system subjected to maintenance activities shall be tested prior to returning the AAC power system to service.

Post-maintenance testing of the AAC power system will be performed and controlled in accordance with Entergy procedures which ensure that portions of the AAC power system subject to maintenance activities are appropriately tested prior to returning the AAC power system to service.

B.9 The AAC power system shall be sized to carry the required shutdown loads for the required coping duration determined in Section 3.2.5, and be capable of maintaining voltage and frequency within limits consistent with established industry standards that will not degrade the performance of any shutdown system or component. At a multi-unit site, except for 1/2 shared or 2/3 emergency AC power configurations, an adjacent unit's Class 1 E power source may be used as an AAC power source for the blacked-out unit if it is capable of powering the required loads at both units.

The SBO DG will be rated for continuous operation at 3,000kW, which is greater than the continuous rating of the onsite emergency AC power sources (EDG unit), which is 2,750kW as specified in UFSAR Section 8.5. As discussed in section B.8(c), the SBO DG will include a dedicated fuel oil storage tank with a capacity sufficient for operation of the DG at 100%

rated load for at least 36 hours4.166667e-4 days 0.01 hours 5.952381e-5 weeks 1.3698e-5 months , which provides significant margin over the existing design basis eight hours coping time. The SBO DG will be capable of maintaining operating voltage and frequency within the limits established for shutdown system components, as demonstrated by analysis and testing.

Acceptance testing of the SBO DG unit will include starting of an unloaded 4kV induction motor that provides a starting current equal to or higher than the largest motor on safety Bus 3 or safety Bus 4, which is the 1000HP Residual Heat Removal (RHR) pump motor. The generator output voltage and frequency will be monitored during the motor start to ensure that allowable limits are not exceeded. This one-time testing will demonstrate the ability of the new generator to start the RHR pump while maintaining operating voltage and frequency within the limits established for safe shutdown components.

BVY 12-084 / Attachment 1 / Page 10 of 22 B.10 Unless otherwise governed by technical specifications, the AAC power source shall be started and brought to operating conditions that are consistent with its function as an AAC source at intervals not longer than three months, following manufacturer's recommendations or in accordance with plant-developed procedures. Once every refueling outage, a timed start (within the time period specified under blackout conditions) and rated load capacity test shall be performed, The SBO DG equipment will be started and brought to approximately rated load capacity (3,000kW) at quarterly intervals in accordance with plant-developed procedures and preventive maintenance work order tasks established in accordance with manufacturer recommendations and industry guidance. The electrical load for the SBO DG for this test will be provided by a permanently installed 3,000kW resistive load bank located adjacent to the SBO DG enclosure.

Once every refueling outage, a timed start will be performed to demonstrate that the AAC power source can be started and aligned to either safety Bus 3 or safety Bus 4 within one (1) hour.

Once every third refueling outage, the SBO DG will be demonstrated by test to be capable of starting the largest available motor on safety Bus 3 or safety Bus 4.

B.11 Unless otherwise governed by technical specifications, surveillance and maintenance procedures for the AAC system shall be implemented considering manufacturer's recommendations or in accordance with plant-developed procedures.

Surveillance and maintenance for the new SBO DG will be implemented considering manufacturer's recommendations in accordance with plant-developed procedures and preventive maintenance work order tasks.

B.12 Unless otherwise governed by technical specifications, the AAC system shall be demonstrated by initial test to be capable of powering required shutdown equipment within one hour of a station blackout event.

VY performed a coping analysis assuming EPU conditions and submitted it to the NRC by letter dated March 24, 2005 (Reference 7.f). Based on the results of the analysis, VY concluded that the plant isable to safely cope with a total loss of AC power for a minimum of 2 hours2.314815e-5 days 5.555556e-4 hours 3.306878e-6 weeks 7.61e-7 months from the onset of the SBO to the restoration of offsite AC power to a 4160-volt emergency bus. The NRC documented a review of the analysis in the EPU safety evaluation, dated March 2, 2006 (Reference 7.b).

The SBO DG will be maintained in a "ready to operate" condition such that it can be started and connected to one of the safety buses (Bus 3 or Bus 4) in a timely manner. Following installation of the new AAC power source, initial testing will be performed to demonstrate that power can be made available up to existing circuit breaker 3V4 within one hour of the onset of station blackout. Energizing Bus 3 or Bus 4 from the AAC power source is not practical due to interlocks associated with circuit breakers 3V and 4V preventing closure of the breakers while the buses are energized from their normal sources (preferred power source). The actions required to complete alignment of the AAC power source to Bus 3 or Bus 4 include closure of two circuit breakers from the VY control room (3V4 and either 3V or 4V, depending on which bus is being energized). Once the AAC power source is energized up to 3V4, it takes very little time to align loads from the control room (less than 10 minutes). Therefore, energizing the AAC power source up to circuit breaker 3V4 within

BVY 12-084 / Attachment 1 / Page 11 of 22 one hour satisfactorily demonstrates that the AAC power source can be made available to power Bus 3 or Bus 4 within the existing coping analysis.

Initial testing will also be performed to load the SBO DG to its rated output (3,000kW) using the permanently installed resistive load bank. This demonstrates that the AAC power source can provide the power required to operate the required shutdown equipment.

B.13 The Non-Class 1E AAC system should attempt to meet the target reliability and availability goals specified below, depending on normal system state. In this context, reliability and availability goals apply to the overall AAC system rather than individual machines, where a system may comprise more than one AAC power source.

VY has established a reliability target of 0.95 for the SBO DG AAC power system in accordance with the Entergy Emergency Diesel Generator Program (EN-DC-1 98), which includes the guidance in NUMARC 87-00, Appendix D. The SBO DG AAC power system will also be included in the scope of the VY Maintenance Rule Program (EN-DC-203),

which will ensure that the AAC power system maintains the reliability target.

Comparison of Proposed Design to Regulatory Guide 1.155 Section 3.3.5

1. The AAC power source should not normally be directly connected to the preferred or the blacked-out unit's onsite emergency ac power system.

The SBO DG will normally be isolated from the 4,160VAC preferred and onsite emergency AC power systems by at least two circuit breakers installed in series, including non-Class 1 E breaker 3V4 installed in safety-related 4,160VAC Bus 3, a new non-Class 1 E breaker installed in the new SBO DG bus, and Class-1 E breakers 3V and 4V. The 3V and 4V breakers are each electrically interlocked to prevent closure when the corresponding normal bus feeder breaker or EDG output breaker is closed. This prevents direct -

connection of the AAC power source to the preferred or onsite emergency AC power systems.

The auxiliary equipment needed to maintain the readiness of the SBO DG (e.g. battery chargers, DG heaters, etc.) will normally be energized from the 4,160VAC SBO DG bus,.

which will normally be energized via the tie line connection from the VHS switchyard. The VHS tie line is not classified as a preferred, Class 1 E, or onsite emergency AC power system. A manually-operated transfer switch will be installed to allow the auxiliary equipment to be energized from the non-safety-related portion of the VY station auxiliary AC power system during those times that the normal AC power source (VHS tie line) is unavailable due to a planned or unplanned outage. The intent of this secondary feed is to maximize the availability of the AAC power source when the VHS tie line is unavailable by keeping a full charge on the SBO DG system batteries and maintaining the equipment in standby status. The use of the transfer switch will be procedurally controlled.

