ML013310523

Issuance of Amendment Emergency Diesel Generator Allowed Outage Time (Tac No. MB2196)

ML013310523
Person / Time
Site:	Millstone
Issue date:	01/04/2002
From:	Harrison J NRC/NRR/DLPM/LPD1
To:	Price J Dominion Nuclear Connecticut
Harrison J, NRR/DLPM, 415-3199
References
TAC MB2196
Download: ML013310523 (17)

Text

January 4, 2002 Mr. J. A. Price Vice President - Nuclear Technical Services - Millstone Dominion Nuclear Connecticut, Inc.

c/o Mr. David A. Smith Rope Ferry Road Waterford, CT 06385

SUBJECT:

MILLSTONE NUCLEAR POWER STATION, UNIT NO. 2 - ISSUANCE OF AMENDMENT RE: EMERGENCY DIESEL GENERATOR ALLOWED OUTAGE TIME (TAC NO. MB2196)

Dear Mr. Price:

The Commission has issued the enclosed Amendment No. 261 to Facility Operating License No. DPR-65 for the Millstone Nuclear Power Station, Unit No. 2, in response to your application dated May 31, 2001, as supplemented August 1, 2001, and September 26, 2001.

The amendment revises the Technical Specifications and Bases associated with operability of A.C. electrical power sources to increase the allowed outage time (AOT) for one inoperable emergency diesel generator (EDG) from 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> to 14 days. This change to the AOT allows the performance of various EDG maintenance and repair activities during plant operation.

A copy of the related Safety Evaluation is also enclosed. Notice of Issuance will be included in the Commission's biweekly Federal Register notice.

Sincerely,

/RA/

John T. Harrison, Project Manager, Section 2 Project Directorate I Division of Licensing Project Management Office of Nuclear Reactor Regulation Docket No. 50-336

Enclosures:

1. Amendment No. 261 to DPR-65

2. Safety Evaluation cc w/encls: See next page

January 4, 2002 Mr. J. A. Price Vice President - Nuclear Technical Services - Millstone Dominion Nuclear Connecticut, Inc.

c/o Mr. David A. Smith Rope Ferry Road Waterford, CT 06385

SUBJECT:

MILLSTONE NUCLEAR POWER STATION, UNIT NO. 2 - ISSUANCE OF AMENDMENT RE: EMERGENCY DIESEL GENERATOR ALLOWED OUTAGE TIME (TAC NO. MB2196)

Dear Mr. Price:

The Commission has issued the enclosed Amendment No. 261 to Facility Operating License No. DPR-65 for the Millstone Nuclear Power Station, Unit No. 2, in response to your application dated May 31, 2001, as supplemented August 1, 2001, and September 26, 2001.

The amendment revises the Technical Specifications and Bases associated with operability of A.C. electrical power sources to increase the allowed outage time (AOT) for one inoperable emergency diesel generator (EDG) from 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> to 14 days. This change to the AOT allows the performance of various EDG maintenance and repair activities during plant operation.

A copy of the related Safety Evaluation is also enclosed. Notice of Issuance will be included in the Commission's biweekly Federal Register notice.

Sincerely,

/RA/

John T. Harrison, Project Manager, Section 2 Project Directorate I Division of Licensing Project Management Office of Nuclear Reactor Regulation Docket No. 50-336

Enclosures:

1. Amendment No. 261 to DPR-65

2. Safety Evaluation cc w/encls: See next page DISTRIBUTION:

PUBLIC EAdensam OGC JClifford MWohl PDI-2 R/F CCowgill, RI ACRS WBeckner TClark GHill (2)

JHarrison OChopra Accession No.: ML013310523 OFFICE PDI-2/PM PDI-2/LA RTSB EEIB OGC PDI-2/SC NAME JHarrison TClark WBeckner CHolden VNerses for JClifford DATE 12/12/01 12/11/01 12/20/01 12/21/01 1/3/02 1/3/02 OFFICIAL RECORD

Millstone Nuclear Power Station Unit 2 cc:

Ms. L. M. Cuoco Senior Nuclear Counsel Dominion Nuclear Connecticut, Inc.

