ML24366A146
| ML24366A146 | |
| Person / Time | |
|---|---|
| Site: | McGuire, Mcguire  |
| Issue date: | 01/03/2025 |
| From: | Markley M Plant Licensing Branch II |
| To: | Pigott E Duke Energy Carolinas |
| Klos L | |
| References | |
| EPID L-2024-LLR-0045, EPID L-2024-LLR-0046 | |
| Download: ML24366A146 (16) | |
Text
January 3, 2025 Edward Pigott Site Vice President Duke Energy Carolinas, LLC McGuire Nuclear Station 12700 Hagers Ferry Road Huntersville, NC 28078-8985
SUBJECT:
WILLIAM B. MCGUIRE NUCLEAR STATION, UNIT NOS. 1 AND 2 - INSERVICE TESTING ALTERNATE RELIEF REQUEST FOR COMPONENT COOLING AND RESIDUAL HEAT REMOVAL PUMPS (EPIDS L-2024-LLR-0045 AND L-2024-LLR-0046)
Dear Edward Pigott:
By letter dated July 1, 2024 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML24183A198), Duke Energy Carolinas, LLC (Duke Energy, the licensee) submitted to the U.S. Nuclear Regulatory Commission (NRC) Alternative Requests MC-SRP-KC-01 and MC-SRP-ND-01 with respect to specific inservice testing (IST) requirements in the 2020 Edition of the American Society of Mechanical Engineers (ASME)
Operation and Maintenance of Nuclear Power Plants, Division 1, OM Code: Section IST (OM Code) for the Fifth Interval IST Program at McGuire Nuclear Station (McGuire), Units 1 and 2.
Specifically, pursuant to subparagraph (1) in paragraph (z), Alternatives to codes and standards requirements, of Section 55a, Codes and standards, in Part 50, Domestic Licensing of Production and Utilization Facilities, in Title 10, Energy, of the Code of Federal Regulations (10 CFR 50.55a(z)(1)), the licensee requested to implement proposed Alternative Request MC-SRP-KC-01 for the component cooling water pumps and Alternative Request MC-SRP-ND-01 for the residual heat removal pumps at McGuire, Units 1 and 2, on the basis that the proposed alternatives will provide an acceptable level of quality and safety.
The NRC staff has reviewed the subject request and finds that that Alternative Request MC-SRP-KC-01 for the specified component cooling water pumps, and MC-SRP-ND-01 for the specified residual heat removal pumps provide an acceptable level of quality and safety at McGuire, Units 1 and 2, in accordance with 10 CFR 50.55a(z)(1). Therefore, the NRC staff authorizes alternative requests MC-SRP-KC-01 and MC-SRP-ND-01 for the Fifth Interval IST Program at McGuire, Units 1 and 2, which begins on March 1, 2025.
All other ASME OM Code requirements as incorporated by reference in 10 CFR 50.55a for which relief or an alternative was not specifically requested, and granted or authorized (as appropriate), in the subject requests remain applicable.
If you have any questions, please contact me at (301) 415-3867 or via email at John.Klos@nrc.gov.
Sincerely, Michael T. Markley, Branch Chief Plant Licensing Branch II-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos. 50-369, 50-370
Enclosure:
Safety Evaluation cc: Listserv Zachary M.
Turner Digitally signed by Zachary M. Turner Date: 2025.01.03 14:16:49 -05'00'
Enclosure SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION ALTERNATIVE REQUESTS MC-SRP-KC-01 AND MC-SRP-ND-01 FIFTH INTERVAL INSERVICE TESTING PROGRAM MCGUIRE NUCLEAR STATION, UNITS 1 AND 2 DOCKET NUMBERS 50-369 AND 50-370 EPID NOS. L-2024-LLR-0045 AND L-2024-LLR-0046
1.0 INTRODUCTION
By letter dated July 1, 2024 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML24183A198), Duke Energy Carolinas, LLC (Duke Energy, the licensee) submitted to the U.S. Nuclear Regulatory Commission (NRC) Alternative Requests MC-SRP-KC-01 and MC-SRP-ND-01 with respect to specific inservice testing (IST) requirements in the 2020 Edition of the American Society of Mechanical Engineers (ASME)
Operation and Maintenance of Nuclear Power Plants, Division 1, OM Code: Section IST (OM Code) for the Fifth Interval IST Program at McGuire Nuclear Station (McGuire), Units 1 and 2.