2. There should be a minimum potential for common cause failure with the preferred or the blacked-out unit's onsite emergency ac power sources. No single-point ,

vulnerability should exist whereby a weather-related event or single active' failure could disable any portions of the blacked-out unit's onsite emergency ac power sources or the preferred power sources and simultaneously fail the AAC power source.

As discussed previously, the SBO DG system will be physically located a considerable distance (at least 800 feet) from the high-voltage switchyard, which will provide protection

BVY 12-084/Attachment 1 / Page 12 of 22 against the effects of likely weather-related events that may initiate the loss of off-site power event. The SBO DG will also be located away from the onsite emergency AC power sources (EDG units), so there is no postulated weather-related event that could disable the onsite EDG units concurrently with the SBO DG.

The SBO DG will be physically isolated from the onsite emergency AC and preferred power sources, so a single active mechanical failure will not disable the AAC power source concurrently with the onsite emergency AC or preferred power sources.

The SBO DG will normally be electrically isolated from the onsite emergency AC and preferred power sources. As discussed in Section B.7, a manually-operated transfer switch will be installed to allow the auxiliary equipment to be energized from the non-safety-related portion of the VY station auxiliary AC power system during those times that the normal AC power source (VHS tie line) is unavailable due to a planned or unplanned outage. In this configuration, a single active failure will not disable the AAC power source concurrently with

.the onsite emergency AC or preferred power sources. An electrical failure initiated at the AAC power source, emergency AC power source, or preferred power sources will be isolated by automatic tripping of circuit breakers prior to propagating to the other AC sources.

3. The AAC power source should be available in a timely manner after the onset of station blackout and have provisions to be manually connected to one or all of the redundant safety buses as required. The time required for making this equipment available should not be more than 1 hour1.157407e-5 days 2.777778e-4 hours 1.653439e-6 weeks 3.805e-7 months as demonstrated bytest. If the AAC power source can be demonstrated by test to be available to power the shutdown buses within 10 minutes of the onset of station blackout, no coping analysis. is required.

The SBO DG will be maintained in a "ready to operate" condition such that it can be started and connected to one of the safety buses (Bus 3 or Bus 4) in a timely manner. Following installation of the new AAC power source, initial testing will be performed to demonstrate that power can be made available up to existing circuit breaker 3V4 within one hour of the onset of station blackout. Energizing Bus 3 or Bus 4 from the AAC power source is not practical due to interlocks associated with circuit breakers 3V and 4V preventing closure of the breakers while the buses are energized from their normal sources (preferred power source). The actions required to complete alignment of the AAC power source to Bus 3 or Bus 4 include closure of two circuit breakers from the VY control room (3V4 and either 3V or 4V, depending on which bus is being energized). Once the AAC power source is energized up to 3V4, it takes very little time to align loads from the control room (less than 10 minutes). Therefore, energizing the AAC power source up to circuit breaker 3V4 within one hour satisfactorily demonstrates that the AAC power source can be made available to power Bus 3 or Bus 4 within the existing coping analysis.

VY performed a coping analysis assuming EPU conditions and submitted it to the NRC by letter dated March 24, 2005. Based on the results of the analysis, VY concluded that the plant is able to safely cope with a total .loss of AC power for a minimum of 2 hours2.314815e-5 days 5.555556e-4 hours 3.306878e-6 weeks 7.61e-7 months from the onset of the SBO to the restoration of offsite AC power to a 4160-volt emergency bus. The NRC documented a review of the analysis in the EPU safety evaluation, dated March 2, 2006.

The testing performed for the new AAC power source will demonstrate that the AAC power source can be aligned to one of the safety buses within one hour; therefore, the existing two-hour coping analysis bounds the interval between onset of an SBO and the start and alignment of the AAC power source.

BVY 12-084 / Attachment 1 / Page 13 of 22

4. The AAC power source should have sufficient capacity to operate the systems necessary for coping with a station blackout for the time required to bring and maintain the plant in safe shutdown.

The SBO DG will be rated for continuous operation at 3,000kW, which is greater than the continuous rating of the onsite emergency AC power sources (EDG unit), which is 2,750kW as specified in UFSAR Section 8.5; therefore, the SBO DG has sufficient capacity to operate the systems necessary to bring the plant to a safe shutdown condition. As discussed in section B.8(c), the SBO DG will include a dedicated fuel oil storage tank with a capacity sufficient for operation of the DG at 100% rated load for at least 36 hours4.166667e-4 days 0.01 hours 5.952381e-5 weeks 1.3698e-5 months , which provides significant margin over the existing design basis eight hours coping duration and is sufficient time to maintain the plant in a safe shutdown condition.

5. The AAC power system should be inspected, maintained, and tested periodically to demonstrate operability and reliability. The reliability of the AAC power system should meet or exceed 95 percent as determined in accordance with NSAC-108 (Ref.

11) or equivalent methodology.

The SBO DG equipment will be started and brought to approximately rated load capacity (3,000kW) at quarterly intervals in accordance with plant-developed procedures and preventive maintenance work order tasks established in accordance with manufacturer recommendations and industry guidance. The electrical load for the SBO DG for this test, will be provided by a permanently installed 3,000kW resistive load bank located adjacent to the SBO DG enclosure.

Once every refueling outage, a timed start will be performed to demonstrate that the AAC power source can be started and aligned to either safety Bus 3 or safety Bus 4 within one hour.

VY has established a reliability target of 0.95 for the standby AAC power system in accordance with the Entergy Emergency Diesel Generator Program (EN-DC-1 98), which includes the guidance in NUMARC 87-00, Appendix D. The AAC power system will also be included in the scope of the VY Maintenance Rule Program (EN-DC-203), which will ensure that the AAC power system maintains the reliability target.

QA Requirements for SBO Equipment that is not Safety-Related (Requlatory Guide 1.155 Appendix A)

1. Design Control and Procurement Documents Control Measures should be established to ensure that all design-related guidelines used in complying with §50.63 are included in design and procurement documents, and that deviations therefrom are controlled.

The AAC power source will be designed, procured and installed in accordance with Entergy's fleet procedures.

2. Instructions. Procedures, and Drawings Inspections, tests, administrative controls, and training necessary for compliance with § 50.63 should be prescribed by documented instructions, procedures, and drawings and should be accomplished in accordance with these documents.

The AAC power source will be installed and operated in accordance with approved installation and testing documents and operating procedures generated in accordance with

BVY 12-084 /Attachment 1 /Page 14 of 22 Entergy's quality assurance program. Design drawings will be entered into the VY drawing database in accordance with Entergy's fleet design change procedures.

3. Control of Purchased Material. Equipment. and Services Measures should be established to ensure that purchased material, equipment, and services conform to the procurement documents.