Rope Ferry Road Waterford, CT 06385 Edward L. Wilds, Jr., Ph.D.

Director, Division of Radiation Department of Environmental Protection 79 Elm Street Hartford, CT 06106-5127 Regional Administrator, Region I U.S. Nuclear Regulatory Commission 475 Allendale Road King of Prussia, PA 19406 First Selectmen Town of Waterford 15 Rope Ferry Road Waterford, CT 06385 Charles Brinkman, Manager Washington Nuclear Operations ABB Combustion Engineering 12300 Twinbrook Pkwy, Suite 330 Rockville, MD 20852 Senior Resident Inspector Millstone Nuclear Power Station c/o U.S. Nuclear Regulatory Commission P.O. Box 513 Niantic, CT 06357 Mr. W. R. Matthews Vice President and Senior Nuclear Executive - Millstone Dominion Nuclear Connecticut, Inc.

Rope Ferry Road Waterford, CT 06385 Ernest C. Hadley, Esquire P.O. Box 1104 West Falmouth, MA 02574-1104 Mr. P. J. Parulis Process Owner - Oversight Dominion Nuclear Connecticut, Inc.

Rope Ferry Road Waterford, CT 06385 Mr. D. A. Christian Senior Vice President - Nuclear Operations and Chief Nuclear Officer Innsbrook Technical Center - 2SW 5000 Dominion Boulevard Glen Allen, VA 23060 Mr. C. J. Schwarz Master Process Owner - Operate the Asset Dominion Nuclear Connecticut, Inc.

Rope Ferry Road Waterford, CT 06385 Mr. John Markowicz Co-Chair Nuclear Energy Advisory Council 9 Susan Terrace Waterford, CT 06385 Mr. Evan W. Woollacott Co-Chair Nuclear Energy Advisory Council 128 Terry's Plain Road Simsbury, CT 06070 Mr. D. A. Smith Process Owner - Regulatory Affairs Dominion Nuclear Connecticut, Inc.

Rope Ferry Road Waterford, CT 06385 Ms. Nancy Burton 147 Cross Highway Redding Ridge, CT 00870

Millstone Nuclear Power Station Unit 2 cc:

Mr. G. D. Hicks Master Process Owner - Training Dominion Nuclear Connecticut, Inc.

Rope Ferry Road Waterford, CT 06385 R. P. Necci Vice President - Nuclear Operations - Millstone Dominion Nuclear Connecticut, Inc.

Rope Ferry Road Waterford, CT 06385

DOMINION NUCLEAR CONNECTICUT, INC.

DOCKET NO. 50-336 MILLSTONE NUCLEAR POWER STATION, UNIT NO. 2 AMENDMENT TO FACILITY OPERATING LICENSE Amendment No. 261 License No. DPR-65

1. The Nuclear Regulatory Commission (the Commission) has found that:

A. The application for amendment by the applicant dated May 31, 2001, as supplemented August 1, 2001, and September 26, 2001, complies with the standards and requirements of the Atomic Energy Act of 1954, as amended (the Act), and the Commission's rules and regulations set forth in 10 CFR Chapter I; B. The facility will operate in conformity with the application, the provisions of the Act, and the rules and regulations of the Commission; C. There is reasonable assurance (i) that the activities authorized by this amendment can be conducted without endangering the health and safety of the public, and (ii) that such activities will be conducted in compliance with the Commission's regulations; D. The issuance of this amendment will not be inimical to the common defense and security or to the health and safety of the public; and E. The issuance of this amendment is in accordance with 10 CFR Part 51 of the Commission's regulations and all applicable requirements have been satisfied.

2. Accordingly, the license is amended by changes to the Technical Specifications as indicated in the attachment to this license amendment, and paragraph 2.C.(2) of Facility Operating License No. DPR-65 is hereby amended to read as follows:

(2)

Technical Specifications The Technical Specifications contained in Appendix A, as revised through Amendment No. 261, are hereby incorporated in the license. The licensee shall operate the facility in accordance with the Technical Specifications.

