ML24144A049
| ML24144A049 | |
| Person / Time | |
|---|---|
| Site: | Callaway  |
| Issue date: | 06/11/2024 |
| From: | Jennivine Rankin Plant Licensing Branch IV |
| To: | Diya F Callaway Energy Center |
| Chawla M | |
| References | |
| EPID L-2023-LLR-0051 | |
| Download: ML24144A049 (1) | |
Text
June 11, 2024
Fadi Diya Senior Vice President and Chief Nuclear Officer Ameren Missouri Callaway Energy Center 8315 County Road 459 Steedman, MO 65077
SUBJECT:
CALLAWAY PLANT, UNIT NO. 1 - REQUESTS FOR RELIEF FROM ASME OM CODE PUMP AND VALVE TESTING REQUIREMENTS FOR THE FIFTH 120-MONTH INSERVICE TESTING INTERVAL (EPID L-2023-LLR-0051)
Dear Fadi Diya:
By letter dated September 27, 2023 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML23270B966), Union Electric Company, doing business as Ameren Missouri (the licensee), submitted Alternative Requests PR-01, PR-02, and PR-03 to the U.S.
Nuclear Regulatory Commission (NRC) proposing the use of an alternative to specific 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 (ASME OM Code) at Callaway Plant, Unit No. 1 (Callaway ) associated with the fifth inservice testing (IST) interval program.
Specifically, pursuant to Title 10 of the Code of Federal Regulations (10 CFR) 50.55a(z)(1),
Acceptable level of quality and safety, the licensee requested to implement Alternative Requests PR-01, PR-02 and PR-03 on the basis that the proposed alternatives would provide an acceptable level of quality and safety. The Callaway fifth IST interval program is scheduled to begin December 20, 2024, and end on December 19, 2034. The licensee proposed that Alternative Requests PR-01, PR-2 and PR-03 be authorized for the fifth IST interval program.
The NRC staff has determined that Alternative Requests PR-01, PR-02, and PR-03 at Callaway, as described in the licensees letter dated September 27, 2023, provide an acceptable level of quality and safety for the proposed testing for the specified pumps at Callaway for the fifth IST interval program. Accordingly, the NRC staff concludes, as set forth in the enclosed safety evaluation that the licensee has adequately addressed the regulatory requirements set forth in 10 CFR 50.55a(z)(1). Therefore, the NRC staff authorizes the use of Alternative Requests PR-01, PR-02, and PR-03 at Callaway for the fifth IST interval program, which is scheduled to start on December 20, 2024, and end on December 19, 2034.
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 request remain applicable.
F. Diya
If you have any questions, please contact the Callaway Project Manager at 301-415-8371 or via email at Mahesh.Chawla@nrc.gov.
Sincerely,
Jennivine K. Rankin, Chief Plant Licensing Branch IV Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation
Docket No. 50-483
Enclosure:
Safety Evaluation
cc: Listserv
SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION
ALTERNATIVE REQUESTS PR-01, PR-02 AND PR-03
FIFTH INSERVICE TESTING PROGRAM INTERVAL
UNION ELECTRIC COMPANY
CALLAWAY PLANT, UNIT 1
DOC K E T N O. 5 0 - 483
1.0 INTRODUCTION
By letter dated September 27, 2023 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML23270B966), Union Electric Company, doing business as Ameren Missouri (the licensee), submitted Alternative Requests PR-01, PR-02, and PR-03 to the U.S. Nuclear Regulatory Commission (NRC) proposing the use of an alternative to specific 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 (ASME OM Code) at Callaway Plant, Unit No. 1 (Callaway ) associated with the fifth inservice testing (IST) interval program.
Specifically, pursuant to Title 10 of the Code of Federal Regulations (10 CFR) 50.55a(z)(1),
Acceptable level of quality and safety, the licensee requested to implement Alternative Requests PR-01, PR-02 and PR-03 on the basis that the proposed alternative would provide an acceptable level of quality and safety.
