ML13282A147
| ML13282A147 | |
| Person / Time | |
|---|---|
| Site: | Wolf Creek  |
| Issue date: | 12/02/2013 |
| From: | Lyon C Plant Licensing Branch IV |
| To: | Matthew Sunseri Wolf Creek |
| Lyon C | |
| References | |
| TAC ME9603 | |
| Download: ML13282A147 (14) | |
Text
UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 December 2, 2013 Mr. Matthew W. Sunseri 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:
REVISE TECHNICAL SPECIFICATION 3.8.1, "AC SOURCES-OPERATING" (TAC NO. ME9603)
Dear Mr. Sunseri:
The U.S. Nuclear Regulatory Commission (the Commission) has issued the enclosed Amendment No. 206 to Renewed Facility Operating License No. NPF 42 for the Wolf Creek Generating Station. The amendment consists of a change to the Technical Specifications (TSs) in response to your application dated September 19, 2012, as supplemented by letter dated July 15, 2013.
The amendment increases the voltage limit for the emergency diesel generator full load rejection test specified by TS 3.8.1, "AC [Alternating Current] Sources - Operating," Surveillance Requirement 3.8.1.1 0.
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.
Docket No. 50-482
Enclosures:
- 1. Amendment No. 206 to NPF-42
- 2. Safety Evaluation cc w/encls: Distribution via Listserv Sincerely, Carl F. Lyon, Project Manager Plant Licensing Branch IV-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation
UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 WOLF CREEK NUCLEAR OPERATING CORPORATION WOLF CREEK GENERATING STATION DOCKET NO. 50-482 AMENDMENT TO RENEWED FACILITY OPERATING LICENSE Amendment No. 206 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)
Renewed Facility Operating License No. NPF-42 filed by the Wolf Creek Nuclear Operating Corporation (the Corporation), dated September 19, 2012, as supplemented by letter dated July 15, 2013, 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 Renewed Facility Operating License No. NPF-42 is hereby amended to read as follows:
(2)
Technical Specifications and Environmental Protection Plan The Technical Specifications contained in Appendix A, as revised through Amendment No. 206, and the Environmental Protection Plan contained in Appendix 8, 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.
Attachment:
Changes to the Renewed Facility Operating License and Technical Specifications FOR THE NUCLEAR REGULA TORY COMMISSION Michael T. Markley, Chief Plant Licensing Branch IV-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Date of Issuance: December 2, 2013
ATIACHMENT TO LICENSE AMENDMENT NO. 206 RENEWED FACILITY OPERATING LICENSE NO. NPF-42 DOCKET NO. 50-482 Replace the following pages of the Renewed Facility Operating License No. NPF-42 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.
Renewed Facility Operating License REMOVE INSERT 4
4 Technical Specifications REMOVE INSERT 3.8-9 3.8-9
4 (5)
The Operating Corporation, pursuant to the Act and 10 CFR Parts 30, 40 and 70, to receive, possess, and use in amounts as required any byproduct, source or special nuclear material without restriction to chemical or physical form, for sample analysis or instrument calibration or associated with radioactive apparatus or components; and (6)
The Operating Corporation, pursuant to the Act and 10 CFR Parts 30, 40 and 70, to possess, but not separate, such byproduct and special nuclear materials as may be produced by the operation of the facility.
C.
This renewed operating license shall be deemed to contain and is subject to the conditions specified in the Commission=s regulations in 10 CFR Chapter I and is subject to all applicable provisions of the Act and to the rules, regulations, and orders of the Commission, now or hereafter in effect; and is subject to the additional conditions specified or incorporated below:
(1)
Maximum Power Level The Operating Corporation is authorized to operate the facility at reactor core power levels not in excess of 3565 megawatts thermal (1 00%
power) in accordance with the conditions specified herein.
(2)
Technical Specifications and Environmental Protection Plan The Technical Specifications contained in Appendix A, as revised through Amendment No. 206, 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)
Antitrust Conditions Kansas Gas & Electric Company and Kansas City Power & Light Company shall comply with the antitrust conditions delineated in Appendix C to this license.