3. This license amendment is effective as of the date of issuance, and shall be implemented within 30 days of issuance.

FOR THE NUCLEAR REGULATORY COMMISSION

/RA VNerses for/

James W. Clifford, Chief, Section 2 Project Directorate I Division of Licensing Project Management Office of Nuclear Reactor Regulation

Attachment:

Changes to the Technical Specifications Date of Issuance: January 4, 2002

ATTACHMENT TO LICENSE AMENDMENT NO. 261 FACILITY OPERATING LICENSE NO. DPR-65 DOCKET NO. 50-336 Replace the following pages of the Appendix A, Technical Specifications, with the attached revised pages. The revised pages are identified by amendment number and contain marginal lines indicating the areas of change.

Remove Insert 3/4 4-4 3/4 4-4 3/4 8-1 3/4 8-1 3/4 8-1a 3/4 8-2 3/4 8-2 B 3/4 4-2a B 3/4 4-2a B 3/4 8-1b B 3/4 8-1b B 3/4 8-1c B 3/4 8-1d

SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO. 261 TO FACILITY OPERATING LICENSE NO. DPR-65 DOMINION NUCLEAR CONNECTICUT, INC.

MILLSTONE NUCLEAR POWER STATION, UNIT NO. 2 DOCKET NO. 50-336

1.0 INTRODUCTION

By letter dated May 31, 2001, as supplemented August 1, 2001, and September 26, 2001, Dominion Nuclear Connecticut, Inc., (the licensee), submitted a request for changes to the Millstone Nuclear Power Station, Unit No. 2 Technical Specifications (TSs) and Bases related to emergency diesel generator (EDG) limiting conditions for operation (LCO) action statements. The proposed change would revise TS 3.8.1.1, Electrical Power Systems - A.C. Sources - Operating, to increase the allowed outage (AOT) for one inoperable EDG from 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> to 14 days. The purpose of this proposed change is to provide the licensee with needed flexibility in performing various EDG maintenance and repair activities during plant operation. The August 1, 2001, and September 26, 2001, supplemental letters provided clarifying information, and did not change the staffs proposed no significant harzards consideration determination.

The Nuclear Regulatory Commission (NRC) staff has reviewed the proposed changes using a deterministic evaluation and reviewed the AOT changes using a probabilistic risk assessment (PRA). Section 3.0 of this evaluation addresses the deterministic aspects of the proposed changes. The probabilistic aspects of this amendment are addressed in Section 5.0.

2.0 BACKGROUND

General Design Criterion (GDC)-17, Electric Power Systems, of Appendix A, General Design Criteria for Nuclear Power Plants, to 10 CFR Part 50 requires, in part, that nuclear power plants have an onsite and offsite electric power system to permit the functioning of structures, systems and components important to safety. The onsite system is required to have sufficient independence, redundancy and testability to perform its safety function, assuming a single failure, and the offsite system is required to be supplied by two independent circuits. In addition, this criteria requires provisions to minimize the probability of losing electric power from the remaining electric power supplies as the result of loss of power from the unit, the offsite transmission network, or the onsite power supplies. GDC-18, Inspection and Testing of Electric Power Systems, requires that electric power systems important to safety be designed to permit appropriate periodic inspection and testing.

Section 8.3.1. of the Millstone Unit 2 final safety analysis report (FSAR) states that Unit 2 has two onsite EDGs and that the functional requirement of the EDGs is to provide a reliable source of power if the preferred source (offsite power) is lost, and that the adequacy of each EDG to perform its functions has been demonstrated. Section 14.0.11 of the FSAR, Plant Licensing Basis and Single Failure Criteria, states that the onsite power system and the offsite power system are designed such that each shall independently be capable of providing power for the engineered safety features to mitigate accident effects and that a loss of offsite power (LOOP) is assumed concurrent with a main steam line break, control rod ejection, loss-of-coolant accident, and loss of normal feedwater.

