NRC-2015-0069, Response to Request for Information Supporting Flooding Hazards Reevaluation Report Audit

Response to Request for Information Supporting Flooding Hazards Reevaluation Report Audit

ML15310A170
Person / Time
Site:	Point Beach
Issue date:	11/06/2015
From:	Mccartney E Point Beach
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
NRC-2015-0069, TAC MF6100, TAC MF6101
Download: ML15310A170 (9)

Text

NEXTeraM ENERGY~

November 6, 2015

~ NRC 2015-0069 10 CFR 50.4 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555 Point Beach Nuclear Plant, Units 1 and 2 Dockets 50-266 and 50-301 Renewed License Nos. DPR-24 and DPR-27 Response to Request for Information Supporting Flooding Hazards Reevaluation Report Audit

References:

(1) NextEra Energy Point Beach, LLC, Response to NRC 10 CFR 50.54(f)

Request for Information Regarding Near-Term Task Force Recommendation 2.1, Flooding -Submittal of Flooding Hazards Reevaluation Report, dated March 12, 2015 (2) Nuclear Regulatory Commission Plan for the Audit of NextEra Energy Point Beach, LLC's Flood Hazard Reevaluation Report Submittal Relating to the Near-Term Task Force Recommendation 2.1 -Flooding for Point Beach Nuclear Plant, Units 1 and 2 (TAC Nos. MF6100 and MF6101), dated June 4, 2015 (3) NextEra/NRC Teleconference Related to Point Beach Flooding Hazards Reevaluation Report on October 29, 2015 By letter dated March 12, 2015, NextEra Energy Point Beach, LLC (NextEra) submitted a Flooding Hazards Reevaluation Report (FHRR) (Reference 1) in response to Title 10 of the Code of Federal Regulations 50.54(f) Request for Information, relating to Recommendation 2.1 .

By letter dated June 4, 2015 (Reference 2) , the NRC notified NextEra of upcoming audit activities related to review of the FHRR submittal. During a teleconference conducted on October 29, 2015 (Reference 3), NRC requested clarifications related to the NextEra FHRR submittal for Point Beach.

Enclosures 1 and 2 provide the requested information.

This letter contains no new commitments and no revisions to existing commitments.

If you have any questions, please contact Mr. Bryan Woyak, Licensing Manager, at (920) 755-7599.

NextEra Energy Point Beach, LLC, 6610 Nuclear Rd., Two Rivers, WI. 54241

Document Control Desk Page 2 Very truly yours ,

NextEra Energy Point Beach, LLC

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Eric McCartney Site Vice President Enclosures cc: Director, Office of Nuclear Reactor Regulation Administrator, Region Il l, USNRC Project Manager, Point Beach Nuclear Plant, USNRC Resident Inspector, Point Beach Nuclear Plant, USNRC Ms. Lisa M. Regner, NRR/JLD/PMB, USNRC Mr. Blake A. Purnell, NRR/JLD/PMB, USNRC Mr. Steven R. Jones, NRR/DSS/SBPB, USNRC

ENCLOSURE 1 NEXTERA ENERGY POINT BEACH, LLC POINT BEACH NUCLEAR PLANT, UNITS 1 AND 2 RESPONSE TO REQUEST FOR INFORMATION SUPPORTING FLOODING HAZARDS REEVALUATION REPORT AUDIT

Clarification Request Describe how the reevaluated flood hazards are compared to the Current Licensing Basis and the Current Design Basis.

Response

All of the subsections in Flooding Hazards Reevaluation Report (FHRR), Section 5, Comparison with Current Design Basis, compare the current design basis flood elevations to the reevaluated flood hazards at Point Beach Nuclear Plant (PBNP). For the postulated flooding events in the FHRR, PBNP does not differentiate between current design basis (COB) and current licensing basis (CLB). COB and CLB are considered synonymous in the FHRR for postulated flooding.

Clarification Request Provide updated figures, where necessary, to accurately distinguish the locations and areal extents of temporary wave barriers. If possible, make door numbers more legible in FHRR Figure 4.5.

Response

FHRR, Figure 4.5, PBNP Door Locations, has been updated to improve the display of the door numbers. The updated figure is included in Enclosure 2.

FHRR, Figure 4.8, LIP [Local Intense Precipitation] Maximum Flow Depths- Scenario B, has been updated to more clearly show the wave/door barriers (wave run-up door barriers) at the Circulating Water Pumphouse. The updated figure is included in Enclosure 2.