(4)
Environmental Qualification (Section 3.11 I SSER #41 Section 3.11 I SSER #5)*
Deleted per Amendment No. 141.
- The parenthetical notation following the title of many license conditions denotes the section of the supporting Safety Evaluation Report and/or its supplements wherein the license condition is discussed.
Renewed License No. NPF-42 Amendment No. 206
AC Sources - Operating 3.8.1 SURVEILLANCE REQUIREMENTS (continued)
SR 3.8.1.7 SR 3.8.1.8 SR 3.8.1.9 SR 3.8.1.10 Wolf Creek - Unit 1 SURVEILLANCE
NOTE----------------------------
All DG starts may be preceded by an engine prelube period.
Verify each DG starts from standby condition and achieves:
- a.
In~ 12 seconds, voltage~ 3740 V and frequency
- 58.8 Hz; and
- b.
Steady state voltage~ 3740 V and~ 4320 V, and frequency;;:: 58.8 Hz and ~ 61.2 Hz.
Not Used.
Not Used.
FREQUENCY 184 days Verify each DG operating at a power factor ~ 0.9 and 18 months
- 0.8 does not trip and voltage is maintained ~ 4992 V and frequency is maintained ~ 65.4 Hz during and following a load rejection of~ 5580 kW and ~ 6201 kW.
(continued) 3.8-9 Amendment No. 123, 154, 161, 163, 206
UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO. 206 TO RENEWED 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 September 19, 2012 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML12272A279), as supplemented by letter dated July 15, 2013 (ADAMS Accession No. ML 1321 OA246), Wolf Creek Nuclear Operating Corporation (the licensee) requested a change to the Technical Specifications (TSs) for Wolf Creek Generating Station (WCGS). The supplemental letter dated July 15, 2013, 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 October 30, 2012 (77 FR 65726).
The proposed change would increase the voltage limit for the emergency diesel generator (DG) full load rejection test specified by TS 3.8.1, "AC [Alternating Current] Sources-Operating,"
Surveillance Requirement (SR) 3.8.1.1 0.
Specifically, the licensee proposes to revise the maximum voltage limit following a DG full load rejection in TS SR 3.8.1.1 0, Full Load Rejection Test, from a value of less than or equal to
(~) 4784 Volts (V) to a value of~ 4992 V.
2.0 REGULATORY EVALUATION
The NRC staff referred to the following regulatory requirements and guidance documents during its review of the application:
The WCGS Updated Safety Analyses Report (USAR) Section 8.1.4.2, "Onsite Power System," states that the offsite power system and the onsite power systems conform to Title 10 of Code of Federal Regulations (1 0 CFR), Part 50, Appendix A, "General Design Criteria for Nuclear Power Plants," General Design Criterion (GDC) 17 and 18.
GDC 17, "Electric power systems," requires, in part, that An onsite electric power system... shall be provided to permit functioning of structures, systems, and components important to safety.... The on site electric power supplies, including the batteries, and the onsite electric distribution system, shall have sufficient independence, redundancy, and testability to perform their safety functions assuming a single failure....
In addition, this criterion requires provisions to minimize the probability of losing electric power from any of the remaining supplies as a result of, or coincident with, the loss of power from the unit, the transmission network, or the onsite electric power supplies.
GDC 18, "Inspection and testing of electric power systems," requires, in part, that Electric power systems important to safety shall be designed to permit appropriate periodic inspection and testing of important areas and features.... The systems shall be designed with a capability to test periodically (1) the operability and functional performance....
In 10 CFR 50.36, "Technical specifications," the NRC established its regulatory requirements related to the content of TSs. Pursuant to 10 CFR 50.36, TSs are required to include items in the following five specific categories related to station operation: (1) safety limits, limiting safety system settings, and limiting control settings, (2) limiting conditions for operations (LCO), (3) surveillance requirements (SR), (4) design features, and (5) administrative controls. The rule does not specify the particular requirements to be included in a plant's TS. The regulations in 10 CFR 50.36(c)(2)(i), state, in part, that the "[l]imiting conditions for operation are the lowest functional capability or performance levels of equipment required for safe operation of the facility." The regulations in 10 CFR 50.36(c)(3) state that "[s]urveillance requirements are requirements relating to test, calibration, or inspection to assure that the necessary quality of systems and components will be maintained within safety limits, and that the limiting conditions for operation will be met."
