L-MT-15-060, Expedited Seismic Evaluation Process (ESEP) - Augmented Approach to Post-Fukushima Near-Term Task Force (NTTF) 2.1 - Clarification of Response to Request for Additional Information

Expedited Seismic Evaluation Process (ESEP) - Augmented Approach to Post-Fukushima Near-Term Task Force (NTTF) 2.1 - Clarification of Response to Request for Additional Information

ML15225A463
Person / Time
Site:	Monticello
Issue date:	08/13/2015
From:	Gardner P Northern States Power Co, Xcel Energy
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
L-MT-15-060
Download: ML15225A463 (11)

Text

Monticello Nuclear Generating Plant 2807 W County Road 75 Monticello, MN 55362 August 13, 2015 L-MT-15-060 10 CFR 50.54(f)

U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 Monticello Nuclear Generating Plant Docket No. 50-263 Renewed Facility Operating License No. DPR-22 Monticello Nuclear Generating Plant: Expedited Seismic Evaluation Process (ESEP) -

Augmented Approach to Post-Fukushima Near-Term Task Force (NTTF) 2.1 -

Clarification of Response to Request for Additional Information

References:

1) NRC Letter, Request for Information Pursuant to Title 10 of the Code of Federal Regulations 50.54(f) Regarding Recommendations 2.1, 2.3, and 9.3, of the Near-Term Task Force Review of Insights from the Fukushima Dai-ichi Accident, dated March 12, 2012. (ADAMS Accession No. ML12056A046)

2) Letter from K. Fili (NSPM) to Document Control Desk (NRC), Request Commitment Change for Response to NRC Request for Information Pursuant to Title 10 of the Code of Federal Regulations 50.54(f) Regarding the Seismic Aspects of Recommendation 2.1 of the Near-Term Task Force Review of Insights from the Fukushima Dai-ichi Accident, L-MT-14-027, dated March 31, 2014. (ADAMS Accession No. ML14090A297)

3) Letter from K. Fili (NSPM) to Document Control Desk (NRC), Monticello Nuclear Generating Plant: Expedited Seismic Evaluation Process (ESEP) - Augmented Approach to Post-Fukushima Near-Term Task Force (NTTF) 2.1, L-MT-14-093, dated December 23, 2014. (ADAMS Accession No. ML14357A280)

4) Email from S. Wyman (NRC) to J. Fields (NSPM), Monticello ESEP Report Clarifications, dated April 8, 2015.

5) Letter from P. Gardner (NSPM) to Document Control Desk (NRC), Monticello Nuclear Generating Plant: Expedited Seismic Evaluation Process (ESEP) -

Augmented Approach to Post-Fukushima Near-Term Task Force (NTTF) 2.1 -

Response to Requests for Additional Information, L-MT-15-030, dated May 22, 2015.

Document Control Desk Page 2 On March 12, 2012, the NRC issued Request for Information Pursuant to Title 10 of the Code of Federal Regulations 50.54(f) Regarding Recommendations 2.1, 2.3, and 9.3, of the Near-Term Task Force Review of Insights from the Fukushima Dai-ichi Accident, (information request) to all NRC power reactor licensees and holders of construction permits in active or deferred status (Reference 1).

On March 31, 2014, in accordance with this information request, Northern States Power Company, a Minnesota corporation (NSPM), doing business as Xcel Energy, committed to provide an Expedited Seismic Evaluation Process (ESEP) report for the Monticello Nuclear Generating Plant (MNGP) to the NRC by December 31, 2014 (Reference 2).

On December 23, 2014, NSPM provided the MNGP ESEP Report to the NRC (Reference 3).

On April 8, 2015, the NRC sent an email (Reference 4) which contained requests for additional information (RAIs) related to the ESEP report provided in Reference 3. On May 22, 2015, NSPM provided responses to the RAIs (Reference 5).

