NRC-19-0084, Response to Request for Additional Information Regarding Inservice Testing Program Relief Request VRR-006 for the Fourth 10-Year Interval

Response to Request for Additional Information Regarding Inservice Testing Program Relief Request VRR-006 for the Fourth 10-Year Interval

ML19340A250
Person / Time
Site:	Fermi
Issue date:	12/06/2019
From:	Peter Dietrich DTE Electric Company, DTE Energy
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
NRC-19-0084
Download: ML19340A250 (10)

Text

Peter Dietrich Senior Vice President and Chief Nuclear Officer DTE Energy Company 6400 N. Dixie Highway, Newport, MI 48166 Tel: 734.586.4153 Fax: 734.586.1431 Email: peter.dietrich@dteenergy.com DTE December 6, 2019 NRC-19-0084 U.S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, DC 20555-0001 Fermi 2 Power Plant NRC Docket No. 50-341 NRC License No. NPF-43

Subject:

Response to Request for Additional Information Regarding Inservice Testing Program Relief Request VRR-006 for the Fourth 10-Year Interval

Reference:

1) DTE Electric Letter to NRC, "Submittal of Valve Relief Requests for the Inservice Testing Program Fourth 10-Year Interval," NRC-19-0047, dated June 14, 2019 (ML19165A134)

In Reference 1, DTE Electric Company (DTE) submitted a relief request under 10 CFR 50.55a(z) for the Inservice Testing (IST) program at Fermi 2.

In an email from Ms. Booma Venkataraman to Mr. Jason Haas dated November 15, 2019, the NRC sent DTE a request for additional information (RAI) regarding relief request VRR-006 of Reference 1. The response to the RAI for relief request VRR-006 is provided in the Enclosure.

No new commitments are being made in this submittal.

Should you have any questions or require additional information, please tact Mr. Jason R.

Haas, Manager - Nuclear Licensing, at (734) 586-1769.

Sincerel Peter Dietrich Senior Vice President and CNO

Enclosure:

Response to Request for Additional Information for Relief Request VRR-006

USNRC NRC-19-0084 Page 2 cc: NRC Project Manager NRC Resident Office Regional Administrator, Region III Michigan Department of Environment, Great Lakes, and Energy

Enclosure to NRC-19-0084 Fermi 2 NRC Docket No. 50-341 Operating License No. NPF-43 Response to Request for Additional Information for Relief Request VRR-006

Enclosure to NRC-19-0084 Page 1 REQUEST FOR ADDITIONAL INFORMATION REQUEST FOR PROPOSED ALTERNATIVE RELIEF REQUEST VRR-006 By application dated June 14, 2019 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML19165A134), DTE Electric Company, (DTE, the licensee) submitted Request for Alternative Relief VRR-006 for Fermi 21. VRR-06 proposes an alternative for preservice testing of butterfly valves, and pursuant to Title 10 Code of Federal Regulations (10 CFR) Section 50.55a, Codes and Standards, paragraph (z)(1), relief is requested to deviate from certain American Society of Mechanical Engineers (ASME) Operation and Maintenance (OM) Code requirements, which requires each valve to be tested in accordance with the requirements prior to implementation of inservice testing (IST). The basis of the relief request is that the proposed alternative will provide an acceptable level of quality and safety.

The U. S. Nuclear Regulatory Commission (NRC) staff is reviewing the submittal and has determined that the additional information below is needed to complete its review.

Applicable Regulations:

10 CFR 50.55a, Codes and Standards lists all the (ASME) Codes that have incorporated by reference including ASME Code for Operation and Maintenance of Nuclear Power Plants with conditions, that the NRC has approved for use. 10 CFR 50.55a defines the requirements for applying industry codes and standards to nuclear power facilities. Each of these facilities is subject to the conditions in paragraphs (a), (b), and (f) of 10 CFR 50.55a, as they relate to IST.

10 CFR 50.55a(f)(4)(ii) requires that an IST activity conducted during each 120-month interval following the initial interval must be conducted in compliance with the requirements of the latest edition and addenda of the OM Code incorporated by reference in the version of 10 CFR 50.55a(a) that is in effect 12 months before the start of the interval and subject to the conditions listed in 10 CFR 50.55a(b). This Code Edition is called the Code of Record. Therefore, the applicable Code of Record for the Fermi 2 fourth 10-year IST interval is 2012 Edition of the OM Code.

10 CFR Part 50, Appendices A and B require that licensees provide confidence that safety-related equipment (including motor operated valves (MOVs)) is capable of performing its safety functions under design-basis conditions.

Pursuant to 10 CFR 50.55a(z)(1) and (2), the Commission may authorize the licensee to implement an alternative to the OM Code requirements, provided that the alternative ensures an acceptable level of quality and safety or the OM Code requirement presents a hardship without a compensating increase in the level of quality and safety.

