ML24045A150
| ML24045A150 | |
| Person / Time | |
|---|---|
| Site: | Prairie Island  |
| Issue date: | 02/15/2024 |
| From: | Ballard B Plant Licensing Branch III |
| To: | Kivi J, Mark Miller Northern States Power Co |
| Kuntz R | |
| References | |
| EPID L-2024-LLR-0015 RR-09 | |
| Download: ML24045A150 (1) | |
Text
From: Brent Ballard To: Miller, Michael A; Kivi, Jeffrey L Cc: Jeff Whited; Dan Tesar
Subject:
Prairie Island Nuclear Generating Plant, Unit 2 - Verbal Authorization of Proposed Alternative RR-09 for Inservice Testing Requirements of Safety Injection System and Volume Control System Category C Check Valves Date: Thursday, February 15, 2024 10:51:00 AM Attachments: FINAL - Prairie Island Unit 2 verbal authorization 2-14-2024.pdf
Good morning,
By web-based submission dated February 11, 2024 (Agencywide Documents Access and Management System (ADAMS) accession number ML24042A001), as supplemented by letter dated February 13, 2024 (ML24044A103), Northern States Power Company (NSPM, the licensee), a Minnesota corporation, doing business as Xcel Energy, requested alternative RR-09 to inservice testing requirements of the American Society of Mechanical Engineers (ASME) Operation and Maintenance of Nuclear Power Plants (OM Code) at Prairie Island Nuclear Generating Plant, Unit 2.
The alternative request RR-09 was submitted in accordance with 10 CFR 50.55a(z)(2) on the basis that performance of inservice testing required by the ASME OM Code for the subject check valves would cause a hardship or unusual difficulty without a compensating increase in the level of quality and safety.
By teleconference on February 14, 2024, the U.S. Nuclear Regulatory Commission (NRC) staff provided a verbal authorization to NSPM for the proposed alternative RR-09. The NRC staffs verbal authorization is attached to this e-mail. The following NRC and licensee personnel participated in the conference call:
NRC Stewart Bailey - Chief, Mechanical Engineering and Inservice Testing Branch Thomas Scarbrough - Mechanical Engineer, Mechanical Engineering and Inservice Testing Branch Jeffrey Whited - Chief, Plant Licensing Branch 3 Brent Ballard - Project Manager, Plant Licensing Branch 3 Luis Cruz Rosado - Project Manager, Plant Licensing Branch 3 Sam Bina - Project Manager, Integrated Program Management and Beyond Design Basis Branch
NSPM Sara Scott - Director, Nuclear Licensing and Regulatory Affairs Michael Miller - Regulatory Affairs Manager Jeffrey Kivi - Senior Nuclear Regulatory Engineer Ronald Jacobson - Senior Nuclear Regulatory Engineer Harrison Bourgoin - Prairie Island Programs Engineer
Please contact me if you have any questions.
Thank you,
Brent Ballard Project Manager Plant Licensing Branch III Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission 301-415-0680
VERBAL AUTHORIZATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION FOR
ALTERNATIVE REQUEST RR-09
SAFETY INJECTION SYSTEM AND VOLUME CONTROL SYSTEM
CATEGORY C CHECK VALVE INSERVICE TESTING
PRAIRIE ISLAND NUCLEAR GENERATING PLANT, UNIT 2
NORTHERN STATES POWER COMPANY
DOCKET NO. 50-306
FEBRUARY 14, 2024
Technical Evaluation r ead by Stewar t Bailey, Chief, Mechanical Engineering and Inservice Testing Branch, Division of Engineering and External Hazards, NRC Office of Nuclear Reactor Regulation
This call is for the NRC to verbally authorize a request by Northern States Power
Company (the licensee), a Minnesota corporation, doing business as Xcel Energy, for an
alternative to inservice testing requirements for specific Category C check valves in the Safety
Injection system and Volume Control system at Prairie Island Nuclear Generating Plant, Unit 2.
In particular, the licensee submitted Alternative Request RR-09 electronically on February 11,
2024, with a supplemental letter dated February 13, 2024, describing its proposal. In the
Alternative Request RR-09, as supplemented, t he licensee proposes to defer certain inservice
tests of the subject check valves required by the American Society of Mechanical Engineers
(referred to herein as ASME) Operation and Maintenance of Nuclear Power Plants (referred to
herein as OM Code) as incorporated by reference in Title 10 of the Code of Federal
Regulations, Section 50.55a, at Prairie Island, Unit 2.