On June 23, 2015, the NRC and NSPM held a conference call to discuss NSPMs response to RAI #6. In this conference call, NSPM provided further information related to validating the seismic adequacy of MNGP inaccessible components.

On August 6, 2015, the NRC and NSPM held a conference call to discuss NSPMs response to RAI #4. In this conference call the NRC requested that NSPM provide additional information relative to the High Confidence of a Low Probability of Failure (HCLPF) values for the specific set of relays discussed in RAI #4. to this letter documents the information provided in the June 23, 2015, conference call and provides additional clarifying information related to RAIs #6. to this letter provides the additional information the NRC requested relative to the HCLPF values for the specific set of relays discussed in RAI #4.

If there are any questions or if additional information is needed, please contact John Fields, Fukushima Response Licensing, at 763-271-6707.

Summary of Commitments This letter contains no new commitments and no revisions to existing commitments.

Document Control Desk Page 3 I declare under penalty of perjury that the foregoing is true and correct.

Executed on A Peter A Site Vic re dent, Monticello Nuclear Generating Plant Northern S es Power Company - Minnesota Enclosures cc: Administrator, Region Ill, USNRC Director of Nuclear Reactor Regulation (NRR), USNRC NRR Project Manager, MNGP, USNRC Senior Resident Inspector, MNGP, USNRC

L-MT-15-060 ENCLOSURE 1 MONTICELLO NUCLEAR GENERATING PLANT RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION #6 CLARIFYING INFORMATION On April 8, 2015, the NRC sent Northern States Power Company, a Minnesota corporation (NSPM), doing business as Xcel Energy, an email (Reference 1) which contained requests for additional information (RAIs) related to the Monticello Nuclear Generating Plant (MNGP) Expedited Seismic Evaluation Process (ESEP) report. On May 22, 2015, NSPM provided responses to the RAIs (Reference 2). On June 23, 2015, the NRC and NSPM held a conference call to discuss NSPMs response to RAI

1. 6. In that conference call, NSPM provided further information related to validating the seismic adequacy of MNGP inaccessible components.

This enclosure documents the information provided in that conference call and provides additional clarifying information related to RAI #6.

The original NRC RAI #6 is provided below in italics font, followed by the original NSPM response (in normal font) (Reference 2), followed by the clarifying information request (in italics font) and finally, the clarification response is provided (in normal font) as discussed on the June 23, 2015 conference call with the NRC.

NRC Question 6 There are approximately 50 ESEL items identified as inaccessible because they are inside the drywell. The licensee does NOT intend to complete a walk-by or remote visual of the inaccessible ESEL items at a later date. It is relying on A-46 walkdown results, which are around 20 years old. This appears to be inconsistent with the augmented approach proposed by EPRI and accepted by NRC. Discuss the technical basis why these approximately 50 items do not need to be looked at, in order to verify condition and re-affirm the A-46 walkdown results.

Original NSPM Response For inaccessible components, NSPM relied on walk downs performed to meet the A-46 issue, the Recommendation 2.3 seismic walk downs performed in 2013 and in specific cases, other information as described below. The 2013 walkdowns Page 1 of 5

L-MT-15-060 observed the following components and areas in the drywell: (1) inboard Main Steam Isolation Valve (MSIV) - AO-2-80A, (2) SRV - RV-2-71A, (3) area walk-bys on the 933 and 951 elevations of the drywell. There was nothing noteworthy found during these walk downs.

The ESEL equipment that was determined to be inaccessible (due to location in the drywell) included valves, accumulators and temperature elements. Each component type was assessed as follows:

For valves, the Seismic Review Team (SRT) gathered valve drawings in addition to the A-46 Screening Evaluation Work Sheets (SEWS) and pictures, and performed the valve evaluation based on the methodology presented in EPRI NP 6041-SL (Reference 4).

Temperature elements were evaluated based on A-46 walk down notes and pictures. These components are directly attached/secured to structural components.

Therefore, the SRT determined that the information was adequate for the ESEP purpose.