1 The application also listed 3 other proposed alternative relief requests (VRR-004, VRR-007 and VRR-009)

Enclosure to NRC-19-0084 Page 2 Responses to RAIs for Relief Request VRR-006 RAI VRR-006-1

Background:

Enclosure 2 of the application, Page 2, Relief Request Section 5, Proposes Alternative and Basis for Use, second paragraph, states that the valves are Class A under the Joint Owners Group (JOG) Periodic Verification approach. Bearing degradation was addressed by applying the JOG threshold Coefficient of Friction (COF) to these valves.

Issue: The JOG program was a 5-year study on a variety of valves with a scope to determine how a valve degrades over time. The JOG data examined friction factors of valves operating under dynamic conditions. The JOG final program plan classified valves based on their type, material makeup, and system operating conditions. The butterfly valve matrix noted that for certain valves under specified conditions that no threshold COF value is required for developing a qualifying basis. All other valves required individual dynamic testing or group dynamic testing of similar valves to obtain the qualifying basis.

Request: The JOG threshold value was never intended to be a bounding number to use when developing a qualifying basis. Please explain why applying the JOG threshold friction value is acceptable.

RESPONSE

Background and Clarification of the Relief Request VRR-006:

DTE Electric Company (DTE) is requesting a delay of diagnostic testing on butterfly valves T4803F601 and T4803F602 from the start of the fourth 10-year interval, which begins on February 17, 2020, until the next refueling outage, which is scheduled for the spring of 2020.

Torque measurement at the valves cannot be conducted during plant online operations, but will be performed during the next refueling outage in spring 2020. The reason for the VRR-006 relief request is that previous testing on the two butterfly valves, which consisted of MCC-based testing, did not conform with the requirements of Appendix III Section 6100, which states torque or other measured engineering parameters correlated to torque may be used to establish acceptance criteria, and further that MCC-based testing is considered acceptable if correlation with testing at the motor operated valve (MOV) has been established. While MCC-based testing can be used to determine motor torque, this practice does not meet the Appendix III Section 6100 requirements since correlation to torque measurements has not yet been performed. Following torque measurements in the next refueling outage in spring 2020, the Appendix III Section 6100 requirements will be met for the rest of the fourth 10-year interval.

Correction of Class of Subject Butterfly Valves:

Relief request VRR-006 stated that the two butterfly valves were determined to be Class A under the Joint Owners Group (JOG) program. During reviews related to preparing these RAI responses, the valves have in fact been determined to be Class B. The appropriate inservice test interval for these low-risk valves will be determined following testing in the upcoming refueling outage in accordance with Appendix III requirements.

Enclosure to NRC-19-0084 Page 3 Response to RAI:

As noted in the NRC RAI, the JOG threshold bearing coefficient is not intended to be used as a bounding value. The Fermi 2 Relief Request VRR-006 did not provide justification that the coefficient was in fact a bounding value. The vendor for valves T4803F601 and T4803F602, Nelles-Jamesbury, provided torque vs. differential pressure curves for the valves with the Fermi 2 seat material and valve orientation based on valve testing the vendor had performed.

The vendor provided documentation that the curves represented breakaway torque, which included bearing and packing torque contributions. The vendor also documented that the breakaway torque bounded total dynamic torque for the subject valves. The calculation of total dynamic torque by DTE using the Electric Power Research Institute (EPRI) methodology and assuming the JOG threshold coefficient resulted in a total dynamic torque value that was greater than the breakaway torque supplied by the vendor. This demonstrated that the use of the JOG threshold bearing coefficient was bounding for the two subject valves. The total dynamic torque using the JOG threshold value was used to determine valve torque requirements at Fermi 2.

These torque requirements were incorporated into the Fermi 2 design basis calculations for the two subject valves. Therefore, the JOG threshold friction value was applied in an acceptable manner to produce bounding results.

Enclosure to NRC-19-0084 Page 4 RAI VRR-006-2

Background:

Enclosure 2 of the application, Page 2, Section 5, Proposed Alternative and Basis for Use, of the application, fourth paragraph, states subsequent to GL 89-10 testing, a plant modification was implemented to remove the torque switch from the valve control circuit for the listed valves. Thus, the original testing methodology of measuring torque at the torque switch trip was no longer possible. Since the valves have significant margin between actuator capability and valve operating requirements, a combination of condition monitoring from periodic motor control center testing and local leak rate testing is used to monitor for valve/actuator degradation. While this practice provides acceptable monitoring of valve/actuator condition, it does not meet Appendix III, Paragraph III- 6100 requirements for acceptance criteria.

Issue: The licensee did not provide information that addresses how the valves significant margin between actuator capability and valve operating requirements is acceptable while using, a combination of condition monitoring from periodic motor control center testing and local leak rate testing is used to monitor for valve/actuator degradation. Further, licensee states that while this practice provides acceptable monitoring of valve/actuator condition, it does not meet Appendix III Section 6100 requirements for acceptance criteria.

Request: Please discuss how condition monitoring and MCC testing will be acceptable when valves have significant margin between actuator capability and valve operating requirements and used this to monitor for valve/actuator degradation. Also, explain how this practice provides acceptable monitoring of valve/actuator condition, when it does not meet the Appendix III, Section 6100 requirements for acceptance criteria for the operational readiness of the MOVs.

