ML20273A088
| ML20273A088 | |
| Person / Time | |
|---|---|
| Site: | Calvert Cliffs  |
| Issue date: | 11/09/2020 |
| From: | Marshall M Plant Licensing Branch 1 |
| To: | Bryan Hanson Exelon Generation Co, Exelon Nuclear |
| Marshall M, NRR/DORL/LPLI, 415-2871 | |
| References | |
| EPID L-2019-LLA-0281 | |
| Download: ML20273A088 (23) | |
Text
November 9, 2020 Mr. Bryan C. Hanson Senior Vice President Exelon Generation Company, LLC President and Chief Nuclear Officer Exelon Nuclear 4300 Winfield Road Warrenville, IL 60555
SUBJECT:
CALVERT CLIFFS NUCLEAR POWER PLANT, UNITS 1 AND 2 - ISSUANCE OF AMENDMENT NOS. 338 AND 316 RE: REVISE EMERGENCY DIESEL GENERATOR SURVEILLANCE REQUIREMENTS FOR FREQUENCY AND VOLTAGE TOLERANCES (EPID L-2019-LLA-0281)
Dear Mr. Hanson:
The U.S. Nuclear Regulatory Commission (the Commission) has issued the enclosed Amendment No. 338 to Renewed Facility Operating License No. DPR-53 and Amendment No. 316 to Renewed Facility Operating License No. DPR-69 for the Calvert Cliffs Nuclear Power Plant, Units 1 and 2 (Calvert Cliffs), respectively. The amendments consist of changes to the technical specifications in response to your application dated December 11, 2019, as supplemented by letter dated June 30, 2020.
The amendments revise certain frequency and voltage acceptance criteria for steady-state emergency diesel generator surveillance testing in Calvert Cliffs Technical Specification 3.8.1, AC [Alternating Current] Sources-Operating.
A copy of our related safety evaluation is also enclosed. Notice of issuance will be included in the Commissions monthly Federal Register notice.
Sincerely,
/RA/
Michael L. Marshall, Jr., Senior Project Manager Plant Licensing Branch I Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos. 50-317 and 50-318
Enclosures:
- 1. Amendment No. 338 to DPR-53
- 2. Amendment No. 316 to DPR-69
- 3. Safety Evaluation cc: Listserv EXELON GENERATION COMPANY, LLC DOCKET NO. 50-317 CALVERT CLIFFS NUCLEAR POWER PLANT, UNIT 1 AMENDMENT TO RENEWED FACILITY OPERATING LICENSE Amendment No. 338 Renewed License No. DPR-53
- 1.
The U.S. Nuclear Regulatory Commission (the Commission) has found that:
A.
The application for amendment by Exelon Generation Company, LLC (Exelon, the licensee), dated December 11, 2019, as supplemented by letter dated June 30, 2020, complies with the standards and requirements of the Atomic Energy Act of 1954, as amended (the Act), and the Commissions 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 Commissions regulations set forth in 10 CFR Chapter I; 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 Commissions 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. DPR-53 is hereby amended to read as follows:
2.
Technical Specifications The Technical Specifications contained in Appendices A and B, as revised through Amendment No. 338, are hereby incorporated into this license. Exelon Generation shall operate the facility in accordance with the Technical Specifications.
3.
This license amendment is effective as of the date of its issuance and shall be implemented within 120 days.
FOR THE NUCLEAR REGULATORY COMMISSION James G. Danna, Chief Plant Licensing Branch I Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation
Attachment:
Changes to the Renewed Facility Operating License and Technical Specifications Date of Issuance: November 9, 2020 James G.
Danna Digitally signed by James G. Danna Date: 2020.11.09 14:37:48 -05'00'
ATTACHMENT TO LICENSE AMENDMENT NO. 338 CALVERT CLIFFS NUCLEAR POWER PLANT, UNIT 1 RENEWED FACILITY OPERATING LICENSE NO. DPR-53 DOCKET NO. 50-317 Replace the following page of the Renewed Facility Operating License with the attached revised page. The revised page is identified by amendment number and contains a marginal line indicating the area of change.
Remove Page Insert Page 3
3 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 Pages Insert Pages 3.8.1-12 3.8.1-12 3.8.1-14 3.8.1-14 3.8.1-15 3.8.1-15 3.8.1-17 3.8.1-17 Amendment No. 338 (4)
Exelon Generation pursuant to the Act and 10 CFR Parts 30, 40, and 70, to receive, possess, and use, in amounts as required, any byproduct, source, and special nuclear material without restriction to chemical or physical form, for sample analysis or instrument calibration or associated with radioactive apparatus or components; and (5)
Exelon Generation pursuant to the Act and 10 CFR Parts 30 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 license is deemed to contain and is subject to the conditions set forth in 10 CFR Chapter I and is subject to all applicable provisions of the Act, and the rules, regulations, and orders of the Commission, now or hereafter applicable; and is subject to the additional conditions specified and incorporated below:
(1)
Maximum Power Level Exelon Generation is authorized to operate the facility at steady-state reactor core power levels not in excess of 2737 megawatts-thermal in accordance with the conditions specified herein.