The Callaway fifth IST interval program is scheduled to begin December 20, 2024, and end on December 19, 2034. The licensee proposed that Alternative Requests PR-01, PR-2 and PR-03 be authorized for the fifth IST interval program.
2.0 REGULATORY EVALUATION
The NRC regulations in 10 CFR 50.55a(f)(4), Inservice testing standards requirement for operating plants, state, 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 inservice test 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
Enclosure
within the limitations of design, geometry, and materials of construction of the components. The inservice test requirem ents for pumps and valves that are within the scope of the ASME OM Code but are not classified as ASME BPV
[Boiler and Pressure Vessel Code ] Code Class 1, Class 2, or Class 3 may be satisfied as an augmented IST program [in accordance with 10 CFR 50.55a(f)(6)(ii) without requesting relief under 10 CFR 50.55a(f)(5) or alternatives under 10 CFR 50.55a(z)]. This use of an augmented IST program [may be]
acceptable provided the basis for deviations from the ASME OM Code, as incorporated by reference in [10 CFR 50.55a], demonstrates an acceptable level of quality and safety, or that implementing the Code provisions would result in hardship or unusual difficulty without a compensating increase in the level of quality and safety, where documented and available for NRC review.
The NRC regulations in 10 CFR 50.55a(z), Alternatives to codes and standards requirements, state:
Alternatives to the requirements of [10 CFR 50.55a(b) through (h)] 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
The information provided by the licensee in support of the request for an alternative to the ASME OM Code requirements, as incorporated by reference in 10 CFR 50.55a, Codes and standards, has been evaluated, and the bases for disposition are documented below.
3.1 Licensees Alternative Request PR-01
Applicable Code Edition
The applicable Code of record for the fifth IST interval program at Callaway is the 2020 Edition of ASME OM Code as incorporated by reference in 10 CFR 50.55a.
ASME Code Components Affected
In its submittal, the licensee proposed alternative testing for the following residual heat removal (RHR) pumps:
Table 1
Pump No. Description ASME Code Class OM Code Category (Note 1)
PEJ01A RHR Pump A 2 Gp A PEJ01B RHR Pump B 2 Gp A Note 1: Category A pumps - Pumps that are operated continuously or routinely during normal operation, cold shutdown, or refueling operations (
Reference:
ISTB-2000, Supplement Definitions).
Applicable Code Requirements
The IST requirements in the ASME OM Code, 2020 Edition, as incorporated by reference in 10 CFR 50.55a, related to this alternative request are as follows:
ASME OM Code, subsection ISTB, Inservice Testing of Pumps in Water-Cooled Reactor Nuclear Power Plants - Pre-2000 Plants, paragraph ISTB-3500, Data Collection, paragraph ISTB-3510, General, subparagraph (b), Range, subparagraph (1) states that [t]he full-scale range of each analog instrument shall be not greater than three times the reference value.
ASME OM Code, subparagraph ISTB-3510(a), Accuracy, states, in part, that
[i]nstrument accuracy shall be within the limits of Table ISTB-3510. If a parameter is determined by analytical methods instead of measurement, then the determination shall meet the parameter accuracy requirements of Table ISTB-3510-1 (e.g., flow rate determination shall be accurate to within +/-2% of actual).
Licensees Proposed Alternative
The licensee proposes to perform the Group A quarterly test by use of the currently installed analog discharge pressure gauge with a range of 0 to 700 pounds per square inch (psig) calibrated to less than or equal to +/- 1.7 percent such that the inaccuracies due to discharge pressure will be less than that required by the Table ISTB-3510-1 of the ASME OM Code (+/-
- 12. 0 psig). The error associated with the discharge gauge would then be no greater than +/- 11.9 pounds per square inch (psi) (700 X 0.017). Use of the installed discharge pressure gauge calibrated to less than +/- 2 percent (+/- 1.7 percent) is equivalent in terms of OM Code compliance for the measurement of discharge pressure.
