ML24298A209
| ML24298A209 | |
| Person / Time | |
|---|---|
| Site: | Columbia  |
| Issue date: | 11/06/2024 |
| From: | Tony Nakanishi Plant Licensing Branch IV |
| To: | Schuetz R Energy Northwest |
| Chawla M | |
| References | |
| EPID L-2024-LLR-0007, EPID L-2024-LLR-0009, EPID L-2024-LLR-0010 | |
| Download: ML24298A209 (1) | |
Text
November 6, 2024 Robert Schuetz Chief Executive Officer Energy Northwest 76 North Power Plant Loop P.O. Box 968 (Mail Drop 1023)
Richland, WA 99352
SUBJECT:
COLUMBIA GENERATING STATION - ALTERNATIVE REQUESTS 5IST-01 (RP01), 5IST-02 (RP02), AND 5IST-03 (RP03) - FIFTH INTERVAL INSERVICE TESTING PROGRAM (EPID L-2024-LLR-0007, EPID L-2024-LLR-0009, AND EPID L-2024-LLR-0010)
Dear Robert Schuetz:
By letter dated January 29, 2024 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML24029A071), as supplemented by letter dated July 29, 2024 (ML24211A126), Energy Northwest (the licensee) submitted Alternative Requests 5IST-01 (RP01), 5IST-02 (RP02), and 5IST-03 (RP03) for pumps to the U.S. Nuclear Regulatory Commission (NRC) for alternatives 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 (OM Code) at the Columbia Generating Station (Columbia) associated with the fifth interval inservice testing (IST) program.
Specifically, pursuant to Title 10 of the Code of Federal Regulations (10 CFR)
Section 50.55a(z)(1), Acceptable level of quality and safety, the licensee requested to implement alternative requests 5IST-01 and 5IST-02 on the basis that the proposed alternatives would provide an acceptable level of quality and safety in lieu of certain requirements in the ASME OM Code as incorporated by reference in 10 CFR 50.55a. Pursuant to 10 CFR 50.55a(z)(2), Hardship without a compensating increase in quality and safety, the licensee proposed to implement alternative request 5IST-03 on the basis that complying with specific requirements in the ASME OM Code as incorporated by reference in 10 CFR 50.55a would result in hardship without a compensating increase in the level of quality and safety.
At the time of the initial submittal, the Columbia fifth IST program interval was scheduled to begin December 13, 2024, and to end on December 12, 2034. In a letter dated July 15, 2024 (ML24197A223), the licensee notified the NRC of its plan to extend the current Columbia fourth 10-year interval IST program by 1 year as allowed by the ASME OM Code, Subsection ISTA, General Requirements, paragraph ISTA-3120, Inservice Examination and Test Interval, which allows a change to the interval start and end dates not to exceed 1 year cumulatively. The licensee proposed that Alternative Requests 5IST-01, 5IST-02, and 5IST-03 be authorized for the fifth interval IST program.
The NRC staff has reviewed the subject requests and concludes, as set forth in the enclosed safety evaluation, that Energy Northwest has adequately addressed all of the regulatory
requirements set forth in 10 CFR 50.55a(z). Therefore, the NRC staff authorizes Alternative Requests 5IST-01 (RP01), 5IST-02 (RP02), and 5IST-03 (RP03) under 10 CFR 50.55a(z) for the fifth interval IST program at Columbia.
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 approved, in the subject requests, remain applicable.
If you have any questions, please contact the Project Manager, Mahesh Chawla, at 301-415-8371 or by email at Mahesh.Chawla@nrc.gov.
Sincerely, Tony T. Nakanishi, Chief Plant Licensing Branch IV Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-397
Enclosure:
Safety Evaluation cc: Listserv Tony T.
Nakanishi Digitally signed by Tony T. Nakanishi Date: 2024.11.06 15:29:00 -05'00'
Enclosure SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION ALTERNATIVE REQUESTS 5IST-01 (RP01), 5IST-02 (RP02), AND 5IST-03 (RP03)
FIFTH INTERVAL INSERVICE TESTING PROGRAM ENERGY NORTHWEST COLUMBIA GENERATING STATION DOCKET NO. 50-397
1.0 INTRODUCTION
By letter dated January 29, 2024 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML24029A071), as supplemented by letter dated July 29, 2024 (ML24211A126), Energy Northwest (the licensee) submitted Alternative Requests 5IST-01 (RP01), 5IST-02 (RP02), and 5IST-03 (RP03) for pumps to the U.S. Nuclear Regulatory Commission (NRC) for alternatives 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 (OM Code) at the Columbia Generating Station (Columbia) associated with the fifth interval inservice testing (IST) program.