Specifically, pursuant to subparagraph (1) in paragraph (z), Alternatives to codes and standards requirements, of Section 55a, Codes and standards, in Part 50, Domestic Licensing of Production and Utilization Facilities, in Title 10, Energy, of the Code of Federal Regulations (10 CFR 50.55a(z)(1)), the licensee requested to implement proposed Alternative Request MC-SRP-KC-01 for the component cooling water pumps and Alternative Request MC-SRP-ND-01 for the residual heat removal pumps at McGuire, Units 1 and 2, on the basis that the proposed alternatives will provide an acceptable level of quality and safety.
The Fifth Interval IST Program at McGuire, Units 1 and 2, is scheduled to begin on March 1, 2025.
2.0 REGULATORY EVALUATION
The NRC regulations in 10 CFR 50.55a(f)(4), Inservice testing standards requirement for operating units, require, in part, that throughout the service life of a boiling or pressurized water-cooled nuclear power facility, pumps and valves that are within the scope of the ASME OM Code must meet the IST requirements (except design and access provisions) set forth in the ASME OM Code and addenda that become effective subsequent to editions and addenda specified in 10 CFR 50.55a(f)(2) and (3) and that are incorporated by reference in 10 CFR 50.55a(a)(1)(iv), to the extent practical within the limitations of design, geometry, and materials of construction of the components.
The NRC regulations in 10 CFR 50.55a(z), Alternatives to codes and standards requirements, state that:
Alternatives to the requirements of paragraphs (b) through (h) of [10 CFR 50.55a] or portions thereof may be used when authorized by the Director, Office of Nuclear Reactor Regulation. A proposed alternative must be submitted and authorized prior to implementation. The applicant or licensee must demonstrate that:
(1) Acceptable level of quality and safety. The proposed alternative would provide an acceptable level of quality and safety; or (2) Hardship without a compensating increase in quality and safety. Compliance with the specified requirements of this section would result in hardship or unusual difficulty without a compensating increase in the level of quality and safety.
3.0 TECHNICAL EVALUATION
3.1 Licensees Alternative Request MC-SRP-KC-01 Applicable ASME OM Code Edition The applicable Code of Record for the Fifth Interval IST Program at McGuire, Units 1 and 2, is the 2020 Edition of ASME OM Code as incorporated by reference in 10 CFR 50.55a.
Applicable ASME OM Code Components At McGuire, Units 1 and 2, component cooling (KC) pumps provide flow to their respective KC trains. Each pump shall start automatically upon receipt of a Safety Injection signal to supply cooling water to the KC System essential header to mitigate the consequences of an accident upon actuation of the Emergency Core Cooling System (ECCS).
In its submittal, the licensee proposed alternative testing for the component cooling pumps listed in Table 1:
Table 1: Applicable ASME OM Code Components for Alternative Request MC-SRP-KC-01 Component ID Pump Description ASME Class ASME OM Code Category 1KCPU0001 1A1 Component Cooling Pump 3
Group A 1KCPU0002 1A2 Component Cooling Pump 3
Group A 1KCPU0003 1B1 Component Cooling Pump 3
Group A 1KCPU0004 1B2 Component Cooling Pump 3
Group A 2KCPU0001 2A1 Component Cooling Pump 3
Group A 2KCPU0002 2A2 Component Cooling Pump 3
Group A 2KCPU0003 2B1 Component Cooling Pump 3
Group A 2KCPU0004 2B2 Component Cooling Pump 3
Group A Applicable ASME OM Code Requirements ASME OM Code, Subsection ISTB, Inservice Testing of Pumps in Water-Cooled Reactor Nuclear Power Plants - Pre-2000 Plants, paragraph ISTB-3500, Data Collection, and paragraph ISTB-3510, General, state in part:
(a) Accuracy. Instrument accuracy shall be within the limits of Table ISTB-3510-1. If a parameter is determined by analytical methods instead of measurement, then the determination shall meet the parameter accuracy requirement of Table ISTB-3510-1 (e.g., flow rate determination shall be accurate to within +/-2% of actual). For individual analog instruments, the required accuracy is percent of full-scale. For digital instruments, the required accuracy is over the calibrated range. For a combination of instruments, the required accuracy is loop accuracy.
(b) Range (1) The full-scale range of each analog instrument shall be not greater than three times the reference value.
