ML080590528

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License Amendment, Revise Technical Specification Surveillance Requirements 3.3.7.3.a and 3.8.1 Degraded Voltage Function Values
ML080590528
Person / Time
Site: San Onofre  Southern California Edison icon.png
Issue date: 03/18/2008
From: Kalyanam N, Kalyanam N
NRC/NRR/ADRO/DORL/LPLIV
To: Rosenblum R
Southern California Edison Co
Kalyanam N, NRR/DORL/LPL4, 415-1480
Shared Package
ML080590305 List:
References
TAC MD4419, TAC MD4420
Download: ML080590528 (19)
v • d • e


Text

March 18, 2008 Mr. Richard M. Rosenblum Senior Vice President and Chief Nuclear Officer Southern California Edison Company San Onofre Nuclear Generating Station P.O. Box 128 San Clemente, CA 92674-0128

SUBJECT:

SAN ONOFRE NUCLEAR GENERATING STATION, UNITS 2 AND 3 -

ISSUANCE OF AMENDMENTS RE: DEGRADED VOLTAGE SETPOINTS (TAC NOS. MD4419 AND MD4420)

Dear Mr. Rosenblum:

The Commission has issued the enclosed Amendment No. 216 to Facility Operating License No. NPF-10 and Amendment No. 208 to Facility Operating License No. NPF-15 for San Onofre Nuclear Generating Station, Units 2 and 3, respectively. The amendments consist of changes to the Technical Specifications (TS) in response to your application dated February 8, 2007, as supplemented by letters dated July 24 and November 15, 2007, and February 19, 2008.

The amendments (1) revise TS Surveillance Requirement (SR) 3.3.7.3.a to lower the allowable value for dropout and raise the allowable value for pickup of the degraded voltage function, and (2) revise TS SR 3.8.1 to lower the allowable minimum diesel generator steady state voltage for the lowered values of the degraded function.

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

Sincerely,

/RA/

N. Kalyanam, Project Manager Plant Licensing Branch IV Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos. 50-361 and 50-362

Enclosures:

1. Amendment No. 216 to NPF-10
2. Amendment No. 208 to NPF-15
3. Safety Evaluation cc w/encls: See next page

(s).: PKG: ML080590305 (Amdt. ML080590528, License/TS Pgs ML080590603)

(*) Editorial changes only from Staff-provided SE (**) See previous concurrence OFFICE NRR/LPL4/PM NRR/LPL4/LA DE/EEEB/BC DE/EICB/BC DIRS/ITSB/BCA OGC-NLO w/comments NRR/LPL4/BC NAME NKalyanam (**) JBurkhardt (**) GWilson (*) WKemper (*) GWaig: N/A RHolmes (**) THiltz DATE 3/7/08 3/7/08 12/19/07 2/28/08 Not Required 3/12/08 3/17/08 San Onofre Nuclear Generating Station (December 2007)

Units 2 and 3 cc:

Douglas K. Porter, Esquire Mayor Southern California Edison Company City of San Clemente 2244 Walnut Grove Avenue 100 Avenida Presidio Rosemead, CA 91770 San Clemente, CA 92672 Dr. David Spath, Chief Mr. James T. Reilly Division of Drinking Water and Southern California Edison Company Environmental Management San Onofre Nuclear Generating Station California Dept. of Health Services P.O. Box 128 850 Marina Parkway, Bldg P, 2nd Floor San Clemente, CA 92674-0128 Richmond, CA 94804 Mr. James D. Boyd Chairman, Board of Supervisors California State Liaison Officer County of San Diego Vice Chair and Commissioner 1600 Pacific Highway, Room 335 California Energy Commission San Diego, CA 92101 1516 Ninth Street, MS 31 Sacramento, CA 95814 Mark L. Parsons Deputy City Attorney Mr. Gary Butner City of Riverside Acting Branch Chief 3900 Main Street Department of Public Health Services Riverside, CA 92522 Radiologic Health Branch MS 7610, P.O. Box 997414 Mr. Gary L. Nolff Sacramento, CA 95899-7414 Assistant General Manager - Resources Riverside Public Utilities Mr. Ross T. Ridenoure City of Riverside, California Vice President and Site Manager 3901 Orange Street Southern California Edison Company Riverside, CA 92501 San Onofre Nuclear Generating Station P.O. Box 128 Regional Administrator, Region IV San Clemente, CA 92674-0128 U.S. Nuclear Regulatory Commission 611 Ryan Plaza Drive, Suite 400 Mr. A. Edward Scherer Arlington, TX 76011-8064 Director, Nuclear Regulatory Affairs Southern California Edison Company Mr. Michael L. De Marco San Onofre Nuclear Generating Station San Diego Gas & Electric Company P.O. Box 128 8315 Century Park Ct. CP21G San Clemente, CA 92674-0128 San Diego, CA 92123-1548 Resident Inspector San Onofre Nuclear Generating Station c/o U.S. Nuclear Regulatory Commission Post Office Box 4329 San Clemente, CA 92674