(2)
Technical Specifications The Technical Specifications contained in Appendices A and B, as revised through Amendment No. 338, are hereby incorporated into this license. Exelon Generation shall operate the facility in accordance with the Technical Specifications.
(a)
For Surveillance Requirements (SRs) that are new, in Amendment 227 to Facility Operating License No. DPR-53, the first performance is due at the end of the first surveillance interval that begins at implementation of Amendment 227. For SRs that existed prior to Amendment 227, including SRs with modified acceptance criteria and SRs whose frequency of performance is being extended, the first performance is due at the end of the first surveillance interval that begins on the date the Surveillance was last performed prior to implementation of Amendment 227.
(3)
Additional Conditions The Additional Conditions contained in Appendix C as revised through Amendment No. 327 are hereby incorporated into this license. Exelon Generation shall operate the facility in accordance with the Additional Conditions.
(4)
Secondary Water Chemistry Monitoring Program Exelon Generation shall implement a secondary water chemistry monitoring program to inhibit steam generator tube degradation. This program shall include:
AC Sources-Operating 3.8.1 CALVERT CLIFFS - UNIT 1 3.8.1-12 CALVERT CLIFFS - UNIT 2 Amendment No.338 Amendment No.316 SURVEILLANCE REQUIREMENTS (continued)
SURVEILLANCE FREQUENCY SR 3.8.1.3
NOTES ----------------
1.
Performance of SR 3.8.1.9 satisfies this Surveillance Requirement.
2.
All DG starts may be preceded by an engine prelube period and followed by a warmup period prior to loading.
3.
A modified DG start involving idling and gradual acceleration to synchronous speed may be used for this Surveillance Requirement as recommended by the manufacturer. When modified start procedures are not used, the voltage and frequency tolerances of SR 3.8.1.9 must be met.
Verify each DG starts and achieves steady state voltage 4060 V and 4310 V, and frequency 59.25 Hz and 60.75 Hz.
In accordance with the Surveillance Frequency Control Program
AC Sources-Operating 3.8.1 CALVERT CLIFFS - UNIT 1 3.8.1-14 CALVERT CLIFFS - UNIT 2 Amendment No.338 Amendment No.316 SURVEILLANCE REQUIREMENTS (continued)
SURVEILLANCE FREQUENCY SR 3.8.1.7 Verify the fuel oil transfer system operates to automatically transfer fuel oil from storage tank[s] to the day tank.
In accordance with the Surveillance Frequency Control Program SR 3.8.1.8 Verify interval between each sequenced load block is within + 10% of design interval for each emergency and shutdown load sequencer.
In accordance with the Surveillance Frequency Control Program SR 3.8.1.9
NOTE --------------------
All DG starts may be preceded by an engine prelube period.
Verify each DG starts from standby condition and achieves, in 10 seconds, voltage
> 4060 V and frequency > 58.8 Hz, and after steady state conditions are reached, maintains voltage 4060 V and 4310 V and frequency of 59.25 Hz and 60.75 Hz.
In accordance with the Surveillance Frequency Control Program SR 3.8.1.10 Verify manual transfer of AC power sources from the normal offsite circuit to the alternate offsite circuit.
In accordance with the Surveillance Frequency Control Program
AC Sources-Operating 3.8.1 CALVERT CLIFFS - UNIT 1 3.8.1-15 CALVERT CLIFFS - UNIT 2 Amendment No.338 Amendment No.316 SURVEILLANCE REQUIREMENTS (continued)
SURVEILLANCE FREQUENCY SR 3.8.1.11 ----------------- NOTE -----------------
1.
Momentary transients outside the load and power factor limits do not invalidate this test.
2.
If performed with the DG synchronized with offsite power, the surveillance test shall be performed at the required power factor. However, if grid conditions do not permit, the power factor limit is not required to be met.
Under this condition, the power factor shall be maintained as close to the limit as practicable.
Verify each DG, operating at a frequency 59.25 Hz and 60.75 Hz, and an appropriate accident load power factor operates for 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> while loaded to 4000 kW for DG 1A and 3000 kW for DGs 1B, 2A, and 2B.
In accordance with the Surveillance Frequency Control Program SR 3.8.1.12 Verify each DG rejects a load 500 hp without tripping.