NRC Regulatory Guide (RG) 1.9, Revision 3, "Selection, Design, Qualification and Testing of Emergency Diesel Generators used as Class 1 E Onsite Electric Power Systems at Nuclear Power Plants," July 1993 (ADAMS Accession No. ML003739929), is referenced by the licensee and describes a method acceptable to the NRC staff for complying with the Commission's regulations with regard to design and testing of onsite DGs.
3.0 TECHNICAL EVALUATION
3.1 Proposed TS Changes
Current SR 3.8.1.1 0 states:
Verify each DG operating at a power factor :s; 0.9 and <::: 0.8 does not trip and voltage is maintained :s; 4784 V and frequency is maintained :s; 65.4 Hz during and following a load rejection of<::: 5580 kW and :s; 6201 kW.
Revised SR 3.8.1.1 0 would state:
Verify each DG operating at a power factor :s; 0.9 and <::: 0.8 does not trip and voltage is maintained :s; 4992 V and frequency is maintained :s; 65.4 Hz during and following a load rejection of<::: 5580 kW and :s; 6201 kW.
3.2
NRC Staff Evaluation
The NRC staff has reviewed the licensee's regulatory and technical analyses in support of its proposed license amendment, which is described in Attachment I of the application dated September 19, 2012.
The offsite and onsite power system at the WCGS is designed to comply with the requirements of GDCs 17 and 18. The WCGS USAR states that the existing onsite power system consists of two physically independent sources of offsite power that are brought to the onsite power system, designed and located so as to minimize the likelihood of simultaneous failure. Each of these independent circuits has the capability to safely shut down the unit.
The standby alternating current (AC) power system for WCGS consists of two DG units separated into two independent divisions. Section 8.3.1.1.3, "Standby Power System," of the USAR states that either DG unit is capable of supplying loads needed to safely shutdown the reactor and maintaining the reactor in a safe shutdown condition after a design basis accident.
Each DG is rated at 6,201 kilowatt (kW) for continuous operation. Additional ratings are 6,635 kW for 2,000 hours0 days <br />0 hours <br />0 weeks <br />0 months <br />, 6,821 kW for 7 days, and 7,441 kW for 30 minutes. The DG 2-hour rating is equal to the 7-day rating. Each DG is connected exclusively to a single 4.16 kiloVolt (kV) engineered safety features (ESF) bus for one load group. The load groups are redundant and have similar safety-related equipment. Each load group is adequate to satisfy minimum ESF demand caused by a loss-of-coolant accident (LOCA) and/or loss of preferred power supply. In the testing section for the standby power system, the USAR states that load rejection tests are performed on the DGs to demonstrate the ability to reject the maximum rated load without exceeding speeds or voltages that cause tripping, mechanical damage, or harmful overstresses.
WCGS relies on the proper operation of the safety-related station auxiliary systems after perturbations in the electrical distribution system. A load rejection by an operating DG can result in high frequency and high voltage on the plant safety busses and challenge the over speed protection scheme of the DG. The plant TSs require testing the performance capabilities of the DG after full load rejection to demonstrate that the DG and any operating safety loads will not be adversely impacted by the perturbation and the DG and the loads will be immediately available to perform the required functions after the event. The full load rejection test envelopes the voltage and frequency variations that will be observed during a partial to full load rejection event with the DG connected to the safety buses. The WCGS SR 3.8.1.1 0 currently has an overvoltage limit of 4784 V for the load rejection test. In its submittal dated September 19, 2012, the licensee stated that the current maximum voltage limit of 4784 V is based on approximately 115 percent of the nominal system voltage of 4160 V. The NRC staff notes that this is an industry accepted parameter, and operating experience has shown no significant adverse impact on operating equipment subjected to 115 percent of nominal voltage for a few cycles. Hence, this parameter was generically quoted in NUREG-0452, Revision 3, "Standard Technical Specifications for Westinghouse Pressurized Water Reactors," November 1980, in effect at the time of licensing for WCGS. The licensee proposes to raise the limit to 4992 V, or 120 percent of nominal 4160 V, due to observed voltages during full load rejection testing when the initial system voltage is higher than 4160 V. This is consistent with the standard industry value for peak voltage of 5000 V in the improved Standard Technical Specifications for Westinghouse Plants, NUREG-1431, Revision 4, SR 3.8.1.1 0.