As described by the licensee's May 31, 2001, application, the Millstone Unit 2 Electrical Distribution System consists of normal and emergency 4160V systems. During normal operation, power is supplied through the Normal Station Service Transformer (NSST) from the main generator via the isolated phase bus, to the normal 4160V buses, 24A and 24B. The normal 4160V buses feed the emergency, or Engineered Safety Features (ESF) buses, 24C and 24D. In the event of a loss of the main generator output, offsite power is automatically supplied through the Reserve Station Service Transformer (RSST) to the 4160V ESF buses, 24C and 24D. Power to the normal 4160V buses, 24A and 24B, will then be supplied from the 4160V ESF buses 24C and 24D. During startup or shutdown, offsite power is supplied via the RSST.

Standby power is supplied by two independent and redundant EDGs. Each EDG is capable of supplying power to the respective emergency 4160V bus. During normal power operation, the EDGs are maintained in a standby mode. The EDGs may be manually started and will automatically start on a loss of power to the respective emergency bus, or a safety injection actuation signal. If the normal and alternate offsite power sources are not available, the EDGs are then automatically connected to the respective emergency bus and sequentially loaded. Upon receiving an automatic start signal, the EDGs are accelerated to rated speed, frequency, and voltage in approximately 15 seconds, and are ready to accept load in accordance with the units sequential loading schedule.

Additionally, the Millstone Unit 2 and Unit 3 electrical systems can be cross connected at the 4160V level by use of a cross-tie from Unit 3 bus 34A or 34B to Unit 2 bus 24E. This cross-tie is used to provide an alternate source of offsite power to Unit 2 from either the Unit 3 RSST or NSST. The cross-tie also provides a source of power for Unit 2 to meet the post-fire Appendix R or dedicated shutdown requirement. It is also used to provide an alternate ac (AAC) source for Unit 2 by utilizing the Unit 3 station blackout (SBO) diesel generator (DG) to supply power via bus 24E.

The main purpose of the proposed TS change is to extend the AOT for the EDGs from the current 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> to 14 days. Additional TS changes are also proposed by the licensee to support the AOT extension change. According to the licensee's application, the proposed change to the AOT would allow the performance of various EDG maintenance and repair activities during plant operation which would reduce plant refueling outage duration and improve EDG availability during shutdown.

3.0 DETERMINISTIC EVALUATION The staff has evaluated the licensees proposed amendment to Millstone Unit 2 TS using both deterministic analysis and probabilistic risk analysis methods. This section provides staffs deterministic evaluation.

3.1 Limiting Conditions For Operation (LCO) 3.8.1.1 Action a.1 This LCO currently requires that if one offsite circuit is inoperable, perform Surveillance Requirement (SR) 4.8.1.1.1 for remaining offsite circuit within 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> and at least once per 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> thereafter. The licensee has proposed to add the phrase prior to or after entering this condition to the within 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> time requirement. The licensee states that this will allow plant operators to verify operability of the remaining offsite circuit prior to removing the other offsite circuit for maintenance, which will reduce the potential to establish an adverse plant configuration. The staff finds the proposed change to be conservative and acceptable.

Additionally, the licensee has proposed to delete the footnote (*) that allowed a one-time extension of the AOT for one inoperable offsite circuit from 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> to 14 days. The footnote was added to allow completion of the work to establish a cross-tie between Millstone Units 2 and 3. Since this project has been completed, the footnote is not needed. Based on the above, the staff finds the proposed change to be acceptable.

3.2 LCO 3.8.1.1. Action b.1 This LCO currently requires that if one EDG is inoperable, perform SR 4.8.1.1.1 for the offsite circuits within 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> and at least once per 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> thereafter. The licensee has proposed to add the phrase prior to or after entering this condition to the within 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> time requirement. As stated in Action a.1, this will allow plant operators to verify operability of the remaining offsite circuit prior to removing the other offsite circuit for maintenance, which will reduce the potential to establish an adverse plant configuration. The staff finds the proposed change to be conservative and acceptable.