Specifically, pursuant to Title 10 of the Code of Federal Regulations (10 CFR)
Section 50.55a(z)(1), Acceptable level of quality and safety, the licensee requested to implement Alternative Requests 5IST-01 and 5IST-02 on the basis that the proposed alternatives would provide an acceptable level of quality and safety in lieu of certain requirements in the ASME OM Code as incorporated by reference in 10 CFR 50.55a, Codes and standards. Pursuant to 10 CFR 50.55a(z)(2), Hardship without a compensating increase in quality and safety, the licensee proposed to implement Alternative Request 5IST-03 on the basis that complying with specific requirements in the ASME OM Code as incorporated by reference in 10 CFR 50.55a would result in hardship without a compensating increase in the level of quality and safety.
At the time of the initial submittal, the Columbia fifth IST program interval was scheduled to begin December 13, 2024, and was scheduled to end on December 12, 2034. In a letter dated July 15, 2024 (ML24197A223), the licensee notified the NRC of its plan to extend the current Columbia fourth 10-year interval IST program by 1 year as allowed by the ASME OM Code, subsection ISTA, General Requirements, paragraph ISTA-3120, Inservice Examination and Test Interval, which allows a change to the interval start and end dates not to exceed 1 year cumulatively. The licensee proposed that Alternative Requests 5IST-01, 5IST-02, and 5IST-03 be authorized for the fifth interval IST 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 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:
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
3.1 Licensees Alternative Request 5IST-01(RP01)
Applicable Code Edition The applicable Code of record for the fifth interval IST program at Columbia is the 2020 Edition of ASME OM Code as incorporated by reference in 10 CFR 50.55a.
ASME Code Components Affected Table 1 lists the pumps at Columbia for which alternative testing is being requested.
Table 1 Pump Number Description (System)
P&ID1 Dwg.2 No.
ASME Code Class OM Code Category (Note 1)*
SW-P-1A Standby SW3 M524, Sh. 1 3
A Pump Number Description (System)
P&ID1 Dwg.2 No.
ASME Code Class OM Code Category (Note 1)*
SW-P-1B Standby SW M524, Sh. 1 3
A HPCS-P-2 Standby SW, HPCS4 M524, Sh1 3
A 1piping and instrumentation diagram (P&ID) 2drawing (Dwg) 3service water (SW) 4high pressure core spray (HPCS)
- Note 1: Category A pumps - Pumps that are operated continuously or routinely during normal operation, cold shutdown, or refueling operations (
Reference:
ASME OM Code, subsection ISTB, paragraph ISTB-2000, Supplemental 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-5200, Vertical Line Shaft Centrifugal Pumps, ISTB-5210, Baseline Testing, states that parameters to be measured are specified in Table ISTB-3000-1, Inservice Test Parameters.
ASME OM Code, Subsection ISTB, ISTB-5210 states, in part, in subparagraph (a) that In systems where resistance can be varied, flow rate and differential pressure shall be measured.
ASME OM Code, subsection ISTB, ISTB-5220, Inservice Testing, ISTB-5221, Group A Test Procedure, states, in part, in subparagraph (b) that the differential pressure shall then be determined and compared to its reference value.
ASME OM Code, subsection ISTB, ISTB-5220, ISTB-5223, Comprehensive Test Procedure, states, in part, in subparagraph (b) that the differential pressure shall then be determined and compared to its reference value.
ASME OM Code, subsection ISTB, ISTB-5220, ISTB-5224, Periodic Verification Test, states that tests shall be performed for pumps identified via ISTB-1400(d). If the required flow and differential pressure cannot be achieved, then the pump is in the action range, and corrective actions shall be taken in accordance with ISTB-6200(b).
ASME OM Code, subsection ISTB, paragraph ISTB-1400, Owners Responsibility, in subparagraph (d) states that the Owners responsibility includes identifying those pumps with specific design basis accident flow rate in the Owners credited safety analysis for inclusion in a pump periodic verification test program.
Licensees Proposed Alternative The licensee indicated that pump discharge pressure will be recorded during the testing of the pumps identified in table 1 of this safety evaluation (SE). Code Acceptance Criteria will be based on discharge pressure instead of differential pressure as specified in table ISTB-5221-1, Vertical Line Shaft Centrifugal Pump Test Acceptance Criteria. The effect of setting the Code Acceptance Criteria on discharge pressure instead of differential pressure as specified in the Code will have no negative impact on detecting pump degradation based on the following:
Pumps SW-P-1A, SW-P-1B, and HPCS-P-2 are vertical line shaft centrifugal pumps, which are immersed in their water source and have no suction line which can be instrumented.