SOUTHERN CALIFORNIA EDISON COMPANY SAN DIEGO GAS AND ELECTRIC COMPANY THE CITY OF RIVERSIDE, CALIFORNIA DOCKET NO. 50-361 SAN ONOFRE NUCLEAR GENERATING STATION, UNIT 2 AMENDMENT TO FACILITY OPERATING LICENSE Amendment No. 216 License No. NPF-10

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

A. The application for amendment by Southern California Edison Company, et al.

(SCE or the licensee), dated February 8, 2007, as supplemented by letters dated July 24 and November 15, 2007, and February 19, 2008, complies with the standards and requirements of the Atomic Energy Act of 1954, as amended (the Act), and the Commission's 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. NPF-10 is hereby amended to read as follows:

(2) Technical Specifications The Technical Specifications contained in Appendix A and the Environmental Protection Plan contained in Appendix B, as revised through Amendment No. 216, are hereby incorporated in the license.

Southern California Edison Company shall operate the facility in accordance with the Technical Specifications and the Environmental Protection Plan.

3. This license amendment is effective as of the date of its issuance and shall be implemented within 60 days of issuance.

FOR THE NUCLEAR REGULATORY COMMISSION

/RA/

Thomas G. Hiltz, Chief Plant Licensing Branch IV Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation

Attachment:

Changes to the Facility Operating License and Technical Specifications Date of Issuance: March 18, 2008

ATTACHMENT TO LICENSE AMENDMENT NO. 216 FACILITY OPERATING LICENSE NO. NPF-10 DOCKET NO. 50-361 Replace the following pages of the Facility Operating License No. NPF-10 and 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.

Facility Operating License REMOVE INSERT Technical Specifications REMOVE INSERT 3.3-34 3.3-34 3.8-5 3.8-5 3.8-7 3.8-7 3.8-8 3.8-8 3.8-9 3.8-9 3.8-10 3.8-10 3.8-11 3.8-11 3.8-12 3.8-12 3.8-14 3.8-14 3.8-15 3.8-15

SOUTHERN CALIFORNIA EDISON COMPANY SAN DIEGO GAS AND ELECTRIC COMPANY THE CITY OF RIVERSIDE, CALIFORNIA DOCKET NO. 50-362 SAN ONOFRE NUCLEAR GENERATING STATION, UNIT 3 AMENDMENT TO FACILITY OPERATING LICENSE Amendment No. 208 License No. NPF-15

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

A. The application for amendment by Southern California Edison Company, et al.

(SCE or the licensee), dated February 8, 2007, as supplemented by letters dated July 24 and November 15, 2007, and February 19, 2008, complies with the standards and requirements of the Atomic Energy Act of 1954, as amended (the Act), and the Commission's 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. NPF-15 is hereby amended to read as follows:

(2) Technical Specifications The Technical Specifications contained in Appendix A and the Environmental Protection Plan contained in Appendix B, as revised through Amendment No. 208, are hereby incorporated in the license.

Southern California Edison Company shall operate the facility in accordance with the Technical Specifications and the Environmental Protection Plan.