The licensee stated in its application that the higher voltage is acceptable as the DG and its support systems will not be degraded because:
- 1.
The generator was satisfactorily tested for a voltage spike of 9320 V, with follow-on tests conducted at 6298 V, as recommended by Institute of Electrical and Electronics Engineers (IEEE) Standard 95-1977, "IEEE Recommended Practice for Insulation Testing of Large AC Rotating Machinery."
- 2.
The generator output cables are rated at 5000 V for continuous use, and the lower voltage exciter feeder cables are rated at a minimum of 600 V, which provides acceptable margin over the 150 V for transient overvoltage conditions.
- 3.
The switchgear can operate continuously at the rated maximum voltage of 4760 V. The switchgear has an impulse withstand voltage insulation level of 60 kV, and the 4992 V transient is within the capability of the switchgear.
- 4.
The control circuitry associated with the DG static exciter voltage regulator (SEVR) system has been evaluated for a voltage transient resulting from the load rejection test and will not be adversely impacted when required to raise DG output voltage above the postulated safety bus voltage.
The NRC staff reviewed the licensee's evaluation of the ability of the DG and the associated support systems to withstand the higher peak voltage. Based on the information provided in the licensee's application (as summarized above), the staff agrees that the proposed upper limit for voltage spike during full load rejection will not adversely impact the DG and its support system, since the proposed limit is within the capability of the impacted components. However, the staff requested further clarification on the acceptance criteria for a DG that exhibits a voltage peak of 4992 V or less but when the magnitude of the spike is greater than normal trends. The staff also requested information regarding the impact of the proposed voltage limit on any operating equipment powered from the DG-supplied busses. By letter dated May 31, 2013 (ADAMS Accession No. ML13149A160), the staff requested additional information to establish:
- 1. The maximum allowable "Initial-to-Peak Voltage" difference that will be used to validate performance capabilities of the DG voltage regulator when compared with historical trends (less than 600 V for both DGs), since the acceptance criteria based on the new limit of 4992 V would span more than 1000 V.
- 2. The potential degradation of safety-related equipment that may be powered from the DG during a load rejection event due to DG high voltage spikes.
The licensee responded to the NRC staff's requests by letter dated July 15, 2013. The response to the first question above stated that there are no plant procedures that provide limitations on acceptance criteria for initial to peak voltage difference during a load rejection test.
However, the full-load rejection test results are trended as a method of monitoring the performance of the DG voltage regulator by the site System Engineering Program. The voltage range (initial-to-peak) is dependent on several factors, such as the initial voltage, reactive power loading, real power loading, and voltage regulator constants and tuning. The licensee stated that load rejection test performance data will be reviewed on the voltage rise alone and compared to past data. If the rise is noted to be beyond the upper or lower range of the past data, it will be further reviewed for initial test conditions that may explain such differences. If the abnormally higher than historical voltage rise cannot be attributed to initial conditions, then it would be considered to be a potential performance deficiency of the voltage regulator, and entered into the plant corrective action program for further consideration. The licensee also clarified that the voltage and frequency swings for the single load rejection test remain within steady-state values during the transient, and will be enveloped by the proposed limit of 4992 V.
The NRC staff reviewed the licensee's response and concluded based on engineering judgment, that the measures detailed by the licensee to evaluate DG performance post load rejection testing and to address abnormal voltage magnitude under the corrective action program, are reasonable and, therefore are acceptable. The staff agrees that a voltage perturbation resulting from a large load rejection will be less than the voltage observed during full load rejection.