Surveillance requirement 3.7.1.1 in the Columbia Technical Specifications specifies the minimum allowable spray pond level to assure adequate net positive suction head and ultimate heat sink capability.
The difference between allowable minimum and overflow pond level is only 21 inches of water or 0.8 pounds per square inch (psi). This small difference will not be significant to the program and suction pressure will be considered constant. Administratively, the pond level is controlled within a 9-inch (0.33 psi) band. Discharge pressure trend data for the previous 2 years is shown for all three pumps.
Acceptable flow rate and discharge pressure will suffice as proof of adequate suction pressure.
These pumps operate with a suction lift. The maximum elevation of spray pond level is 434 feet, 6 inches, and minimum elevation of discharge piping for these pumps is 442 feet 5/8 inches. Thus, discharge pressure for these pumps will always be lower than the calculated differential pressure for the entire range of suction pressures. Therefore, acceptance criteria based on discharge pressure is conservative.
In its letter dated July 29, 2024, the licensee provided additional justification for Alternative Request 5IST-01 as follows:
The effect of setting the acceptance criteria on discharge pressure rather than differential pressure, as specified in the ASME OM Code, provides a more conservative test methodology. The very small suction pressure variations noted in Section 5.3 of Alternative Request 5IST-01 (RP01) are insignificant and do not adversely impact Energy Northwests ability to monitor pump degradation.
Therefore, the proposed alternative provides an acceptable level of quality and safety.
Alternative Request 5IST-01 (RP01) was intended to be used as an alternative to all paragraphs under ASME OM Code, Subsection ISTB-5220, Inservice Testing, which includes ISTB-5223, Comprehensive Test Procedure. The provisions in Alternative Request 5IST-01 (RP01) will be applied to the comprehensive test procedures for the pumps listed in Alternative Request 5IST-01 (RP01) during the Fifth 10-Year Interval IST Program. Pump discharge pressure will be recorded during the testing of these pumps in lieu of the differential pressure requirement of ASME OM Code, Subsection ISTB, Paragraph ISTB-5223(b).
Alternative Request 5IST-01 (RP01) was intended to be used as an alternative to all paragraphs under ASME OM Code, Subsection ISTB-5220, which includes ISTB-5224, Periodic Verification Test. The provisions in Alternative Request 5IST-01 (RP01) will be applied to the periodic verification test procedures for the pumps listed in Alternative Request 5IST-01 during the Fifth 10-Year Interval IST Program. Pump discharge pressure will be recorded during the testing of these pumps in lieu of the differential pressure requirement of ASME OM Code, Subsection ISTB, Paragraph ISTB-5224.
Licensees Reason for Request In its letter dated January 29, 2024, the licensee states:
There are no inlet pressure gauges installed in the inlet of these vertical line shaft centrifugal pumps, making it impractical to directly measure inlet pressure for use in determining differential pressure for the pump.
NRC Staff Evaluation
Pursuant to 10 CFR 50.55a(z)(1), the licensee submitted Alternative Request 5IST-01 for SW pumps SW-P-1A, and SW-P-1B, and HPCS pump HPCS-P-2, on the basis that the proposed alternative would provide an acceptable level of quality and safety in lieu of the applicable requirements in the ASME OM Code as incorporated by reference in 10 CFR 50.55a. As the pumps within the scope of Alternative Request 5IST-01 are vertical line shaft centrifugal pumps, the licensee proposes to implement its alternative in lieu of the requirements of ASME OM Code, subsection ISTB, table ISTB-3000-1, and paragraphs ISTB-5210, ISTB-5221, ISTB-5223, and ISTB-5224, for measuring pump differential pressure during Baseline Tests, Group A Test, Comprehensive Tests, and Periodic Verification Tests. Paragraphs ISTB-5210(a), ISTB-5221(b), and ISTB-5223(b) require that where resistance can be varied, flow rate and differential pressure shall be measured. The licensee proposed alternative measures and evaluated the pumps operational readiness based on their discharge pressure because inlet suction pressure instrumentation is not available with the pumps immersed in their water source.
The licensee states in Alternative Request 5IST-01 that the difference between minimum and overflow pond level is only 21 inches of water, or 0.8 psi, which is further administratively controlled to a 9-inch band, which equates to 0.33 psi. This small variation makes the suction pressure essentially constant.
