NRC-20-0057, Response to Request for Additional Information Regarding License Amendment Request to Revise Technical Specifications to Change Surveillance Intervals to Accommodate a 24-Month Fuel Cycle

Response to Request for Additional Information Regarding License Amendment Request to Revise Technical Specifications to Change Surveillance Intervals to Accommodate a 24-Month Fuel Cycle

ML20255A166
Person / Time
Site:	Fermi
Issue date:	09/11/2020
From:	Peter Dietrich DTE Electric Company
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
NRC-20-0057
Download: ML20255A166 (10)

Text

Peter Dietrich Senior Vice President and Chief Nuclear Officer DTE Electric Company 6400 N. Dixie Highway, Newport, MI 48166 Tel: 734.586.4153 Fax: 734.586.1431 Email: peter.dietrich@dteenergy.com September 11, 2020 NRC-20-0057 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 License Amendment Request to Revise Technical Specifications to Change Surveillance Intervals to Accommodate a 24-Month Fuel Cycle

Reference:

1) DTE letter NRC-19-0054, License Amendment Request to Revise Technical Specifications to Change Surveillance Intervals to Accommodate a 24-Month Fuel Cycle, dated November 8, 2019 (ML19312A110)

In Reference 1, DTE Electric Company (DTE) requested an amendment to the Renewed Facility Operating License NPF-43 for Fermi Unit 2 (Fermi 2) Technical Specifications (TS), in accordance with the provisions of 10 CFR 50.90, Application for amendment of license, construction permit, or early site permit. The Reference 1 submittal requested modification of the Renewed Facility Operating License to modify the Fermi 2 TS to support a 24 Month Fuel Cycle (24 MFC) in accordance with the guidance of NRC Generic Letter 91-04, Changes in Technical Specification Surveillance Intervals to Accommodate a 24-Month Fuel Cycle, dated April 2, 1991. In an email from Mr. Surinder Arora to Ms. Margaret Offerle dated August 12, 2020, the NRC sent DTE a Request for Additional Information (RAI) regarding the license amendment request (LAR). The responses to the questions in the RAI are provided in the Enclosure to this letter.

No new commitments are being made in this submittal.

USNRC NRC-20-0057 Page 2 Should you have any questions or require additional information, please contact Ms. Margaret Offerle, Manager -Nuclear Licensing, at (734)586-5076.

I declare under penalty of perjury that the foregoing is true and c r t.

Executed on September 1 , 20 Peter Dietrich Senior Vice President and Chief Nuclear Officer

Enclosure:

Response to Request for Additional Information cc: NRC Project Manager NRC Resident Office Regional Administrator, Region III Michigan Department of Environment, Great Lakes, and Energy

Enclosure to NRC-20-0057 Fermi 2 NRC Docket No. 50-341 Operating License No. NPF-43 Response to Request for Additional Information

Enclosure to NRC-20-0057 Page 1 Response to Request for Additional Information By letter dated November 8, 2019, (Agencywide Documents Access Management System (ADAMS) Accession No. ML19312A110), DTE Energy Company (DTE), the licensee, submitted for staff review and approval a license amendment request (LAR) to the Fermi Unit 2 (Fermi 2)

Technical Specifications (TS). The proposed amendment requests changes to the Fermi 2 TS surveillance requirements (SRs) to accommodate a 24-month fuel cycle.

Applicable Regulation and Guidance Title 10 of the Code of Federal Regulations (10 CFR), Section 50.36(c)(3) states, in part, that SRs relating to test, calibration, or inspection, to assure that the necessary quality of the system and components is maintained, that facility operation will be within safety limits, and that the limiting conditions for operation will be met. Generic Letter (GL) 91.04, Changes in Technical Specification Surveillance Intervals to Accommodate a 24-Month Fuel Cycle states, in part, that the effect on safety due to the increase in SR intervals is small based contingent upon historical plant performance data and that previous assumptions in the plant licensing basis for the affected equipment are not invalidated by the proposed SR interval increase.

Based on the above, the U.S. Nuclear Regulatory Commission (NRC) staff requests the following additional information to confirm that Response Time Testing (RTT) surveillance tests proposed new intervals, will be based on verifiable methodologies. This information is needed to provide a sufficient technical basis for satisfying the requirements of 10 CFR 50.36(c).

EICB-RAI-01A Engineering Report DTE-19001 Surveillance Historical Failure Analysis in Support of a 24 Month Fuel Cycle License Amendment Request (ADAMS Accession No. ML20175A788), , Fermi 2 Technical Specification Event Unique Failures states, in part, with regard to the failure of transmitter B21N095B that the identified failure is unique and does not occur on a repetitive basis and is not associated with a time-based failure mechanism. The report also concludes that this failure will have no impact on an extension to a 24-month surveillance. This is consistent with the description of the failure of the same transmitter described In the Fermi 2 LAR for TS 3.3.2.2, Feedwater and Main Turbine High Water Level Trip Instrumentation". With regard to B21N095Bs failure, the licensee notes ".and no time-based failure mechanism was apparent since there were no similar failures identified."