3.3 LCO 3.8.1.1.1. Action b.3 The licensee proposes to replace Action b.3 with new Action b.3, b.4, and b.5. This LCO currently requires that if one EDG is inoperable restore the inoperable EDG to operable status within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> or be in hot standby within the next 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> or be in cold shutdown within the following 30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br />. The licensee has proposed to extend the AOT for an inoperable EDG from the current 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> to 14 days if the additional power source requirements specified in Action Requirement b.4 are met. The purpose of the proposed change to TS 3.8.1.1, Action b, to extend the EDG AOT from the current 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> to 14 days, is to allow the licensee to perform various maintenance and repair activities on-line and to provide the licensee with increased flexibility in the scheduling of preventative maintenance and repairs of EDGs. The licensee states that it intends to use the proposed 14 day AOT for performing a planned major overhaul at a frequency of no more than once per EDG per operating cycle. Beyond that, the licensee shall continue to minimize the time periods to complete any unplanned maintenance and repair activity. In addition, the licensee states that proposed change would also improve EDG availability and reliability during shutdown.

Millstone has an AAC source available as a backup to the EDGs. The AAC source can be available within 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> of the onset of an SBO and has sufficient capacity and capability to operate systems necessary to maintain the plant in a safe shutdown condition. Thus, in the event of a LOOP and failure of the operable EDG during the extended AOT, power will be supplied from the AAC source to Millstone Unit 2 by use of a cross-tie from Unit 3 bus 34A or 34B to Unit 2 bus 24E.

The AAC is tested periodically to ensure that power supply is available upon demand.

Further, in the event an EDG is inoperable, TS 3.0.5 requires that within 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> all of the redundant systems, subsystems, trains, components and devices that depend on the remaining operable EDG as a source of emergency power are verified operable. This required action provides assurance that a LOOP event will not result in a complete loss of safety function of critical systems during the period that one of the EDGs is inoperable.

In addition, the licensee will take the following compensatory measures during the extended EDG AOT as described by the proposed Bases changes:

1. The extended diesel generator maintenance outage shall not be scheduled when adverse or inclement weather conditions and/or unstable grid conditions are predicted or present.

2. The availability of the Millstone Unit No. 3 SBO DG shall be verified by test performance within the previous 30 days prior to allowing a Millstone Unit No. 2 diesel generator to be inoperable for greater than 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />.

3. All activity in the switchyard shall be closely monitored and controlled. No elective maintenance within the switchyard that could challenge offsite power availability shall be scheduled.

The Bases also include the statement that plant configuration shall be controlled during the EDG maintenance and repair activities to minimize plant risk consistent with a Configuration Risk Management Program (CRMP), as required by 10 CFR 50.65(a)(4). Therefore, additional elective equipment maintenance or testing that requires equipment to be removed from service or that may increase the likelihood of a plant transient will be evaluated. The licensee stated in their September 26, 2001, supplement that activities that yield unacceptable evaluation results under their CRMP will be avoided.

The licensee has also proposed to add new Action Requirements b.3 and b.4. Action Requirement b.3 will verify that the steam driven auxiliary feedwater (SDAFW) pump is operable when one EDG is inoperable. This requirement will ensure sufficient auxiliary feedwater capability is available if a LOOP were to occur. If the SDAFW is inoperable and one EDG is also inoperable, restoration within 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> will be required or a plant shutdown will be necessary. Action Requirements b.4 will address the additional requirement for the Millstone Unit 3 EDG(s) to be operable and the Millstone Unit 3 SBO DG to be available to use the proposed 14-day AOT for one inoperable EDG. In addition, this requirement will limit the time Millstone Unit 2 can remain in operation with one EDG inoperable and a required Millstone Unit 3 EDG inoperable or the SBO DG unavailable to 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />. The staff finds the proposed changes to be conservative and acceptable.