RESPONSE

Torque testing will be performed during the next refueling outage at Fermi 2 (spring 2020).

Going forward following completion of that testing, DTE will use a combination of valve seat leakage monitoring, preventive maintenance, and condition monitoring, along with valve torque measurement to maintain the overall valve condition and demonstrate operational readiness of the subject valves for the rest of the fourth 10-year interval. This combination of activities will meet the Appendix III Section 6100 requirements.

During the third 10-year interval, which ends on February 16, 2020, DTE has used a combination of condition monitoring based on MCC-based testing, monitoring of seat leakage results, and preventive maintenance to demonstrate / maintain operational readiness of the valves. Included in condition monitoring has been a review for any anomalous behavior such as increases in unseating or running loads that could indicate degradation of MOV functional margin. Motor torque has also been estimated from MCC testing results, which would provide a quantitative measure of any changes. Reviews of numerous MCC tests on each valve has not revealed any

Enclosure to NRC-19-0084 Page 5 appreciable changes in behavior that would indicate a loss of MOV functional margin is occurring.

In summary, the combination of activities described above that has been previously performed during the third 10-year interval will provide assurance of the operational readiness of the two butterfly valves during the very brief period from the start of the fourth 10-year interval (i.e.,

February 17, 2020) until torque testing is performed during the next refueling outage (i.e., spring 2020). Following the completion of torque testing during the refueling outage and for the rest of the fourth 10-year interval, operational readiness of the two butterfly valves will be assured by meeting the requirements of Appendix III Section 6100.

Enclosure to NRC-19-0084 Page 6 RAI VRR-006-3

Background:

Enclosure 2 of the application, Page 2, Section 5, Proposed Alternative and Basis for Use, fifth paragraph states, in part, while some local leak rate results have necessitated corrective actions, the causes of the leakage were not related to actuator capability or valve operational capability. This provides confidence that these valves and actuators will remain capable of meeting design basis requirements until the preservice test is performed.

Issue: The licensee did not address the reason how the cause of the leakage were not related to actuator capability or valve operational capability.

Request: Please explain how situations where local leak rate results (asserted to be unrelated to actuator capability or valve operational capability) that necessitated corrective actions did not challenge confidence in the operational readiness of the valves.

RESPONSE

DTE did not intend to indicate that the excessive seat leakage events did not impact overall valve operational capability, only that they did not impact performance as revealed by diagnostic testing. Diagnostic testing may not detect conditions affecting seat leakage. Thus, seat leakage results are used in conjunction with diagnostic testing to assess valve condition. Review of excessive seat leakage results since January 2000 identified leakage causes such as scratches/debris on the seating surface, improper procedure guidance on seat adjustment, misaligned disc, packing leakage and improper switch settings following maintenance. In these cases, no diagnostic testing failure occurred. These conditions did impact valve condition (i.e.,

seat leakage) but were not identified by diagnostic testing. These conditions were entered into the Fermi 2 Corrective Action Program (CAP) and subsequently resolved; this is consistent with Appendix III Section 6500.

The intent of the discussion in Enclosure 2 of the application, page 2, section 5, was to identify that DTE uses a combination of activities to monitor valve performance. This combination of activities has been successful during the third 10-year interval at verifying operational readiness of the valves or, in some cases, at identifying conditions that do impact operational readiness so they can be promptly resolved through the Fermi 2 CAP. As a result, DTE has confidence of the operational readiness of the subject valves for the very brief period from February 17, 2020 until the Appendix III Section 6100 required torque testing can be performed during the spring 2020 refueling outage.

Enclosure to NRC-19-0084 Page 7 RAI VRR-006-4

Background:

ASME OM Code, Mandatory Appendix III, Paragraph III-3100, Design Basis Verification Test, states, in part, that a one-time test is to be conducted to verify capability of each MOV to meet its safety-related design- basis requirements. Paragraph III-3100 also states that where design-basis testing of the specific MOV being evaluated is impracticable, or not meaningful (provides no additional useful data), data from other MOVs may be used if justified by engineering evaluation.

Issue: Enclosure 2 of the application, Page 2, Section 5, Proposed Alternative and Basis for Use, second paragraph, states, in part, that butterfly valves T4803F601 an T4803F602 are not practicable to test under dynamic conditions.

Request: Please explain the engineering evaluation that justifies that these butterfly valves will meet their design-basis capability requirements.

RESPONSE

As noted in the RAI background discussion above, data from other MOVs may be used if justified by engineering evaluation to verify capability of an MOV to meet design-basis requirements in the event dynamic testing is not practicable. In this case, as described in detail in the DTE response to RAI VRR-006-1, data from other MOVs was used by the valve vendor, Nelles-Jamesbury, to provide valve torque requirements based on testing results. An engineering evaluation was then performed by DTE which confirmed the JOG threshold bearing coefficient was bounding. These bounding torque requirements determined by DTE were incorporated into Fermi 2 design-basis calculations. Therefore, engineering evaluation was used per Appendix III Section 3100 and documented to justify that the subject butterfly valves will meet their design-basis capability requirements.