ML051120065

License Amendment 161 Regarding Emergency Diesel Generator Voltage and Frequency Limits

ML051120065
Person / Time
Site:	Wolf Creek
Issue date:	04/21/2005
From:	Donohew J NRC/NRR/DLPM/LPD4
To:	Muench R Wolf Creek
Donohew J N, NRR/DLPM,415-1307
Shared Package
ML051120075	List: ML051120065 ML051120197
References
TAC MC5382
Download: ML051120065 (11)

Text

April 21, 2005 Mr. Rick A. Muench President and Chief Executive Officer Wolf Creek Nuclear Operating Corporation Post Office Box 411 Burlington, KS 66839

SUBJECT:

WOLF CREEK GENERATING STATION - ISSUANCE OF AMENDMENT RE: EMERGENCY DIESEL GENERATOR VOLTAGE AND FREQUENCY LIMITS (TAC NO. MC5382)

Dear Mr. Muench:

The Commission has issued the enclosed Amendment No. 161 to Facility Operating License No. NPF-42 for the Wolf Creek Generating Station. The amendment consists of changes to the Technical Specifications (TSs) in response to your application dated December 13, 2004.

The amendment revises Technical Specification (TS) Surveillance Requirements (SR) 3.8.1.7 (fast-start test), SR 3.8.1.12 (safety injection actuation signal test), SR 3.8.1.15 (hot restart test), and SR 3.8.1.20 (redundant unit test) to clarify what voltage and frequency limits are applicable during the transient and steady state portions of the diesel generator start testing performed by these SRs.

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

Sincerely,

/RA/

Jack Donohew, Senior Project Manager, Section 2 Project Directorate IV Division of Licensing Project Management Office of Nuclear Reactor Regulation Docket No. 50-482

Enclosures:

1. Amendment No. 161 to NPF-42

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

Wolf Creek Generating Station cc:

Jay Silberg, Esq. Vice President Operations/Plant Manager Shaw Pittman, LLP Wolf Creek Nuclear Operating Corporation 2300 N Street, NW P.O. Box 411 Washington, D.C. 20037 Burlington, KS 66839 Regional Administrator, Region IV Supervisor Licensing U.S. Nuclear Regulatory Commission Wolf Creek Nuclear Operating Corporation 611 Ryan Plaza Drive, Suite 400 P.O. Box 411 Arlington, TX 76011-7005 Burlington, KS 66839 Senior Resident Inspector U.S. Nuclear Regulatory Commission U.S. Nuclear Regulatory Commission Resident Inspectors Office/Callaway Plant P.O. Box 311 8201 NRC Road Burlington, KS 66839 Steedman, MO 65077-1032 Chief Engineer, Utilities Division Kansas Corporation Commission 1500 SW Arrowhead Road Topeka, KS 66604-4027 Office of the Governor State of Kansas Topeka, KS 66612 Attorney General 120 S.W. 10th Avenue, 2nd Floor Topeka, KS 66612-1597 County Clerk Coffey County Courthouse 110 South 6th Street Burlington, KS 66839 Vick L. Cooper, Chief Air Operating Permit and Compliance Section Kansas Department of Health and Environment Bureau of Air and Radiation 1000 SW Jackson, Suite 310 Topeka, KS 66612-1366

April 21, 2005 Mr. Rick A. Muench President and Chief Executive Officer Wolf Creek Nuclear Operating Corporation Post Office Box 411 Burlington, KS 66839

SUBJECT:

WOLF CREEK GENERATING STATION - ISSUANCE OF AMENDMENT RE: EMERGENCY DIESEL GENERATOR VOLTAGE AND FREQUENCY LIMITS (TAC NO. MC5382)

Dear Mr. Muench:

The Commission has issued the enclosed Amendment No. 161 to Facility Operating License No. NPF-42 for the Wolf Creek Generating Station. The amendment consists of changes to the Technical Specifications (TSs) in response to your application dated December 13, 2004.

The amendment revises Technical Specification (TS) Surveillance Requirements (SR) 3.8.1.7 (fast-start test), SR 3.8.1.12 (safety injection actuation signal test), SR 3.8.1.15 (hot restart test), and SR 3.8.1.20 (redundant unit test) to clarify what voltage and frequency limits are applicable during the transient and steady state portions of the diesel generator start testing performed by these SRs.