1
The NRC staff is allowed to verbally authorize alternatives to inservice testing
requirements under paragraph (z) of 10 CFR 50.55a in circumstances where the licensee has
docketed all pertinent information, the NRC staff has completed its review, and there is not
enough time for the NRC to issue its written safety evaluation before the alternative is needed.
That is the case here.
The licensee submitted Alternative Request RR-09 in accordance with 10 CFR
50.55a(z)(2) on the basis that performance of inservice testing required by the ASME OM Code
for the subject check valves in the Safety Injection and Volume Control Systems would cause a
hardship or unusual difficulty without a compensating increase in the level of quality and safety.
The NRC regulations in 10 CFR 50.55a(f) require licensees to implement inservice
testing programs for pumps, valves, and dynamic restraints that meet the requirements of the
ASME OM Code as incorporated by reference in 10 CFR 50.55a. Prairie Island is currently
implementing its Fifth 10-Year Interval Inservice Testing Program with the 2004 Edition through
the 2006 Addenda of the ASME OM Code as the I nservice Testing Code of Record. The Fifth
10- Year Inservice Testing Program interval for Prairie Island, Unit 2, began on December 21,
2014, and is currently scheduled to end on December 20, 2024. The ASME OM Code
requirements applicable to Alternative Request RR-09 include ASME OM Code, Subsection
ISTC, paragraph ISTC -3510, titled Exercising Test Frequency, and paragraph ISTC-3522,
Category C Check Valves, paragraph ISTC-3570, Valves in Systems Out of Service, and
paragraph ISTC-5221, Valve Obturator Movement.
In support of the startup of Prairie Island, Unit 2, following an extended maintenance
outage, the licensee proposes in Alternative Request R R-09 that the ASME [OM] Code test
intervals specified in ISTC-3510, ISTC-3522(f), and ISTC-3570 be extended for check valves
2SI-7-1 and 2SI-7-2 in the S afety Injection system and check valves 2VC 1, 2, 3, 4, and 5,
2 and 2VC 1 in the Volume Control system. The check valves are OM Category C (which
means self-actuating) valves without leakage limitation requirements.
The licensee proposes that the specified test intervals for the subject check valves be
extended until the end of the Fifth 10- Year Inservice Testing Program interval. The licensee
plans to apply the provision allowed with conditions in the ASME OM Code, Subsection ISTA,
paragraph ISTA-3120, to extend the Fifth 10-Year Inservice Test Program interval for 1 year to
a new end date of December 20, 2025, which will encompass the next refueling outage for
Prairie Island, Unit 2, scheduled for the fall of 2025. If the Fifth 10- Year Inservice Testing
Program interval is not extended, the licensee will need to conduct the required OM Code
testing of the subject check valves by the current interval end date, or submit a request under
10 CFR 50.55a(z) for an alternative approach applicable to the Sixth Inservice Testing Program
interval in a timely manner. In addition to the provision for testing the subject check valves by
the end of the Fifth 10-Year Inservice Testing Program interval, Alternative Request RR-09, as
supplemented by the licensees letter dated February 13, 2024, indicates that the subject check
valves will undergo the required OM Code testing the next time plant conditions support
conducting the tests.
The licensee stated that the ASME OM Code testing of the subject check valves would
require flooding the refueling cavity by overflowing the reactor vessel flange. Flooding the
refueling cavity would result in increased radioactive exposure to plant workers with the
subsequent need for decontamination activities. The licensee also noted that the completion of
the testing of the subject check valves would result in further outage time for Prairie Island, Unit
2.
In Alternative Request RR-09, the licensee provided the results of its review of the
maintenance and testing history of the subject check valves since 2019. For example, the
licensee reported that all testing of the subject Safety Injection check valves has been
3 satisfactory. Further, the licensee conducted successful preventive maintenance of Safety
Injection check valve 2SI-7-1, including an internal inspection, in 2021. The licensee also
conducted an internal inspection of V olume Control check valves 2VC-8-1 and 2VC-8-4 in 2021.