In accordance with the Surveillance Frequency Control Program
AC Sources-Operating 3.8.1 CALVERT CLIFFS - UNIT 1 3.8.1-17 CALVERT CLIFFS - UNIT 2 Amendment No.338 Amendment No.316 SURVEILLANCE REQUIREMENTS (continued)
SURVEILLANCE FREQUENCY SR 3.8.1.15 ----------------- NOTE --------------------
All DG starts may be preceded by an engine prelube period.
Verify on an actual or simulated loss of offsite power signal in conjunction with an actual or simulated Engineered Safety Feature actuation signal:
a.
De-energization of emergency buses; b.
Load shedding from emergency buses; c.
DG auto-starts from standby condition and:
1.
energizes permanently connected loads in 10 seconds, 2.
energizes auto-connected emergency loads through load sequencer, 3.
maintains steady state voltage 4060 V and 4310 V, 4.
maintains steady state frequency of 59.25 Hz and 60.75 Hz, and 5.
supplies permanently connected and auto-connected emergency loads for 5 minutes.
In accordance with the Surveillance Frequency Control Program EXELON GENERATION COMPANY, LLC DOCKET NO. 50-318 CALVERT CLIFFS NUCLEAR POWER PLANT, UNIT 2 AMENDMENT TO RENEWED FACILITY OPERATING LICENSE Amendment No. 316 Renewed License No. DPR-69 1.
The U.S. Nuclear Regulatory Commission (the Commission) has found that:
A.
The application for amendment by Exelon Generation Company, LLC (Exelon, the licensee) dated December 11, 2019, as supplemented by letter dated June 30, 2020, complies with the standards and requirements of the Atomic Energy Act of 1954, as amended (the Act), and the Commissions 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 Commissions regulations set forth in 10 CFR Chapter I; 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 Commissions 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. DPR-69 is hereby amended to read as follows:
2.
Technical Specifications The Technical Specifications contained in Appendices A and B, as revised through Amendment No. 316, are hereby incorporated into this license. The licensee shall operate the facility in accordance with the Technical Specifications.
3.
This license amendment is effective as of the date of its issuance and shall be implemented within 120 days.
FOR THE NUCLEAR REGULATORY COMMISSION James G. Danna, Chief Plant Licensing Branch I Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation
Attachment:
Changes to the Renewed Facility Operating License and Technical Specifications Date of Issuance: November 9, 2020 James G.
Danna Digitally signed by James G. Danna Date: 2020.11.09 14:38:29 -05'00'
ATTACHMENT TO LICENSE AMENDMENT NO. 316 CALVERT CLIFFS NUCLEAR POWER PLANT, UNIT 2 RENEWED FACILITY OPERATING LICENSE NO. DPR-69 DOCKET NO. 50-318 Replace the following page of the Renewed Facility Operating License with the attached revised page. The revised page is identified by amendment number and contains a marginal line indicating the area of change.
Remove Page Insert Page 3
3 Calvert Cliffs Nuclear Power Plant, Unit 2, uses the same Appendix A Technical Specifications as Calvert Cliffs Nuclear Power Plant, Unit 1. Accordingly, the Unit 1 Renewed Facility Operating License has been updated with the following pages, which are applicable to both Units 1 and 2.
Remove Pages Insert Pages 3.8.1-12 3.8.1-12 3.8.1-14 3.8.1-14 3.8.1-15 3.8.1-15 3.8.1-17 3.8.1-17 Amendment No. 316 (4)
Exelon Generation pursuant to the Act and 10 CFR Parts 30, 40, and 70, to receive, possess, and use, in amounts as required, any byproduct, source, and special nuclear material without restriction to chemical or physical form, for sample analysis or instrument calibration or associated with radioactive apparatus or components; and (5)
Exelon Generation pursuant to the Act and 10 CFR Parts 30 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 license is deemed to contain and is subject to the conditions set forth in 10 CFR Chapter I and is subject to all applicable provisions of the Act, and the rules, regulations, and orders of the Commission, now or hereafter applicable; and is subject to the additional conditions specified and incorporated below:
(1)
Maximum Power Level Exelon Generation is authorized to operate the facility at steady-state reactor core power levels not in excess of 2737 megawatts-thermal in accordance with the conditions specified herein.
(2)
Technical Specifications The Technical Specifications contained in Appendices A and B, as revised through Amendment No. 316, are hereby incorporated into this license. The licensee shall operate the facility in accordance with the Technical Specifications.
(a)
For Surveillance Requirements (SRs) that are new, in Amendment 201 to Facility Operating License No. DPR-69, the first performance is due at the end of the first surveillance interval that begins at implementation of Amendment 201. For SRs that existed prior to Amendment 201, including SRs with modified acceptance criteria and SRs whose frequency of performance is being extended, the first performance is due at the end of the first surveillance interval that begins on the date the Surveillance was last performed prior to implementation of Amendment 201.