Procurement of material, equipment and services will be controlled in accordance with a Critical Procurement Plan (CPP) generated per Entergy's fleet procedures. The CPP provides a mechanism to ensure that all applicable requirements are met for the material, equipment, and services being procured.

4. Inspection A program for independent inspection of activities required to comply with § 50.63 should be established and executed by (or for) the organization performing the activity to verify conformance with documented installation drawings and test procedures for accomplishing the activities.

Peer inspections will be performed for critical installation and testing steps, as documented in the initial testing documents generated in accordance with Entergy's fleet design change process.

In-process witness and acceptance testing is specified by contract and in the CPP.

5. Testinq and Test Control A test program should be established and implemented to ensure that testing is performed and verified by inspection and audit to demonstrate conformance with design and system readiness requirements. The tests should be performed in accordance with written test procedures; test results should be properly evaluated and acted on.

The AAC power source will be periodically tested in accordance with procedures developed in accordance with Entergy's quality assurance program. Initial testing will be performed using Engineering Change Test procedure(s) generated in accordance with Entergy's fleet design change process.

6. Inspection, Test and Operating Status Measures should be established to identify items that have satisfactorily passed required tests and inspections.

The AAC power source will be periodically tested in accordance with procedures developed in accordance with Entergy's quality assurance program. Initial testing will be performed using Engineering Change Test procedure(s) generated in accordance with Entergy's fleet design change process. Preventive maintenance work order tasks will be established in accordance with manufacturer recommendations and industry guidance.

7. Non Conforming Items Measures should be established to control items that do not conform to specified requirements to prevent inadvertent use or installation.

Non conforming items will be segregated and controlled in accordance with the corrective action program.

BVY 12-084 / Attachment 1 / Page 15 of 22

8. Corrective Action Measures should be established to ensure that failures, malfunctions, deficiencies, deviations, defective components, and nonconformances are promptly identified, reported, and corrected.

Conditions adverse to quality will be entered into the corrective action program.

9. Records Records should be prepared and maintained to furnish evidence that the criteria enumerated above are being met for activities required to comply with § 50.63.

Records documenting the quality related activities will be retained in accordance with the quality records program.

10. Audits Audits should be conducted and documented to verify compliance with design and procurement documents, instructions, procedures, drawings, and inspection and test activities developed to comply with § 50.63.

Station Blackout is included in the quality master audit plan as an element that can be selected for audit.

Guidance Regarding System and Station Equipment Specifications (Regulatory Guide 1.155 Appendix B)

Safety-Related Equipment (Compliance with IEEE-279)

Existing Class 1E electrical systems will continue to meet all VY applicable safety-related criteria.

Diversity from Existing EDGs Addressed in Comparison of Proposed Design to Regulatory Guide 1.155 Section 3.3.5.

Independence from Existing Safety-Related Systems Addressed in Section B.7 of Comparison of Proposed Design to AAC Power Source Design Criteria (Appendix B of NUMARC 87-00, Rev. 1).

Environmental Consideration Addressed in Section B.3 of Comparison of Proposed Design to AAC Power Source Design Criteria (Appendix B of NUMARC 87-00, Rev. 1).

Capacity Addressed in Comparison of Proposed Design to Regulatory Guide 1.155 Section 3.3.5.

Quality Assurance Addressed in QA Requirements for SBO Equipment that is not Safety-Related (Regulatory Guide 1.155 Appendix A).

BVY 12-084 / Attachment 11 Page 16 of 22 Technical Specification for Maintenance, Limiting Condition, FSAR, etc.

No new Technical Specification Limiting Conditions for Operation or Surveillance Requirements are being proposed in this amendment. Proposed changes to the VY UJFSAR are discussed above.

Instrumentation and Monitoring Addressed in Control Room Monitoring section below.

Common Cause Failure (CCF)

Addressed in section B.8 of Comparison of Proposed Design to AAC Power Source Design Criteria (Appendix B of NUMARC 87-00, Rev. 1).

Control Room Monitoring (from SRP Section 8.4)

Plant staff in the control room monitor the performance of the AAC power source. As a minimum, monitoring should include the voltage, current, frequency,.and circuit breaker position.

An OIP will be installed in the VY Control Room to provide monitoring and control capability for the AAC power system when it is in service. The OIP will provide information on the critical operating parameters for the SBO DG and its associated bus, including system voltage, current, frequency, and circuit breaker position, as well as any alarm conditions that impact the operation of the AAC power system. The OIP is powered from Vital AC, which will remain energized through a station blackout event, allowing the SBO DG to be started and the critical operating parameters monitored from the Control Room.

An existing spare annunciator window on existing Control Room Panel 9-8 will be configured to alert operators to any alarm condition from the AAC power system. This annunciator window is separate from the 0IP installed in the Control. Room.

Operating Procedures and Traininq (from SRP Section 8.4)

Proceduresneed to:

A. Cope with the occurrence of an SBO for the specified coping duration during all modes of plant operation and include actions necessary to place AAC power sources in service and maintain acceptable environmental conditions for equipment necessary to mitigate the event. Procedures developed to cope with an SBO should be integrated with the plant-specific technical guidelines and emergency operating procedures developed using the emergency operating procedure upgrade program established in response to Supplement 1 of NUREG-0737. The task analysis portion of the emergency operating procedure upgrade program should include an analysis of instrumentation adequacy during an SBO.

Procedures are in place to allow the plant to cope with a SBO for the 2 hour2.314815e-5 days 5.555556e-4 hours 3.306878e-6 weeks 7.61e-7 months coping duration. EOPs are symptom based and do not specifically address SBO. Off-normal procedures contain guidance to implement actions to restore power following a SBO.

Procedures will be revised to include actions to place the new AAC power source in service.

BVY 12-084 / Attachment 1 / Page 17 of 22 B. Restore standby (Class 1 E) power sources when the EAC power system is unavailable.

Procedures contain the necessary direction to restore the Class 1 E power sources in service if the emergency AC power system becomes unavailable.

C. Restore offsite power sources and use of nearby power sources (which may include nearby or onsite gas turbine generators, portable generators, hydrogenerators, and black start fossil power plants) in the event of a LOOP.

As a minimum, the following potential causes for a LOOP should be considered:

i. Grid undervoltage and collapse.

ii. Weather-induced power loss.

iii. Preferred power distribution system faults that could result in the loss of normal power to essential switchgear buses. This includes such failures as distribution system hardware, switching and maintenance errors, and lightning-induced faults.

Existing procedures contain direction to contact the regional grid (ISO-NE) and transmission (Vermont Electric Power Company (VELCO)) operators to restore offsite power to the plant in the event of a LOOP. Guidance is also included to contact equipment vendors to supply portable generators which can be connected to energize vital equipment.

The priority of establishing reliable power to nuclear generators is contained in ISO-NE procedure OP-6, Appendix A (System Restoration Guidelines).

D. Actions necessary to restore normal long-term core cooling/decay heat removal once ac power is restored.

Existing site procedures direct operators to commence a cool down and establish long term core cooling/decay heat removal once conditions allow. The proposed SBO DG will be capable of commencing a cool down and establishing long term core cooling / decay heat removal.