3.4 LCO 3.8.1.1 Action c This LCO currently requires, in part, that if one offsite circuit and one DG are inoperable perform SR 4.8.1.1.1 for the remaining offsite circuit within 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> and at least once per 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> thereafter and demonstrate that the operable DG is not inoperable due to a common cause failure within 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> or perform SR 4.8.1.1.2.a.2 for the operable DG within 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />. The licensee has proposed to add a new Action Requirement c.3. This requirement will verify that the SDAFW pump is operable when one diesel generator and one offsite circuit are inoperable. This will ensure sufficient auxiliary feedwater capability is available if a LOOP were to occur. If the SDAFW pump is not operable, restoration of the SDAFW pump within 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> will be required or a plant shutdown will be necessary. Therefore, the staff finds the proposed change to be acceptable.

Action Requirements c.3 and c.4 will be renumbered as c.4 and c.5 to support the new action requirement. The staff finds the proposed change to be editorial and acceptable.

3.5 LCO 3.4.4 Action b This LCO currently states that the pressurizer shall be operable with at least two groups of pressurizer heaters each having a capacity of at least 130 kW capable of being supplied by emergency power. The associated surveillance requirement (SR) 4.4.4.2, requires verification that at least two groups of pressurizer heaters, which are supplied by emergency power, each have a capacity of at least 130 kW at least once per 92 days. The licensee has proposed to eliminate the capable of being supplied by emergency power from the LCO and eliminate which are supplied by emergency power from the associated SR.

The licensee proposed these changes to support the extended AOT because the current requirement could not be met when the associated EDG is inoperable because the EDG is the emergency source of power for the proportionally controlled pressurizer heaters, as shown in FSAR Figure 08.02-01. Without the proposed changes, the pressurizer would not meet the limiting condition for operation which would require plant shutdown.

The staff finds the proposed changes to the pressurizer TS consistent with the proposed changes to the EDG AOT. In addition, since the pressurizer proportional heaters are supplied from the emergency 480V electrical buses, which can also be powered through the cross-tie to Unit 3, power is available to the heaters during either a LOOP or an SBO. Therefore, the staff finds the proposed change acceptable and the associated Bases changes consistent with the TS changes.

4.0 DETERMINISTIC CONCLUSION The staff finds that an extension of the AOT for an inoperable EDG from 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> to 14 days along with the associated pressurizer heater TS changes acceptable for the following reasons:

(1) the availability of a cross tie to Unit 3 which is capable of providing Unit 2 with an alternate source of power from either the Unit 3 generator, the Unit 3 offsite power sources, or the Unit 3 SBO DG; (2) the compensatory measures that verify the operability of supporting equipment, including the operability of the SDAFW pump, operability of the Unit 3 EDG(s) and SBO DG, as reflected by the proposed TS changes; and, (3) the compensatory measures reflected by the proposed changes to the TS Bases which include controlling plant configuration during diesel maintenance and repair to minimize plant risk in accordance with the licensee's configuration risk management program. In addition, the longer AOT would reduce the number of entries into the LCO, reduce the number of EDG starts for major EDG maintenance activities, and will minimize the occurrence of an SBO during the extended AOT. The proposed Bases changes are also consistent with the proposed changes to the TSs.

5.0 PRA EVALUATION The licensee has performed a PRA of the proposed 14-day EDG AOT at Millstone Unit 2. This evaluation utilized the three-tiered approach to evaluate the risk impact of the proposed 14-day AOT.

Tier 1: PRA Insights With a 14-day AOT, it is assumed that the unavailability values will range between 200 hr/yr to 300 hr/yr per EDG. Substituting 200 hr/yr into the PRA model yields a baseline core damage frequency (CDF) of 7.41 E-05/yr compared with the current baseline CDF of 7.39 E-05/yr. This constitutes a 0.02 E-05/yr increase in CDF. If the unavailability were to become 300 hr/yr, the baseline CDF would be 7.46 E-05/yr which constitutes a 0.05 E-05 increase in CDF. The changes in CDF are within the acceptability range of Regulatory Guide (RG) 1.174. Similarly, substituting 200 hr/yr into the PRA model yields a baseline large early release frequency (LERF) of 7.920 E-07/yr, compared with the current baseline LERF of 7.917 E-07/yr, a very small increase of 0.003 E-07/yr. If the unavailability value were to become 300 hr/yr, the baseline LERF would become 7.922 E-07/yr, an increase of 0.005 E-07/yr. These changes in LERF are within the acceptability range of RG 1.174.

