ML23041A426
| ML23041A426 | |
| Person / Time | |
|---|---|
| Site: | Quad Cities  |
| Issue date: | 02/14/2023 |
| From: | Nancy Salgado Plant Licensing Branch III |
| To: | Rhoades D Constellation Energy Generation, Constellation Nuclear |
| Kuntz R | |
| References | |
| EPID L-2022-LLR-0070 | |
| Download: ML23041A426 (1) | |
Text
February 14, 2023 Mr. David P. Rhoades Senior Vice President Constellation Energy Generation, LLC President and Chief Nuclear Officer Constellation Nuclear 4300 Winfield Road Warrenville, IL 60555
SUBJECT:
QUAD CITIES NUCLEAR POWER STATION, UNITS 1 AND 2 - PROPOSED ALTERNATIVE TO THE REQUIREMENTS OF THE ASME OM CODE (EPID L-2022-LLR-0070)
Dear Mr. Rhoades:
By letter dated October 7, 2022 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML22280A124) and supplemented by a letter dated January 17, 2023 (ML23017A218), Constellation Energy Generation LLC (the licensee) submitted Alternative Request RV-04 to the U.S. Nuclear Regulatory Commission (NRC) in lieu of specific inservice testing (IST) requirements in the 2017 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 implementation during the sixth 10-year IST program interval at Quad Cities Nuclear Power Station, Units 1 and 2 (Quad Cities).
Specifically, pursuant to Title 10 of the Code of Federal Regulations (10 CFR), part 50, section 55a, paragraph (z), subparagraph (1) (10 CFR 50.55a(z)(1)), to implement alternative request RV-04 for the frequency of functional verification test on the drain pot level limit switches and the associated control room annunciators for the high-pressure injection (HPCI) drain pot solenoid valves at Quad Cities. The alternative proposes testing of the subject components at least once every 2 years as an alternative to the requirements in ASME OM Code, subsection ISTC, Inservice Testing of Valves in Water-Cooled Reactor Nuclear Power Plants, paragraph ISTC-5150, Solenoid-Operated Valves, specifically, paragraph ISTC-5151, Valve Stroke Testing, paragraph ISTC-5152, Stroke Test Acceptance Criteria, and paragraph ISTC-5153, Stroke Test Corrective Action.
The NRC staff has reviewed the subject request and concludes, as set forth in the enclosed safety evaluation (SE), that the licensee has justified that the approach proposed in alternative request RV-04 (as supplemented) for indirect functional testing of the HPCI drain pot solenoid valves and for an extension of the interval between functional tests to every refueling outage, or once every 2 years, at Quad Cities will provide reasonable assurance of the operational readiness of those subject valves to perform their safety functions. Accordingly, the licensee has adequately addressed the regulatory requirements set forth in 10 CFR 50.55a(z)(1) for an acceptable level of quality and safety with respect to alternative request RV-04 for the HPCI drain pot solenoid valves at Quad Cities. Therefore, the NRC staff authorizes alternative request
D. Rhoades RV-04 (as supplemented) for the sixth 10-year IST program interval at Quad Cities, which is scheduled to begin on February 18, 2023, and to end on February 17, 2033.
All other ASME OM Code requirements as incorporated by reference in 10 CFR 50.55a for which an alternative was not specifically requested and authorized in the subject request remain applicable.
If you have any questions, please contact the Project Manager, Robert Kuntz at 301-415-3733 or via e-mail at Robert.Kuntz@nrc.gov.
Sincerely, Nancy L. Salgado, Chief Plant Licensing Branch III Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos. 50-254 and 50-265
Enclosure:
Safety Evaluation cc: Listserv Nancy L.
Salgado Digitally signed by Nancy L. Salgado Date: 2023.02.14 13:26:11 -05'00'
Enclosure SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO ALTERNATIVE REQUEST RV-04 CONSTELLATION ENERGY GENERATION, LLC QUAD CITIES NUCLEAR POWER STATION, UNITS 1 AND 2 DOCKET NOS. 50-254 AND 50-265
1.0 INTRODUCTION
By letter dated October 7, 2022 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML22280A124) and supplemented by a letter dated January 17, 2023 (ML23017A218), Constellation Energy Generation LLC (the licensee) submitted Alternative Request RV-04 to the U.S. Nuclear Regulatory Commission (NRC) in lieu of specific inservice testing (IST) requirements in the 2017 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 implementation during the sixth 10-year IST program interval at Quad Cities Nuclear Power Station, Units 1 and 2 (Quad Cities).