Licensees Reason for Request
In its letter dated September 27, 2023, the licensee states in part:
The range of the installed analog discharge pressure gauges for the RHR pumps is 0 - 700 psig. Because the reference values for pump discharge pressure
during lnservice Testing are less than 234 psig [are less than 234 psig in the submittal], the instrument range exceeds the requirement of ISTB-3510(b)(1).
Pump discharge pressure indication is used along with pump suction pressure indication to determine pump differential pressure. Discharge pressure reference values for the RHR pumps during lnservice Testing are between 200 psig and 234 [234 in the submittal] psig. Based on ISTB-3510(b)(1), this would require as a maximum, a gauge with a range of 0 to 600 psig (3 X 200 psig) to bound the lowest reference value for discharge pressure. Applying the accuracy requirement of +/-2% for the Group A test, the resulting inaccuracies due to discharge pressure effects would be +/-12.0 psig (0.02 X 600 psig).
NRC Staff Evaluation
The licensee requests an alternative to the ASM E OM Code instrumentation requirements of ASME OM Code, subsection ISTB, paragraph ISTB-3510(b)(1), for the pressure gauge that is used to measure the discharge pressure of RHR pumps PEJ01A and PEJ01B. Paragraph ISTB-3510(b)(1) requires that the full-scale range of each instrument be no greater than three times the reference value . The licensee proposes to use the installed discharge pressure gauge that does not meet this requirement.
The installed discharge pressure gauge for the RHR pumps has a range of 0 to 700 psig. The typical discharge pressure reference values for the RHR pumps during testing are 200 to 234 psig. T he NRC staff agrees that the use of 200 psig to calculate a conservative reading error is appropriate for these pumps. Therefore, the effective gauge accuracy of the installed pressure gauge when calibrated to less than or equal to +/- 1 .7 percent is 5.95 percent, which is less than the resulting measurement accuracy of +/- 6 percent for Group A tests if ASME OM Code requirements were met. This request for alternative applies only to Group A testing of RHR pumps PEJ01A and PEJ01B.
Table 2 below contains details related to the RHR pump discharge pressure gauge as provided by the licensee, the ASME OM Code requirem ents, and notes pertaining to the NRC staff's evaluation. The use of the existing gauges is supported by the guidance in NUREG-1482, Revision 3, Guidelines for Inservice Testing at Nuclear Power Plants: Inservice Testing of Pumps and Valves and Inservice Examination and Testing of Dynamic Restraints (Snubbers) at Nuclear Power Plants, July 2020 (ML20202A473), subsection 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. The RHR pumps' discharge pressure gauge yields readings at least equivalent to the readings achieved from instruments that meet ASME OM Code requirements for Group A tests as required in ISTB-3510(b)(1). The NRC staff finds that this approach is consistent with the ASME OM Code, subparagraph ISTB-3510(a), which states, in part, that [i]f a parameter is determined by analytical methods instead of measurement, then the determination shall meet the parameter accuracy requirements of Table ISTB-3510-1.
Therefore, the NRC staff finds that the licensee's proposed alternative provides an acceptable level of quality and safety because the installed instrumentation provides a measurement accuracy that exceeds the resulting measurement accuracy of +/- 6 percent for Group A tests if ASME OM Code requirements are met.
Table 2: Pump and Gauge Information for Alternative Request PR-01
Items RHR Pumps: Discharge Remarks Pump No. PEJ01A and PEJ01B Type of Inservice Test Group A Test Discharge Pressure Gauge Range (psig) 0-700 Discharge Reference Value Range (psig) 200-234 Three times the Reference Value (3 X 200) = 600 psig Note 1 Effective Gauge Accuracy of Installed Instrument (+/- 1.7%) of (700/200) = +/- 5.95%
if Calibrated to +/- 1.7%
Actual Accuracy of Instrument that Meets ASME OM Code Requirements for Group A Testing (+/- 2%) X (600/200) = +/- 6%
Acceptable Alternative to the ASME OM Code Yes Requirement for Group A Testing Note 1: Actual reference value range is between 200 and 234 psig; 200 psig is used for conservative results.