Assuming a 14-day AOT, the incremental conditional core damage probability (ICCDP) is 3.57 E-07, within the RG 1.177 guideline value of 5.0 E-07. The incremental large early release probability (ICLERP) is 2.07 E-09, within the RG 1.177 guideline value of 5.0 E-08.

Tier 2: Avoidance of Risk-Significant Plant Configurations A Configuration Risk Management Program (CRMP) is in place at Millstone as required by the Maintenance Rule (10 CFR 50.65(a)(4)). The licensee states that the program provides assurance that risk-significant plant equipment configurations are precluded or minimized when plant equipment is removed from service. When a Millstone Unit No. 2 EDG is removed from service, the licensee states that the following additional requirements specific to this activity are necessary to minimize plant risk:

The extended EDG outage will not be scheduled when adverse weather conditions are predicted.

Millstone Unit No. 3 EDGs will be operable, as required by Millstone Unit 3 TSs, during the Unit No. 2 EDG outage.

The availability of the Millstone Unit No. 3 SBO DG will be verified by test performance within the previous 30 days prior to allowing a Millstone Unit No. 2 DG to be inoperable for greater than 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />.

While in the proposed extended EDG AOT, additional elective equipment maintenance or testing that requires the equipment to be removed from service will have the impact of this action evaluated and activities that yield unacceptable results will be avoided.

Tier 3: Risk-Informed Configuration Risk Management Consistent with 10 CFR 50.65(a)(4), the licensee has developed a program that ensures that the risk impact of out-of-service equipment is appropriately evaluated prior to performing a maintenance activity. The licensee performs an integrated review (both probabilistic and deterministic) to identify risk significant plant equipment outage configurations in a timely manner both during the work management process and for emergent conditions during normal plant operation. Appropriate consideration is given to equipment unavailability, operational activities such as testing or load dispatching, and weather conditions. This program includes provisions for performing a configuration-dependent assessment of the overall risk impact of proposed plant configurations prior to, and during, the performance of maintenance activities that remove equipment from service. The licensee re-assesses risk if an equipment failure/malfunction or emergent condition produces a plant configuration whose risk has not been previously assessed.

For planned maintenance activities, the licensee performs an assessment of the overall risk of the activity on plant safety, including benefits to system reliability and performance prior to scheduled work. This assessment includes the following considerations:

Maintenance activities that affect redundant and diverse structures, systems, and components (SSCs) that provide backup for the same function are minimized.

The licensee does not schedule work that is highly likely to exceed a TS or Technical Requirements Manual completion time requiring a plant shutdown.

For Maintenance Rule Program high risk SSCs, the impact of the planned activity on unavailability performance criteria is evaluated.

As a final check, the licensee performs a quantitative risk assessment to ensure that the activity does not pose any unacceptable risk. This evaluation is performed with the licensees Level 1 PRA model.

The licensees emergent work is reviewed by the plants Operations Shift Management to ensure that the work is in agreement with the assumptions made during the work management process.

Prior to starting any work, the licensee critically reviews the work scope and schedule to ensure that the nuclear safety and plant operations groups are consistent with management expectations. Individual work activities that potentially have an impact on plant risk are evaluated by the licensee using system impact matrices, work document job details, plant drawings, or additional means to effectively determine the overall impact on plant risk of maintenance activities.