Specifically, pursuant to Title 10 of the Code of Federal Regulations (10 CFR), part 50, section 55a, paragraph (z), subparagraph (1) (10 CFR 50.55a(z)(1)), to implement Alternative Request RV-04 for the frequency of functional verification test on the drain pot level limit switches and the associated control room annunciators for the high-pressure injection (HPCI) drain pot solenoid valves at Quad Cities. The alternative proposes testing of the subject components at least once every 2 years as an alternative to the requirements in ASME OM Code, subsection ISTC, Inservice Testing of Valves in Water-Cooled Reactor Nuclear Power Plants, paragraph ISTC-5150, Solenoid-Operated Valves, specifically, paragraph ISTC-5151, Valve Stroke Testing, paragraph ISTC-5152, Stroke Test Acceptance Criteria, and paragraph ISTC-5153, Stroke Test Corrective Action.
The sixth 10-year IST program at Quad Cities is scheduled to start on February 18, 2023, and to end on February 17, 2033.
2.0 REGULATORY EVALUATION
2.1 Regulatory Requirements The NRC regulations in 10 CFR 50.55a(z), Alternatives to codes and standards requirements, state that 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.
2.2 ASME OM Code Requirements The applicable Code of Record for the sixth 10-year IST interval at Quad Cites is the 2017 Edition of ASME OM Code as incorporated by reference in 10 CFR 50.55a.
The IST requirements in the ASME OM Code, as incorporated by reference in 10 CFR 50.55a, related to Alternative Request RV-04 are as follows:
ISTC-3300, Reference Values, states in part:
Reference values shall be determined from the results of preservice testing or from the results of inservice testing.
ISTC-3310, Effects of Valve Repair, Replacement, or Maintenance on Reference Values, states part:
When a valve or its control system has been replaced, repaired, or has undergone maintenance that could affect the valve's performance, a new reference value shall be determined, or the previous value reconfirmed.
ISTC-3500, Valve Testing Requirements, states:
Active and passive valves in the categories defined in para. ISTC-1300 shall be tested in accordance with the paragraphs specified in Table ISTC-3500-1 and the applicable requirements of paras. ISTC-5100 and ISTC-5200.
ISTC-3560, Fail-Safe Valves, states in part:
Valves with fail-safe actuators shall be tested by observing the operation of the actuator upon loss of valve actuating power in accordance with the exercising frequency of para.
ISTC-3510.
ISTC-5151, Valve Stroke Testing, states in part:
(a) Active valves shall have their stroke times measured when exercised in accordance with para. ISTC-3500.
(b) The limiting value(s) of full-stroke time of each valve shall be specified by the Owner.
(c) Stroke time shall be measured to at least the nearest second.
ISTC-5152, Stroke Test Acceptance Criteria, states in part:
Test results shall be compared to reference values established in accordance with para.
ISTC-3300, ISTC-3310, or ISTC-3320.
ISTC-5153, Stroke Test Corrective Action, subparagraph (b) states:
Valves with measured stroke times that do not meet the acceptance criteria of para. ISTC-5152 shall be immediately retested or declared inoperable. If the valve is retested and the second set of data also does not meet the acceptance criteria, the data shall be analyzed within 96 hr to verify that the new stroke time represents acceptable valve operation, or the valve shall be declared inoperable. If the second set of data meets the acceptance criteria, the cause of the initial deviation shall be analyzed and the results documented in the record of tests (see para. ISTC-9210).
3.0 TECHNICAL EVALUATION
3.1 Alternative Request RV-04 3.1.1 ASME Code Components Affected The request as supplemented proposed alternative testing for the following solenoid valves:
Component Number System Code Class OM Category 1-2301-032-SO HPCI 2
B 2-2301-032-SO HPCI 2
B 3.1.2 Reason for Request In Alternative Request RV-04, the licensee specified the reason for its request under 10 CFR 50.55a(z)(1) for an alternative to the requirements of ASME OM Code, subsection ISTC, paragraph ISTC-5150 (specifically, paragraphs ISTC-5151, 5152, and 5153), for the subject valves. The request states that the basis of the request is that the proposed alternative would provide an acceptable level of quality and safety.