A review of the applicable Fermi 2 SR history for this function identified only one occurrence where the as-found calibration data for the Division 2 Reactor Level Narrow Range Transmitter (B21N095B) exceeded the specified as-found tolerance for the transmitter. The licensee indicated that this failure would have been discovered solely through the performance of this SR.

The same transmitter, i.e., B21N095B, was also cited under TS 3.5.5.1, "Emergency Core Cooling System (ECCS) Instrumentation" with a similar discussion that this transmitter's malfunction was solely detectable through surveillance testing but was a unique failure.

Enclosure to NRC-20-0057 Page 2 However, for transmitter B21N095B, the failure analysis report, DTE-19001 revision 1, under , event #0766, documents that the work order (WO) 29640637 that analyzed this transmitter's failure concluded, "Transmitter probably an original Installation, went out due to age." A transmitter failing due to age would presumably have a time-based failure mechanism.

This does not appear consistent with statements in the Fermi LAR that suggest there was no time-based failure mechanism for transmitter B21N095B considering the referenced WO states that the transmitter failure was likely due to age. It also does not appear consistent with the evaluation of event #0766 in Attachment 5 of DTE-19001 revision 1.

In this circumstance, age-related failure presents a greater potential for being undetected for a longer period of time with an Increased surveillance Interval of 24 months. In addition, the failure analysis report states that this transmitter was an original Installation, which suggests that this may not be the only transmitter with extended Inservice time since it was installed.

However, the failure analysis report does not reach this level of detail.

Provide more detail about how the proposed surveillance testing Interval increase to 24 months would be sufficient to address age-related failures such as the that described for transmitter B21N095B considering this transmitters failure was deemed age related and presumably could remain in a potentially inoperable condition for a longer period of time without detection with a 24 month interval.

Clarify if there is a program in place to replace transmitters and other electronic equipment at the end of their expected life If so, please provide a description of this program and verify this program is accounted for in the proposed 24-month surveillance program as supported by the technical basis provided in this LAR.

DTE RESPONSE Sections 5 and 6 of DTE-19001 describe the philosophy and approach used in qualitatively evaluating historical surveillance performance data. This approach is consistent with guidance of Generic Letter 91-04 as used in previous applications. The basis for conclusion presented in DTE-19001 regarding the Category D unique failure of transmitter B21N095B is discussed below.

The conclusions presented in DTE-19001 are based on review of at least five performances of 18-month surveillance test results and maintenance history. This number of surveillance performances and maintenance history covers approximately seven years of performances.

Generally, six performances were considered covering a period from the Spring 2009 refueling outage through the Spring 2017 refueling outage. Six performances were considered for transmitter B21N095B.

The failure of transmitter B21N095B was identified on April 2, 2009 during performance of an 18-month channel calibration surveillance. Transmitter B21N095B was installed as part of a plant modification that was implemented in the second refueling outage (RF02, March - June, 1991). Transmitter B21N095B is a Rosemount, model 1153DB4RCN0037, with a qualified life

Enclosure to NRC-20-0057 Page 3 exceeding 50 years and had been in service for approximately 18 years at the time of failure.

Absent a forensic evaluation, a failure occurring at less than half of the qualified life can reasonably be considered not to be age-related. No forensic evaluation was performed for this failure.

The failure of transmitter B21N095B was entered into the Fermi 2 Corrective Action Program when it was identified on April 2, 2009. The initiating Condition Assessment and Resolution Document (CARD) was classified as "Broke/Fix" in accordance with program guidance. A CARD with a "Broke/Fix" classification initiates a corrective maintenance work order. No additional cause analysis was required, and none was specified in the work order. Absent a formal cause analysis, the "age-related" statement in the work order was dispositioned as an unsupported opinion during the DTE-19001 review. The DTE-19001 conclusion that the failure of transmitter B21N095B was not repetitive or associated with a time-based failure mechanism is supported by the absence of any similar Category D failures. Furthermore, the transmitter failed in the first half of the qualified life. Based on the transmitter age at time of failure it is reasonable to conclude that the failure was not the result of a time-based failure mechanism. Accordingly, it is appropriate to conclude that the failure of transmitter B21N095B is a Category D unique failure. Notwithstanding, the LAR (NRC-19-0054) and DTE-19001 did not adequately explain the basis for this conclusion. A CARD was initiated to document the inadequate explanation provided in DTE-19001.