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

Sincerely,

/RA/

Jack Donohew, Senior Project Manager, Section 2 Project Directorate IV Division of Licensing Project Management Office of Nuclear Reactor Regulation Docket No. 50-482 DISTRIBUTION PUBLIC GHill (2)

Enclosures:

1. Amendment No. 161 to NPF-42 PDIV-2 Reading RidsNrrPMDJaffe

2. Safety Evaluation RidsNrrDlpmPdiv(HBerkow)

RidsNrrPMJDonohew cc w/encls: See next page RidsNrrLALFeizollahi RidsOgcRp RidsAcrsAcnwMailCenter RidsRegion4MailCenter(DGraves)

RJenkins TBoyce RidsNrrDlpmPdiv2(RGramm)

TS: ML051120197 NRR-100 RidsNrrDlpmDpr ACCESSION NO.: ML051120065 PKG. ML051120075 *Nlo w/comments/corrected 4/13/05 NRR-058 OFFICE PDIV-2/PM PDIV-2/LA PDIV-1/LPM EEIB/SC OGC PDIV-2/SC NAME JDonohew LFeizollahi DJaffe RJenkins *APHoefling RGramm DATE 3/24/05 3/25/05 03/24/05 4/4/05 4/06/05 4/18/05 DOCUMENT NAME: E:\Filenet\ML051120065.wpd OFFICIAL RECORD COPY

WOLF CREEK NUCLEAR OPERATING CORPORATION WOLF CREEK GENERATING STATION DOCKET NO. 50-482 AMENDMENT TO FACILITY OPERATING LICENSE Amendment No. 161 License No. NPF-42

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

A. The application for amendment to the Wolf Creek Generating Station (the facility) Facility Operating License No. NPF-42 filed by the Wolf Creek Nuclear Operating Corporation (the Corporation), dated December 13, 2004, 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, as amended, 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 license 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-42 is hereby amended to read as follows:

2. Technical Specifications The Technical Specifications contained in Appendix A, as revised through Amendment No. 161, and the Environmental Protection Plan contained in Appendix B, both of which are attached hereto, are hereby incorporated in the license. The Corporation shall operate the facility in accordance with the Technical Specifications and the Environmental Protection Plan.

3. The license amendment is effective as of its date of issuance and shall be implemented within 90 days of the date of issuance.

FOR THE NUCLEAR REGULATORY COMMISSION

/RA/

Robert A. Gramm, Chief, Section 2 Project Directorate IV Division of Licensing Project Management Office of Nuclear Reactor Regulation

Attachment:

Changes to the Technical Specifications Date of Issuance: April 21, 2005

ATTACHMENT TO LICENSE AMENDMENT NO. 161 FACILITY OPERATING LICENSE NO. NPF-42 DOCKET NO. 50-482 Replace the following pages of the Appendix A Technical Specifications with the attached pages. The revised pages are identified by amendment number and contain marginal lines indicating the areas of change. The corresponding overleaf pages are provided to maintain document completeness.

REMOVE INSERT 3.8-8 3.8-8 3.8-10 3.8-10 3.8-12 3.8-12 3.8-16 3.8-16

SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO. 161 TO FACILITY OPERATING LICENSE NO. NPF-42 WOLF CREEK NUCLEAR OPERATING CORPORATION WOLF CREEK GENERATING STATION DOCKET NO. 50-482

1.0 INTRODUCTION

By application dated December 13, 2004, the Wolf Creek Nuclear Operating Corporation (the licensee) requested changes to the Technical Specifications (TSs, Appendix A to Facility Operating License No. NPF-42) for the Wolf Creek Generating Station (WCGS).

The proposed amendment would revise TS Surveillance Requirements (SR) 3.8.1.7 (fast-start test), SR 3.8.1.12 (safety injection actuation signal test), SR 3.8.1.15 (hot restart test), and SR 3.8.1.20 (redundant unit test) to clarify what voltage and frequency limits are applicable during the transient and steady state portions of the emergency diesel generator (EDG) start testing performed by these SRs.