3. This license amendment is effective as of the date of its issuance and shall be implemented within 60 days of issuance.

FOR THE NUCLEAR REGULATORY COMMISSION

/RA/

Thomas G. Hiltz, Chief Plant Licensing Branch IV Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation

Attachment:

Changes to the Facility Operating License and Technical Specifications Date of Issuance: March 18, 2008

ATTACHMENT TO LICENSE AMENDMENT NO. 208 FACILITY OPERATING LICENSE NO. NPF-15 DOCKET NO. 50-362 Replace the following pages of the Facility Operating License No. NPF-15 and 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.

Facility Operating License REMOVE INSERT Technical Specifications REMOVE INSERT 3.3-34 3.3-34 3.8-5 3.8-5 3.8-7 3.8-7 3.8-8 3.8-8 3.8-9 3.8-9 3.8-10 3.8-10 3.8-11 3.8-11 3.8-12 3.8-12 3.8-14 3.8-14 3.8-15 3.8-15

SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO. 216 TO FACILITY OPERATING LICENSE NO. NPF-10 AND AMENDMENT NO. 208 TO FACILITY OPERATING LICENSE NO. NPF-15 SOUTHERN CALIFORNIA EDISON COMPANY SAN DIEGO GAS AND ELECTRIC COMPANY THE CITY OF RIVERSIDE, CALIFORNIA SAN ONOFRE NUCLEAR GENERATING STATION, UNITS 2 AND 3 DOCKET NOS. 50-361 AND 50-362

1.0 INTRODUCTION

By application dated February 8, 2007 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML070440046), as supplemented by letters dated July 24 and November 15, 2007, and February 19, 2008 (ADAMS Accession Nos. ML072060651, ML073300559, and ML080520372, respectively), Southern California Edison Company (SCE, the licensee) requested changes to the Technical Specifications (TS) for San Onofre Nuclear Generating Station (SONGS), Units 2 and 3. The supplemental letters dated July 24 and November 15, 2007, and February 19, 2008, provided additional information that clarified the application, did not expand the scope of the application as originally noticed, and did not change the U.S. Nuclear Regulatory Commission (NRC) staff's original proposed no significant hazards consideration determination as published in the Federal Register on March 27, 2007 (72 FR 14307).

The changes revise TS 3.3.7, "Diesel Generator (DG) - Undervoltage Start," Surveillance Requirement (SR) 3.3.7.3.a to lower the allowable value for dropout and raise the allowable value for pickup of the degraded voltage function. In addition, in TS 3.8.1, "AC [Alternating Current] Sources - Operating," the changes revise SR 3.8.1.2, 3.8.1.7, 3.8.1.9, 3.8.1.11, 3.8.1.12, 3.8.1.15, 3.8.1.16, 3.8.1.17, 3.8.1.19, and 3.8.1.20 to lower the allowable minimum DG steady state voltage for the lowered values of the degraded function.

2.0 EVALUATION 2.1 INSTRUMENTATION AND CONTROL 2.1.1 Regulatory Evaluation The NRC staff used the following regulatory bases and guidance documents in its evaluation of the license amendment request (LAR):