(3)
Less Than Four Pump Operation The licensee shall not operate the reactor at power levels in excess of five (5) percent of rated thermal power with less than four (4) reactor coolant pumps in operation. This condition shall remain in effect until the licensee has submitted safety analyses for less than four pump operation, and approval for such operation has been granted by the Commission by amendment of this license.
(4)
Environmental Monitoring Program If harmful effects or evidence of irreversible damage are detected by the biological monitoring program, hydrological monitoring program, and the
SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO. 338 TO RENEWED FACILITY OPERATING LICENSE NO. DPR-53 AND AMENDMENT NO. 316 TO RENEWED FACILITY OPERATING LICENSE NO. DPR-69 EXELON GENERATION COMPANY, LLC CALVERT CLIFFS NUCLEAR POWER PLANT, UNITS 1 AND 2 DOCKET NOS. 50-317 AND 50-318
1.0 INTRODUCTION
By application dated December 11, 2019 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML19346E536), as supplemented by letter dated June 30, 2020 (ADAMS Accession No. ML20182A110), Exelon Generation Company, LLC (Exelon, the licensee) requested changes to the Calvert Cliffs Nuclear Power Plant (Calvert Cliffs), Units 1 and 2, Technical Specifications (TSs). The supplemental letter dated June 30, 2020, 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, the Commission) staffs original proposed no significant hazards consideration determination as published in the Federal Register on February 11, 2020 (85 FR 7791).
The proposed amendments would revise certain frequency and voltage acceptance criteria for steady-state emergency diesel generator (EDG) surveillance requirement (SR) testing in Calvert Cliffs TS 3.8.1, AC [Alternating Current] Sources-Operating. The calculations supporting the request were revised using methodology described in WCAP-17308-NP-A, Revision 0, Treatment of Diesel Generator (DG) Technical Specification Frequency and Voltage Tolerances, dated July 2017 (ADAMS Accession No. ML17215A232).
2.0 REGULATORY EVALUATION
2.1 Description of the Emergency Diesel Generators In accordance with the Calvert Cliffs Updated Final Safety Analysis Report, Section 8.1.2, each of the two units has two dedicated EDGs that provide power (upon loss of normal offsite power) to reliably shut down the unit and maintain it in a safe shutdown condition under all conditions, including accidents. The EDGs are designed as Class 1E systems, and each supplies power to one of the four 4.16 kilovolt (kV) engineered safety feature (ESF) buses. One EDG from each unit provides sufficient power to the necessary ESF loads to shut down both units for an accident in one unit and a station loss-of-offsite power. Each EDG will start automatically upon receiving a safety injection actuation signal or an undervoltage on its assigned 4.16 kV ESF bus.
Three of the four EDGs are rated 4.16 kV, three-phase, 60-cycle, manufactured by Fairbanks Morse, with nominal kiloWatts (kW) ratings as follows:
3,000 kW continuous 3,300 kW 2000 hour0.0231 days <br />0.556 hours <br />0.00331 weeks <br />7.61e-4 months <br /> The fourth EDG is rated 4.16 kV, three-phase, 60-cycle tandem-engine, manufactured by Societe Alsacienne De Constructions Mecaniques De Mulhouse (SACM), with a nominal kW rating as follows:
5,400 kW continuous 5,940 kW 2 hour2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> In the license amendment request (LAR), the licensee stated that the above four EDGs meet the recommendations of Regulatory Guide 1.9, Revision 3, Selection, Design, Qualification, and Testing of Emergency Diesel Generator Units used as class 1E Onsite Electric Power Systems at Nuclear Power Plants, dated July 1993 (ADAMS Accession No. ML003739929),
regarding restoring the frequency within 2 percent of nominal within 60 percent of each load sequence time interval and restoring the voltage within 10 percent of nominal within 60 percent of each load sequence time interval.
2.2 Proposed Change In the LAR, the licensee stated that for the events that assume offsite power is lost, the EDGs provide power to safety-related pumps, motor-operated valves (MOVs), and fans/blowers.
Historically, the EDG frequency and voltage tolerances associated with the governor and voltage regulator have not been considered in the steady-state evaluation of these components.
The licensees analyses of these components typically assumed that the steady-state EDG frequency is 60 hertz (Hz), and voltage is 4,160 volt (V) after the EDG starting and loading transients. However, the Calvert Cliffs TSs contain SRs with certain limits on the EDG steady-state frequency and voltage ranges.
The current TS tolerances of maintaining EDG voltage greater than 4,060 V and less than 4,400 V, and frequency greater than 58.8 Hz and less than 61.2 Hz, were intended to apply to the EDG starting and loading transients and were not intended to apply to the steady-state operation. Current Calvert Cliffs TSs have four SRs that specify EDG steady-state frequency and voltage acceptance criteria with uncertainty ranges, as follows:
SR 3.8.1.3:
Verify each DG starts and achieves steady state voltage 4060 V and 4400 V, and frequency 58.8 Hz and 61.2 Hz.
