ML25087A158
| ML25087A158 | |
| Person / Time | |
|---|---|
| Site: | Wolf Creek  |
| Issue date: | 04/04/2025 |
| From: | Geoffrey Miller NRC/RGN-IV/DORS |
| To: | Reasoner C Wolf Creek |
| References | |
| EAF-RIV-2025-0091 IR 2024003 | |
| Download: ML25087A158 (1) | |
See also: IR 05000482/2024003
Text
April 04, 2025
EAF-RIV-2025-0091
Cleve Reasoner, Chief Executive Officer
and Chief Nuclear Officer
Wolf Creek Nuclear Operating Corp.
P.O. Box 411
Burlington, KS 66839
SUBJECT:
WOLF CREEK GENERATING STATION - NRC INSPECTION REPORT
05000482/2024003, DISPUTED NON-CITED VIOLATION RESCINDED
Dear Cleve Reasoner:
On November 1, 2024, the U.S. Nuclear Regulatory Commission (NRC) issued the subject report,
Agencywide Documents Access and Management System (ADAMS) Accession No. ML24295A379.
The inspection report documented a non-cited violation (NCV) for failure to remove motor-operated
valve thermal overload bypass jumpers during surveillance testing and system maintenance
In a letter dated December 31, 2024, you provided a written response and denied NCV 05000482/2024003-01 (ML24366A161). On January 24, 2025, the NRC acknowledged receipt of your
letter (ML25023A044).
The NRC conducted a detailed review of your December 31, 2024, letter and examined
circumstances and applicable regulatory requirements in accordance with Part I, Section 2.8 of
the NRC Enforcement Manual. This review was performed by a staff member who was not
involved in the original inspection effort.
In your letter dated December 31, 2024, you contested that the NCV 05000482/2024003-01, Failure
to Remove Motor-Operated Valve Thermal Overload Bypass Jumpers during Surveillance Testing
and System Maintenance, should not have been issued against the requirements of the licensees
commitment to Regulatory Guide 1.106, Thermal Overload Protection for Electric Motors on Motor-
Operated Valves, revision 1. The independent reviewer concluded that the inspection report
incorrectly documented an NCV of 10 CFR Part 50, Appendix B, Criterion III, Design Control, and
NCV 05000482/2024003-01 will be rescinded. We will revise and reissue NRC Inspection Report 05000482/2024003 to reflect this change. The details of the NRCs evaluation are contained in the
enclosure to this letter.
C. Reasoner
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In accordance with 10 CFR 2.390 of the NRCs Agency Rules of Practice and Procedure, a copy of
this letter and its enclosure will be made available electronically for public inspection in the NRC
Public Document Room and from the NRCs ADAMS, accessible from the NRC website at
http://www.nrc.gov/reading-rm/adams.html.
If you have any questions concerning this matter, please contact Ami Agrawal of my staff at
(817) 200-1411.
Sincerely,
Geoffrey B. Miller, Director
Division of Operating Reactor Safety
Docket No. 050000482
License No. NPF-42
Enclosure:
As stated
Signed by Miller, Geoffrey
on 04/04/25
OFFICE
SES:ACES
SRI:DORS/PBD
C:DORS/PBB
TL:ACES
RC
NAME
ARoberts
NCuevas
AAgrawal
BAlferink
DCylkowski
SIGNATURE
/RA/ E
/RA/ E
/RA/ E
/RA/ E
/RA/ E
DATE
03/28/25
03/28/25
03/28/25
03/31/25
03/31/25
OFFICE
D:DORS
NAME
DJones
GMiller
SIGNATURE
/RA/ E
/RA/ E
DATE
04/01/25
04/04/25
Enclosure
NRC Evaluation of Licensee Response to a Non-Cited Violation (NCV)
Restatement of NCV 05000482/2024003-01
Title 10 CFR Part 50, Appendix B, Criterion III, Design Control, requires, in part, that measures shall
be established to assure that applicable regulatory requirements and the design basis, as defined in
[10 CFR] 50.2 and as specified in the license application, for those structures, systems, and
components to which this appendix applies are correctly translated into procedures and instructions.
Contrary to the above, from November 2013 to September 2024, the licensee failed to establish
measures to assure that applicable regulatory requirements and the design basis, as defined in 50.2,
and as specified in the license application assure the applicable design requirements were correctly
translated into procedures and instructions. Specifically, the licensee failed to implement their design
basis commitment to Regulatory Guide (RG) 1.106, Thermal Overload Protection for Electric Motors
on Motor-Operated Valves, by failing to translate into maintenance and surveillance procedures and
instructions, the regulatory guide position to place thermal overloads in force during stroking of
safety-related motor-operated valves.
Summary of Licensees Response
In response dated December 31, 2024, the licensee stated that the NCV is based on two main
reinterpretations of the licensing basis:
Reinterpretation 1: That WCGS shall always remove Thermal Overload Relay jumpers during testing.
The licensee stated that they are committed to RG 1.106, revision 1, and that the NRC staff approved
the approach of leaving thermal overloads permanently bypassed prior to initial fuel loading (the NRC
staff approved this approach during WCNOCs licensing application process, noting that the use of
thermal overloads during testing is a prudent operational practice but only a staff observation, not
a requirement). The licensee stated that they reviewed their own licensing basis documents,
including responses to Generic Letter (GL) 89-10, and identified no new commitments related to
thermal overload jumpers during testing.
Reinterpretation 2: That motor-operated valve periodic or maintenance testing, as used in Regulatory
Guide (RG) 1.106, revision 1, includes surveillance and post-maintenance operability testing.