E. The procedure should specify actions necessary to assure that Shutdown equipment (including support systems) necessary in an SBO can operate without ac power.

Procedures are in place to assure that shutdown equipment (including support systems) necessary in an SBO can operate without AC power. Existing procedures require reduction of nonessential loads in an SBO to maximize the capability of backup DC power sources.

F. The procedure should recognize the importance of decay heat removal systems (auxiliary feedwater, high-pressure coolant injection, high-pressure core spray, reactor core isolation cooling) during the early stages of the event and direct operators to invest appropriate attention to ensuring their continued reliable operation throughout the event.

Existing procedures recognize the importance and direct operations of necessary decay heat removal systems during a station blackout event. The procedures direct the required cool down rates for an event and actions to conserve DC power to ensure the reactor core isolation cooling and high-pressure coolant injection systems maintain reliable operation throughout the event.

BVY 12-084 / Attachment 1 / Page 18 of 22 G. Plant operating procedures should identify the sources of potential inventory loss and specify actions to prevent or limit significant loss.

Symptom-based site approved procedures do not specifically address potential inventory loss.

H. Plant operating procedures should ensure the prompt establishment of a flowpath for makeup flow from the Condensate Storage Tank (CST) to the steam generator/nuclear boiler and identify backup sources to the CST in order of intended use. In addition, plant operating procedures should specify clear criteria for transferring to the next preferred source of water.

Existing emergency procedures identify make up sources of water and ensure the prompt establishment of a flowpath from the CST to the nuclear boiler. Procedures contain direction and precautions/administrative limits for transferring water source supplies when required.

I. The procedure should identify individual loads that need to be stripped from the plant dc buses (both Class 1 E and non-Class 1 E) to conserve dc power.

Existing site procedures identify securing of DC loads, as plant conditions allow, to conserve DC power.

J. Plant operating procedures should specify actions to permit appropriate containment isolation and safe-shutdown valve operations while ac power is unavailable.

Existing site procedures identify actions to maintain operation of containment isolation/safe shutdown valve operation while AC power is unavailable.

K. Plant operating procedures should identify the portable lighting necessary for ingress and egress to plant areas containing shutdown or AAC equipment requiring manual operation.

An existing plant procedure lists the Appendix R lighting installed in the plant that-will automatically illuminate in the event of a loss of normal power.

L. Plant operating procedures should consider the effects of ac power loss on area access, as well as the need to gain entry to other locked areas where remote equipment operation is necessary.

The SBO DG can be operated from the Control Room. Access to the SBO DG does not rely on AC power. Access to other vital areas can be gained by use of issued keys.

M. Plant operating procedures should consider the effects of a loss of ac power on communications capabilities, including the potential for a loss of communications with offsite agencies.

Existing plant procedures describe the communications available during emergencies, including the loss of AC power. Installation of the SBO DG will have no impact on station communication capabilities.

BVY 12-084 / Attachment 1 / Page 19 of 22 N. Plant operating procedures should consider the loss of heat tracing effects for equipment necessary to cope with an SBO.

The SBO DG will not contain a heat trace system. The loss of existing site heat tracing has no impact on the SBO DG. The loss of heat tracing effects for equipment necessary to cope with an SBO are unaffected by the installation and use of the SBO DG.

0. To provide assurance that the Nuclear Power Plant (NPP) operator will be kept aware of changes in the plant switchyard and offsite power grid, plant or site procedures should establish appropriate communication protocols between the NPP and its transmission system operator. With regard to SBO, these protocols should aid the operator in determining the following:

i. The performance of grid-risk-sensitive maintenance activities (such as surveillances, post maintenance testing, and preventive and corrective maintenance) that could increase the likelihood of an SBO or impact the plant's ability to cope with an SBO, such as out-of-service risk-significant equipment (e.g., an EDG, a battery, a steam-driven pump, an AAC power source).

ii. The availability of local power sources and transmission paths that could be made available to resupply the plant following a LOOP event.

Agreements are in place between Entergy, VELCO and ISO-NE to communicate grid-risk-sensitive maintenance testing and preventative and corrective maintenance that could increase the likelihood of a SBO event. The agreement includes restoring power to the plant in priority based ISO rules. The priority of establishing reliable power to nuclear generators is contained in ISO-NE procedure OP-6, Appendix A (System Restoration Guidelines).

Comparison of Proposed Design to 10 CFR 50.2 Definition of Alternate AC Source Alternate ac source means an alternating current (ac) power source that is available to and located at or nearby a nuclear power plant and meets the following requirements:

1. Is connectable to but not normally connected to the offsite or onsite emergency ac power systems;

2. Has minimum potential for common mode failure with offsite power or onsite emergency ac power sources;

3. Is available in a timely manner after onset of station blackout; and

4. Has sufficient capacity and reliability for operation of all systems required for coping with station blackout and for the time required to bring and maintain the plant in safe shutdown (non-design basis accident).

The SBO DG will be located within the VY protected area boundary.

1. The SBO DG will be connectable, but not normally connected, to the onsite emergency ac power sources. VY does not utilize an offsite emergency ac power source. This is discussed in section B.7 of the comparison to the NUMARC 87-00 criteria and section 1 of the comparison to the Section 3.3.5 criteria of Regulatory Guide 1.155.

2. The SBO DG has minimum potential for common mode failure with onsite emergency ac power sources. This is discussed in section B.8 of the comparison to the NUMARC 87-00 criteria and section 2 of the comparison to the Section 3.3.5 criteria of Regulatory Guide 1,155.

BVY 12-084 / Attachment 1 / Page 20 of 22.

3. The SBO DG will be available in a timely manner after onset of station blackout. This is discussed in section B.12 of the comparison to the NUMARC 87-00 criteria and section 3 of the comparison to the Section 3.3.5 criteria of Regulatory Guide 1.155.

4. The SBO DG will have sufficient capacity and reliability for operation of all systems required for coping with station blackout and for the time required to bring and maintain the plant in safe shutdown. This is discussed in section B.9 of the comparison to the NUMARC 87-00 criteria and section 4 of the comparison to the Section 3.3.5 criteria of Regulatory Guide 1.155.

Precedence The NRC found the use of a non safety-related DG as the AAC power source at Calvert Cliffs Nuclear Power Plant (Reference 7.g) and Pilgrim Nuclear Power Station (References 7.h and 7.i) to be acceptable.

Conclusions In conclusion, based on the considerations discussed above, (1) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed

-manner, (2) such activities will be conducted in compliance with the Commission's regulations, and (3) the issuance of the amendment will not be inimical to the common defense and security or to the health and safety of the public.

5. EVALUATION OF SIGNIFICANT HAZARDS CONSIDERATION Pursuant to 10 CFR 50.92, Vermont Yankee (VY) has reviewed the proposed amendment and concludes that the change does not involve a significant hazards consideration since the proposed amendment satisfies the criteria in 10 CFR 50.92(c). These criteria require that operation of the facility in accordance with the proposed amendment would not (1) involve a significant increase in the probability or consequences of an accident previously evaluated; (2) create the possibility of a new or different kind of accident from any accident previously evaluated; or (3) involve a significant reduction in a margin of safety.