SR 3.8.1.9:
, and after steady state conditions are reached, maintains voltage 4060 V and 4400 V and frequency of > 58.8 Hz and 61.2 Hz.
SR 3.8.1.11: Verify each DG, operating at a frequency 58.8 Hz and 61.2 Hz, and an appropriate accident load power factor operates for 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> while loaded to 4000 kW for DG 1A and 3000 kW for DGs 1B, 2A, and 2B.
SR 3.8.1.15:
- 3. maintains steady state voltage 4060 V and 4400 V,
- 4. maintains steady state frequency of 58.8 Hz and 61.2 Hz, and The licensee has proposed to reduce the EDG steady-state frequency and voltage variations in the following TS 3.8.1 SRs that contain those limits. The proposed changes are indicated in bold:
SR 3.8.1.3:
Verify each DG starts and achieves steady state voltage 4060 V and 4310 V, and frequency 59.25 Hz and 60.75 Hz.
SR 3.8.1.9:
, and after steady state conditions are reached, maintains voltage 4060 V and 4310 V and frequency of > 59.25 Hz and 60.75 Hz.
SR 3.8.1.11: Verify each DG, operating at a frequency 59.25 Hz and 60.75 Hz, and an appropriate accident load power factor operates for 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> while loaded to 4000 kW for DG 1A and 3000 kW for DGs 1B, 2A, and 2B.
SR 3.8.1.15:
- 3. maintains steady state voltage 4060 V and 4310 V,
- 4. maintains steady state frequency of 59.25 Hz and 60.75 Hz, and The licensee applied methodology from the Pressurized Water Reactor Owners Group Topical Report WCAP-17308-NP-A, Revision 0, approved by the NRC, to evaluate the impact of EDG steady-state frequency and voltage variation on the essential motor loads.
2.3 Applicable Regulatory Requirements and Guidance Requirements Title 10 of Code of Federal Regulations (CFR) Part 50, Domestic Licensing of Production and Utilization Facilities, Section 50.36, Technical specifications, establishes the regulatory requirements related to the contents of TSs. The regulations under 10 CFR 50.36(c)(3) require, in part, that TSs include Surveillance Requirements (SRs), 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 (LCOs) will be met.
Guidance Regulatory Guide 1.9, Revision 3, Selection, Design, Qualification, and Testing of Emergency Diesel Generator Units Used as Class 1E Onsite Electric Power Systems at Nuclear Power Plants(ADAMS Accession No. ML003739929), which provides the capability requirements for EDGs selected for use in onsite electric power systems.
WCAP-17308-NP-A, Revision 0, was approved by the NRC by letter dated April 17, 2017 (ADAMS Accession No. ML17074A121). The front section of this report also includes the safety evaluation dated April 17, 2017, performed by the NRC staff. WCAP-17308-NP-A, Revision 0, provides a methodology to evaluate the impact of EDG steady-state frequency and voltage variation on essential motor loads such as emergency core cooling system pumps, MOVs, and fans/blowers. The report states that the impact of EDG steady-state frequency and voltage variation on the motor-driven pump parameters, such as flow rate and MOV actuation speed, can be compared to their expected performance values that are verified to be met on a periodic basis. Regarding the performance of emergency core cooling system pumps, the effect of frequency and voltage variation can be combined with other uncertainties to revise the limiting pump inservice test (IST) curves to account for those variables. The impact of frequency and voltage variation on the EDG loading and fuel oil consumption and the performance of MOVs and fans/blowers are determined in plant-specific evaluations.
3.0 TECHNICAL EVALUATION
3.1 Impact on Safety-Related Functions WCAP-17308-NP-A, Revision 0, notes that the steady-state EDG operation at the extremes of the frequency and voltage limits would impact the following: (1) pump performance; (2) EDG loading; (3) EDG fuel oil consumption; (4) MOV performance; and (5) heating, ventilation, and air conditioning fan/blower performance. The pump, MOV, and fan/blower performance are addressed in this section of the safety evaluation, EDG loading is addressed in Section 3.3, and EDG fuel oil consumption is addressed in Section 3.4.
Utilizing the WCAP-17308-NP-A, Revision 0, methodology, the licensee performed calculation CA10309, Evaluation of Fans, Pumps, and MOVs, for the Effects of Emergency Diesel Generator Voltage and Frequency Variations, for all safety-related pumps, fans, and MOVs, which the licensee determined as being impacted by EDG voltage and frequency variations.
The calculation considered the proposed EDG steady-state frequency of 60 +/- 0.75 Hz, the EDG steady-state minimum voltage as 4,060 V (no change in minimum voltage), and the EDG maximum voltage as 4,310 V (approximately plus 3.6 percent of rated 4,160 V). The calculation results are summarized in the following appendices to CA10309.