Specifically, the solenoid valves 1(2)-2301-032-SO function as a backup to the exhaust line drain pot steam trap. During normal operation of the HPCI turbine using high-quality steam, the drain path to the torus via the steam trap is adequate to remove condensate from the turbine exhaust line. However, during HPCI turbine operation with low pressure and low-quality steam, condensate collects in the drain pot faster than it can be drained through the trap, such that the solenoid valves 1(2)-2301-032-SO open automatically to drain the gland seal condenser. These valves are not equipped with position indicators; therefore, the valve position cannot be verified by direct observation. Due to the absence of a visible valve stem and light indication, switch to light stroke-timing cannot be performed.
The request states that the valve actuation may be indirectly verified by removing the HPCI system from service, filling the drain pot with water until the high-level alarm is received, and observing that the high-level alarm clears. The steam line drain pot is not equipped with direct level indication. Thus, the time required for the alarm to clear might vary significantly and stroke timing of the valves 1(2)-2301-032-SO cannot be verified by operation of the hand switch.
The request states that compliance with the quarterly stroke timing and fail-safe requirements of the ASME OM Code would require either system modification to replace these valves with ones of a testable design, or to purchase non-intrusive test equipment and develop new test methods and procedures. The licensee indicates the modifications are expected to be costly for installing a remote valve indication solely for meeting the ASME OM Code requirement.
3.1.3 Licensees Proposed Alternative and Basis for Use In Alternative Request RV-04, the licensee proposes to conduct a functional verification test on the drain pot level limit switches and the associated control room annunciators for the HPCI drain pot solenoid valves at Quad Cities at least once every 2 years as an alternative to the requirements in ASME OM Code, subsection ISTC, paragraph ISTC-5150, including paragraphs ISTC-5151, ISTC-5152, and ISTC-5153. Specifically, the valve actuation will be indirectly verified by removing the HPCI system from service, filling the drain pot with water until the high-level alarm is received, and observing a positive draining of the HPCI drain pot as indicated by a level increase in gland seal condenser and the high-level alarm clearing.
The licensee states that the following provisions of ISTC-5153, Stroke Test Corrective Action, continue to apply:
If a valve fails to exhibit the required change of obturator position, the valve shall be immediately declared inoperable.
Valves declared inoperable may be repaired, replaced, or the data may be analyzed to determine the cause of the deviation and the valve shown to be operating acceptably.
Valve operability based upon analysis shall have the results of the analysis recorded in the record of tests (see ISTC-9120).
Before returning a repaired or replacement valve to service, a test demonstrating satisfactory operation shall be performed.
As the basis for use of the proposed approach, the licensee states that a biennial exercise of the 1(2)-2301-032-SO valves is currently being performed, and its associated level switches operate as proven by the receipt of the HPCI TURBINE EXH DRAIN POT HIGH LEVEL alarm and reset. The valve solenoid is also verified as actuated by use of a test probe. This testing approach provides adequate assurance that the valves function as required and satisfies the exercising and fail-safe test requirements of paragraphs ISTC-3510 and ISTC-3560.
The licensee did not identify any instances of these valves failing to stroke open since they were added to the IST program scope at Quad Cities in November 1994. The station also has a preventive maintenance activity to replace these valves once every sixth refueling outage. This activity was last performed on March 23, 2021, on Unit 1, and on April 9, 2020, on Unit 2, and no defects were noted. Lastly, using the provisions of this request as an alternative to the specific requirements of paragraph ISTC-5150 will provide adequate indication of valve performance and continue to provide an acceptable level of quality and safety. Therefore, pursuant to 10 CFR 50.55a(z)(1), the licensee requests authorization of its alternative to the specific ISTC requirements identified in Alternative Request RV-04.
3.2
NRC Staff Evaluation
In Alternative Request RV-04, the licensee states that RV-04 for the fifth 10-year IST program interval was the precedent for the request for the sixth 10-year IST program interval. However, the licensees letter dated February 15, 2012 (ML12046A334), describing Alternative Request RV-04 for the fifth 10-year IST program interval at Quad Cities stated that a functional verification test is conducted on the drain pot level limit switches and the associated control room annunciators at least once every 92 days. The NRC staff relied on this functional verification test schedule in its safety evaluation dated February 14, 2013 (ML13042A348), in authorizing Alternative Request RV-04 for the fifth 10-year IST program interval at Quad Cities.
