LR-N15-0101, Response to Request for Additional Information Regarding Flooding Aspects of Recommendations 2.1 of the Near-Term Task Force Review of Insights from the Fukushima Dai-ichi Accident

Response to Request for Additional Information Regarding Flooding Aspects of Recommendations 2.1 of the Near-Term Task Force Review of Insights from the Fukushima Dai-ichi Accident

ML15128A371
Person / Time
Site:	Salem
Issue date:	05/07/2015
From:	Jamila Perry Public Service Enterprise Group
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
LR-N15-0101
Download: ML15128A371 (8)

Text

PSEG Nuclear LLC P.O. Box 236, Hancocks Bridge, NJ 08038-0236 10 CFR 50.54(f)

LR-N15-0101 MAY 07 2015 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 Salem Generating Station Units 1 and 2 Renewed Facility Operating License Nos. DPR-70 and DPR-75 NRC Docket Nos. 50-272 and 50-311

Subject:

Salem Generating Station's Response to Request for Additional Information Regarding Flooding Aspects of Recommendation 2.1 of the Near-Term Task Force Review of Insights from the Fukushima Dai-ichi Accident

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

2. PSEG Letter LR-N14-0042, "PSEG Nuclear LLC's Response to Request for Information Regarding Flooding Aspects of Recommendation 2.1 of the Near-Term Task Force Review of Insights from the Fukushima Dai-ichi Accident - Salem Generating Station Flood Hazard Reevaluation," dated March 11, 2014

3. NRC Letter, "Salem Nuclear Generating Station, Units 1 and 2, Request for Additional Information Regarding Flooding Hazard Reevaluation (TAC Nos. MF3790 and MF3791)," dated June 28, 2014

4. PSEG Letter LR-N14-0170, "PSEG Nuclear LLC's 30-day Response to Request for Additional Information Regarding Flooding Aspects of Recommendation 2.1 of the Near-Term Task Force Review of Insights from the Fukushima Dai-ichi Accident," dated July 28, 2014

MAY 07 20i5 10 CFR 50.54(f)

Page 2 LR-N15-0101

5. PSEG Letter LR-N14-0207, "PSEG Nuclear LLC's 90-day Response to Request for Additional Information Regarding Flooding Aspects of Recommendation 2.1 of the Near-Term Task Force Review of Insights from the Fukushima Dai-ichi Accident," dated September 23, 2014

6. NRC e-mail to PSEG, "Salem and Hope Creek Request for Additional Information RE: flood hazard reevaluation report submitted in response to NRC 50.54(f) letter," dated April 13, 2015 On March 12, 2012, the Nuclear Regulatory Commission (NRC) sent PSEG Nuclear LLC (PSEG) a request for information (Reference 1) pursuant to 10 CFR 50.54(f),

associated with Near-Term Task Force (NTTF) Recommendation 2.1 for flooding.

PSEG responded by providing a flooding hazard reevaluation report (FHRR) for the Salem Generating Station (SGS) (Reference 2). Reference 3 transmitted an NRC Request for Additional Information (RAI) regarding the FHRR, to which PSEG responded in References 4 and 5. In Reference 6, the NRC requested additional information to support its review of the SGS flooding hazard reevaluation. Attachment 1 provides the additional information requested by Reference 6 for SGS Units 1 and 2.

There are no regulatory commitments contained in this letter.

If you have any questions or require additional information, please do not hesitate to contact Mr. Brian Thomas at 856-339-2022.

I declare under penalty of perjury that the foregoing is true and correct.

Executed on _ __;:;)

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(Date)

Sincerely, J1:7 Site Vice President Salem Generating Station

Attachment:

1. Salem Generating Station Units 1 and 2 Response to Request for Additional Information (RAI) Regarding Flooding Hazard Reevaluation

MAY *07 2015 10 CFR 50.54(f)

Page 3 LR-N15-0101 cc:

Mr. William Dean, Director of Office of Nuclear Reactor Regulation Mr. Daniel Dorman, Administrator, Region I, NRC Ms. Carleen Sanders-Parker, Project Manager, NRC NRC Senior Resident Inspector, Salem Mr. Patrick Mulligan, Manager IV, NJBNE Mr. Thomas Cachaza, Salem Commitment Tracking Coordinator Mr. Lee Marabella, PSEG Commitment Coordinator- Corporate