Appendix A - motor speeds Appendix B - fans Appendix C - pumps Appendix D - MOVs The NRC staff performed an audit of calculation CA10309, including its four appendices, as described in the NRC staffs audit summary dated June 30, 2020 (ADAMS Accession No. ML20174A059). The NRC staff notes that the licensees implementation of the WCAP-17308-NP-A, Revision 0, methodology, including the application of plant-specific considerations for Calvert Cliffs, was appropriate for this LAR. Additional details of the NRC staffs review are included below.
In Appendix A of the calculation, the licensee calculated the motor speeds for fans, pumps, and MOVs, and through an iterative process in Appendices B, C, and D, the licensee determined the new proposed TS EDG steady-state frequency and voltage tolerance values.
Impact on Motor Speeds The NRC staff performed an audit of Appendix A of calculation CA10309 and verified that the licensee used the methodology provided in Section 2.5.3, Equation 12 of WCAP-17308-NP-A, Revision 0, to calculate the impact on motor speeds, considering the proposed variations in EDG steady-state frequency and voltage. During the audit, the NRC staff found that the licensee used a conservative approach for voltage values in Equation 12 by considering
+/- 10 percent of 4 kV and 460 V motor-rated voltage values to account for cable voltage drops from the EDG to the respective motor terminals. This appendix calculated the minimum and maximum motor speeds to be used in Appendices B and C of the same calculation. The NRC staff finds the motor-speed calculation methodology to be acceptable because (1) it is based on WCAP-17308-NP-A, Revision 0, and (2) it considered the voltage values that are bounding with respect to the TS proposed voltage values.
In the LAR, the licensee also stated that recent test history demonstrates that the EDGs consistently run near their nominal setpoints and are expected to run within the proposed voltage and frequency limits.
Impact on Operation of Fans As described in Section 3.2 of the LAR, Appendix B of calculation CA10309 evaluated the impact on airflow produced by the EDG-powered fans when the EDG is operated at minimum voltage and frequency. At EDG minimum voltage and frequency, the EDG-powered fan airflows are reduced by 1.45-2.32 percent due to the motor reduced speeds. Since these changes in airflow are small, they will not impact fan design functions. Airflows for fans operating with motor speeds above rated were not evaluated because an increase in motor speed will result in increased airflows, and thus, better fan performance.
The NRC staff performed an audit of Appendix B of calculation CA10309 and verified that the licensee calculated variations in air flow due to variation in speed using methodology provided in Section 5.1, Equation 34, of WCAP-17308-NP-A, Revision 0. According to Section 5.2 of WCAP-17308-NP-A, Revision 0, typically, if the fans speed and corresponding airflow do not vary more than +/-10 percent of the specified system flow rate, the fan can be expected to be performing within its expected operating range. The NRC staff finds the calculation methodology acceptable because (1) it is based on WCAP-17308-NP-A, Revision 0, and (2) the determined fan airflow variations are small and will have an insignificant impact on safety-related functions of the fans.
Impact on Operation of Safety-Related Pumps In the LAR, the licensee stated that an evaluation was performed in Appendix C of calculation CA10309, for all the EDG-powered pumps to determine new IST limits (i.e., pressures versus flows) based on the methodology specified in WCAP-17308-NP-A, Revision 0. These new IST limits were compared to existing limits. Based on the calculations, the licensee identified changes to existing IST limits for some pumps. The licensee also stated that based on review of recent test data of pumps, all pumps are expected to operate within any revised IST limits.
The NRC staff performed an audit of Appendix C of calculation CA10309 and verified that the licensee calculated new IST limits for pumps, considering the methodology provided in Sections 2.2 and 2.3 of WCAP-17308-NP-A, Revision 0. The NRC staff finds the calculation methodology to determine new IST curves acceptable because (1) it is based on WCAP-17308-NP-A, Revision 0, and (2) the licensee verified that the respective EDG-powered pumps are expected to operate within those new IST limits.
Insufficient net positive suction head (NPSH) margin can result in pump cavitation and pump performance degradation. Changes in pump frequency affect the available and required NPSH.
Therefore, the proposed frequency tolerance could affect the available and required NPSH of the affected pumps. As reviewed above, Appendix C to CA10309 evaluated the EDG-powered pumps by determining and comparing new IST limits for the pumps based on the methodology specified in WCAP-17308-NP-A, Revision 0. In a supplement dated June 30, 2020, the licensee identified that operation of the pumps within the new IST limits provides assurance that the affected pumps will operate within the analytical limits, and thus, will have sufficient NPSH margin for proper pump operation. The NRC staff agrees that there is sufficient NPSH margin to prevent pump cavitation and pump performance degradation concerns because the required NPSH margin is one of the criteria used in defining the analytical limits, which is enveloped by the IST limits that the pumps are expected to operate within.