  • Part 50 of Title 10 of the Code of Federal Regulations (10 CFR) includes NRCs requirement that TS shall be included by applicants for a license authorizing operation of a production or utilization facility. 10 CFR 50.36(d) requires that TSs include items in five specific categories related to station operation. These categories are (1) safety limits, limiting safety system settings, and limiting control settings; (2) limiting conditions for operations (LCOs); (3) SR; (4) design features; and (5) administrative controls.
  • Section 50.36, ATechnical specifications,@ of 10 CFR states A[e]ach applicant for a license authorizing operation of a production or utilization facility shall include in his application proposed technical specifications in accordance with the requirements of this section.@ Specifically, 10 CFR 50.36(d)(1)(ii)(A) states A[w]here a limiting safety system setting is specified for a variable on which a safety limit has been placed, the setting must be so chosen that automatic protective action will correct the abnormal situation before a safety limit is exceeded.@ Furthermore, 10 CFR 50.36(d)(3) states A[s]urveillance requirements are requirements relating to test, calibration, or inspection to assure that the necessary quality of systems and components is maintained, that facility operation will be within safety limits, and that the limiting conditions for operation will be met.@
  • 10 CFR Part 50, Appendix A, AGeneral Design Criteria [GDC] for Nuclear Power Plants,@ GDC 13, AInstrumentation and control,@ requires, in part, that the instrumentation be provided to monitor variables and systems and that controls be provided to maintain these variables and systems within prescribed operating ranges.
  • 10 CFR Part 50, Appendix A, GDC 20, AProtection system functions,@ requires, in part, that the protection system be designed to initiate operation of appropriate systems to ensure that the specified acceptable fuel design limits are not exceeded.
  • Regulatory Guide (RG) 1.105, Revision 3, ASetpoints for Safety-Related Instrumentation,@ describes a method acceptable to the NRC staff for complying with the NRC=s regulations for ensuring that setpoints for safety-related instrumentation are initially within and remain within the TS limits. The RG endorses Part I of ISA

[Instrumentation, Systems, and Automatic Society]-S67.04-1994, ASetpoints for Nuclear Safety Instrumentation,@ subject to the NRC staff clarifications.

  • NRC Regulatory Issue Summary (RIS) 2006-17, ANRC Staff Position on the Requirements of 10 CFR 50.36, Technical Specifications, Regarding Limiting Safety System Settings During Periodic Testing and Calibration of Instrument Channels,@

dated August 24, 2006 (ADAMS Accession No. ML051810077), addresses the NRC=s

requirements on LSSS assessed during periodic testing and calibration of instrumentation. This RIS discusses issues that could occur during testing of LSSS and which, therefore, may have an adverse effect on equipment operability.

  • Letter from Patrick L. Hilland, NRC, to NEI [Nuclear Energy Institute] Setpoint Methods Task Force, ATechnical Specification for Addressing Issues Related to Setpoint Allowable Values,@ dated September 7, 2005 (ADAMS Accession No. ML052500004).

This letter addresses the footnotes that should be added to the SR related to setpoint verification surveillance for instrument functions on which a safety limit (SL) has been placed and the information to be included to ensure operability of the instruments following surveillance tests related to instrument setpoints.

  • Letter from Bruce A. Boger, NRC, to Alexander Marion, Nuclear Energy Institute (NEI),

AInstrumentation, Systems, and Automatic Society (ISA) S67.04 Methods for Determining Trip Setpoints and Allowable Values for Safety-Related Instrumentation,@

dated August 23, 2005 (ADAMS Accession No. ML051660447).

  • Letter from James A. Lyons, NRC, to Alexander Marion, NEI, AInstrumentation, Systems and Automation Society S67.04 Methods for Determining Trip Setpoints and Allowable Values for Safety-Related Instrumentation,@ dated March 31, 2005 (ADAMS Accession No. ML050870008).

2.1.2 Technical Evaluation In its letter dated February 8, 2007, the licensee stated that currently it is performing surveillance tests at increased frequencies because of the tighter band between dropout and pickup of degraded voltage relays. The licensee is replacing two related feeder cables to reduce voltage drop in those limiting feeders. The licensee proposes to lower the degraded voltage relay dropout voltage from A$ 4123.0 V [Volts]@ to A$ 4109.0 V@ and increase the pickup voltage from A# 4144.6 V@ to A# 4153.1 V@ in SR 3.3.7.3.a and lower the lower limit of steady state voltage from A$ 4297 V@ to A$ 4161 V@ in SR 3.8.1.2.a, 3.8.1.7.a, 3.8.1.7.b, 3.8.1.9.b, 3.8.1.11.c.2, 3.8.1.12.a, 3.8.1.12.b, 3.8.1.15.a, 3.8.1.15.b, 3.8.1.16.c.1, 3.8.1.17.a.1, 3.8.1.19.c.3, 3.8.1.20.a, and 3.8.1.20.b in TS 3.8.1, AAC Sources B Operating.@ The licensee stated that increasing the operating band will allow it to return to a TS surveillance interval of 24 months.