3.2 Licensees Alternative Request PR-02
Applicable Code Edition
The applicable Code of record for the fifth IST interval program at Callaway is the 2020 Edition of ASME OM Code as incorporated by reference in 10 CFR 50.55a.
ASME Code Components Affected
In its submittal, the licensee proposed alternative testing for the following Centrifugal Charging Pumps:
Table 3
Pump No. Description ASME Code Class OM Code Category (Note 1)
PBG05A Centrifugal Charging Pump A 2 Gp B PBG05B Centrifugal Charging Pump B 2 Gp B Note 1: Category B pumps - Pumps in standby systems that are not operated routinely except for testing (
Reference:
ISTB-2000, Supplement Definitions)
=
Applicable Code Requirement===
The IST requirements in the ASME OM Code, 2020 Edition, as incorporated by reference in 10 CFR 50.55a, related to this alternative request are as follows:
ASME OM Code, subsection ISTB, subparagraph ISTB-3510(b)(1), states that [t]he full-scale range of each analog instrument shall be not greater than three times the reference value.
ASME OM Code, subparagraph ISTB-3510(a), states, in part, that [i]nstrument 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 requirements of Table ISTB-3510-1 (e.g., flow rate determination shall be accurate to within +/-2% of actual).
Licensees Proposed Alternative
The licensee proposes to perform the Group B quarterly test by use of the currently installed analog suction pressure gauge (0 to 150 psig) calibrated to less than or equal to +/-1 .2 percent, such that the inaccuracies due to suction pressure will be less than that required by the ASME OM Code (+/-1.8 psig). The error associated with the suction gauge would then be no greater than +/-1.8 psi (150 X 0.012). The use of the installed suction pressure gauge calibrated to less than +/- 2 percent (+/- 1.2 percent) is equivalent in terms of ASME OM Code compliance for the measurement of suction pressure.
Licensees Reason for Request
In its letter dated September 27, 2023, the licensee states in part:
The range of the installed analog suction pressure gauges for the centrifugal charging pumps is 0 - 150 psig. Because the reference values for suction pressure during lnservice Testing are less than 50 psig, the instrument range exceeds the requirement of ISTB-3510(b)(1).
Pump suction pressure indication is used along with pump discharge pressure indication to determine pump differential pressure. Suction pressure reference values for the centrifugal charging pumps during lnservice Testing are between 30 psig and 45 psig . Based on ISTB-3510(b)(1) , this would require as a maximum, a gauge with a range of 0 to 90 psig (3 X 30 psig) to bound the lowest reference value for suction pressure . Applying the accuracy requirement of +/- 2 %
for the quarterly Group B pump test, the resulting inaccuracies due to suction pressure effects would be +/- 1.8 psig (0 .02 X 90 psig).
NRC Staff Evaluation
The licensee requests an alternative to the in strumentation requirements of ASME OM Code, Subsection ISTB, paragraph ISTB-3510(b)(1) for the pressure gauges that are used to measure the suction pressure of centrifugal charging pumps PBG05A and PBG05B.
Paragraph ISTB-3510(b)(1) requires that the full-scale range of each instrument be no greater than three times the reference value. The licensee proposes to use the installed suction pressure gauges that do not meet this requirement.
The installed suction pressure gauges for the centrifugal charging pumps have a range of 0 to 150 psig. The typical suction pressure reference values for the centrifugal charging pumps during testing are 30 to 40 psig. The NRC staff agr ees that the use of 30 psig to calculate a conservative reading error is appropriate for these pumps. Therefore, the effective gauge accuracy of the installed pressure gauge when calibrated to less than or equal to +/- 1.2 percent is 6 percent, which is equal to the resulting measurement accuracy of +/- 6 percent for Group B
tests if the ASME OM Code requirements were met. This request for an alternative applies only to Group B testing of centrifugal charging pumps PBG05A and PBG05B.