Accumulators were evaluated based on the A-46 notes and pictures. Typically two large U bolt connections were utilized to secure the accumulator. With the large margin of these items, the SRT determined that the information was adequate for the ESEP purpose.

Clarifying Information Request From the June 23, 2015 conference call with the NRC regarding ESEP RAI #6, the NRC requested that NSPM provide further information related to validating the seismic adequacy of inaccessible components for MNGP. Specifically, the NRC requested that NSPM provide justification for each inaccessible item type stating why the current evaluation performed by NSPM (i.e., using the 20 year old walkdown data/photos) is acceptable.

NSPM Response The information below describes the approach NSPM used to evaluate the inaccessible items for seismic adequacy. In summary, as described in the initial response to RAI #6, NSPM relied on information performed to meet the A-46 requirements, the Near Term Task Force (NTTF) Recommendation 2.3 seismic walk-bys and walk-downs of the Drywell (DW), and other available information.

NSPM affirms that the inaccessible components seismic evaluation has been completed in accordance with EPRI NP 6041-SL and that no further evaluation is required.

Page 2 of 5

L-MT-15-060 Below is the specific list of MNGP inaccessible components with further justification for each components seismic adequacy evaluation.

Safety Relief Valves (SRVs) - RV-2-71A through RV-2-71H NSPM reviewed the SEWS evaluation from 1995 with photos.

A walk by was performed in 2013 (DW elevation 951).

The valves are located in an inert environment during plant operation.

RV-2-71A was specifically walked down in 2013 and documented on a Seismic Walkdown Checklist (SWC) with photos taken. The other seven valves are supported in a similar manner.

Valve drawings were reviewed.

The valves are rigidly mounted on seismic piping with supporting seismic analysis.

The NSPM design control program is applicable to these components and assesses any proposed changes to MNGP to ensure the seismic qualification continues to meet design and licensing requirements.

Discharge Vacuum Relief Valves (8 inch valves) - RV-3242A, RV-3243A, RV-3244A, RV-3245A, RV-7440A, RV-7441A, RV-7467A and RV-7468A NSPM reviewed the SEWS evaluation from 1995 with photos.

A walk by was performed in 2013 (DW elevation 951) and documented on an Area Walk-By Checklist (AWC).

The valves are located in an inert environment during plant operation.

These valves are supported in a similar manner as other seismic valves integral to piping systems.

The valves are rigidly mounted on seismic piping with supporting seismic analysis.

The NSPM design control program is applicable to these components and assesses any proposed changes to MNGP to ensure the seismic qualification continues to meet design and licensing requirements.

Drywell Purge/Vent Valves - AO-2386 and AO-2387 NSPM reviewed the SEWS evaluation performed in 2014.

The valves have a similar mounting as other seismically designed valves integral to piping systems.

NSPM did not walk by these valves due to their location in a locked high radiation area (located in Reactor Water Cleanup Pump Room).

The material condition of the valves was observed to be satisfactory during performance of a Local Leak Rate Test (LLRT) in 2015.

Valve drawings were reviewed.

Page 3 of 5

L-MT-15-060 The NSPM design control program is applicable to these components and assesses any proposed changes to MNGP to ensure the seismic qualification continues to meet design and licensing requirements.

High Pressure Coolant Injection/Reactor Core Isolation Cooling Steam Isolation Valves - MO-2035 and MO-2076 NSPM reviewed the SEWS evaluation from 1995 with photos.

Valve drawings were reviewed.

A walk by was performed in 2013 (Steam Chase) and documented on an AWC.

These valves are supported in a similar manner as other seismic valves integral to piping systems.

The NSPM design control program is applicable to these components and assesses any proposed changes to MNGP to ensure the seismic qualification continues to meet design and licensing requirements.

SRV Air System Solenoid Valves - SV-2-71A through SV-2-71M NSPM reviewed the SEWS evaluation from 1995 with photos.

An area walk by was performed in 2013 (DW elevation 951).