In response to the NRC staff's second question, the licensee stated that the WCGS electrical distribution system has overvoltage protection provided by surge limiters that are installed on each phase of the 4.16 kV switchgear breakers. The surge limiters have been sized to protect the plant equipment from damage caused by transient overvoltage conditions. The licensee also stated that the generator, transformers, equipment cables, and motors all have allowable overvoltage test values that exceed 5.5 kV for durations of over 1 0 seconds. Since a transient overvoltage from a DG load reject event lasts only for a few cycles, the proposed upper limit of 4992 V for a voltage spike will not degrade operating equipment on the plant safety busses.
The NRC staff reviewed the licensee's response and agrees that the overvoltage protection scheme, coupled with the existing rating of the installed equipment, provides reasonable assurance that the proposed high voltage for load rejection test will not adversely impact the operating equipment on safety-related busses.
In summary, the licensee stated that a voltage perturbation of 4992 V lasting a few cycles, observed during a full load reject event, is below the tested values of the DG insulation and will not adversely impact the capability of the DGs to perform their safety function. The associated DG output cables, switchgear, exciter, and loads supplied by the DGs are capable of withstanding surge voltage above the proposed value. The licensee provided details on actions that it will take if an overvoltage spike of magnitude greater than the normal trend is observed and confirmed that other operating equipment on busses supplied by the DGs is adequately protected and rated to withstand a voltage spike of 4992 V for a few cycles. The licensee concluded that there are no adverse impacts on the onsite power and distribution system under the postulated load reject scenarios. The NRC staff reviewed the licensee's evaluation of the ability of the DG, the associated DG support systems, and the equipment supplied by the DGs to withstand the higher peak voltage. The staff also reviewed the proposed actions for any abnormal voltage rise observed during a load rejection test. Based on its review of the licensee's analyses, the NRC staff agrees that the licensee's conclusions are reasonable and acceptable, that there are no adverse impacts to the onsite power and distribution system under the postulated load reject scenarios.
In conclusion, the licensee stated that the consequences of a voltage perturbation of 4992 V lasting a few cycles, observed during a full load reject event, will not adversely impact the capabilities of the DGs to perform their safety function. In addition, the proposed voltage limit is within the short-term insulation rating of the safety-related loads on busses supplied by the DGs and, therefore, will not damage safety-related equipment that may be operating. The NRC staff reviewed the licensee's evaluations of the impact of the higher voltage on safe shutdown equipment and finds the licensee's conclusions reasonable and acceptable, because the proposed higher voltage limit will not adversely impact the capabilities of the DGs and the associated equipment to perform their safety function.
Based on its evaluation, the NRC staff determined that the proposed change to the SR 3.8.1.1 0 is consistent with the recommendations of the NRC guidance in RG 1.9, Revision 3, and meets the requirements in 10 CFR 50.36{c)(3) for SRs to assure that the necessary quality of systems and components, i.e., the DG and safety-related equipment supplied by the DG, will be maintained within safety limits, and that the limiting conditions for operation will be met. The staff also concludes that the proposed TS change will not degrade the capability of the onsite source to mitigate the consequences of an accident and, so, complies with requirements in GDC 17. The load rejection test is in accordance with requirements of GDC 18 governing the design, operation, and testing of the electrical power systems and provides adequate assurance of system operability. Since the proposed change is consistent with the NRC's regulations and regulatory guidance, the NRC staff concludes the change 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 an inspection or surveillance requirement. 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 October 30, 2012 (77 FR 65726). 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) there is reasonable assurance that 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: G. Matharu, EEEB S. Basturescu, EEEB Date: December 2, 2013
- via memo dated October 4, 2013 OFFICE NRR/DORULPL4-1/PM NRR/DORULPL4-1/LA NRR/DSS/STSB/BC NRR/DE/EEEB/BC*
NAME Flyon JBurkhardt REIIiott JZimmerman DATE 11/13/13 11/7113 11/15/13 10/4/13 OFFICE OGC-NLO NRR/DORLILPL4-1/BC NRR/DORULPL4-1/PM NAME EHouseman MMarkley Flyon DATE 11/25/13 12/2/13 12/2113