ASME OM Code, Subsection ISTB, Table ISTB-3510-1, Required Instrument Accuracy, specifies the accuracy requirements for gauges used in testing pumps in the IST Program.
Licensees Proposed Alternative and Basis for Use In Alternative Request MC-SRP-KC-01, the licensee requested authorization to use the installed process instrumentation to measure component cooling water pump suction pressure during their quarterly Group A testing as providing an acceptable level of quality and safety in accordance with 10 CFR 50.55a(z)(1), although this instrumentation does not meet the specific requirements in the ASME OM Code.
In the letter dated July 1, 2024, the licensee stated that at McGuire Unit 1, the installed process instrumentation for measurement of component cooling water pump suction consists of gauges with a range of 0 to 60 pounds per square inch gage (psig). The licensee also stated that at McGuire Unit 2, the installed instrumentation for measurement of component cooling water pump suction consists of gauges with a range of 0 to 30 psig. The licensee further stated that during the Fifth Interval IST Program, the accuracy of these gauges will be 0.5 percent for Unit 1 and 1 percent for Unit 2.
At McGuire, Units 1 and 2, the component cooling water pumps are tested quarterly (Group A) and biennially (comprehensive) as required by the IST Program. The proposed alternative is for the Group A test only. The licensee also stated that comprehensive test is performed using temporarily installed test instruments to meet the requirements for comprehensive pump testing instrument accuracy.
At McGuire Unit 1, the licensee further stated that the typical suction pressure readings during the quarterly Group A component cooling water pump testing are between 13 and 16 psig; therefore, the Unit 1 component cooling water pump suction pressure gauges do not meet the three times criterion in ASME OM Code, Subsection ISTB, paragraph ISTB-3510(b)(1). The accuracy of the Unit 1 component cooling water suction gauges (0.5 percent) meets the requirements specified in ASME OM Code, Subsection ISTB, Table ISTB-3510-1, for pressure instrument accuracy (2 percent for Group A tests). A gauge that meets the ASME OM Code range requirements of three times the reference value, and has a 2 percent accuracy, results in a reading error of 6 percent. Given the 0.5 percent calibration of the 0 to 60 psig gauge, the licensee stated that the actual reading error to satisfy the Code equivalent 6 percent uncertainty at suction pressures of 5 psig and higher (60 / 5
- 0.005 = 6 percent). With the typical suction pressure readings of between 13 to 16 psig, the licensee documented that the Code equivalent 6 percent uncertainty can be obtained during the quarterly Group A component cooling water pump testing at McGuire Unit 1 using the 0 to 60 psig gauges with a 0.5 percent of full-scale calibration.
At McGuire Unit 2, the licensee further stated that the typical suction pressure readings during the Group A component cooling water pump testing are between 8.5 and 10.5 psig; therefore, the Unit 2 component cooling water pump suction pressure gauges do not meet the three times criterion in the ASME OM Code, Subsection ISTB, paragraph ISTB-3510(b)(1). The accuracy of the Unit 2 component cooling water suction gauges (1 percent) meets the requirements specified in ASME OM Code, Subsection ISTB, Table ISTB-3510-1, for pressure instrument accuracy (2 percent for Group A tests). Given the 1.0 percent calibration of the 0 to 30 psig gauge, the licensee stated that the actual reading error to satisfy the Code equivalent 6 percent uncertainty at suction pressures of 5 psig and higher (30 / 5
- 0.01 = 6 percent). With the typical suction pressure readings between 8.5 and 10.5 psig, the licensee documented that the Code equivalent 6 percent uncertainty suction pressures can be obtained during the quarterly Group A component cooling water pump testing at McGuire Unit 2 using the 0 to 30 psig gauges with a 1.0 percent of full-scale calibration.
When the requirements of ASME OM Code, Subsection ISTB, paragraph ISTB-3500 and Table ISTB-3510-1 are combined, the licensee stated that the actual instrument error introduced for component cooling water pump suction pressure is less than the equivalent Code allowable uncertainty (6 percent), given the full-scale calibrations of that instrumentation in McGuire Unit 1 (0.5 percent) and McGuire Unit 2 (1.0 percent). The licensee documented that the use of the process instrumentation for component cooling water pump suction pressure data meets the overall intent of the instrumentation requirements of the ASME OM Code; just not the specific range requirements of ASME OM Code, Subsection ISTB, paragraph ISTB-3510. The licensee stated that Alternative Request MC-SRP-KC-01 for suction pressure instrumentation during quarterly Group A testing of the component cooling water pumps at McGuire, Units 1 and 2, provides an acceptable level of quality and safety in accordance with 10 CFR 50.55a(z)(1).