Alternative Request 5IST-01 in section 5.3 of the letter dated January 29, 2024, provides discharge pressure data for the pumps within the scope of the request. For the past 2 years, the discharge pressure for SW Pumps SW-P-1A and SW-P-1B has ranged from 213.71 to 220.33 pounds per square inch gage (psig), which results in a 0.33 psig suction pressure being less than 0.2 percent of discharge pressure. For the past 2 years, the discharge pressure for pump HPCS-P-2 has ranged from 59.44 to 61.75 psig, which results in a 0.33 psig suction pressure being less than 0.6 percent of discharge pressure. This very small suction pressure variation is insignificant and does not adversely impact the licensees ability to monitor these pumps for degradation.
In this instance, measurement of pump discharge pressure is more conservative because the measurement is uncorrected for elevation. With the spray pond level at a lower elevation than the discharge piping, the pump discharge pressure is less than the pump differential pressure.
Therefore, the discharge pressure for each pump is less than the calculated differential pressure for the entire range of suction pressures.
Based on its review, the NRC staff has determined that the testing proposed by the licensee for SW pumps SW-P-1A and SW-P-1B, and HPCS pump HPCS-P-2 provides an acceptable level of quality and safety in lieu of the specific ASME Code requirements. Therefore, the NRC staff finds that Alternative Request 5IST-01 (RP01) may be authorized under 10 CFR 50.55a(z)(1) for the fifth interval IST program at Columbia.
3.2 Licensees Alternative Request 5IST-02 (RP02)
Applicable Code Edition The applicable Code of record for the fifth interval IST program at Columbia is the 2020 Edition of the ASME OM Code as incorporated by reference in 10 CFR 50.55a.
ASME Code Components Affected Table 2 below lists the residual heat removal (RHR) and HPCS pumps at Columbia for which alternative testing is testing is being requested.
Table 2 Pump Number Description P&ID Dwg. No.
ASME Code Class OM Code Category (Note 1)
RHR-P-2A RHR Pump M521, Sh. 1 2
A RHR-P-2B RHR Pump M521, Sh. 1 2
A RHR-P-2C RHR Pump M521, Sh. 1 2
B HPCS-P-1 HPCS M520 2
B Note 1: Category A pumps - Pumps that are operated continuously or routinely during normal operation, cold shutdown, or refueling operations, and Category B pumps - Pumps in standby systems that are not operated routinely except for testing (
Reference:
ASME OM Code, subsection ISTB, paragraph ISTB-2000, Supplemental 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-3500, Data Collection, ISTB-3510, General, subparagraph (b), Range, in item (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, ISTB-3510, subparagraph (a,) Accuracy, states, in part, that
[i]nstrument accuracy shall be within the limits of Table ISTB-3510-1. Subparagraph ISTB-3510(a) also states 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 (e.g., flow rate determination shall be accurate to within +/-2% of actual).
Licensees Proposed Alternative The licensee proposes that during the Group A and Group B quarterly test, pump discharge, which is used to determine differential pressure, shall be measured by respective Transient Data Acquisition System (TDAS) points listed below for each pump. TDAS data readings will be taken each second.
Subparagraphs ISTB-3510(a) and ISTB-3510(b)(1) specify both accuracy and range requirements for each instrument used in measuring pump performance parameters. The purpose of instrument requirements is to ensure that pump test measurements are sufficiently accurate and repeatable to permit evaluation of pump condition and detection of degradation.
Instrument accuracy limits the inaccuracy associated with the measured test data. Thus, higher instrument accuracy lowers the uncertainty associated with the measured data. The purpose of the OM Code range requirement is to ensure reading accuracy and repeatability of test data.
Since the TDAS data are being obtained to an accuracy of +/-1 percent of full scale, it consistently yields measurements more accurate than would be provided by instruments meeting the OM Code instrument accuracy requirement of +/-2 percent of full scale and range requirement of three times the reference value. Equivalent accuracy being obtained by TDAS measurements is calculated in table 2-1 below.
Table 2-1: Pumps and Instrument Affected by Alternative Request 5IST-02 Pump Test Parameter Instrument I.D.
Range (PSIG)
- Ref.