In reviewing Alternative Request RV-04, the NRC staff provided a request for additional information (RAI) (ML22348A143) from the licensee regarding the basis for the functional verification test schedule in Alternative Request RV-04 for the sixth 10-year IST program interval in comparison to the referenced precedent in RV-04 for the fifth 10-year IST program interval at Quad Cities.
In its letter dated January 17, 2023, the licensee responded in part as follows:
Quad Cities Nuclear Power Station (QCNPS) relief RV-04 for alternative testing of high pressure coolant injection (HPCI) valves 1-2301-032-SO and 2-2301-032-SO was authorized for the 5th Inservice Testing (IST) interval in ML13042A348 based on the alternative functional verification testing occurring once every 92 days (e.g., a quarterly interval). The original 6th interval RV-04 incorrectly referenced the prior [] interval QCNPS RV-04 approval as precedent, when the 6th interval request extends the frequency between performance of the functional tests proposed as the alternative test to every refueling outage, or once every 2 years.
In its January 17, 2023, letter, the licensee clarified its current request by stating that Alternative Request RV-04 for the fifth 10-year IST program interval is not a precedent for the Alternative Request RV-04 for the sixth 10-year IST program interval at Quad Cities. In Alternative Request RV-04 (as supplemented) for the sixth 10-year IST program interval at Quad Cities, the licensee provides justification that the proposed alternative would provide an acceptable level of quality and safety for the testing of the HPCI drain pot solenoid valves. Specifically, the licensee stated that the testing and maintenance history demonstrates reliable performance of the subject valves such that testing every 92 days does not warrant the safety impact of removing the HPCI system from service to perform the testing. The licensee reported that its review of the corrective action program, work history, and IST history of the HPCI drain pot solenoid valves did not identify any instances where these valves failed to stroke open since their initial addition to the IST program scope at Quad Cities in 1994. Also in its request, the licensee indicates that the testing of the subject valves while online exposes personnel to an industrial safety hazard because the test requires connecting to and draining the drain pot level switch volume which might contain hot, pressurized steam.
The NRC staff reviewed the alternative functional testing of the HPCI drain pot solenoid valves described in RV-04 (as supplemented). As specified in this request, the functional testing for valve actuation will include removing the HPCI system from service, filling the drain pot with water until the high-level alarm is received, and observing a positive draining of the HPCI drain pot as indicated by a level increase in gland seal condenser and the high-level alarm clearing.
The NRC staff finds that this indirect functional testing of the HPCI drain pot solenoid valves provides reasonable assurance of the operational readiness of these valves to perform their safety functions.
Based on its review, the NRC staff finds that the licensee has justified that the provisions of Alternative Request RV-04 (as supplemented) for performing indirect functional testing of the HPCI drain pot solenoid valves and extending the interval for performance of the functional tests to every refueling outage, or once every 2 years, will provide reasonable assurance of the operational readiness of the HPCI drain pot solenoid valves within the scope of the request.
Therefore, the staff finds that Alternative Request RV-04 for the HPCI drain pot solenoid valves provides an acceptable level of quality and safety for testing the subject valves pursuant to 10 CFR 50.55a(z)(1) for implementation during the sixth 10-year IST program interval at Quad Cities.
4.0 CONCLUSION
As described above, the NRC staff concludes that the licensee has justified that the approach proposed in Alternative Request RV-04 (as supplemented) for indirect functional testing of the HPCI drain pot solenoid valves and for an extension of the interval between functional tests to every refueling outage, or once every 2 years, at Quad Cities will provide reasonable assurance of the operational readiness of those subject valves to perform their safety functions.
Accordingly, the licensee has adequately addressed the regulatory requirements set forth in 10 CFR 50.55a(z)(1) for an acceptable level of quality and safety with respect to alternative request RV-04 for the HPCI drain pot solenoid valves at Quad Cities. Therefore, the NRC staff authorizes Alternative Request RV-04 (as supplemented) for the sixth 10-year IST program interval at Quad Cities, which is scheduled to begin on February 18, 2023, and to end on February 17, 2033.
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: Tristan Villarreal, NRR Thomas Scarbrough, NRR Date: February 14, 2023
ML23041A426 OFFICE NRR/DORL/LPL3/PM NRR/DORL/LPL3/LA NRR/DEX/EMIB/BC NRR/DORL/LPL3/BC NAME RKuntz SRohrer SBailey NSalgado DATE 2/10/23 2/13/23 2/9/23 2/14/23