Licensees Reason for Request The licensee submitted Alternative Request MC-SRP-KC-01 under 10 CFR 50.55a(z)(1) because the McGuire Unit 1 component cooling water pumps have suction pressure gauges with a range of 0 to 60 psig, and typical pressure readings of 13 to 16 psig. Further, the McGuire Unit 2 component cooling water pumps have suction pressure gauges with a range of 0 to 30 psig, and typical pressure readings of 8.5 to 10.5 psig. As such, the ASME OM Code requirement that the full-scale range of each analog instrument shall be not greater than three times the reference value cannot be met for the installed instrumentation used to measure suction pressure of the component cooling water pumps during the quarterly Group A testing at McGuire, Units 1 and 2.
NRC Staff Evaluation
In Alternative Request MC-SRP-KC-01, the licensee requested authorization to use the installed instrumentation to measure the suction pressure of the component cooling water pumps during the quarterly Group A testing as an alternative to the ASME OM Code requirements of Subsection ISTB, paragraph ISTB-3510. The currently installed instrumentation used to measure component cooling water pump suction pressure during quarterly Group A testing does not meet the specific requirement in ASME OM Code, Subsection ISTB, paragraph ISTB-3510, that the full-scale range of each analog instrument shall be no greater than three times the reference value. The licensee states that the currently installed instrumentation provides an acceptable level of quality and safety in accordance with 10 CFR 50.55a(z)(1) for the quarterly Group A testing of the component cooling water pumps in McGuire, Units 1 and 2.
At McGuire Unit 1, the installed suction pressure gauges for the component cooling water pumps have a range of 0 to 60 psig and a calibrated accuracy of +/- 0.5 percent. The licensee calculated that a suction pressure of at least 5 psig will meet the equivalent uncertainty of 6 percent for the ASME OM Code requirements for the upper instrument range of 60 psig and an instrument accuracy of +/- 0.5 percent. The licensee stated that the typical value for the suction pressure of the component cooling water pumps at McGuire Unit 1 during quarterly Group A testing is 13 to 16 psig. The NRC staff used 13 psig to calculate the reading error for the instrument range for these pumps. As shown in Table 2 of this safety evaluation, the effective gauge accuracy of the installed instruments is +/- 2.3 percent, which is better than the equivalent measurement uncertainty of 6 percent if the specific ASME OM Code requirements were met.
At McGuire Unit 2, the installed suction pressure gauges for the component cooling water pumps have a range of 0 to 30 psig and a calibrated accuracy of +/- 1 percent. The licensee stated that a suction pressure of at least 5 psig will meet the equivalent uncertainty of 6 percent for the ASME OM Code requirements for the upper range of 30 psig and an instrument accuracy of +/- 1 percent. The licensee stated that the typical value for the suction pressure of the component cooling water pumps at McGuire Unit 2 during quarterly Group A testing is 8.5 to 10.5 psig. The NRC staff used 8.5 psig to calculate the reading error for the instrument range for these pumps. As shown in Table 2 of this safety evaluation, the effective gauge accuracy of the installed instruments is +/- 3.5 percent, which is better than the equivalent measurement uncertainty of 6 percent if the specific ASME OM Code requirements were met.
Table 2 contains details of NRC staff evaluation of the accuracy of the installed instrumentation to be used to measure the suction pressure of the component cooling water pumps during quarterly Group A testing at McGuire, Units 1 and 2. The NRC staff discusses the use of the existing gauges in NUREG-1482, Guidelines for Inservice Testing at Nuclear Power Plants, Revision 3, Paragraph 5.5.1, Range and Accuracy of Analog Instruments, when the combination of range and accuracy yields a reading at least equivalent to the reading achieved from instruments that meet the ASME OM Code requirements. As indicated in Table 2, the NRC staff has determined that the installed instrumentation used to measure the suction pressure for the component cooling water pumps during quarterly Group A testing at McGuire, Units 1 and 2, will provide readings at least equivalent to the readings achieved from instruments that meet the ASME OM Code requirements.
Table 2: Pump and Gauge Information for Alternative Request MC-SRP-KC-01 Items Unit 1 Component Cooling Water Pumps: Suction Unit 2 Component Cooling Water Pumps:
Suction Remark Pump No.