Table 4 contains details related to the centrifugal charging pump suction pressure gauges as provided by the licensee, the ASME OM Code requirements, and notes pertaining to the NRC staff's evaluation. The use of the existing gauges is supported by the guidance in NUREG-1482, Revision 3, subsection 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. The centrifugal charging pumps' suction pressure gauges yield readings at least equivalent to the readings achieved from inst ruments that meet ASME OM Code requirements for Group B tests as required in ISTB-3510(b)(1). The NRC staff finds that this approach is consistent with the ASME OM Code, subparagraph ISTB- 3510(a) which states, in part, that [i]f a parameter is determined by analytical methods instead of measurement, then the determination shall meet the parameter accuracy requirements of Table ISTB-3510-1.
Therefore, the NRC staff concludes that the licensee's proposed alternative provides an acceptable level of quality and safety because the installed instrumentation provides a measurement accuracy that equals the resulting measurement accuracy of +/- 6 percent for Group B tests if ASME OM Code requirements were met.
Table 4: Pump and Gauge Information for Alternative Request PR-02
Centrifugal Charging Items Pumps: Suction Remark Pump No. PBG05A, PBG05B Type of lnservice Test Group B Test Suction Pressure Gauge Range (psig) 0-150 Suction Reference Value Range (psig) 30-40 Three times the Reference Value (3 X 30) = 90 psig Note 1 Effective Gauge Accuracy of Installed (+/- 1.2 %) of (150/30) = +/- 6 %
Instrument if Calibrated to +/- 1.2%
Actual Accuracy of Instrument that Meets (+/- 2 %) x (90/30) = +/- 6%
ASME OM Code Requirements for Group B Testing Acceptable Alternative to the ASME OM Code Yes Requirement for Group B Testing Note 1: Actual reference value range is between 30 and 40 psig; 30 psig is used for conservative results.
3.3 Licensees Alternative Request PR-03
Applicable Code Edition
The applicable Code of record for the fifth IST Interval program at Callaway is the 2020 Edition of ASME OM Code as incorporated by reference in 10 CFR 50.55a.
ASME Code Components Affected
In its submittal, the licensee proposed alternative testing for the following Boric Acid Transfer pumps:
Table 5
Pump No. Description ASME Code Class OM Code Category (Note 1)
PBG02A Boric Acid Transfer 3 Gp A Pump A PBG02B Boric Acid Transfer Pump B 3 Gp A Note 1: Category A pumps - Pumps that are operated continuously or routinely during normal operation, cold shutdown, or refueling operations (
Reference:
ISTB-2000, Supplement Definitions).
=
Applicable Code Requirement===
The IST requirements in the ASME OM Code, 2020 Edition, as incorporated by reference in 10 CFR 50.55a, related to this alternative request are as follows:
ASME OM Code, subsection ISTB, paragraph ISTB-5120, Inservice Testing, paragraph ISTB- 5121, Group A Test Procedure, states, in part, that,
Group A tests shall be conducted with the pump operating as close as practical to a specified reference point and within the variances from the reference point as described in this paragraph. The test parameters shown in Table ISTB-3000-1 shall be determined and recorded as required by this paragraph.
ASME OM Code, paragraph ISTB-5121, subparagraph (c), states that,
Where it is not practical to vary system resistance, flow rate and pressure shall be determined and compared to their respective reference values.
ASME OM Code, Table ISTB-3000-1, Inservice Test Parameters, indicates which parameters must be measured during Baseline, Group A, Group B, Comprehensive, and Pump Periodic Verification Tests (where identified in ISTB-1400(d)). Subparagraph (d) in paragraph ISTB-1400, Owners Responsibility, requires the Owner to identify those pumps with specific design-basis accident flow rates in the Owners credited safety analysis for inclusion in a pump periodic verification test program.