In response to the NRC staffs request for additional information, by letter dated November 15, 2007, the licensee stated that the proposed TS changes are not SL-related because the voltage on Class 1E buses provides a support function to SL-related components, but does not trigger any function in the Engineered Safety Features Activation Systems (ESFAS) or the Reactor Protection System (RPS). The staff concurs with this justification and agrees that there is no need to add the two footnotes to the TS for the revised setpoints as specified in the NRC letter dated September 7, 2005.

By letter dated November 15, 2007, the licensee provided setpoint calculation E4C-130-ECN A47480, ATLU [Total Loop Uncertainties] Calculation for Undervoltage Relay Circuit at Class 1E 4 kV [kiloVolt] Switchgear,@ for the proposed TS changes. In this calculation, the licensee assumed a relay drift of "0.45 percent in calculating the acceptable as-found value.

The licensee used square root of sum of the squares of the independent variables in

calculating the TLU and arrived at a value of "0.5934 percent. The staff questioned the validity of assuming a relay drift of "0.45 percent when the TLU is "0.5934 percent. In response, the licensee provided Section 3.2.2 of calculation E4C-130-ECN A47480 which included field data on the plant as-found test values between July 2005 and July 2007. This drift evaluation demonstrated that the selected relay drift of "0.45 percent provided at least 95 percent probability that the selected relay drift contains 95 percent of the population of interest in conformance with RG 1.105. In Section 2.2.7 of the calculation E4C-130-ECN A47480, it is stated that the implementation of the relay drift value will be tracked by Action Report (i.e., Corrective Action Plan) AR 0601140-24. By letter dated February 19, 2008, the licensee stated that the setting tolerance of "0.05 V alternating current (Vac), which corresponds to the acceptable as-left tolerance, was based on plant experience. Compared to the calculated TLU and the as-found tolerance, this as-left tolerance is reasonably low.

The degraded voltage setpoint calculation has an upper limit and a lower limit for the various setpoint parameters, e.g. Analytical Limit, AV, acceptable as-found value, and acceptable as-left value. In addition, the degraded voltage relay has pick-up (PU) and drop-out (DO) settings. The licensee used the acceptable as-found limit as the AV and added margin to TLU in calculating the NTSP. Listed below are the important setpoint parameters:

Parameter Calculated Voltage Upper Analytical Limit 4161 Upper Margin 2 TLU 24.5 NTSP PU 4134.5 NTSP DO 4127.5 AV tolerance 18.5 Upper AV < 4153.1 Lower AV > 4109 Lower Margin 3.1 Lower Analytical Limit 4100 By letter dated November 15, 2007, the licensee provided Test Procedure SO2-II-11.1A(B)-2, which provides the details of SR performed every 24 months to verify the as-found relay settings and adjust the relay settings within the as-left values provided in the setpoint calculations. The licensee also stated that the inoperable or degraded channels are entered into the plant corrective action program per plant procedures, SO 123-I-1.3, Work Activity Guidelines, SO 123-0-A5, and TS Limiting Condition for Operation Action Requirement/

Equipment Deficiency Mode Restraint. In addition, by letter dated February 19, 2008, the licensee provided the following commitments:

  • If the as-found relay setpoint is conservative with respect to the Allowable Value but outside its predefined as-found acceptance criteria band, then the relay shall be evaluated to verify that it is functioning as required before returning the channel to service. If the as-found relay setpoint is not conservative with respect to the Allowable Value, the relay shall be declared inoperable.
  • The relay setpoint shall be reset to a value that is within the as-left tolerance of the nominal relay setpoint; otherwise, the relay shall be declared inoperable.
  • If the as-found trip setpoint (TSP) is found to be non-conservative with respect to the allowable value (AV) specified in the Technical Specifications (TSs), the relay shall be declared inoperable and the associated TS action statement followed.
  • If the as-found TSP is found to be conservative with respect to the AV, and outside the as-found predefined acceptance criteria band, but SCE is able to determine that the relay is functioning as required and can be reset to within the setting tolerance of the limiting TSP, or a value more conservative than the limiting TSP, then the relay may be considered operable. If it cannot be determined that the relay is functioning as required, it shall be declared inoperable and the associated TS actions followed.
  • If the as-found TSP is outside the as-found predefined acceptance criteria band, the condition shall be entered into the corrective action program for further evaluation.