PRA Quality and Chronology A brief chronology of the Millstone Unit No. 2 PRA model development:

1991: Internal Events PRA completed 1993: Internal Flooding Analysis completed 1993: Internal Events model updated to reflect the as-designed, as operated plant 12/93: Individual Plant Examination (IPE) submitted 05/94: Supplement regarding a potential vulnerability identified in the IPE submittal 09/95: Responses to requests for additional information (RAIs) on the IPE submittal 12/95: Individual Plant Examination of External Events (IPEEE) submitted 05/96: IPE review completed by staff, SER issued 11/99: Combustion Engineering Owners Group (CEOG) Peer Review completed 01/00: PRA updated (Rev. 0); Plant-specific data incorporated 06/00: PRA updated (Rev. 1); Incorporated changes to address significant peer review comments and corrections of modeling errors 01/01: IPEEE completed by staff, SER issued 04/01: PRA updated (Rev. 2), Incorporating the U1/U2 electrical separation and the Unit 2 connection to Unit 3 In response to Generic Letter, (GL) 88-20, Individual Plant Examination for Severe Accident Vulnerabilities-10 CFR 50.54(f), the Millstone Unit No. 2 IPE was submitted to the NRC by letter dated December 30, 1993. The staff SER for the I.P.E.concluded that the study meets the intent of GL 88-20. The staff did, however, identify weaknesses in portions of the Level 1 and Human Reliability Analysis of the IPE. The licensee has evaluated these weaknesses and concluded that they do not impact the proposed change to the EDG AOT. These same areas were identified by the CEOG peer review, which was conducted in October 1999, and are being resolved through the licensees corrective action process.

External Events The Millstone Unit No. 2 Individual Plant Examination of External Events (MP2 IPEEE) was submitted by letter dated December 29, 1995. The staff SER on the IPEEE was received in a letter dated January 12, 2001. The staff concluded that Millstone Unit No. 2 has an acceptably low level of risk due to external events. No vulnerabilities were identified in the seismic, fire, or other external event areas. However, 29 issues were identified in the IPEEE submittal and were referred to in the IPEEE SER as opportunities for safety enhancements for further investigation and resolution.

Of the 29 issues identified, 8 issues remain under investigation and are currently being tracked by the licensees corrective action program. The licensee states that these eight issues do not impact the present license amendment request.

Pertaining to the requested change in the EDG AOT time, issues relating to high winds and tornadoes are of particular interest due to past history, and the resulting LOOP. The licensee has dispositioned issues identified with the high wind and tornado areas. This includes the issue of DG cooling ducts and dampers potentially being vulnerable to the 1.0 E-06/yr tornado pressure transient loading. The seismically related issue pertaining to a cracked isolation mount housing for a local control panel on EDG H7A has been addressed. The licensee repaired this housing in 1995.

6.0 PRA CONCLUSION The staff concludes that, since the impacts on CDF and LERF of a 14-day EDG AOT for Millstone Unit No. 2 are within the RG 1.174 guidelines and the ICCDP and ICLERP values are within the RG 1.177 guidelines, and the licensee has an acceptable configuration risk management program, a 14-day EDG AOT is acceptable. In addition, the proposed Bases changes are consistent with the proposed changes to the TSs.

7.0 STATE CONSULTATION

In accordance with the Commission's regulations, the Connecticut State official was notified of the proposed issuance of the amendment. The State official had no comments.

8.0 ENVIRONMENTAL CONSIDERATION

The amendment changes a requirement with respect to installation or use of a facility component located within the restricted area as defined in 10 CFR Part 20 and changes surveillance requirements. The NRC staff has determined that the amendment involves no significant increase in the amounts, and no significant change in the types, of any effluents that may be released offsite, and that there is no significant increase in individual or cumulative occupational radiation exposure. The Commission has previously issued a proposed finding that the amendment involves no significant hazards consideration, and there has been no public comment on such finding (66 FR 41614). Accordingly, the amendment meets the eligibility criteria for categorical exclusion set forth in 10 CFR 51.22(c)(9). Pursuant to 10 CFR 51.22(b) no environmental impact statement or environmental assessment need be prepared in connection with the issuance of the amendment.

9.0 CONCLUSION

The Commission has concluded, based on the considerations discussed above, that: (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.

Principal Contributors: O. Chopra M. Wohl Date: January 4, 2002