This proposed amendment would replace the Vernon Hydroelectric Station (VHS) with an onsite station blackout diesel generator (SBO DG) as the source of alternate AC (AAC) power credited for compliance with 10 CFR 50.63 "Loss of all alternating current power." The SBO DG will satisfy the criteria contained in Appendix B to NUMARC 87-00 Revision 1 "Guidelines and Technical Bases for NUMARC Initiatives Addressing Station Blackout at Light Water Reactors" and Section 3.3.5 and Appendices A and B of Regulatory Guide 1.155 "Station Blackout" and portions of Standard Review Plan Section 8.4 as detailed in the application.

The discussion below addresses each of these criteria and demonstrates that the proposed amendment does not constitute a significant hazard.

1.' Does the proposed amendment involve a significant increase in the Probability or consequences of an accident previously evaluated?

Response: No.

The proposed amendment does not significantly increase the probabiEity or consequences of an accident. The proposed amendment replaces one AAC power source (the VHS) with an additional onsite AAC power source (diesel generator). This equipment can not initiate a design basis accident and is not used to mitigate the consequences of design basis accidents.

BVY 12-084 / Attachment 1 / Page 21 of 22 The equipment is used to mitigate the consequences of a station blackout as required by 10 CFR 50.63. Station blackout events are not considered design basis accidents and do not result in radiological consequences. Therefore, the proposed amendment does not involve a significant increase in the probability or consequences of an accident previously evaluated.

2. Does the proposed amendment create the possibilitV of a new or different kind of accident from any accident Previously evaluated?

Response: No.

The proposed amendment does not involve any new modes of operation. The change provides an alternate means to provide AAC power to the station. The location of the SBO DG does not create the possibility of a different kind of accident. No new accident precursors are introduced. Station procedures will be revised to align the AAC source to provide the required power within established coping times. The methods governing plant operation remain bounded by current safety analysis assumptions. Therefore, the proposed change does not create the possibility of a new or different kind of accident from any accident previously evaluated.

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

Response: No.

The design of the new AAC source will accommodate the loading associated with the proceduralized station blackout response and safety margins will be maintained. The design of the system will meet regulatory guidance and be within station design analysis. The station safety analysis results are unchanged and margin to regulatory limits is not affected.

Therefore, the proposed amendment will not involve a significant reduction in the margin of safety.

Based on the above, Entergy concludes that the proposed amendment presents no significant hazards consideration under the' standards set forth in 10 CFR 50.92(c), and, accordingly, a finding of "no significant hazards consideration" is justified.

6. ENVIRONMENTAL CONSIDERATIONS This amendment request meets the eligibility criteria for categorical exclusion from environmental review set forth in 10 CFR 51.22(c)(9) as follows:

(i) The amendment involves no significant hazards determination.

As described in Section 5 of this evaluation, the proposed change involves no significant hazards consideration.

(ii) There is no significant change in the types or significant increase in the amounts of any effluent that may be released offsite.

The proposed amendment does not involve any physical alterations to the plant configuration that could lead to a significant change in the type or amount of effluent release offsite.

(iii) There is no significant increase in individual or cumulative occupational radiation exposure.

BVY 12-084/Attachment 1 / Page 22 of 22 The proposed amendment does not involve a significant increase in individual or cumulative occupational radiation exposure.

Based on the above, VY concludes that the proposed change meets the eligibility criteria for categorical exclusion as set forth in 10 CFR 51.22(c)(9). Pursuant to 10 CFR 51.22(b), no environmental impact statement or environmental assessment need be prepared in connection with the issuance of this amendment.

7. REFERENCES

a. Letter, USNRC to VY, Supplemental Safety Evaluation of Vermont Yankee Nuclear Power Station, Station Blackout Rule (10.CFR 50.63) (TAC No. M68620), dated September 1,1992, NVY 92-163

b. Letter, USNRC to Entergy Nuclear Operations, Inc., Vermont Yankee Nuclear Power Station -Issuance of Amendment Re: Extended Power Uprate (TAC No. MC0761),

dated March 2, 2006, NVY 06-028

c. NUMARC 87-00, Revision 1, Guidelines and Technical Bases for NUMARC Initiatives Addressing Station Blackout at Light Water Reactors, dated August 1991

d. Regulatory Guide 1.155, Station Blackout, dated August 1988

e. NUREG-0800, Standard Review Plan, Section 8.4 Station Blackout, Revision 1, dated May 2010

f. Letter, Entergy Nuclear Operations, Inc. to USNRC, Technical Specifications Proposed Change No. 263 - Supplement No. 25 Extended Power Uprate - Station Blackout and Appendix R Analyses, BVY 05-030, dated March 24, 2005

g. Letter, USNRC to Calvert Cliffs Nuclear Power Plant, Alternate AC Power Source Design Report - Calvert Cliffs Nuclear Power Plant, Unit Nos. 1 and 2 (TAC Nos.

M89086 & M89087), dated October 3, 1994

h. Letter, USNRC to Pilgrim Nuclear Power Station, Safety Evaluation of the Pilgrim Nuclear Power Station Response to the Station Blackout Rule (TAC No. 68585), dated February 13, 1991

i. Letter, USNRC to Pilgrim Nuclear Power Station, Supplemental Safety Evaluation (SSE) of the Pilgrim Nuclear Power Station Response to the Station Blackout Rule (TAC No. 68585), dated January 15, 1992

BVY 12-084 Docket No. 50-271 Attachment 2 Vermont Yankee Nuclear Power Station Markup of Current UFSAR Pages

conditions. Station Blackout (SBO) Diesel conditons. Generator (DG)

Two diesel generator sets are capable of being conn cted to the station switchgear to provide emergency power, as required. Upon loss of normal ac power, each of these diesel generator sets starts a tomatically and becomes available to assume the necessary electrical load o the station's Engineered Safeguards Systems within the time required by the a cident analysis. The SBODG 13.2 kV underground power line runs from the adjace t Vernon Hydroel ctric Station to a 13.2-4.16 kV transformer near the coolin towers. From t re, a 4160 V underground power line connects to the sfafLin switchgear. Tbig power source, Vermont Yankee's Station Blackout Alternate ac power source, is considered to be a highly reliable source for station backup emErgency power.

If one of the two diesel generators is not available, then the yRH xngi-rrL .At intnlncan be made available by a manual tr nsfer to the associated engineered sa eguard switchgear. a ....

ISBODG

/-, -- and then goes on to

..... Y *the station switchgear In addition to the above features, the VY N S Auxiliary QUL oy*Lrln- MU1515L of 4160 buses; 480 V buses; 480 V MCCs, inci ding two 480 V MCCs dedicated to ECCS MOVs and which are powered by dedicated UPSs; a 120/240 V uninterruptible ac bus; 125 V dc station batteries; a +/-24 V c power system for neutron monitoring and radiation monitoring; and an CCS 24 V dc power system.