The valves are located in an inert environment during plant operation.

The valves are light weight and rigidly mounted to a steel frame.

All of these solenoid valves have a similar mounting.

The NSPM design control program is applicable to these components and assesses any proposed changes to MNGP to ensure the seismic qualification continues to meet design and licensing requirements.

DW Temperature Elements (TEs) - TE-4247A through TE-4247H NSPM reviewed four SEWS (TE-4247A, C, F, H) evaluations from 1995 with photos.

Photos show that these light weight TEs are rigidly mounted to DW structural steel.

An area walk by was performed in 2013 for TEs 4247A - D (TEs 4247E - H are located at higher elevations in the DW with similar mounting but are not as accessible).

Components are located in an inert environment during plant operation.

TEs are inherently rugged, and mounted to large I-beams.

The NSPM design control program is applicable to these components and assesses any proposed changes to MNGP to ensure the seismic qualification continues to meet design and licensing requirements.

Page 4 of 5

L-MT-15-060 SRV Accumulators - T-57A through T-57H NSPM reviewed SEWS evaluations from 1995 with photos.

Accumulator drawings were reviewed.

An area walk by was performed in 2013 (DW elevation 951).

Accumulators are fabricated from stainless steel, and are located in an inert environment during plant operation.

The accumulators are mounted to DW structural steel I-beams with stainless steel 3/4 U-bolts and nuts.

Mounting is similar for all these accumulators.

The NSPM design control program is applicable to these components and assesses any proposed changes to MNGP to ensure the seismic qualification continues to meet design and licensing requirements.

References

1) Email from S. Wyman (NRC) to J Fields (NSPM), Monticello ESEP Report Clarifications, dated April 8, 2015.

2) Letter from P. Gardner (NSPM) to Document Control Desk (NRC), Monticello Nuclear Generating Plant: Expedited Seismic Evaluation Process (ESEP) -

Augmented Approach to Post-Fukushima Near-Term Task Force (NTTF) 2.1 -

Response to Requests for Additional Information, L-MT-15-030, dated May 22, 2015.

3) Not Used.

4) EPRI Report No.: NP-6041-SL, A Methodology for Assessment of Nuclear Power Plant Seismic Margin, Revision 1.

Page 5 of 5

L-MT-15-060 ENCLOSURE 2 MONTICELLO NUCLEAR GENERATING PLANT RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION #4 CLARIFYING INFORMATION On August 6, 2015, the NRC and Northern States Power Company, a Minnesota corporation (NSPM), doing business as Xcel Energy, held a conference call to discuss Request for Additional Information (RAI) #4 from Reference 1. In the conference call the NRC requested additional clarifying information regarding the High Confidence of a Low Probability of Failure (HCLPF) values presented in Table 4-1.

This enclosure provides the additional clarifying information related to RAI #4 that the NRC requested.

Clarifying Information Request From the August 6, 2015 conference call with the NRC regarding ESEP [Expedited Seismic Evaluation Process] RAI #4, the NRC requested that Table 4-1 from Reference 1 be augmented to also provide the HCLPF values that represent the ground level acceleration through to the anchorage or functional capacity of the installed component. This should include the peak acceleration when reporting the value.

NSPM Response In NSPM letter to NRC dated May 22, 2015 (Reference 1), NSPM provided Table 4-1 which included the functional capacities HCLPF values for 17 relays.

NSPM is providing Table 4 Revised, HCLPF for Relays, below. This revised table includes the same 17 relays provided in the original Table 4-1. The revised table provides the HCLPF values that represent the ground level acceleration through to the anchorage or functional capacity of the installed component. These values include peak acceleration.