Fermi 2 has several programmatic requirements that would detect and address trends in equipment performance, including instrumentation. These programs were fully reviewed for impact and accounted for in the proposed 24-month surveillance extension project activities and planning. The Environmental Qualification (EQ) Program establishes the qualified life for equipment within the scope defined by 10 CFR 50.49, Environmental Qualification of Electric Equipment Important to Safety for Nuclear Power Plants. The EQ Program defines preventive maintenance and surveillance requirements to ensure that plant equipment within the EQ scope remains qualified. The periodic EQ preventive maintenance requirements are implemented via the Fermi 2 Preventive Maintenance (PM) Program. The EQ preventive maintenance requirements include replacement or other appropriate maintenance activities to maintain qualification of installed equipment.

Additionally, I&C Surveillance Test and Setpoint Trending is procedurally required. Instruments are monitored and trended in accordance with station procedures including recording of as-found and as-left calibration data. Out of tolerance conditions are entered into the corrective action program and are evaluated and trended. This approach identifies occurrences of instruments found outside of the allowable tolerance limits and instruments whose performance is not as assumed in the instrument uncertainty and/or setpoint analysis. When the as found conditions are outside the allowable tolerance limits, an evaluation is performed in accordance with the station corrective action program to evaluate the effect, if any, on plant safety and identify appropriate corrective measures.

Enclosure to NRC-20-0057 Page 4 The Maintenance Rule Program monitors the health of systems important to safety, including associated instrumentation. The program monitors performance trends that drive actions to maintain system health.

In summary, the conclusion that the subject failure for this RAI was a random failure and not indicative of a time-based failure mechanism is correct, even though the work order suggested that the failure was age-related without evidence of age-related failure. Additionally, the EQ, Maintenance Rule and I&C Surveillance Test and Setpoint Trending programs were fully reviewed for impact and accounted for in the proposed 24-month surveillance extension project activities and planning. These programs provide measures to replace transmitters and other components prior to the end of their expected life or for other causes.

EICB-RAI-01B Engineering Report DTE-19001, revision 1, Section 6.1, defines UNIQUE FAILURES, or Category D as a type of failure that does not occur on a repetitive basis and is not associated with a time-based failure mechanism. Section 8, Conclusions and Recommendations of DTE-19001 goes on to state, in part, that there is no evidence of time-based failure mechanism that would invalidate conclusions regarding impact on safety or system availability. A similar statement regarding system availability is also located in the Category D definition. The goal of a surveillance test is to ensure that a structure, system or component is operable.

Verify that the conclusion statements in DTE-19001, revision 1, refer to sufficient evidence that system operability determinations will not be impacted by the proposed surveillance interval increase.

DTE RESPONSE The proposed changes to surveillance intervals in no way alter the meaning of the Technical Specifications (TS) definition of OPERABILITY, or alter the determination of OPERABILITY.

The process and criteria for determining OPERABILITY when a SR is not satisfied remains the same for all SRs, regardless of the frequency. The Shift Manager evaluates failures to satisfy SR acceptance criteria and any other problems encountered during the performance of a SR, determines OPERABILTY and enters TS prescribed ACTIONs as needed. The corrective action program (CARD process) facilitates these activities. CARDs that affect plant equipment are reviewed by the Shift Manager who makes the OPERABILITY determination. This process and OPERABILITY criteria are not affected by the proposed SR frequency changes.

Sections 5 and 6 of DTE-19001 describe the philosophy and approach used in qualitatively evaluating historical surveillance performance data consistent with GL 91-04. DTE-19001 statements regarding "system availability" are made in the context of the guidance provided by GL 91-04 Enclosure 1 regarding the evaluation of historical plant maintenance and surveillance data to support a conclusion that the effect on safety of increasing surveillance to 24-months is small. GL 91-04 describes the basis for this conclusion.

Enclosure to NRC-20-0057 Page 5 Generic Letter 91-04, Enclosure 1 states in part:

"The NRC staff has reviewed a number of requests to extend 18-month surveillances to the end of a fuel cycle and a few requests for changes in surveillance intervals to accommodate a 24-month fuel cycle. The staff has found that the effect on safety is small because safety systems use redundant electrical and mechanical components and because licensees perform other surveillances during plant operation that confirm that these systems and components can perform their safety functions. Nevertheless, licensees should evaluate the effect on safety of an increase in 18-month surveillance intervals to accommodate a 24-month fuel cycle. This evaluation should support a conclusion that the effect on safety is small. Licensees should confirm that historical plant maintenance and surveillance data support this conclusion. Also, licensees should confirm that assumptions in the plant licensing basis would not be invalidated on the basis of performing any surveillance at the bounding surveillance interval limit provided to accommodate a 24-month fuel cycle. In consideration of these confirmations, the licensees need not quantify the effect of the change in surveillance intervals on the availability of individual systems or components."