Details of the 4160 V ac and 480 V ac auxili ry buses are found on Drawings G-191299, G-191300, Sh.l and 2, G-191301, Sh.l and 2. Drawing G-191372, Sh.l, 2 and 3 shows the 125 V dc one-line diagram, a Drawing G-191372, Sh.4 and 5 shows the 120/240 V instrumentation one-line iagram.

The line from the Vernon Hydroelectric Station can be used as an additional sour of backup power.

VYNPS UFSAR Revision 24 8.1-4 of 4

first approximately one-mile segment out of the Vernon substation and the Newfane loop, will utilize wood H-Frame structures similar to the existing 340 line. Single-pole steel structures will be utilized along the first approximately one-mile segment, matching the existing single steel poles in that location.

Wooden structures supporting the 345 kV lines are designed to meet or exceed the requirements for Grade B construction for heavy loading districts of the National Electric Safety Code. The lines are also designed for a 104 mile per hour wind speed.

The 115 kV K-186 line is carried from the 115 kV switchyard to the river crossing point on separate wooden structures which are designed to meet the requirements for heavy loading districts of the National Electric Safety Code.

This line crosses the river to New Hampshire utilizing the spare side of one of the steel towers which is used for the 345 kV circuit river crossing. At the New Hampshire side of the river, this 115 kV line is split into two segments: one segment is routed approximately three miles north and then west across the Connecticut River to the Vernon Road substat Station Blackout t is routed easterly approximately ten miles to Keene, e, (SBO) Diesel terminations at the Chestnut Hill substation and taps a Generator (DG) substations (VHS) uctures which are designed to meet he requirements for and then heavy lo ing is ricts of the National Electric Safe y Code. goes on to ISBO DG the station A 13.2 underground power line runs f m the adjace t Vernon Hydroelec switchgear Station to a 13.2-4.16 kV transformer ne r the coolinl towers. Fro here, a 4160 V underground power line connects t the +/- switchgear. At VYNPS, thi lix*acan be connected to either of he 4160 V emergency buses through manually perated circuit breakers. The lin_, which has been designated as the Stati n Blackout Alternate ac source, is used to meet Station Blackout requirem nts as described in Section 8.5.5. The has the capacity to support he engineered safeguard load of the bus to hich it is connected.

Based on VY commitments to satisfy the I0CFR50.63 Stat n Blackout Rule, the time req ired for startup and alignment of the alternate power source is demonstr ted by test every t.hir-d-refueling outage. A load c acity test of the alt rnate ac power source is also conducted qu rterly SBO.DGorteVHS the SBO DG or the IVHS ngland area is served by a mber of interconnected electric

..... ..... . generating unit operatio , scheduling of unit outages, and scheduling of reserve capacity is coordin ed on an area-wide basis. The Vermont Yankee Nuclear Power Station ca bility is included with other New England capabilities required to meet e load and reserve requirements of the areas. Once every third refueling outage, the alternate ac power source is demonstrated by test to be capable of VYNPS staring the largest available motor on safety Bus 3 or UFSAR Revision 24 safety Bus 4. 8.3-6 of 10

numerical relays. High speed line current differential relay tripping is achieved over redundant diverse fibers connected to the primary and secondary relays. Additional relaying functionality includes local breaker failure tripping and remote breaker failure transfer tripping. The primary and secondary line current differential relay schemes associated with the 3340 and 3381 tie lines each trip their associated primary and secondary lockout relays preventing auto reclosing of the faulted tie line.

The Keene 115 kV line also has primary and backup relay systems with independent sensing and tripping circuits and independent trip coils. The primary system is a two zone step distance scheme employing digital relays.

The backup system consists of line differential relays with a transfer trip.

The 115 kV circuit also has a breaker failure relay scheme with transfer trip of remote breakers.

The VY 400 MVA autotransformer and the Vernon 440 MVA autotransformers are protected by redundant differential current relay systems that extend out around the breakers that isolated the zone of protection and by a secondary protection scheme that includes a relay which detects a sudden rise in the transformer tank pressure.

The 345 kV and 115 kV switchyards each have a primary and secondary bus differential relay system. These systems are independent of one another and the tripping of one will not cause tripping of breakers in the other substation, with the exception that the 115 kV secondary side breaker on the 400 MVA autotransformer will be tripped for a fault on the 345 kV switchyard's north bus.

In the unlikely event that the two sources to the 115 kV primary of the station startup transformers, that is, the 345/115 kV autotransformer supply from the VY 345 kV switchyard, or the tie line to the Vernon 115 kV switchyard become disconnected, the station emergency load can be supplied from off-site power by establishing a backfeed from the 345 kV switchyard by opening the generator no-load disconnect in the isolated phase bus duct. Two emergency diesels described in Section 8. AnHthe Station Blackout Alternate ac source, the line to Vernon Hydroelect c Station, would also be a ailable.

The 115KV switchyard contains three capacitor banks, one OMVAr bank and two 15MVAr banks. Each bank has its own breaker connecting it to the 115KV bus.

These breakers are individually controlled by the system o erator via SCADA.

Phase and ground overcurrent, unbalance, over-voltage and reaker failure protection is provided for each bank breaker. IDiesel Generator and VYNPS UFSAR Revision 24 8.3-9 of 10

8.4.5.1 4160 V Switchgear The 4160 V buses are arranged with all ac operated emergency loads required under postulated design basis-conditions connected to Buses 3 and 4, either directly or through 4160-480 V transformers, with the exception of the loads on MCCs 89A and 89B, which are dedicated to ECCS MOVs, and are powered by dedicated UPSs. See Drawings G-191299, G-191300, Sh. 1 and 2, G-191301, Sh.l and 2. The balance-of-plant auxiliary loads are connected to.Buses 1, 2, 5A, and 5B, as shown on Drawing G-191299.

The normal supply for the 4160 V load is unit auxiliary transformer (T-2),

except for 4160 V Buses 5A and 5B, which are supplied from startup transformer (T-3B). The unit auxiliary transformer is supplied from the station main generator through the isolated phase bus duct. An alternate supply to the 4160 V Auxiliary System is available from the startup transformers (T-3A and T-3B) which are supplied from the 345/115 kV Transmission System.

The startup transformers are used during plant shutdown and while the station is being started and synchronized with the Transmission System. Normally after synchronization is accomplished, the entire auxiliary load, with the exception of the cooling tower load, is supplied by the main generator by manually transferring the load to the unit auxiliary transformer. After the transfer, the startup transformers remain energized with T73B carrying the cooling tower load, if required. The startup transformers have adequate capacity for startup and full load operation of the station, as well as for normal and emergency shutdown., Upon loss of the main generator as a source, the entire auxiliary load is transferred by an automatic fast transfer to the startup transformers, thus maintaining the integrity of the Auxiliary System.

The automatic fast transfer is supervised by a high speed synchro check relay.

If the automatic fast transfer is not successful and voltage is available on the startup transformer, an automatic delayed residual voltage-transfer is attempted. If there is no power available from the Transmission System, transfer is blocked. Loss of power will be sensed on the emergency buses and the diesel generators will start as described in Section 8.5.