1A1, 1A2, 1B1, 1B2 2A1, 2A2, 2B1, 2B2 Type of lnservice Test Group A Test Group A Test Suction Pressure Gauge(s) Range (psig) 0-60 0-30 Suction Reference Value Range (psig) 13-16 8.5-10.5 Three times the Reference Value (3 X 13) = 39 psig (3 x 8.5) = 25.5 psig Note 1 Effective Gauge Accuracy of Installed Instrument
(+/- 0.5%) of (60 / 13)
= +/-2.3%
(+/- 1%) of (30 / 8.5)
= +/-3.5%
Actual Accuracy of Instruments that Meet ASME OM Code Requirements for Group A Testing
(+/- 2 %} X (39/13)
= +/-6%
(+/- 2 %} X (25.5/8.5)
= +/-6%
Acceptable Alternative to the ASME OM Code Requirement for Group A Testing Yes Yes Note 1: Actual reference value range is between 13 and 16 psig for Unit 1; 13 psig is used for conservative results. Actual reference value range is between 8.5 and 10.5 psig for Unit 2; 8.5 psig is used for conservative results.
Based on its independent review, the NRC staff has determined that the currently installed instrumentation for the measurement of suction pressure of the specified component cooling water pumps at McGuire, Units 1 and 2, during quarterly Group A tests provides a measurement accuracy that meets the equivalent measurement uncertainty of 6 percent if the ASME OM Code requirements were met. Therefore, the staff finds that Alternative Request MC-SRP-KC-01 provides an acceptable level of quality and safety for quarterly Group A testing of the specified component cooling water pumps at McGuire, Units 1 and 2, in accordance with 10 CFR 50.55a(z)(1).
3.2 Licensees Alternative Request MC-SRP-ND-01 Applicable ASME OM Code Edition The applicable Code of Record for the Fifth Interval IST Program at McGuire, Units 1 and 2, is the 2020 Edition of ASME OM Code as incorporated by reference in 10 CFR 50.55a.
Applicable ASME OM Code Components At McGuire, Units 1 and 2, the Residual Heat Removal (ND) pumps provide flow to the ND heat exchangers and support removal of residual heat during the hot and cold shutdown modes of normal plant operation. The ND pumps support operation of the ECCS in cooling the reactor core and controlling reactivity following a postulated Large-Break Loss of Coolant Accident (LOCA). These pumps actuate upon a Safety Injection signal and deliver borated water from the Refueling Water Storage Tank to the Reactor Coolant System. The injected water would offset inventory loss due to a LOCA. The injected boron would provide an addition of negative reactivity to maintain the reactor subcritical following a LOCA.
In the letter dated July 1, 2024, the licensee proposed alternative testing for the residual heat removal pumps listed in Table 3:
Table 3: ASME Code Affected Components for Alternative Request MC-SRP-ND-01 Component ID Pump Description ASME Class ASME OM Code Category 1NDPU0001 1A Residual Heat Removal Pump 2
Group A 1NDPU0002 1B Residual Heat Removal Pump 2
Group A 2NDPU0001 2A Residual Heat Removal Pump 2
Group A 2NDPU0002 2B Residual Heat Removal Pump 2
Group A Applicable ASME OM Code Requirements ASME OM Code, Subsection ISTB, Inservice Testing of Pumps in Water-Cooled Reactor Nuclear Power Plants - Pre-2000 Plants, paragraph ISTB-3500, Data Collection, and paragraph ISTB-3510, General, state in part:
(a) Accuracy. Instrument accuracy shall be within the limits of Table ISTB-3510-1. If a parameter is determined by analytical methods instead of measurement, then the determination shall meet the parameter accuracy requirement of Table ISTB-3510-1 (e.g., flow rate determination shall be accurate to within +/-2% of actual). For individual analog instruments, the required accuracy is percent of full-scale. For digital instruments, the required accuracy is over the calibrated range. For a combination of instruments, the required accuracy is loop accuracy.
(b) Range (1) The full-scale range of each analog instrument shall be not greater than three times the reference value.
ASME OM Code, Subsection ISTB, Table ISTB-3510-1, Required Instrument Accuracy, specifies the accuracy requirements for gauges used in testing pumps in the IST Program.