The staff finds that the above commitments on plant procedures for surveillance tests conform to the NRC letter dated September 7, 2005, and therefore, acceptable.

The staff also finds the deletion of the footnote A*Dropout and pickup values will be set to

$ 4151.0 V and # 4172.8 V, respectively, until actions identified in SCE submittal dated May 27, 2005 are completed,@ from SR 3.3.7.3.a is administrative in nature and, therefore, acceptable.

2.1.3 Summary The staff finds that the proposed TS changes do not trigger any engineered safety features actuation systems or the reactor protection system and, therefore, is not SL-Related and the footnotes specified in the NRC letter dated September 7, 2005, need not be added to the proposed TS changes. Furthermore, the methodology for calculating the setpoints conform to RG 1.105, RIS 2006-17, and NRC letter dated September 7, 2005.

The licensee committed to perform SR that conform to the NRC letter dated September 7, 2005. The NRC staff finds that reasonable controls for the implementation and for subsequent evaluation of proposed changes pertaining to the regulatory commitments are best provided by the licensee's administrative processes, including its commitment management program. The regulatory commitments do not warrant the creation of regulatory requirements (items requiring prior NRC approval of subsequent changes).

The proposed deletion of the footnote to SR 3.3.7.3.a is administrative in nature and, therefore, acceptable to the staff. In conclusion, the staff finds all the three TS changes listed in Section 1.0 acceptable.

2.2 ELECTRICAL AND DISTRIBUTION 2.2.1 Regulatory Evaluation The NRC staff used the following regulatory requirements and guidance documents to review the LAR:

  • 10 CFR Part 50, Appendix A, GDC 17, "Electric power systems," requires, in part, that an offsite electric power system shall be provided to permit functioning of structures, systems, and components important to safety. The safety function for each system shall be to provide sufficient capacity and capability to assure that (1) specified acceptable fuel design limits and design conditions of the reactor coolant pressure boundary are not exceeded as a result of anticipated operational occurrences and (2) the core is cooled and containment integrity and other vital functions are maintained in the event of postulated accidents.

The degraded grid voltage relay and loss of voltage relay trip set points and associated time delays assure proper operation of safety-related loads as required by GDC 17 of 10 CFR Part 50, Appendix A.

  • 10 CFR, Part 50, Section 50.36(d)(3), technical specifications for surveillance requirements, which are requirements relating to test, calibration, or inspection to assure that the necessary quality of systems and components is maintained, that facility operation will be within safety limits, and that the limiting conditions for operation will be met.
  • RG 1.9, Revision 3, ASelection, Design, Qualification, and Testing of Emergency Diesel Generator Units Used as Class 1E Onsite Electric Power systems at Nuclear Power Plants,@ describes a method acceptable to the NRC staff for complying with the Commission=s regulations with regard to periodic testing of diesel generators.
  • Standard Review Plan for the Review of Safety Analysis Reports for Nuclear Power Plants (NUREG-0800), Appendix 8-A, Branch Technical Position PSB-1, AAdequacy of Station Electric Distribution System Voltages,@ provides guidance for degraded voltage protection.

2.2.2 Technical Evaluation 2.2.2.1 Changes to Allowable Values for Degraded Voltage Function Existing Design The degraded voltage protection at SONGS 2 and 3 ensures that the 4160 V Class 1E buses (1) do not separate from the offsite power/normal preferred source when the switchyard voltage is at or above 218 kV, and (2) provide adequate voltage to support operability of plant safety equipment to meet the requirements of GDC 17. The degraded voltage function is designed with (1) a long-time delay assuming sustained degraded conditions, and (2) a short-time delay (to ride through a voltage transient).