The licensee discussed how the commitments made were based on the regulatory guides and
definitions in effect at the time of licensing. The licensee stated the newer RG 1.160, Monitoring the
Effectiveness of Maintenance at Nuclear Power Plants, revision 4, does not retroactively apply to
RG 1.106, revision 1.
The licensee highlighted the importance that testing the valve in its design safety configuration,
bypassing the thermal overload protection as it would be during an accident, is critical to ensure the
valve performs its safety function.
The licensee continued to interpret RG 1.106, revision 1, pointing out that words like shall were not
used, as implying flexibility in the requirements for thermal overloads. The licensee highlighted the
NRCs words in the Safety Evaluation Report, that placing thermal overloads in force is a prudent
operational choice, and the licensee further discussed how the commitment for thermal overloads
has remained constant through revisions to the motor-operated valve commitments and response to
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NRC Evaluation
The NRC staff performed an independent review of the licensees position as described in
WCNOC letter dated December 31, 2024, related to NCV 05000482/2024003-01. The NRC
staff reviewed:
Design basis information regarding thermal overloads in Wolf Creek Generating
Station Updated Safety Analysis Report (UFSAR)
NUREG-0881, Supplement 5, Safety Evaluation Report Related to the Operation of
Wolf Creek Generating Station, Unit No. 1
Regulatory requirements in 10 CFR 50 Appendix B
Regulatory requirements in RG 1.106 revision 1
Regulatory requirements in Generic Letter 89-10, Safety-Related Motor Operated
Valve Testing and Surveillance
WCNOC Commitments to Generic Letter 89-10
Several Condition Reports relating to MOV failures
The Updated Safety Analysis Report, Section 8.3.1.1.2.e, states, in part, all starters for
motor-operated valves are equipped with thermal overload relays. The thermal overload
relay trip contacts located in 480-volt motor control centers for all safety-related valves are
bypassed in accordance with Regulatory Guide 1.106, Thermal Overload Protection for
Electric Motors on Motor-Operated Valves, revision 1, dated March 1977.
Regulatory Guide 1.106, revision 1, position 1, states, in part, provided that the completion
of the safety function is not jeopardized or that other safety systems are not degraded,
(a) the thermal overload protection devices should be continuously bypassed and
temporarily placed in force only when the valve motors are undergoing periodic or
maintenance testing. Section 8.3.3.1.2 of the Safety Evaluation Report states, the
applicant indicated that the thermal overload relay trip contacts for all Class 1E valves will
be permanently bypassed with jumpers before fuel loading. Prior to initial plant operation,
revision 10 to the UFSAR stated that the thermal overload relay trip contacts for all Class
1E valves will be permanently bypassed with jumpers before fuel loading. Additionally, the
Safety Evaluation Report stated,
The staff concludes that the permanent bypass resolves the original SER concern
relating to inadvertent operation of thermal overloads under accident conditions;
thus, Technical Specifications for this item are no longer required. The staff notes,
however that it is not the intent of RG 1.106 to totally eliminate the use of thermal
overloads on motor-operated valves. RG 1.106 is intended to ensure that, under
accident conditions, the valve will not be hindered from performing its safety
function by a spurious trip of its thermal overload protective circuits. For the majority
of valve operations such as during valve test or operation during nonaccident
conditions, the use of thermal overload protective circuits is a prudent operational
practice to minimize motor damage as a result of overload. This is only a staff
observation, and it is not considered an open or confirmatory item.
This verbiage further suggests that RG 1.106 was written with the intent to ensure that the
thermal overloads, when in force, do not prevent or jeopardize the safety function of the
valve during a design basis event.
The independent reviewer determined that RG 1.106 is written in a flexible manner in terms
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of testing and maintenance, consistent with the Safety Evaluation Report position above,
and more specifically it does not prescribe what constitutes periodic maintenance and
testing. That specificity is left to the judgement of the licensee, so long as their method
does not jeopardize the safety function or degrade other safety systems. With this
interpretation, testing the valve during a safeguards test in an outage does not require the
licensee to place the thermal overloads in force. Therefore, the performance deficiency as
written in NCV 05000482/2024003-01 is not an example of a failure to implement the
licensees design basis commitment to Regulatory Guide 1.106.
The reviewer concluded the safeguards test of the MOV on March 29, 2014, supported the
intent of RG 1.106; that is, the valve opened and demonstrated the capability to complete
its safety function during a simulated design basis condition. Thus, the safety function of
the MOV was not jeopardized by not having the thermal overloads in force. If the licensee
had implemented position 1.b of RG 1.106 during the safeguards test, the thermal overload
would have been bypassed, and the outcome would have been the same: the valve would
have opened with a locked rotor overthrust condition caused by a failed limit switch. This
suggests that the proximate cause of the damage to the MOV motor on March 29, 2014,
was not the licensees failure to implement their design basis commitment to Regulatory
Guide 1.106. The reviewer considered that during the testing of motor operated valve
EFHV0092, the plant was in Mode 5, and the safety train was not in the mode of
applicability and was not being used for shutdown risk.
NRC Conclusion
The NRC staff concludes that the NCV 05000482/2024003-01 should be rescinded. The
proximate cause of the 2014 event was a limit switch failure, rather than a failure by the
licensee to meet a design basis commitment. Regulatory Guide 1.106, revision 1, to which
the licensee is committed, does not require the licensee to remove the thermal overload
bypass for all testing, especially safeguards testing.