Clarification Request The FHRR states that the elevations of the grid cells to the east of the Turbine Building were manually set at 589.3 ft NAVD88 (+8ft -Plant Datum) for reasons of accurately determining flood elevations and model stability. Provide more information on the modification of the Digital Terrain Model to 589.3 ft NAVD88 (+8 ft-Piant Datum). Specifically, what was the original elevation and why was that elevation revised for accuracy and model stability?

Response

A supplemental figure, titled "Original Elevations East of Turbine Hall" is provided in . The figure shows the unaltered elevation data for the area east of the Turbine Building. The elevation cells within the black outline were manually set to +8 ft-Piant Datum

(+589.3 ft-NAVD88). The ground elevations in that area range from approximately +7.0 ft-Piant Datum to +8.4 ft-Piant Datum. Based on the construction drawings of the Turbine Building, the floor at the east end of the building (where Doors 1, 2, 4, 11 and 13 are located) are at an elevation of +8 ft-Piant Datum. The model cells adjacent to these doors, interpolated from site survey data, were at elevations other than +8 ft-Piant Datum originally. To properly represent the door elevations, all the cells within the black outline were manually adjusted to +8 ft-Piant Datum. Although the manual alteration of grid cell elevations changes the surface topography, it does so in a conservative manner. In most of the area, storage capacity was removed by increasing the cell elevation to +8 ft-Piant Datum, which would slightly increase the maximum Local Intense Precipitation water surface elevations.

Page 1 of 2

Clarification Request Section 5. 1 of the FHRR states that "The FHR WSELs and maximum flow depths exceed the CLB at each PO/." Door 600 for the Diesel Generator Building is noted as 608. 2ft NA VDBB in the CLB Table 3.1, which exceeds the 607. 7ft NAVDBB recorded for Door 600 in the updated LIP analysis in Table 4.2. Door 601 has the same flow depth for the CLB and the updated LIP analysis. Clarify this data reported in Section 5. 1.

Response

In FHRR, Section 5.1, Precipitation Flooding, the text should read "The FHR maximum flow depths exceed the CLB at each POl, with the exception of Door 601, which remained the same", without comparison of the water surface elevations (WSELs).

The CLB runoff model was aligned with respect to North, whereas the FHRR runoff model was aligned with building edges with an approximately 25 degrees clockwise from North rotation.

Accordingly, the topographic interpolation at certain model cells differed between the CLB and FHRR models (e.g., Door 600 ground elevation differed by 0.5 ft). Correspondingly, the water depth result in the cell adjacent to Door 600 is a better comparison of the CLB and FHRR values. For example, the maximum flow depth at Door 600 increased from <0.1 ft ('N/A' in FHRR, Table 3.1) to 0.2 ft (FHRR, Table 4.2). The maximum depth at Door 601 remained at 0.1 ft, although it should be noted that the FHRR water depth was slightly higher beyond the significant digits reported.

Page 2 of 2

ENCLOSURE 2 NEXTERA ENERGY POINT BEACH, LLC POINT BEACH NUCLEAR PLANT, UNITS 1 AND 2 RESPONSE TO REQUEST FOR INFORMATION SUPPORTING FLOODING HAZARDS REEVALUATION REPORT AUDIT REVISED FIGURES Figure 4.5, PBNP Door Locations FHRR, Figure 4.8, LIP Maximum Flow Depths- Scenario B Supplemental Figure- Original Elevations East of Turbine Hall 3 pages follow

Legend e Doors with Wave Runup Barriers 0 Door locations c::::J Temporary Structure Permanent Structure I I Other C ] CWPH NextE~l1.Energy (NEE} rF::~ ENERCON Point Beach Nuclear Plant (PBNP)

Figure 4.5 Flooding Hazards Reevaluation Report (FHRR)

PBNP Door locations

NextEra Energy (NEE)

Point Beach Nuclear Plant (PBNP)

ENERCON Flooding Hazards Reevaluation Report (FHRR)

Figure4.8 UP MaxirrJUm Flow Depths- Scenario B

D PermBJ> erll Strue!tJ res Bev. (ft.-Plant Datum)

IH - 6.7 6.8 0 7 0 1.1 0 7.2

!~"------1 D 7.3 0 7.4 0 7.5 0 7.6 0 7.7 Turbine Building

-8 0 7.8 CJ 7.9 8.1 8.2 8.3 CWPH

- 8.4

. 8.5

. 8.6 Original Elevations East of the Turbine Hall