Based on this guidance, a failure of an 18-month SR after the interval was increased to 24 months would have a small effect on safety because of redundant trains and components, and that other more frequently performed SRs "confirm that these systems and components can perform their safety functions," essentially, the TS definition of OPERABILITY. DTE-19001 examines the historical data for 18-month SRs to support this conclusion.

The vast majority of the 18-month SRs reviewed by DTE-19001 were successfully completed.

Identified SR failures were further screened as described in DTE-19001, Sections 5 and 6.

Sections 5 and 6 discuss the definition and application of the screening categories. Category A assesses whether a SR failure involved a loss of safety function, i.e., inoperablity. Further screening (Category D) determines whether the failure is repetitive or involves an age-related failure mechanism. Absent an age-related failure mechanism, or a failure being repetitive in nature, it would be expected that SRs performed at the proposed increased interval would continue to be completed successfully thereby demonstrating OPERABILIY. DTE-19001 identified no SR failures that involved an age-related failure mechanism. Therefore, DTE-19001 provides ample evidence that system OPERABILITY would not be impacted by the proposed surveillance interval increase.

EICB-RAI-02 In DTE-18001, Revision 0, Instrument Drift Analysis Design Guide in Support of 24-Month Fuel Cycle Extension Project, ADAMS Accession No. ML19312A110 (Enclosure 7) Section 2, Drift Analysis Scope states, in part, that the approaches described in this design guide can be applied to all devices that are surveilled or calibrated where As-Found and As-Left data is recorded and that a given device may be justified not to require drift analysis in accordance with this design guide, if appropriate. Justification for not requiring drift analysis may potentially be

Enclosure to NRC-20-0057 Page 6 appropriate for digital components such as transmitters. It is not clear if the design guide considers potential digital technologies and it does not make any specific distinction for digital components or their unique aspects beyond an acknowledgement for digital indicators. The staff recognizes that digital technologies may have unique failure modes different than the conventional analog components.

Justify that the drift analysis methodology in DTE-18001, Rev. 0, adequately accounts for digital components and their unique aspects that could affect instrument drift (e.g. potential digital failure modes).

DTE RESPONSE NRC-19-0054 Enclosure 7, Instrument Drift Analysis Design Guide, DTE-18001, Revision 0, was applied to the specific instrumentation listed in Enclosure 6, Applicable Instrumentation. As discussed in Enclosure 5, GL 91-04 Evaluation, the instrumentation identified in Enclosure 6 includes: transmitters/sensors (e.g., pressure, level, temperature); certain trip units; and time delay relays, generally associated with actuation functions (e.g., Reactor Protection System trip functions, Engineered Safety Features actuation functions). Enclosure 6 includes no digital components.

Conventional methods were used to evaluate drift for other instrumentation devices not included in Enclosure 6 (e.g., recorders/indicators, resistors, isolators, modulators/demodulators, and transmitters/sensors, some of which are digital). These same methods were employed for the current calibration interval. In cases where Vendor Drift (VD) is specified, the VD is extrapolated to reflect the calibration interval. Where VD is not specified, the drift contribution is assumed to be negligible, or included in the vendor accuracy specified for the device. The overall absence of 18-month calibration failures identified in DTE-19001 supports a conclusion that this approach is sound.

DTE-18001 (NRC-19-0054 Enclosure 7) provides the methodology used for analyzing historical instrument as-found and as-left calibration data to establish drift at the current calibration interval and to extrapolate the drift to a proposed interval. The methodology presumes that the instrumentation has recordable as-found and as-left calibration data to be analyzed. As a part of any instrument calibration, the device will be exercised throughout the range of the instrument, proving that the device is appropriately and accurately responding to the input provided. Thus, failures of the device would be detected, no matter whether the device is analog or digital. If digital failure modes cause signal freezing, scaling factor corruption, etc., that could impact the required indication or response of the device, the calibration as-found and as-left data would be impacted and detected as a failure, most likely during the calibration activities, or as a part of the drift analysis - data entry and checking process, where the data is analyzed for outliers or other erroneous situations. Devices which perform significantly worse than other similar devices within the drift analysis are identified as poor performers (DTE-18001 Section 3.2.1.1) and evaluated for repair or replacement.

Enclosure to NRC-20-0057 Page 7 In conclusion, the drift analysis methodology in DTE-18001, Rev. 0, adequately accounts for digital components and their unique aspects that could affect instrument drift (e.g., potential digital failure modes). However, no digital components were evaluated using the DTE-18001 drift methodology. Drift for digital components, such as indicators and recorders was evaluated using conventional methods.