Page 1 of 3

L-MT-15-060 Enclosure 2 Table 4 Revised - HCLPF for Relays GenRS Peak -

SFc2 min Relay Maximum Horizontal Host (clipped 4 - 16 Hz Functional Host Cabinet / Bldg /

Component (capacity/demand) HCLPF Floor Acceleration for Cabinet Demand (g)/Max Capacity Elevation ID of peak/ZPA (g) Host Cabinet (g) HCLPF (g)

ZPA1(g)) Peak/ZPA (g) 13A-K1 1.76/0.71 6.00/2.40 3.38 0.64 C-30/Admin/ 939 1.76 0.21 13A-K2 1.76/0.71 6.00/2.40 3.38 0.64 C-30/Admin/ 939 1.76 0.21 13A-K6 1.76/0.71 6.00/2.40 3.38 0.64 C-30/Admin/ 939 1.76 0.21 13A-K7 1.76/0.71 8.00/3.20 4.51 0.86 C-30/Admin/ 939 1.76 0.21 13A-K10 1.76/0.71 6.00/2.40 3.38 0.64 C-30/Admin/ 939 1.76 0.21 13A-K12 1.76/0.71 6.00/2.40 3.38 0.64 C-30/Admin/ 939 1.76 0.21 13A-K16 1.76/0.71 6.00/2.40 3.38 0.64 C-30/Admin/ 939 1.76 0.21 13A-K18 1.76/0.71 6.00/2.40 3.38 0.64 C-30/Admin/ 939 1.76 0.21 13A-K19 1.76/0.71 6.00/2.40 3.38 0.64 C-30/Admin/ 939 1.76 0.21 13A-K22 1.76/0.71 6.00/2.40 3.38 0.64 C-30/Admin/ 939 1.76 0.21 13A-K27 1.76/0.71 6.00/2.40 3.38 0.64 C-30/Admin/ 939 1.76 0.21 13A-K31 1.76/0.71 8.00/3.20 4.51 0.86 C-33/Admin/ 939 1.76 0.21 13A-K32 1.76/0.71 6.00/2.40 3.38 0.64 C-33/Admin/939 1.76 0.21 13A-K33 1.76/0.71 10.00/4.00 5.63 1.07 C-30/Admin/ 939 1.76 0.21 13A-K34 1.76/0.71 6.00/2.40 3.38 0.64 C-30/Admin/ 939 1.76 0.21 13A-K37 1.76/0.71 12.00/4.80 6.76 1.28 C-30/Admin/ 939 1.76 0.21 K102A 1.76/0.71 2.64/1.06 1.49 0.28 C-303A/Admin/939 1.76 0.21 1

ZPA = Zero Period Acceleration 2

SFC = ComponentSpecific Scale Factor Page 2 of 3

L-MT-15-060 The Review Level Ground Motion (RLGM) was determined by linearly scaling the MNGP Safe Shutdown Earthquake (SSE) for the structure by the maximum Safety Factor3 between the 1 and 10 Hz range.

The method used to derive the ESEP in-structure response spectra (ISRS) was to uniformly scale the existing SSE-based ISRS by the maximum SF between the SSE and the RLGM.

In order to eliminate conservatism for the components in Table 4 Revised, the In-Cabinet Response Spectra (ICRS) was generated through the application of the GenRS software. GenRS was used because the peak frequency of the input In-Structure Response Spectra (ISRS) was significantly different than the natural frequency of the subject cabinets.

The relays in Table 4 Revised used functional capacities drawn from EPRI NP-7147-SL (Reference 2), manufacturer test data, and Seismic Qualification Utility Reports and Testing Standardization (SQURTS) reports.

References

1) Letter from P. Gardner (NSPM) to Document Control Desk (NRC), Monticello Nuclear Generating Plant: Expedited Seismic Evaluation Process (ESEP) -

Augmented Approach to Post-Fukushima Near-Term Task Force (NTTF) 2.1 -

Response to Requests for Additional Information, L-MT-15-030, dated May 22, 2015.

2) EPRI Report No.: NP-7147-SL, Seismic Ruggedness of Relays, August 1991.

3 Safety Factor = Ground Motion Response Spectra (GMRS)/SSE ratio Page 3 of 3