Licensees Proposed Alternative and Basis for Use In Alternative Request MC-SRP-ND-01, the licensee requested authorization to use the installed process instrumentation to measure residual heat removal pump suction and discharge pressure during the quarterly Group A testing as providing an acceptable level of quality and safety in accordance with 10 CFR 50.55a(z)(1), although this instrumentation does not meet the specific requirements in ASME OM Code.
At McGuire, Units 1 and 2, the installed process instrumentation for the residual heat removal pumps consists of two suction pressure gauges with a range of 0 to 60 psig and a range of 0 to 600 psig, and one discharge pressure gauge with a range of 0 to 1000 psig. The licensee stated that each gauge has an accuracy of 0.5 percent.
At McGuire, Units 1 and 2, the residual heat removal pumps are tested quarterly (Group A) and biennially (comprehensive) as required by the IST Program. The proposed alternative is for the Group A test only. The licensee also stated that comprehensive testing is performed using temporarily installed test instruments to meet the requirements for the comprehensive pump testing instrument accuracy.
The licensee stated that the typical values for residual heat removal pump suction pressure during the quarterly Group A testing are between 48 and 81 psig. Therefore, there is a range (greater than 60 psig) in which the 0 to 600 psig gauge is required and will not meet the three times criterion in ASME OM Code, Subsection ISTB, paragraph ISTB-3510(b)(1). The accuracy of this process instrument (0.5 percent) meets the requirements specified in ASME OM Code, Subsection ISTB, Table ISTB-3510-1, for instrument accuracy (2 percent for Group A tests). A gauge that meets the ASME OM Code range requirements of three times the reference value and has a 2 percent accuracy results in a reading error of 6 percent. Given the 0.5 percent calibration of the 0 to 600 psig gauge, the licensee stated that the actual reading error to satisfy the Code equivalent 6 percent uncertainty at suction pressures of 50 psig and higher (600 / 50
- 0.005 = 6 percent). For suction pressures of 50 psig and higher, the licensee also stated that the Code equivalent 6 percent uncertainty for suction pressure can be obtained during the quarterly Group A residual heat removal pump testing using the 0 to 600 psig range gauge with 0.5 percent full-scale calibration. For suction pressures below 50 psig, the licensee will use the tighter range (0 to 60 psig) suction pressure gauge to meet the ASME OM Code requirements for range and accuracy during the quarterly Group A residual heat removal pump testing.
The licensee stated that the typical values for residual heat removal pump discharge pressure during the quarterly Group A testing are between 230 and 260 psig. Therefore, the process range for the discharge pressure gauge (0 to 1000 psig) will not meet the three times criterion in ASME OM Code, Subsection ISTB, paragraph ISTB-3510(b)(1). The accuracy of this process instrument (0.5 percent) meets the requirements specified in ASME OM Code, Subsection ISTB, Table ISTB-3510-1, for instrument accuracy (2 percent for Group A tests).
Given the 0.5 percent calibration of the 0 to 1000 psig discharge pressure gauge, the licensee stated that the actual reading error to satisfy the Code equivalent 6 percent uncertainty at discharge pressures of 84 psig and higher (1000 / 84
- 0.005 = 6 percent). With the typical values for residual heat removal pump discharge pressure during the quarterly Group A testing of between 230 and 260 psig, the licensee stated that the Code equivalent 6 percent uncertainty discharge pressures can be obtained during the quarterly Group A residual heat removal pump testing using the 0 of 1000 psig gauge with 0.5 percent full-scale calibration.
When the requirements of ASME OM Code, Subsection ISTB, paragraph ISTB-3500 and Table ISTB-3510-1 are combined, the licensee stated that the actual instrument error introduced for suction and discharge pressure during the quarterly Group A residual heat removal pump testing is less than the equivalent ASME OM Code allowable uncertainty (6 percent), given the full-scale calibration of 0.5 percent of the instrumentation. The licensee stated that the use of the process instrumentation for the residual heat removal pumps pressure data meets the overall intent of the instrumentation requirements of the ASME OM Code; just not the specific range requirements of ASME OM Code, Subsection ISTB, paragraph ISTB-3510. The licensee also stated that Alternative Request MC-SRP-ND-01 for suction pressure instrumentation during quarterly Group A testing of the residual heat removal pumps at McGuire, Units 1 and 2, provides an acceptable level of quality and safety in accordance with 10 CFR 50.55a(z)(1).