(1) Sustained Degraded Voltage Protection (with long-time delay)

The voltage and time delay settings are such that the connected Class 1E loads will not be damaged due to a long or sustained degraded voltage condition.

Four undervoltage relays (ASEA Brown Boveri ABB 27N, definite time delay solid state relay),

127D1, 2, 3, and 4, along with four timing relays, 162D1, 2, 3, and 4, are provided on each 4160 V Class 1E bus for the sustained degraded voltage detection scheme. The 127D relays are set to operate at nominal value of 4132.1 V (99.3 percent), with a response time of 2 seconds.

The 162D timing relays are set at nominal 110 seconds. These signals are combined in a two-out-of-four logic, and the resulting signal is referred to as the Sustained Degraded Voltage Signal (SDVS). As such, an SDVS is generated in approximately 112 seconds after detection of degraded voltage.

The SDVS performs the following functions:

  • SDVS without safety injection actuation signal (SIAS) will transfer the 4160 V Class 1E bus to the alternate preferred power source, based on a slow transfer scheme (a residual voltage relay initiates the bus transfer when the residual voltage at the 4160 V bus decreases below 25 percent of 4160 V). If the alternate preferred power source is not available, SDVS will transfer the 4160 V Class 1E bus to the DG; and
  • SDVS with SIAS will transfer the 4160 V Class 1E bus directly to the DG (transfer to alternate source is bypassed). The SDVS signal is blocked when the 4160 V Class 1E bus is powered from the DG.

(2) Degraded Grid Voltage with SIAS (with short-time delay)

This protection is designed to actuate in the event of an SIAS with a degraded grid condition.

Following the acceleration of first load group during post-accident engineered safety features (ESF) load sequencing, the degraded voltage scheme senses the voltage on the 4160 V Class 1E bus. If the voltage is below the minimum analyzed value, the 4160 V Class 1E bus will separate from the preferred power source and transfer to the DG. The time delay for this signal is chosen to ride through the voltage transients and to ensure that adequate voltage is available on the 4160 V Class 1E buses during post-accident ESF load sequencing.

One output contact from each of the 127D1, 2, 3, and 4 undervoltage relays along with short-time delay signals from timers 162S1, 2, 3, and 4 (nominal 4.3 second time delay), and timers 162T1, 2, 3, and 4 (nominal 1.25 second time delay, as detailed in Figure D-17 in final safety analysis report (FSAR)), concurrent with SIAS signal are combined in a two-out-of-four logic, and the resulting signal is referred to as Degraded Grid Voltage with SIAS Signal (DGVSS). In its letter dated November 15, 2007, the licensee explained that the 162T timers are used to "close" the DGVSS window. The 162S and 162T timers ensure that (1) load shedding and transfer of the bus to the DGs occurs within the time allowed in the safety analyses, and (2) the voltage dip caused by the starting of the ESF load group 2 does not generate a spurious DGVSS. The DGVSS window will enable detection of the degraded

voltage in the first ESF load group sequence and will not be affected by the subsequent ESF load-starting transients.

Currently, the SR 3.3.7.3.a, ADegraded Voltage Function,@ has the following dropout and pickup values. The corresponding analytical values are also listed:

Pickup # 4144.6 V (TS Upper Allowable Value)

Dropout $ 4123.0 V (TS Lower Allowable Value)

Upper Analytical Limit: 4161.0 V Lower Analytical Limit: 4106.0 V The current allowable and analytical values were discussed in a previous LAR dated May 27, 2005 (ADAMS Accession No. ML051530034), which was approved by NRC on July 1, 2005 (ADAMS Accession No. ML051860407).