2.0 REGULATORY EVALUATION

The regulatory requirements which the staff applied in its review of the amendment included:

General Design Criterion (GDC)-17, "Electric Power System," of Appendix A, "General Design Criteria for Nuclear Power Plants," to Title 10 of Code of Federal Regulations (10 CFR) Part 50, "Domestic Licensing of Production and Utilization Facilities." GDC-17 requires that an onsite electric power system and an offsite electric power system be provided to permit functioning of structures, systems, and components important to safety. GDC-17 further requires as follows:

the onsite system to have sufficient independence, redundancy, and testability, to perform its safety function, assuming a single failure. The offsite power system is required to supply electric power with two physically independent circuits that are designed and located so as to minimize, to the extent practical, the likelihood of their simultaneous failure under operating and postulated accident and environmental conditions. In addition, this criterion requires provisions to minimize the probability of losing electric power from the remaining electric power supplies as a result of loss of power from the unit, the offsite transmission network, or the onsite power supplies.

Criterion 18, "Inspection and Testing of Electric Power Systems," of Appendix A to 10 CFR Part 50, requires that electric power systems that are important to safety must be designed to permit appropriate periodic inspection and testing.

As stated in 10 CFR 50.36, "Technical Specifications," a licensees TSs will be derived from the analyses and evaluation included in the safety analysis report. Section 50.36 also requires TSs to include SRs relating to test, calibration, or inspection, to assure that necessary quality of systems and components is maintained, that the facility operation will be within safety limits, and that the limiting conditions for operation will be met.

Regulatory Position C.5 of Regulatory Guide (RG) 1.9, "Selection, Design, Qualification, and Testing of Emergency Diesel Generator Units Used as Class 1E Onsite Electric Power Systems at Nuclear Power Plants," states that each diesel engine should be capable of starting and accelerating to rated speed, and that all the necessary engineered safeguards features and emergency shutdown loads should be loaded onto the bus in an appropriate sequence.

Regulatory Position C.2.a(i) of RG 1.108, "Periodic Testing of Diesel Generator Units Used as Electric Power Systems at Nuclear Power Plants," states that at least once per 18 months, the EDG should be started and attain the required voltage and frequency within acceptable limits and times. This demonstration also needs to be performed on a periodic basis during normal operations.

3.0 TECHNICAL EVALUATION

The WCGS EDGs are described in Section 8.3.1.1.3, of "Standby Power Supply," the Wolf Creek Updated Safety Analysis Report. The WCGS has two EDGs, each with a continuous rating of 6201 kW. The design function of the EDGs is to provide alternating current power to safety systems within a specific time period during any loss of offsite power (LOOP) event. In this regard, WCGS TS Basis 3.8.1 states that, "Each DG must be capable of starting, accelerating, to rated speed and voltage, and connecting to its respective ESF [engineered safety feature] bus on detection of bus undervoltage. This will be accomplished within 12 seconds." During these LOOP events the EDGs start, and output breakers close on the de-energized bus to supply power. The EDG, once loaded, will maintain steady state voltage and frequency.

The proposed amendment would modify the acceptance criteria for SRs that verify the capability of the EDGs to start and subsequently supply the necessary safety related equipment within the time assumed in the safety analysis for the limiting accident. At the present time, the referenced SRs contain a single acceptance criterion: In #12 seconds [achieve] voltage

$3740 V [volts] and #4320 and frequency $58.8 Hz and # 61.2 Hz. The revised SRs would have two acceptance criteria: (a) In #12 seconds, [achieve] voltage $3740 V and frequency

$58.8 Hz and (b) Steady state voltage $3740 V and #4320 and frequency $58.8 Hz and

1. 61.2 Hz.

3.1 Division of Acceptance Criteria into Two Parts In the initial part of the EDG SR testing, an EDG start and acceleration, the test is performed with the EDG breaker open. The adjustment of the EDG governor is the primary consideration as to whether the EDG can satisfy the requirements of the surveillance. A balance exists between the stability of the EDG and the speed at which it accelerates to rated nominal values.

With minor degradation, the EDG will not be stable enough to satisfy the existing acceptance criteria, or the EDG will not provide rated voltage and frequency within 12 seconds.

The EDG output breaker does not automatically close unless certain conditions are satisfied.