Licensees Reason for Request The licensee submitted Alternative Request MC-SRP-ND-01 under 10 CFR 50.55a(z)(1) because the residual heat removal pumps at McGuire, Units 1 and 2, have process instrumentation installed such that there are two suction pressure gauges (0 to 60 psig and 0 to 600 psig), and one discharge pressure gauge (0 to 1000 psig). The typical suction and discharge pressure readings during quarterly Group A testing of the residual heat removal pumps are 48 to 81 psig and 230 to 260 psig, respectively. As such, the ASME OM Code requirement that the full-scale range of each analog instrument shall be not greater than three times the reference value cannot be met for the installed instrumentation used to measure pressure of the residual heat removal pumps during the quarterly Group A testing at McGuire, Units 1 and 2.
NRC Staff Evaluation
In Alternative Request MC-SRP-ND-01, the licensee requested authorization to use the installed instrumentation to measure the suction and discharge pressure of the residual heat removal pumps during their quarterly Group A testing as an alternative to the ASME OM Code requirements of Subsection ISTB, paragraph ISTB-3510. The currently installed instrumentation used to measure residual heat removal pump suction and discharge pressure during quarterly Group A testing does not meet the specific requirements in ASME OM Code, Subsection ISTB, paragraph ISTB-3510(b)(1), that the full-scale range of each analog instrument shall be no greater than three times the reference value. The licensee stated that the currently installed instrumentation provides an acceptable level of quality and safety in accordance with 10 CFR 50.55a(z)(1) for the quarterly Group A testing of the residual heat removal pumps in McGuire, Units 1 and 2.
With respect to the discharge pressure measurements, the installed discharge pressure gauges for the residual heat removal pumps at McGuire, Units 1 and 2, have a range of 0 to 1000 psig and a calibration accuracy of +/- 0.5 percent. The licensee also stated that the typical value of the discharge pressure of the residual heat removal pumps during testing ranges from 230 to 260 psig. Therefore, the process range for the discharge pressure gauge (0 to 1000 psig) will not meet the three times criterion in ASME OM Code, Subsection ISTB, paragraph ISTB-3510(b)(1). The licensee stated that a discharge pressure of at least 84 psig will meet the ASME OM Code equivalent uncertainty of 6 percent for the instrument range of 1000 psig and an instrument accuracy of +/- 0.5 percent. The NRC staff used 230 psig to calculate the reading error for the instrument range of these pumps. As shown in Table 4 of this safety evaluation, the effective gauge accuracy of the installed instruments is +/- 2.2 percent, which is better than the equivalent measurement uncertainty of 6 percent for Group A tests if the specific ASME OM Code requirements were met.
Table 4 contains details of the NRC staff evaluation of the accuracy of the installed instrumentation to measure discharge pressure of the residual heat removal pumps during quarterly Group A testing at McGuire, Units 1 and 2. The NRC staff discussed the use of the existing gauges in NUREG-1482, Revision 3, Paragraph 5.5.1, when the combination of range and accuracy yields a reading at least equivalent to the reading achieved from instruments that meet the ASME OM Code requirements. As indicated in Table 4, the NRC staff has determined that the installed instrumentation used to measure residual heat removal pump discharge pressure during quarterly Group A testing at McGuire, Units 1 and 2, will provide readings at least equivalent to the readings achieved from instruments that meet the ASME OM Code requirements.
Table 4: Pump Discharge and Gauge Information for Alternative Request MC-SRP-ND-01 Items Residual Heat Removal Pumps:
Discharge Remark Pump No.
1A, 1B, and 2A, 2B Type of lnservice Test Group A Test Discharge Pressure Gauge(s) Range (psig) 0-1000 Discharge Reference Value Range (psig) 230-260 Three Times the Reference Value (3 X 230) = 690 psig Note 1 Effective Gauge Accuracy of
(+/- 0.5 %) of Installed Instrument (1000/230)
= +/-2.2 %
Actual Accuracy of Instruments that Meet ( 2 %) X (690/230)
ASME OM Code Requirements for Group A Testing
=+/-6%
Acceptable Alternative to the ASME OM Code Requirement Yes Note 1: Actual reference value range is between 230 and 260 psig; 230 psig is used for conservative results.