There are two 2750 kW, 4160 V standby diesel generators, one connected to Bus 3 and the other to Bus 4. Each diesel generator has sufficient capacity to supply each of the redundant emergency loads required under postulated design basis accident conditions. Further description of the standby power sources is given in Section 8.5.

In addition to the main generator, the start-up transformers, and the two standby diesel generators, a backfeed from off-site power through the main VYNPS UFSAR Revision 25 8.4-4 of 12

step-up transformer nmA q I t-j-

.* 1 - t- znji i Y-r fv-nn h t-hr ¶lhrnnn Wyrnia1pr--ri _vtAn i Tl~h1*i The Station Blackout source provide-emergency backup po er at 4160 V, and can manually connected to either Emergency Bus 3 or.

The switchgear for he 4160 V Auxilia y System is of th metal-clad indoor type, exce I" An .... and 5B which are Vernon units.

C , a feed from the le, air reak typ Hydroelectric 9rated from Vernon the statiO Hydroelectric Control power fo Station and the iormally supplied f Station and the -ion Batt ry A-1 with an alternate feed from Main Station Ba Station Blackout manual transfer switch. Control power for 4160 V Bus 4 is Diesel Generator from 125 V Main Station Battery B-1 with an alternate are available. Shutdo Battery AS-2 through a manual transfer switch.

8.4.5.2 480 V Buses leithersour The 480 V auxiliary power is supplied from the 4160 V Auxiliary System through nine 4160-480 V station service transformers. The 480 V system consists of seven switchgear buses and twenty-eight motor control centers. The 480 V emergency loads, required under postulated design basis accident conditions, are powered from 480 V Buses 8 and 9, and Motor Control Centers 8A, 8B, 8C, 8E, 9A, 9B, 9C, 9D, 89A, and 89B. In addition to the emergency loads, there are a limited number of nonessential loads connected to these buses and motor control centers. Selected nonessential loads are disconnected when off-site power is lost.

The 480 V switchgear buses are self-supporting, metal-clad structures with draw-out circuit breakers. Control power for 480 V Bus 8 is normally supplied from 125 V Main Station Battery A-1 with an alternate feed available from Main Station Battery B-1 through a manual transfer switch. Control power for 480 V Bus 9 is normally supplied from 125 V Main Station Battery B-1 with an alternate feed available from Alternate Shutdown Battery AS-2 through a manual transfer switch.

8.4.5.2.1 480 V MCCs 89A and 89B Motor Control Centers 89A and 89B, which are dedicated to the ECCS motor operated valve loads, are powered from two redundant 480 V uninterruptible power systems (UPS-lA and UPS-lB) in lieu of Buses 3 or 4. The UPS consists of a Motor Generator (MG) set, storage batteries, and a separate control panel. The MG set consists of an ac motor, ac generator, and a dc machine which can operate as a motor or a generator. During normal plant operating VYNPS UFSAR Revision 25 8.4-5 of 12

in-line mechanical strainers and normally three of four pumps are operated to remove plant service heat loads. Two pumps provide sufficient capacity to remove heat loads during accident conditions. Active components considered necessary to provide cooling water to a diesel generator are: a service water pump (one of four) and a control valve (FCV-28A, 28B) located downstream of the diesel coolers. Note that while one SW pump is sufficient to meet the Design Basis Accident (DBA) heat loads (diesel generator heat exchanger, RHR heat exchanger, SFPC heat exchanger, and ECCS Room coolers), two pumps are required to operate following a DBA to account for water diverted to other nonessential loads, including through failed piping lines (see FSAR Section 10.6.5).

A worst case consequence as a result of a single failure to the above arrangement is the loss of one diesel generator. Failure of one service water pump or one strainer would not result in loss of cooling to either generator.

Each strainer is designed to pass full flow from four service water pumps, and the service water headers are cross-connected thereby permitting one strainer to pass water for both headers. Failure of a control valve in the closed position would result in loss of cooling to the respective diesel generator.

It is concluded that the most significant result from a single failure would be the loss of one diesel generator.

8.5.5 Loss of Diesel Generator A loss of a single diesel generator and its associated emergency bus is a predicted failure. Nonetheless, should such a loss occur, design features have been provided to connect the emergency bus to another available source of power. /Station Blackout (SBO) the

/ Diesel Generator (DG) I If a loss of ac occurs on Eme gency Bus 3 and Diesel Generator lB (connect d to Bus 3) fails to start, or fails while running, then the power line from Vernon Hydroelectric Station can be connected manually to Bus 3. If the above described situation arises on Emergency Bus 4, the Vernon power line can be connected manually to Bus 4. If loss of ac occurs on bot buses, procedures direct the operator to restore power to only one bus.

I/SBQ DGI The 4160 V tie from VYNPS to the Vernon Hydroelectric Station is connected through a transformer located at Vermont Yankee to the Vernon Hydroelectric Station 3.2 kV switchyard. The Vernon Hydroelectric Station feed to Vermont Yankee is energized and available whether the Vernon generators are operating or not. T connection provides more than adequate capacity for either Bus 3 or Bus 4 eng'neered safeguards loads.

the SBO DG switchgear to VYNPS UFSAR Revision 25 8.5-10 of 18

/SBO DG I/SBO DG I/SBO DG The swi ching arrangement for connection of the Vernon 1L1 line to a Verm nt Yankee mergency Bus is shown on Drawing G-191299. Three circuit breaker are used: V, to connect to Emergency Bus 3; 4V, to connect to Emergency Bus 4; and 3V , which is the feeder breaker for the Vernon Hydroelectric Station +/-.P line. The control switches for the three breakers are located on the electr cal section of the main control board, and the availability of the Vernon~ti- line is indicated continuously by a voltmeter and ammeter adjacent to the control switches. The Vernon Tie .i-s also annunciated on CRP 9-8 upon a "Low Bus Voltage/Loss of Power" conditio' The Vernon Hydroelectric Station is controlled and monitored upstream by the Wilder Hydroelectric Station.

VYNPS can contact the Wilder Hydroelectr i Station by commercial telephone if necessary.

Fand the SBO DG are The 125 V dc control power for breaker 3V, 4V, and 3V4 is supplied from Main Station Batteries Al, Bl, and Alternate Shutdown Battery AS-l, respectively.

Breakers 3V, 4V, and 3V4 are normally open and can only be closed by manual operation, and the breaker control circuits are interlocked to ensure that the Vernon tie line cannot be connected to a live emergency bus. The control circuit for Breaker 3V4 is interlocked so Breakers 3V and 4V must both be open before 3V4 can be closed. Once 3V4 is closed, in order to close Breaker 3V and energize Emergency Bus 3, the breaker for Diesel Generator lB and Breaker 3TI must both be open. The same logic applies to the closing of Breaker 4V to energize Bus 4.

I/sBo DGI Breakers 3V and 4V are norm ly open and only one of them has to be closed to tie in the Vernon -eed- With the above interlock logic for breaker closing, no single failure of the controls will result in the closing of 3V and 4V at the same time, thus the electrical independence of the redundant emergency buses is assured.