Value (psig)
Instrument Loop Accuracy Equivalent Code Accuracy RHR-P-2A Discharge Pressure RHR-PT-37A TDAS PT 155 0-600 143
+/- 1%,
+/- 6 psig
[6/(3x143)] x 100
= 1.47%
RHR-P-2B Discharge Pressure RHR-PT-37B TDAS PT 076 0-600 148.3
+/- 1%,
+/- 6 psig
[6/(3x148.3)] x 100
= 1.35%
RHR-P-2C Discharge Pressure RHR-PT-37C TDAS PT 091 0-600 143.23
+/- 1%,
+/- 6 psig
[6/(3x143.23)] x 100
= 1.40%
HPCS-P-1 Discharge Pressure HPCS-PT-4 TDAS PT 107 0-1500 448.2 (dP)
+/- 1%,
+/- 15 psig
[15/(3x448.2)] x 100
= 1.11%
- The above table reflects the latest reference values as specified in the implementing procedures. This table will not be updated to reflect small changes in future reference values.
Procedure reference value for HPCS-P-1 is differential pressure.
Thus, the range and accuracy of TDAS instruments being used to measure pump discharge pressure result in data measurements of higher accuracy than that required by the OM Code and thus, will provide reasonable assurance of pump operational readiness. It should also be noted that the TDAS system averages many readings, therefore giving a significantly more accurate reading than would be obtained by using the averaging technique as allowed by paragraph ISTB-3510(d) on visual observation of a fluctuating test gauge.
The range of the pressure transmitters (PTs) used for these applications was selected to bound the expected pump discharge pressure range during all normal and emergency operating conditions (the maximum expected discharge pressure for the RHR and HPCS pumps is approximately 450 psig and 1,400 psig, respectively). However, during inservice testing, the pumps are tested at full flow, resulting in lower discharge pressures than the elevated discharge pressure that can occur during some operating conditions. For this reason, the pump reference value is significantly below the maximum expected operational discharge pressure. A reduction of the range of the PTs to three times the reference value would, in these cases, no longer bound the expected discharge pressure range for these pumps, and therefore is not practicable.
If a PT were to fail, a like-for-like replacement would have to be used to ensure suitability for all pump flow conditions. However, this is not a concern because the existing instrumentation provides pump discharge pressure indication of higher accuracy and better resolution than that required by the Code for evaluating pump condition and detecting degradation.
In its letter dated July 29, 2024, the licensee provided the following information in support of Alternative Request 5IST-02:
As discussed in Sections 5.2 and 5.3 of Alternative Request 5IST-02 (RP02), the data obtained from the Transient Data Acquisition System (TDAS) is of higher accuracy than required by ASME OM Code, which helps ensure that the pumps listed in Alternative Request 5IST-02 (RP02) are performing at the flow and pressure conditions required to fulfill their design function. TDAS data is sufficiently accurate for evaluating pump condition and in detecting pump degradation. Therefore, the proposed alternative provides an acceptable level of quality and safety.
Energy Northwest inadvertently used the term preservice tests rather than baseline tests in Alternative Request 5IST-02 (RP02). The intent of the last sentence of Section 4, Reason for Request, in Alternative Request 5IST-02 (RP02) was to apply to comprehensive, baseline, and periodic verification tests.
Temporary test gauges meeting the ASME OM Code requirements shall be used to meet the requirements in ISTB-5210, Baseline Testing, and ISTB-5224, for pumps RHR-P-2A, RHR-P-2B, RHR-P-2C, and HPCS-P-1 listed in Alternative Request 5IST-02 (RP02).
An accuracy of +/-15 psig over a calibrated range of 0 to 1,500 psig provides a loop accuracy of +/-1%, with an equivalent ASME OM Code accuracy of 1.11%,
which exceeds the requirement in Table ISTB-3510-1 of +/-2% for Group A and Group B tests. The range of the pressure transmitters used for the pumps listed in Alternative Request 5IST-02 (RP02) were selected to bound the expected pump discharge pressure range during all normal and emergency operating conditions, which is 1,400 psig for the HPCS pump.
The Equivalent Code Accuracy field for pump RHR-P-2A in the table under Section 5.2 should be 1.40 percent, rather than 1.47 percent.
Licensees Basis for Use 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 (ML20202A473), section 5.5.1,Range and Accuracy of Analog Instruments, states, in part:
When the range of a permanently installed analog instrument is greater than three times the reference value, but the accuracy of the instrument is more conservative than that required by the OM Code, the NRC staff may grant relief or authorize an alternative when the combination of the range and accuracy yields a reading that is at least equivalent to that achieved using instruments that meet the OM Code requirements (i.e. up to +/-6 percent for Group A and B tests, and +/-1.5 percent for pressure and differential pressure instruments for Preservice and CPTs [Comprehensive Pump Test]).