With respect to the suction pressure measurements, the residual heat removal pumps at McGuire, Units 1 and 2, have a low range installed gauge (0 to 60 psig) and a high range installed gauge (0 to 600 psig). The licensee stated that typical values for residual heat removal suction pressure are between 48 and 81 psig during the quarterly Group A tests. Therefore, there is a range (greater than 60 psig) in which the 0 to 600 psig gauge is required and will not meet the three times criterion in ASME OM Code, Subsection ISTB, paragraph ISTB-3510(b)(1). For suction pressure below 50 psig, the tighter range (0 to 60 psig) pressure gauge will be used to meet the ASME OM Code requirements for range and accuracy.
Table 5 contains details of the NRC staff evaluation of the accuracy of the installed instrumentation to be used to measure the suction pressure of the residual heat removal pumps during quarterly Group A testing at McGuire, Units 1 and 2. Table 5 shows that when measuring a 60 psig pressure on the 0 to 600 psig gauge, the effective accuracy of the installed residual heat removal pump suction instrumentation is +/- 5 percent, which is better than the equivalent measurement uncertainty of 6 percent for Group A tests if specific ASME OM Code requirements were met. The NRC staff discusses the use of the existing gauges in NUREG-1482, Revision 3, Paragraph 5.5.1, when the combination of range and accuracy yields a reading at least equivalent to the reading achieved from instruments that meet the ASME OM Code requirements. As indicated in Table 5, the NRC staff has determined that the installed instrumentation used to measure suction pressure for the residual heat removal pumps during quarterly Group A testing at McGuire, Units 1 and 2, will provide readings at least equivalent to the readings achieved from instruments that meet the ASME OM Code requirements.
Table 5: Pump Suction and Gauge Information for Alternative Request MC-SRP-ND-01 Items Residual Heat Removal Pumps:
Suction Remark Pump No.
1A, 1B, and 2A, 2B Type of lnservice Test Group A Test Suction Pressure Gauge - High Range Suction Pressure Gauge - Low Range 0-600 psig 0-60 psig Suction Reference Value Range 48-81 psig Three times the Reference Value (3 X 60) = 180 psig Note 1 Effective Gauge Accuracy of
(+/- 0.5 %) of (600/60)
Installed Instrumentation
= +/-5%
Actual Accuracy of Instruments that Meet
(+/- 2 %) X (600/200)
ASME OM Code Requirements for Group A
=+/-6%
Testing Acceptable Alternative to the ASME OM Code Requirement Yes Note 1: Actual reference value range is between 48 and 81 psig; pressures within the range of the 0-60 psig gauge are measured with low range pressure gauge. A 60psig reading on the high range pressure gauge is used for conservative results.
Based on its independent review, the NRC staff has determined that the currently installed instrumentation for the measurement of suction and discharge pressure of the specified residual heat removal pumps at McGuire, Units 1 and 2, during quarterly Group A tests provides a measurement accuracy that meets the equivalent measurement uncertainty of 6 percent if the ASME OM Code requirements were met. Therefore, the staff finds that Alternative Request MC-SRP-ND-01 provides an acceptable level of quality and safety for quarterly Group A testing of the specified residual heat removal pumps at McGuire, Units 1 and 2, in accordance with 10 CFR 50.55a(z)(1).
4.0 CONCLUSION
As described above, the NRC staff has determined that the proposed Alternative Requests MC-SRP-KC-01 and MC-SRP-ND-01 for the use of installed instrumentation during quarterly Group A tests of the component cooling water pumps and residual heat removal pumps, respectively, at McGuire, Units 1 and 2, as described in the licensees submittal dated July 1, 2024, provide an acceptable level of quality and safety when compared to the instrumentation that would meet the ASME OM Code requirements. Accordingly, the NRC staff concludes that the licensee has adequately addressed the regulatory requirements set forth in 10 CFR 50.55a(z)(1). Therefore, the NRC staff authorizes Alternative Requests MC-SRP-KC-01 and MC-SRP-ND-01 for the Fifth Interval IST Program at McGuire, Units 1 and 2, which begins on March 1, 2025.
All other ASME OM Code requirements as incorporated by reference in 10 CFR 50.55a for which relief or an alternative was not specifically requested, and granted or authorized (as appropriate), in the subject requests remain applicable.
Principal Contributor: Yuken Wong, NRR Thomas G. Scarborough, NRR Date: January 3, 2025
- by email OFFICE DORL/LPL2-1/PM DORL/LPL2-1/LA NRR/DEX/EMIB/BC* DORL/LPL2-1/BC NAME JKlos KZeleznock SBailey MMarkley (ZTurner for)
DATE 12/31/2024 01/02/2025 12/4/2024 01/03/2025