Proposed Modification The licensee proposed to reduce the lower analytical limit by 6 V (from 4106.0 V to 4100.0 V), and specify a wider band of allowable values (i.e., pickup and dropout values) for the degraded voltage protection function. The proposed new values are as follows:

Pickup # 4153.1 V (Increase in TS Upper Allowable Value)

Dropout $ 4109.0 V (Decrease in TS Lower Allowable Value)

Upper Analytical Limit: 4161.0 V (no change)

Lower Analytical Limit: 4100.0 V (6V Decrease in Value)

The licensee stated in the LAR that it has been performing the SR at an increased frequency because of a tighter band of allowable values. A reduction in the lower analytical limit helps in specifying a wider range of allowable values and returning to TS surveillance interval of 24 months. The proposed dropout and pickup allowable values are based on ATLU Calculation for Undervoltage Relay Circuits at Class 1E 4 kV Switchgear,@ performed by the licensee. An excerpt of this calculation was enclosed with the licensee=s letter dated November 15, 2007.

The licensee will be modifying the two limiting power feeders (increasing the effective size of the power feeders) to reduce voltage drop to facilitate a reduction in the lower analytical voltage from 4106.0 V to 4100.0 V. The modifications that will be implemented are as follows:

1. Add feeder cable to MCC 2BD in parallel with the existing feeder from Load Center 2B04 to reduce the voltage drop in the feeder.
2. Increase 120 Vac power feeder size to 120 Vac panel 2L541 from MCC panel 2Q039 by replacing the feeder cable from #12 AWG to #8 AWG for reducing voltage drop in the feeder circuit.

The NRC staff evaluated the reduction in the lower analytical limit of the degraded voltage analysis and considered it to be acceptable in view of the proposed modifications to the two limiting power feeders. Since the revised upper and lower allowable values are within the upper and lower analytical values, the staff considers the revised allowable values acceptable.

2.2.2.2 DG Minimum Output Voltage Presently, in TS 3.8.1, SR 3.8.1.2, 3.8.1.7, 3.8.1.9, 3.8.1.11, 3.8.1.12, 3.8.1.15, 3.8.1.16, 3.8.1.17, 3.8.1.19, and 3.8.1.20, the minimum DG voltage is specified as 4297 V. The licensee has also proposed to revise this value as 4161 V as the minimum DG voltage necessary to support operability of the DG. The 4161 V value is based on the upper analytical limit. The licensee stated that this change will allow DG voltage regulator to be set closer to nominal design (4360 V "80 V instead of 4460 V "80 V presently set).

The NRC staff review found that the revised 4161 V value is above the minimum allowable value of the degraded voltage function which is necessary to provide adequate voltage to emergency core coolant system equipment. In its letter dated July 24, 2007, the licensee confirmed that the proposed changes to TS 3.8.1 SR (i.e., 4161 V minimum DG steady state voltage) will not impact the DG capability to meet the guidance of RG 1.9, Revision 3, Section C.1.4 pertaining to the starting and load-accepting capability of the DG. This section of RG 1.9 states that, each diesel generator unit design should be capable of starting and accelerating to rated speed, in the required sequence, all the needed engineered safety feature and emergency shutdown loads. The diesel generator unit design should be such that at no time during the loading sequence should the frequency decrease to less than 95 percent of nominal nor the voltage decrease to less than 75 percent of nominal.

Therefore, the staff concludes that the proposed changes to TS 3.8.1, SR 3.8.1.2, 3.8.1.7, 3.8.1.9, 3.8.1.11, 3.8.1.12, 3.8.1.15, 3.8.1.16, 3.8.1.17, 3.8.1.19, and 3.8.1.20 are acceptable.

2.2.3 Summary The NRC staff has reviewed the licensee=s proposed TS changes and supporting documentation. Based on the review discussed above, the NRC staff concluded that the proposed changes will not impact the licensee=s compliance to the regulatory requirements listed in Section 2.2.1 of this evaluation. Therefore, the changes are acceptable.

3.0 STATE CONSULTATION

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

4.0 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. 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 published in the Federal Register on March 27, 2007 (72 FR 14307). 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.

5.0 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 amendments will not be inimical to the common defense and security or to the health and safety of the public.

Principal Contributors: V. Goel S. Mazumdar Date: March 18, 2008

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