Licensees Reason for Request The licensee states that the installed test gauges used to measure the pump discharge pressure, which is used to determine differential pressure, do not meet the OM Code range requirements. RHR and HPCS pumps discharge pressure instruments (RHR-PT37A, RHR-PT37B, RHR-PT-37C, and HPCS-PT-4) exceed, or may exceed (dependent upon measured parameters), the Code allowable range limit of three times the reference value. An alternative is proposed for Group A, and Group B inservice tests only. Temporary test gauges meeting the OM Code requirements shall be used for comprehensive and preservice tests.
NRC Staff Evaluation
In Alternative Request 5IST-02, the licensee requests an alternative to the ASME OM Code instrument range requirements of ASME OM Code, Subsection ISTB, paragraphs ISTB-3510(a) and ISTB-3510(b)(1), for the instruments listed in table 2-1 above, which are used for Group A and Group B tests of vertical shaft centrifugal pumps RHR-P-2A/2B/2C and HPCS-P-1. Paragraph ISTB-3510(b)(1) requires that the full-scale range of each instrument shall be not greater than three times the reference value. The licensee proposes to use the installed instrumentation to measure pump discharge pressure.
Table 2-1 above contains details related to vertical shaft centrifugal pumps and instruments as provided by the licensee. The installed instruments are calibrated to an accuracy of +/-1 percent of full scale. The licensee's calculations provided in table 2-1 above demonstrate that the actual variance has a value which is less than the maximum variance allowed by the ASME OM Code. The installed instrumentation provides an acceptable level of quality and safety because the variance in the actual test results is more conservative than that allowed by the ASME OM Code for analog instruments.
The use of the existing instruments listed in table 2-1 above is supported by 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. For the pumps listed in table 2 of this SE, the installed instruments (pressure gauges) listed in table 2-1 yield readings at least equivalent to the readings achieved from instruments that meet ASME OM Code requirements for Group A and Group B tests as required in ISTB-3510(b)(1).
Based on its review, the NRC staff finds that the approach described in Alternative Request 5IST-02 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 has determined 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 A and Group B tests if ASME OM Code requirements were met. Therefore, the NRC staff finds that Alternative Request 5IST-02 (RP02) may be authorized under 10 CFR 50.55a(z)(1) for the fifth interval IST program at Columbia.
3.3 Licensees Alternative Request 5IST-03 (RP03)
Applicable Code Edition The applicable Code of record for the fifth interval IST program at Columbia is the 2020 Edition of ASME OM Code as incorporated by reference in 10 CFR 50.55a.
ASME Code Components Affected Table 3 lists standby liquid control pumps for Columbia for which alternative testing is being requested.
Table 3 Pump No.
Description (System)
P&ID Dwg. No.
ASME Code Class OM Code Category (Note 1)
SLC-P-1A Standby Liquid Control M522 2
B SLC-P-1B Standby Liquid Control M522 2
B Note 1: Category B pumps - Pumps is standby systems that are not operated routinely except for testing (
Reference:
ASME OM Code, subsection ISTB, paragraph ISTB-2000, Supplemental 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-3550, Flow Rate, states, in part, When measuring flow rate, a rate or quantity meter shall be installed in the pump circuit.
If a meter does not indicate the flow rate directly, the record shall include the method used to reduce the data.
ASME OM Code, paragraph ISTB-5300, Positive Displacement Pumps, subparagraph (a), Duration of Tests, item (1), states For the Group A test and the comprehensive test, after pump conditions are as stable as the system permits, each pump shall be run at least 2 min [minutes]. At the end of this time at least one measurement or determination of each of the quantities required by Table ISTB-3000-1 shall be made and recorded. Subparagraph (2) states For the Group B test, after the pump conditions are stable, at least one measurement or determination of the quantity required by Table ISTB-3000-1 shall be made and recorded.
ASME OM Code, paragraph ISTB-5323, Comprehensive Test Procedure, states, in part, that Comprehensive 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-5324, Periodic Verification Test, states that Tests shall be performed for pumps identified via ISTB-1400(d).
ASME OM Code, paragraph ISTB-1400, Owners Responsibility, states, in part, in paragraph (d) that the Owners responsibility includes identifying 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, table ISTB-3000-1, Inservice Test Parameters, indicates which parameters must be measured during Baseline Tests, Group A Tests, Group B Tests, Comprehensive Tests, and Pump Periodic Verification Tests (where identified in ISTB-1400(d)).
ASME OM Code, table ISTB-3510-1, Required Instrument Accuracy, indicates the required instrument accuracy for Group A and Group B Tests, Comprehensive and Baseline Tests, and Pump Periodic Verification Tests.