One of these permissives is a de-energized bus; another is voltage and frequency within a specified range. Once these permissives are met, the breaker will close. With the breaker closed, the governor is essentially locked in and the EDG output is highly stable. The EDG is periodically tested with the breaker closing to verify that this capability (representative of a LOOP) is maintained. The testing performed with the breaker open only verifies the acceleration of the EDG and the voltage and frequency range that a steady state condition would provide.

Replacing each of the referenced SRs, which contain a single acceptance criterion, with an SR containing two separate criteria more closely follows the postulated accident scenario to provide fewer unnecessary test deficiencies and more stable EDG output without decreasing the efficacy of EDG testing. There is no effect on the EDG capability to supply the minimum voltage and frequency required within the 12 seconds during EDG start and acceleration or the steady state EDG voltage and frequency requirements associated with a postulated accident.

The EDGs will continue to perform their intended safety function in accordance with the design basis of the plant. The benefits of replacing a single EDG SR acceptance criterion with two criteria was accepted by the Nuclear Regulatory Commission (NRC) staff, generically, with the adoption of Revision 2 of Industry/Technical Specification Task Force (TSTF) Standard TS Change Traveler, TSTF-163, "Minimum vs. Steady State Voltage and Frequency."

The time for the EDG to reach steady state operation, unless the modified start method is utilized, is periodically monitored and the trend evaluated to identify degradation of the governor and voltage regulator performance.

On the basis of its review, the NRC staff concludes that the proposed two-part acceptance criteria in SR 3.8.1.7 (fast-start test), SR 3.8.1.12 (safety injection actuation signal test),

SR 3.8.1.15 (hot restart test), and SR 3.8.1.20 (redundant unit test) is acceptable, since the proposed changes will have no effect on the EDG capability to supply the minimum voltage and frequency required within the 12-second acceptance criteria or the steady state voltage and frequency necessary to support accident analyses assumptions.

3.2 Selection of Voltage and Frequency Limits In selecting the voltage and frequency limits for the revised, two-part acceptance criteria, the existing WCGS TS Bases 3.8.1 states:

Where the SRs discussed herein specify voltage and frequency tolerances, the following is applicable. This minimum steady state output voltage of 3740 V is 90% of the nominal 4160 V output voltage. This value, which is specified in ANSI [American National Standards Institute]

C84.1 ..., allows for voltage drop to the terminals of 4000 V motors whose minimum operating voltage is specified as 90% or 3600 V. It also allows for voltage drops to motors and other equipment down through the 120 V level where minimum operating voltage is also usually specified as 90% of name plate rating.

This value provides for the OPERABILITY of required loads as shown by

load flow calculations in support of NRC Branch Technical Position PSB-1 [of NRC Standard Review Plan, NUREG-800]. The specified maximum steady state output voltage of 4320 V ensures that for a lightly loaded distribution system, the voltage at the terminals of 4000 V motors is no more than the maximum rated operating voltages. The specified minimum and maximum frequencies of the DG [EDG] are 58.8 Hz and 61.2 Hz nominal frequency and are derived from the recommendations given in Regulatory Guide 1.9 ....

In a conference call conducted March 22, 2005, the licensee clarified the above statement from the TS Bases and explained that the "minimum steady state output voltage of 3740 V" for the EDGs mentioned above is the lower voltage limit that determines the EDGs are operable in SRs 3.8.1.2, 3.8.1.7, 3.8.1.11, 3.8.1.12, 3.8.1.15, 3.8.1.19, and 3.8.1.20. The licensee stated that this lower limit of operability for the EDG is above the minimum acceptable voltage for the 4160 V bus to operate the safety related loads during accidents to ensure that, if the EDGs are considered operable in terms of output voltage, they can adequately provide power to the safety loads on the 4160 V bus.

Based upon the above, the NRC staff concludes that the selection of voltage and frequency limits for the revised acceptance criteria continues to meet the plant-specific minimum steady state bus voltage limit, and established regulatory requirements and criteria, and is, therefore, acceptable. Based on this, the NRC staff also concludes that the proposed amendment is acceptable.

4.0 STATE CONSULTATION

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

5.0 ENVIRONMENTAL CONSIDERATION

The amendment changes the 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 (70 FR 2904). 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.

6.0 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 Contributor: D. Jaffe Date: April 21, 2005