The lower pump discharge pressures resulting from the proposed low-end frequency tolerance (59.25 Hz) could cause low pressure switches to trip. Similarly, the higher discharge pressure from pumps resulting from the proposed high-end frequency tolerance (60.75 Hz) could cause relief valves to lift on affected discharge piping. In its supplement dated June 30, 2020, the licensee confirmed that by operating the safety-related pumps within the new IST limits, the affected pumps will operate within the limits of low pressure switches and any relief valves in the discharge piping. The NRC staff concludes that these conditions have been sufficiently considered to prevent unexpected low pressure switch or relief valve activation.
Impact on Operation of Motor-Operated Valves In the LAR, the licensee stated that an evaluation was performed in Appendix D of calculation CA10309 for all EDG-powered MOVs based on the methodology specified in WCAP-17308-NP-A, Revision 0. The increased EDG voltage and frequency variations from the nominal 4,160 V and 60 Hz would result in increased torque and thrust of MOVs. The licensee stated that increased torque and thrust remain bounded by the 5 percent engineering safety factor applied in the MOV Integrated Data Acquisition System (MIDAS) calculations. MIDAS is an MOV software used to implement the engineering design and margin management for safety-related MOVs. No changes were identified to the MIDAS calculations or test limits.
In the LAR, the licensee stated that, according to WCAP-17308-NP-A, Revision 0, there were four potential effects on MOVs due to EDG frequency and voltage tolerance: (1) increased MOV inertia due to increased EDG frequency/speed, (2) the potential effect of higher pump motor frequency on the differential pressure across an MOV, (3) the impact of voltage below nominal on the motor operator capability, and (4) increased stroke time. The licensee stated that, based on Appendix D of calculation CA10309, all safety-related EDG-powered MOVs were evaluated, and no issues were found at the proposed new TS SR EDG frequency and voltage uncertainty values.
In the NRC staffs safety evaluation of WCAP-17308-NP-A, Revision 0, the NRC staff found that frequency variation can impact MOV motor inertia. The licensee stated that increasing the EDG frequency and voltage increases the MOV motor speed, torque, and the kinetic energy in the motor operator. For torque seated valves, the obturator (the closing element that has some flexibility) contacts the valve seat with increased motor torque until the MOV motor trips. After the motor trips, the kinetic energy of the moving actuator components must be absorbed by the valve and actuator, which results in increased seating load. The increased seating load impact is considered in the MOV evaluation.
During the audit performed on Appendix D of calculation CA10309, the NRC staff found that the licensee followed the methodology of Section 4.2 of WCAP-17308-NP-A, Revision 0, for calculating increased motor inertia and the resulting torque of each MOV. The NRC staff finds the increased torque for each evaluated MOV remains bounded by the 5 percent engineering safety factor considered in the MIDAS calculations mentioned above, and therefore, is acceptable.
The licensee stated that new IST limits for pumps were determined and were verified as being within the bounds of the existing hydraulic and accident analyses. This ensures no changes to existing system design calculations. Therefore, the design differential pressure across the MOVs is not expected to be increased due to increased EDG frequency. The evaluation of the safety-related pumps conducted in Appendix C of calculation CA10309 considered no change to the existing pump hydraulic and accident analyses as a result of the EDG frequency and voltage tolerance.
The NRC staff finds the above analyses and criteria are acceptable and agrees with the conclusion of the evaluation that increased EDG frequency will not impact the designed MOV differential pressure.
Voltage variations can have significant effects on valve torque. The licensee stated that, in a separate calculation, the affected MOV motors have been evaluated to operate successfully for a minimum voltage at their upstream Class 1E bus voltage of 3,630 V (which is a transient undervoltage relay setpoint). As the minimum acceptable steady-state EDG operating voltage per the current TS is 4,060 V (i.e. > 3,630 V), the existing MOV voltage drop analyses remain bounding, and no further evaluation is required.
The NRC staff finds that the existing licensee calculation is currently based on a lower bounding voltage, and therefore, the proposed EDG voltage TS lower limit will have no impact on the MOV motor operator capability.
In the NRC staffs safety evaluation of WCAP-17308-NP-A, Revision 0, the NRC staff found that frequency variation can impact MOV stroke times. The licensee considered the increase in stroke times of various MOVs due to the proposed EDG frequency tolerance. The MOV stroke time will be increased by no greater than 1.25 percent as a result of the minimum diesel generator frequency of 59.25 Hz. In Appendix D of calculation CA10309, the licensee verified that increases in the MOV stroke times by 1.25 percent would remain below the maximum allowable stoke times.
The NRC staff finds the above analyses/criteria for MOV stroke times to be acceptable since the calculated strokes times are below the MOVs maximum allowable stroke times.