Licensees Proposed Alternative In its letter dated January 29, 2024, the licensee states in part:
Pump flow rate will be determined by measuring the volume of fluid pumped and dividing by the corresponding pump run time. The volume of fluid pumped will be determined by the difference in fluid level in the test tank at the beginning and end of the pump run (test tank fluid level corresponds to volume of fluid in the tank). The pump flow rate calculation methodology meets the accuracy requirements of [ASME] OM Code, Table ISTB-3510-1. The pump flow rate calculation is identified on the record of test and ensures that the method for the flow rate calculation yields an acceptable means for the detection and monitoring of potential degradation of the Standby Liquid Control Pumps and therefore, satisfies the intent of OM Code Subsection ISTB.
In this type of testing, the requirement to maintain a 2-minute hold time after stabilization of the system is unnecessary and provides no additional increase of the ability of determining pump condition.
In its letter dated July 29, 2024, the licensee provided the following information in support of Alternative Request 5IST-03:
As discussed in Section 5 of Alternative Request 5IST-03 (RP03), the pump flow rate calculation methodology meets the accuracy requirements of ASME OM Code, Table ISTB-3510-1, Required Instrument Accuracy. The test methodology, which includes running the pumps for a minimum time to ensure that ASME OM Code required accuracy for flow rate measurement of +/-2% is satisfied, provides adequate assurance of acceptable pump performance. Calculation methods are specified in the surveillance procedures for the pumps listed in Alternative Request 5IST-03 (RP03) and meet the quality assurance requirements for Columbia. Therefore, the proposed alternative provides an acceptable level of quality and safety.
Energy Northwest inadvertently used the term preservice tests rather than baseline tests in Alternative Request 5IST-03 (RP03). The intent of the last sentence of Section 3, Applicable Code Requirements, in Alternative Request 5IST-03 (RP03) was to apply to Group B comprehensive, baseline, and periodic verification tests.
Paragraphs ISTB-5210 and ISTB-5224 are only applicable to vertical line shaft centrifugal pumps. The Standby Liquid Control pumps at Columbia are positive displacement pumps, which are tested in accordance with ISTB-5300, Positive Displacement Pumps.
Alternative Request 5IST-03 (RP03) was intended to be used as an alternative to ASME OM Code, Subsection ISTB-5310, Baseline Testing, and ISTB-5324, Periodic Verification Test. The provisions in Alternative Request 5IST-03 (RP03) will be applied to the baseline and periodic verification test procedures for the pumps listed in Alternative Request 5IST-03 (RP03) during the Fifth 10-Year Interval IST Program. Pump flow rate will be recorded per the test tank methodology, as discussed in NUREG-1482, Inservice Testing of Pumps and Valves and Inservice Examination and Testing of Dynamic Restraints (Snubbers) at Nuclear Power Plants, Revision 3, Section 5.5.2, and without the use of the required two-minute hold time during ISTB-5310 and ISTB-5324 testing.
In Alternative Request 5IST-03 (RP03), Energy Northwest is requesting relief from the ISTB-3550, Flow Rate, requirement of an installed rate or quantity meter. The two-minute hold time pertaining to running the pump to ensure pump conditions are stable, would not be necessary with the use of the alternative.
Although the title of Alternative Request 5IST-03 (RP03) addresses a portion of the request, a more suitable title should have addressed the entirety of the request. A title such as Alternative for Standby Liquid Control Pump Flow Determination may have been more appropriate.
Alternative Request 5IST-03 (RP03) applies to the use of the test tank in lieu of the required ISTB-3550 installed rate or quantity meter, as discussed in Section 5.5.2 of NUREG-1482, Revision 3. With the use of this alternative, the requirement to maintain a two-minute hold time after stabilization of the system is burdensome, unnecessary and provides no additional increase in the ability of determining pump condition. Therefore, Energy Northwest is requesting elimination of the two-minute hold time.
Licensees Reason for Request The licensee provided the following reason for its request:
A rate or quantity meter is not installed in the test circuit. To have one installed would be costly and time consuming with few compensating benefits.
As a result of a rate or quantity meter not being installed in the test circuit, it is impractical to directly measure the flow rate for the Standby Liquid Control pumps. Therefore, the requirement for allowing a 2-minute hold time for pump tests is an unnecessary burden which provide no additional assurance of determining pump operational readiness.
Licensees Basis for Use The guidance in NUREG-1482, Revision 3, section 5.5.2, Use of Tank Level to Calculate Flow Rate for Positive Displacement Pumps, states, in part Requiring licensees to install a flow meter to measure the flow rate and to guarantee the test tank size, such that the pump flow rate will stabilize and then be run for 2 minutes before recording the data would be a burden because of the design and installation changes to be made to the existing system. Therefore, compliance with the [ASME] OM Code requirements would be a hardship.