ASME OM Code, paragraph ISTB-3500, requires, in part, that instrument accuracy shall be within the limits of Table ISTB-3510-1.
Licensees Proposed Alternative
In its letter dated September 27, 2023, the licensee states in part:
As an alternative to measuring differential pressure and flow during the Group A quarterly test, only the differential pressure will be measured and compared to its reference value. Additionally , vibration measurements are also recorded and compared to their reference values.
The Group A test will be performed using the [minimum flow] recirculation flow path shown on Attachment 1 [Figure 1 below], with the throttle valve
[BGV209(210)] remaining in its locked position. The reference value is approximately 112 psig at an estimated flow rate of 15 gpm [gallon per minutes].
At 15 gpm, the pump curves exhibit a small degree of slope/linearity, although not nearly as linear as the 75 gpm flow rate during the biennial comprehensive pump test. Because the throttle position of the applicable globe valve (BGV2O9/210) remains in its locked position, the flow rate for the quarterly testing is essentially a fixed value. T he lack of flow measurement during quarterly testing does not prevent the detection of pump degradation. With the system resistance fixed, flow can be assumed to be constant and pump degradation may be detected by comparing successive measurements of pump differential pressure. Based on this, it is not warranted to install additional instrumentation to provide for flow measurement.
During the comprehensive pump test when flow may be measured, full spectrum vibration analysis will be performed, which is beyond the vibration analysis required by the [ASME OM] Code. The vibration measurements will be recorded and compared to their reference values. Thus, when performing the comprehensive pump test, all required parameters will be measured and compared to their reference values. The performance of full spectrum analysis, in addition to continued Group A quarterly and comprehensive testing, will ensure that an accurate assessment of pump health and operational readiness is determined.
Figure 1
Licensees Reason for Request
In its letter dated September 27, 2023, the licensee provided the following reason for its request:
Pursuant to 10 CFR 50.55a, Codes and standards, paragraph (z)(1), an alternative is proposed to the above-noted testing requirements of the ASME OM Code. The basis of the request is that the proposed alternative would provide an acceptable level of quality and safety. Specifically, this alternative is requested for Group A testing for the Boric Acid Transfer pumps
The normal test loop for the subject pumps consists of suction from the applicable Boric Acid Tank and discharge through a mini-flow recirculation line back to the Boric Acid Tank; however, flow measuring instrumentation is not installed in this flow path. Installing permanent flow instrumentation would require a costly system modification. The most s uitable location for use of a temporary ultrasonic flow meter (UFM) has numerous small bore instrument lines interfering with the use of a ladder to reach the applicable Boric Acid Transfer piping.
Callaway would also have to implement new and more costly calibration requirements for the UFM equipment.
The mini-flow recirculation line contains a locked throttle valve set to allow for the minimum pump recirculation flow (approximately 15 gpm). The throttled position of this valve is important to provide for the minimum recirculation flow necessary to protect the pump while minimizing the diversion of flow from the primary discharge path to the Charging system to allow for immediate boration in emergency conditions. Unlocking and adjusting the throttle valve on a quarterly basis for lnservice Testing would create the potential for mis-positioning of the throttle valve and thus an adverse effect on system capability . Based on this, the mini-flow recirculation line is considered a fixed resistance flow path.
An alternate test circuit is available in which the flow rate may be measured; however, this flow path requires injection of highly concentrated boric acid solution into the reactor coolant system. During the quarterly Group A test at normal power operations, this test is highly impractical since severe power level fluctuations would be created which could cause a trip of the reactor. Performing this test at cold shutdown intervals would also result in excessive boration of the reactor coolant system resulting in potential difficulties and delays in restarting the plant.
NRC Staff Evaluation
The licensee requested an alternative to the Group A pump test requirements of ASME OM Code, subsection ISTB, paragraph ISTB-5121(c), fo r flow rate and pressure measurement of the boric acid transfer pumps. Paragraph ISTB-5121(c) requires that, [w]here it is not practical to vary system resistance, flow rate and pressure shall be determined and compared to their respective reference values. The licensee's proposal to measure only the differential pressure and vibration does not meet these requirements.