Based on the information provided in the LAR, the audit performed on calculation CA10309 and its appendices, and additional information provided in the licensees supplement dated June 30, 2020, the NRC staff finds all safety-related fans, pumps, and MOVs affected by the proposed TS changes will remain operable across the full range of the proposed EDG frequency and voltage tolerances.
3.2 Impact on Emergency Diesel Generator Loading In the LAR, the licensee stated that loadings on the EDGs were determined in Exelon Design Analysis E-88-015, Diesel Generator Loading Calculation Revision 6, dated April 30, 2019.
Based on WCAP-17308-NP-A, Revision 0, the motor loads operating above the rated 60 Hz would result in increased load on an EDG. The licensee revised Design Analysis E-88-015 to incorporate the impact of the proposed EDG upper TS frequency limit of 60.75 Hz, including the impact of the EDG minimum voltage (4,060 V), not previously considered in the calculation of record. According to revised Design Analysis E-88-015, the loadings would remain within the EDG ratings, as summarized in Table 1 of the LAR:
The NRC staff performed an audit of Design Analysis E-88-015 as described in the audit summary issued on June 30, 2020. The NRC staff verified that the licensee calculated the revised loading on the EDG in accordance with Section 3.1 of WCAP-17308-NP-A, Revision 0.
The calculation considered various EDG loading scenarios at the proposed maximum frequency and minimum voltage, which resulted in the maximum EDG loadings as provided in Table 1 above. The NRC staff finds the licensee conservatively calculated the EDG loadings, which continue to demonstrate margin; therefore, the results are acceptable.
3.3 Impact on Emergency Diesel Generator Fuel Oil Consumption In the LAR, the licensee stated that diesel fuel oil consumption (the fuel oil consumption rate and minimum tank level requirements) is based on the maximum kW output of the diesel generators. For the Fairbanks Morse diesel generators, this corresponds to a rating of 3,000 kW. For the SACM diesel generators, this corresponds to a rating of 5,400 kW. Based on revised Design Analysis E-88-015 for the EDG loadings, the licensee determined that, at the increased frequency, both the Fairbanks Morse and the SACM diesel generators would continue to operate within their kW ratings. As such, the results of the existing licensees fuel oil consumption calculations remain bounding, and therefore, no changes are required.
The NRC staff finds that, at the proposed EDG TS upper frequency limit of 60.75 Hz, the revised EDG loadings (as evaluated in Section 3.3 above) would remain within kW EDG ratings.
Since the fuel oil consumption is determined based on EDG kW rating, the NRC staff finds that there would be no impact on the EDG fuel oil consumption for any EDG.
3.4 Technical Conclusion Based on the technical evaluation provided in Section 3.0 above, the NRC staff finds the licensee has adequately evaluated the impact of the proposed TS changes on the safety-related loads fed by the EDGs. The proposed TS changes would have minimal or no impact on the continued safe operation and shutdown capability of loads fed by the EDGs. Consistent with 10 CFR 50.36(c)(3), the licensees proposed change to the SRs would continue to maintain Table 1 - Highest Predicted EDG Loading @ 60.75 Hz, 4,060 V EDG TS Limit (kW)
Highest Predicted (kW)
Margin to Limit Comparison to kW @ rated 60 Hz, 4160 V 1A (SACM) 4000 3599.6 10.0%
3523.3 (11.9%)
1B, 2A, 2B 3000 2944.4 1.9%
2853.7 (4.9 %)
reasonable assurance that the necessary quality of systems and components are being maintained. Therefore, the NRC staff finds the proposed TS changes are acceptable.
4.0 STATE CONSULTATION
In accordance with the Commissions regulations, the Maryland State official was notified of the proposed issuance of the amendments on September 28, 2020. The State official had no comments.
5.0 ENVIRONMENTAL CONSIDERATION
The amendments change a requirement with respect to installation or use of a facility component located within the restricted area as defined in 10 CFR Part 20 or change SRs. The NRC staff has determined that the amendments involve 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 amendments involve no significant hazards consideration, and there has been no public comment on such finding published in the Federal Register on February 11, 2020 (85 FR 7791). Accordingly, the amendments meet 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 amendments.
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 Commissions 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 I. Tseng Date: November 9, 2020
- by email OFFICE DORL/LPL1/PM* DORL/LPL1/LA*
DEX/EEOB/BC*
DEX/EMIB/BC* DSS/STSB/BC*
NAME MMarshall LRonewicz BTitus ABuford VCusumano DATE 10/02/2020 10/02/2020 08/24/2020 09/24/2020 10/27/2020 OFFICE OGC - NLO*
DORL/LPL1/BC*
DORL/LPL1/PM*
NAME JScro JDanna MMarshall DATE 10/27/2020 11/09/2020 11/09/2020