NRC Staff Evaluation
ASME OM Code, subsection ISTB, paragraph ISTB-3550, requires that when measuring flow rate, a rate or quantity meter shall be installed in the test circuit. If a meter does not indicate directly, the record shall include the method used to reduce the data. Additionally, paragraph ISTB-5200(a) requires that for the Group A test and Comprehensive Test, after pump conditions are as stable as the system permits, each pump shall be run at least 2 minutes.
For the specified standby liquid control pumps at Columbia, the licensee stated in Alternative Request 5IST-03 that to install a flow meter to measure the flow rate and to guarantee the test tank size, such that the pump flow rate will stabilize in 2 minutes before recording the data, would be a burden because of the design and installation changes to be made to the existing system. In NUREG-1482, Revision 3, section 5.5.2, the NRC staff noted that requiring licensees to install a flow meter to measure the flow rate and to guarantee the test tank size, such that the pump flow rate will stabilize in 2 minutes before recording the data, would be a burden because of the design and installation changes to be made to the existing system, and that compliance with the ASME OM Code requirements would be a hardship.
The licensee's proposed alternative for measuring the flow rate for these pumps is to use a test tank and determine the pump flow rate by measuring the volume of fluid pumped and dividing the volume by the corresponding pump run time. The volume of fluid pumped will be determined by the difference in fluid level in the test tank at the beginning and end of the pump run. The test methodology used to calculate pump flow rate will provide results consistent with ASME OM Code requirements and will provide adequate assurance of acceptable pump performance.
The pump flow rate calculation methodology meets the accuracy requirements of table ISTB-3510-1 of the ASME OM Code. The pump flow rate calculation from the surveillance test performed as part of the IST program is identified on the record of the surveillance test and ensures that the method for the flow rate calculation yields an acceptable means for the detection and monitoring of potential degradation of the pumps. In this type of testing, the requirement to maintain a 2-minute hold time after stabilization of the system is unnecessary and provides no additional increase of the ability to determine pump condition.
Based on its review, the NRC staff has determined that complying with the specified ASME OM Code, Subsection ISTB, requirements for the standby liquid control pumps within the scope of Alternative Request 5IST-03 would result in a hardship or unusual difficulty without a compensating increase in the level of quality and safety. The staff finds that the alternative testing proposed by the licensee provides reasonable assurance that the applicable pumps will be operationally ready to perform their safety functions. Therefore, the NRC staff finds that Alternative Request 5IST-03 (RP03) may be authorized under 10 CFR 50.55a(z)(2) for the fifth interval IST program at Columbia.
4.0 CONCLUSION
As set forth above, the NRC staff has determined that Alternative Requests 5IST-01 (RP01) and 5IST-02 (RP02) provide an acceptable level of quality and safety under 10 CFR 50.55a(z)(1) for the proposed testing of the applicable pumps in lieu of the specified ASME OM Code requirements during the fifth interval IST program at Columbia. In addition, the staff has determined that compliance with the specified ASME OM Code requirements for the applicable pumps within the scope of Alternative Request 5IST-03 (RP03) would result in a hardship or unusual difficulty without a compensating increase in the level of quality and safety. The staff determined that the alternative testing proposed by the licensee in Alternative Request 5IST-03 (RP-03) provides reasonable assurance that the applicable pumps will be operationally ready to perform their safety functions. As a result, the staff finds that Alternative Request 5IST-03 may be authorized under 10 CFR 50.55a(z)(2) for the fifth interval IST program at Columbia.
The NRC staff has reviewed the subject requests and concludes, that Energy Northwest has adequately addressed all of the regulatory requirements set forth in 10 CFR 50.55a(z).
Therefore, the NRC staff authorizes Alternative Requests 5IST-01 (RP01), 5IST-02 (RP02),
and 5IST-03 (RP03) for the fifth IST program interval at Columbia.
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 Contributors: Gurjendra Bedi, NRR Thomas Scarbrough, NRR Date: November 6, 2024
- via e-mail OFFICE NRR/DORL/LPL4/PM*
NRR/DORL/LPL4/LA*
NRR/DEX/EMIB/BC*
NAME MChawla PBlechman SBailey DATE 10/23/2024 10/29/2024 10/17/2024 OFFICE NRR/DORL/LPL4/BC*
NAME TNakanishi DATE 11/06/2024