8.5.5.1 Station Blackout - 10CFR50.63 Vermont Yankee meets the requirements of 10CFR50.63. This regulation requires that plants determine a "coping duration" using the methodology of USNRC Regulatory Guide 1.155 and demonstrate the ability to withstand an extended loss of all ac power for the coping duration. Vermont Yankee is categorized as an eight-hour duration plant and uses fha A1ATilhlý tg ]in,- tr, 1rnnn

.qtatian.asan alternate ac source to mee- the requirements of the regulation.

In addition, Vermont Yankee has implemen ed initiatives to maintain diesel generator reliability at a level of 0.95 or greater to minimize the probability of experiencing an extended tation blackout.

an on site Station Blackout VYNPS ,Diesel Generator UFSAR Revision 25 8.5-11 of 18

BVY 12-084 Docket No. 50-271 Attachment 3 Vermont Yankee Nuclear Power Station Markup of Current TS Bases Page

VYNPS BASES:

3.10 AUXILIARY ELECTRIC POWER SYSTEMS A. The objective of this Specification is to assure that adequate power will be available to operate the emergency safeguards equipment. Adequate power can be provided by any one of the following sources: an immediate access source through both startup transformers, backfeed through the main transformer, or either of the two diesel generators. The backfeed through the main transformer is a delayed access off-site power source. The delayed access source is made available by opening the generator no load disconnect switch and establishing a feed from the 345 kV switchyard through the main generator step up transformer and unit auxiliary transformer to the 4.16 kV buses. The delayed access source is available within an hour of loss of main generator capability to assure that fuel design limits and design conditions of the reactor coolant pressure boundary are not exceeded.

Electric power can be supplied from the off-site transmission network to the on-site Emergency Safeguards Electric Power Distribution System by two independent sources, one immediate access and one delayed access, designed and located so as to minimize to nshe extent practicable the likelihood of their simultaneous failure L un*und.iting and postulated accident and environmental conditions An AHHifinn1 nff-gite qir,,rr 41f) V ti- linm A1 tr XfcVrnnn 1udrinn-ll ri r- vt-At*n In c-An ýiipplW

H-h*r A41Cn V7 *miýrpgnrx hilu Tf i-_c*cl tr mpt qt-t-inn hAnrcI anA *ppc-nHyi R licrnzinc Off-site power is supplied to the Vermont Yankee (VY) 345 kV switchyard from the transmission network via two independent 345 kV tie lines from the Vernon 345 kV switchyard. Both 345 kV tie lines are sized to carry the entire output of Vermont Yankee. Each 345 kV tie line is protected by two diverse and redundant channels of line protection. The loss of one tie line does not affect the reliability or operability of the other. The new Vernon 345 kV switchyard is located just north of the VY 345 kV switchyard. The Vernon 345 kV switchyard is connected to the 345 kV grid by four 345 kV transmission lines utilizing a "breaker and a half" scheme.

With this redundant configuration, either 345 kV tie line meets the requirements for an operable delayed access source.

In the VY 345 kV switchyard, a 400 MVA autotransformer is connected between the 345 kV north bus and the VY 115 kV bus through the K-1 breaker. A second 400 MVA transformer, located in the new Vernon switchyard, connects the Vernon 345 kV switchyard to the Vernon 115 kV yard. This second autotransformer also feeds the VY 115 kV switchyard through the 115 kV K-40 tie line from the Vernon 115 kV switchyard. The two autotransformers are operated in parallel to feed the VY 115 kV bus but are physically separated and electrically independent. The loss of one autotransformer will not cause loss of the other one. The two autotransformers are the normal source of power for the 115 kV bus and the station startup transformers. They also feed the 115 kV transmission line to Chestnut Hill/Vernon Road.

The immediate access source power is provided to the 4160 buses through two startup transformers fed from the VY 115 kV switchyard through disconnect T-3. It is available within seconds following a design basis accident to assure core cooling, containment integrity and other vital functions are being maintained. The normal supply to the VY 115 kV switchyard bus is from the two paralleled, but independent, 345 kV/115 kV autotransformers described above. In the unlikely event that both autotransformers are out of service, an alternate immediate access source through the Chestnut Hill/Vernon Road line, Vernon 115 kV yard and K-40 Tie Line may be made available. Its availability is dependent on its preloading of the Chestnut Hill/Vernon Road line which must be limited by system Amendment No. 2-6, 4-2-4, 4-5-, .... n1 52, -44,BVY 08 060, .VY 10 027, 220 Rvy in-n1lfS

Insert 1 An additional on-site Station Blackout Diesel Generator and an off-site source, a 4160 V tie line to Vernon Hydroelectric Station, can supply either 4160 V emergency bus. The on-site Station Blackout Diesel Generator is used to meet station blackout licensing requirements. The 4160 V tie line is used to meet Appendix R licensing requirements.

BVY 12-084 Docket No. 50-271 Attachment 4 Vermont Yankee Nuclear Power Station List of Regulatory Commitments

BVY 12-084 / Attachment 4 / page 1 of 1 List of Regulatory Commitments 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.

TYPE (Check one) SCHEDULED ONE-TIME CONTINUING COMPLETION DATE COMMITMENT ACTION COMPLIANCE (If Required)

Acceptance testing of the SBO DG unit will x Prior to September include starting of an unloaded 4kV 1,2013 induction motor that provides a starting current equal to or higher than the largest motor on safety Bus 3 or safety Bus 4, which is the 1000HP Residual Heat Removal (RHR) pump motor. The generator output voltage and frequency will be monitored during the motor start to ensure that allowable limits are not exceeded. This one-time testing will demonstrate the ability of the new generator to start the RHR pump while maintaining operating voltage and frequency within the limits established for safe shutdown components.

Following installation of the new AAC power x Prior to September source, initial testing will be performed to 1, 2013 demonstrate that power can be made available up to existing circuit breaker 3V4 within one hour of the onset of station blackout.

The SBO DG equipment will be started and x brought to approximately rated load capacity (3,000kW) at quarterly intervals in accordance with plant-developed procedures and preventive maintenance work order tasks established in accordance with manufacturer recommendations and industry guidance. The electrical load for the SBO DG for this test will be provided by a permanently installed 3,000kW resistive load bank located adjacent to the SBO DG enclosure.

Once every refueling outage, a timed start x First test in RFO 31 will be performed to demonstrate that the AAC power source can be started and aligned to either safety Bus 3 or safety Bus 4 within one (1) hour.

Once every third refueling outage, the SBO x First test in RFO 31 DG will be demonstrated by test to be capable of starting the largest available motor on safety Bus 3 or safety Bus 4.

v t e Letter Sequence Request
TAC:MF0422, (Approved, Closed)
Initiation Request, Request Acceptance Supplement, Supplement, Supplement, Supplement, Supplement, Supplement, Supplement Administration Questions 21 February 2013 22 March 2013 8 April 2013 Answers Results Approval Other:
MONTHYEAR2013-03-22 [Table View]

BVY 12-084, License Amendment Request; Changes to 10CFR50.63 Licensing Basis

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BVY 12-084, License Amendment Request; Changes to 10CFR50.63 Licensing Basis

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