ASME OM Code, paragraph ISTB-5121, pump test requires that the pump parameters shown in Table ISTB-3000-1 must be measured and evaluated to determine pump condition and detect degradation. Pump differential pressure and flow rate are two parameters that are measured and evaluated together to determine pump hydraulic performance. The Callaway boric acid transfer pumps PBG02A and PBG02B have a normal test loop where suction is from the boric acid tank and discharge is through a mini-flow recirculation line back to the boric acid tank. This mini-flow line is the only line available for Group A pump testing. The Group A pump testing is required to meet the instrument accuracy spec ified in paragraph ISTB-3500 to provide accurate flow rate measurement during pump testing so that the data can be evaluated with measured pump differential pressure to monitor for pump hydraulic degradation.
Pump differential pressure and flow rate are two parameters that are measured and evaluated together to determine pump hydraulic performance. However, the minimum flow return lines at Callaway used for quarterly Group A testing of the boric acid transfer pumps are of fixed resistance due to the locked valves BGV209 and BGV210, do not provide the ability to vary flow rate, and are not instrumented for flow rate. As an alternative to measuring differential pressure and flow during the Group A test, the licensee proposed that only the differential pressure will be measured and compared to its reference value. The differential pressure reference value is approximately 112 psig at a flow rate of 15 gpm.
Measurement of the boric acid pump differential pressure and a comparison to the reference value, along with vibration measurement during Group A testing, will provide assessment of the pump performance. This alternative request applies only to Group A testing of boric acid transfer pumps PBG02A and PBG02B.
During Group A testing, vibration measurements are recorded and compared to their reference values as required by the ASME OM Code. Also, during the biennial comprehensive test, all required parameters are measured and compared to their reference values. In addition, the licensee states that a full-spectrum vibr ation analysis will be performed during the comprehensive test, which is beyond the vibr ation analysis required by the ASME OM Code.
Further, ASME OM Code, subsection ISTB, paragraph ISTB- 5124, Periodic Verification Test, requires a periodic verification test for pumps identified in accordance with ISTB-1400(d) to verify that the pump can meet the required (differential or discharge, as applicable) pressure at its highest design-basis accident flowrate.
The licensee states that the installation of permanently installed flow instrumentation would require a costly modification. The best location in the boric acid transfer piping for a temporary UFM has numerous instrument lines that would interfere with access to the location. Also, the licensee would have to implement new and more co stly calibration requirements for the UFM equipment. The licensee states that the pump curves for the boric acid transfer pumps indicate a performance slope at a flow rate of 15 gpm for the proposed Group A test such that pump degradation can be detected because the pump flow rate is essentially fixed.
The NRC staff finds that the licensee's proposed alte rnative to test the boric acid transfer pumps by measuring the differential pressure and comparing it to the reference value, as discussed above, provides an acceptable level of quality and safety.
4.0 CONCLUSION
As set forth above, the NRC staff has determined that Alternative Requests PR-01, PR-02, and PR-03 at Callaway as described in the licensee letter dated September 27, 2023, provide an acceptable level of quality and safety for the proposed testing for the specified pumps at Callaway for the fifth IST interval program. 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 the use of Alternative Requests PR-01, PR-02, and PR-03 at Callaway, for the fifth IST interval program, which is scheduled to start on December 20, 2024, and end on December 19, 2034.
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 request remain applicable.
Principal Contributors: Gurjendra S. Bedi, NRR Thomas G. Scarbrough, NRR
Date: June 11, 2024
ML24144A049 *concurrence via email OFFICE NRR/DORL/LPL4/PM NRR/DORL/LPL4/LA* NRR/DEX/EMIB/BC* NRR/DORL/LPL4/BC*
NAME MChawla PBlechman SBailey JRankin DATE 5/21/2024 5/29/2024 4/2/2024 6/11/2024