The licensee reported that all testing of the subject Volume Control check valves (with the
exception of check valve 2VC-8-3) has been satisfactory. The licensee found that the closure
test process for check valve 2VC-8-3 had not been validating forward flow prior to the closure
test in accordance with the ASME OM Code. However, the licensee reported that check valve
2VC-8-3 met the differential pressure criteria for validating closure in each of the previous three
refueling outages with no adverse trends.
In addition to the closure test process for check valve 2VC-8-3, the licensee identified
discrepancies related to the accuracy of its current IST Program Plan for the test intervals for
certain check valves during its preparation of the alternative request. T he licensee stated that
these discrepancies have been entered into its correction action program for resolution. The
NRC staff notes that this authorization relates to future activities and does not address review of
OM Code compliance for previous test activities.
Based on the information provided by the licensee, the NRC staff finds that a hardship
exists without a compensating increase in the level of quality and safety, in accordance with 10
CFR 50.55a(z )(2), for the performance of specific inservice tests as scheduled in the ASME OM
Code for the subject check valves as described in Alternative Request R R-09, as
supplemented, at Prairie Island, Unit 2. Therefore, the NRC staff finds that the licensees
proposed alternative to defer OM Code tests for the subject check valves until the end of the
Fifth 10-Year Inservice Testing Program interval, or at the next opportunity that plant conditions
support such testing prior to the end of the program interval, will not adversely impact the
reasonable assurance that those components will be operationally ready to perform their safety
functions. Based on its review, the NRC staff authorizes Alternative Request RR-09 to defer the
4 specified inservice tests for the subject check valves until the end of the Fifth 10-Year Inservice
Testing Program interval, or at the next opportunity that plant conditions support such testing
prior to the end of the program interval at Prairie Island, Unit 2. The NRC staff does not
authorize Alternative Request RR-09 beyond the end of the F ifth 10- Year Inservice Testing
Program interval, or the next opportunity that plant conditions support the OM Code testing of
the subject check valves prior to the end of the program interval at Prairie Island, Unit 2.
All other ASME OM Code requirements for which relief or alternative was not specifically
requested and granted or authorized as part of this alternative request remain applicable. If the
licensee identifies a performance issue with any of the Safety Injection system or Volume
Control system components, the licensee will be expected to take action to implement the
requirements of its Technical Specifications. The NRC staffs review of Alternative Request R R-
09 for Prairie Island, Unit 2, will be described in detail in a separate safety evaluation.
NRC Staff Conclusion r ead by Jeffrey Whited, Chief, Plant Licensing Branch 3 Division of Operating Reactor Licensing, NRC Office of Nuclear Reactor Regulation
As Chief of Plant Licensing Branch 3, I concur with the conclusions of the Mechanical
Engineering and Inservice Testing Branch.
The NRC staff concludes that Alternative Request RR-09, as supplemented, addresses
the identified hardships or unusual difficulty without a compensating increase in the level of
quality and safety for the performance of certain inservice testing required by the ASME OM
Code for the specified Safety Injection system and Volume Control system check valves until
the end of the Fifth 10-Year Inservice Testing Program interval, or at the next opportunity that
plant conditions support such testing prior to the end of the program interval at the Prairie
Island, Unit 2.
5 Accordingly, the NRC staff concludes that the licensee has adequately addressed all of
the regulatory requirements set forth in 10 CFR 50.55a(z)(2) to justify the requested alternative
to defer the ASME OM Code inservice testing requirements for the specified Safety Injection
system and Volume Control system check valves until the end of the Fifth 10- Year Inservice
Testing Program interval, or at the next opportunity that plant conditions support such testing
prior to the end of the program interval.
Therefore, on February 14, 2024, the NRC authorizes Alternative Request RR-09, as
supplemented, until the end of the Fifth 10- Year Inservice Testing Program interval, or at the
next opportunity that plant conditions support the subject check valve testing prior to the end of
the program interval at Prairie Island, Unit 2. All other requirements of the ASME OM Code, for
which relief or an alternative was not specifically requested and authorized by the NRC staff,
remain applicable.
This verbal authorization does not preclude the NRC staff from asking additional
questions and clarifications regarding the licensees proposed alternative while preparing the
subsequent written safety evaluation.
6