LR-N15-0101 Attachment 1 Salem Generating Station Units 1 and 2 Response to Request for Additional Information (RAI) Regarding Flooding Hazard Reevaluation

LR-N15-0101 Salem Generating Station Units 1 and 2 Response to Request for Additional Information (RAI) Regarding Flooding Hazard Reevaluation RAI 1 : Local Intense Precipitation (LIP) - Event Duration and Distribution The flood hazard reevaluation report (FHRR) presents a local intense precipitation (LIP) flood reevaluation for a 1-hour, front-loaded probable maximum precipitation (PMP) event using Hydrometeorological Report (HMR) Nos. 51 and 52. Provide justification that the LIP analysis presented in the FHRR is bounding in terms of warning time, flood depth, and flood duration. This justification can include sensitivity analysis of LIP event duration to consider localized (one square mile) PMP events up to 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> in duration (e.g., 1-, 6-, 12-, 24-, 48-, 72-hour PMPs) and various rainfall distributions (e.g.,

center-loaded and others in addition to a front-loaded distribution). The evaluations could identify potentially bounding scenarios with respect to flood height, event duration, and associated effects.

Response to RAI 1 : Local Intense Precipitation (LIP) - Event Duration and Distribution From NUREG/CR-7046 Section 3.2 (Reference 1) :

"Local intense precipitation is a measure of the extreme precipitation at a given location. The duration of the event and the support area are needed to qualify an extreme precipitation event fully. Generally, the amount.of extreme precipitation decreases with increasing duration and increasing area. The PMP values for areas of the United States east of the 105th meridian are presented in HMRs 51 (Schreiner and Riedel 1978) and 52 (Hansen et al. 1982). The 1-hr, 2.56-km2 (1-mi2) PMP was derived using single-station observations of extreme precipitation, coupled with theoretical methods for moisture maximization, transposition, and envelopment. HMR 52 recommended that no increase in PMP values 2

for areas smaller than 2.56 km (1 mi'} should be considered over the 2 2 1-hr, 2.56-km (1-mi ) PMP. The local intense precipitation is, 2 2 therefore, deemed equivalent to the 1-hr, 2.56-km (1-mi ) PMP at the location of the site."

Since the 1-hr, 1-mi2 LIP event bounds the Salem Generating Station (SGS) drainage area, the evaluation of a longer duration and larger storm event was not warranted.

This approach is consistent with the definition of a LIP event per NUREG/CR-7046 (Reference 1) as described above. The rainfall data for the LIP event was developed using HMR-52 (Reference 2).

The 1-hr PMP event temporal distribution was developed in accordance with HMR-52 and NUREG/CR-7046. In accordance with HMR-52 and NUREG/CR-7046, the sub-1-hr PMP depths were obtained by applying multiplication factors from HMR-52, 1 of 4

LR-N15-0101 Figures 36, 37, and 38. The PMP rainfall distribution and hyetograph were developed in accordance NUREG/CR-7046 Appendix B. The front-loaded PMP event was selected for SGS because it results in maximum flood depths early in the event and consequently the shortest response time. SGS is equipped with flood protection features, including watertight doors, which are rated to significantly greater elevations than any possible LIP flood depth. The only response to the LIP event is closing the existing watertight doors. Therefore, the most conservative LIP event for SGS is one that has the shortest response time for watertight door closure. The duration of the flooding is non-consequential once the watertight doors are closed. In addition, procedural changes have been made to close the doors well in advance of a Ll P event so that the warning time significantly bounds the response time for door closure.

RAI 2: Streams and Rivers - PMF The flood hazard reevaluation report (FHRR) presents a streams and rivers probable maximum flood (PMF) reevaluation for two probable maximum precipitation (PMP) events based on HMR Nos. 51 and 52. Present-day regulatory guidance recommends consideration of snowmelt as a contributor to flooding in evaluating the PMF from precipitation. However, the FHRR does not describe whether snowpack and snowmelt were considered. Provide a description of snowpack and snowmelt characteristics that were considered in the streams and rivers flood reevaluation. Justify why evaluating snowmelt as a contributor to the PMF is not necessary, or provide an evaluation of snowmelt contribution to flooding as described in present-day regulatory guidance.

Response to RAI 2: Streams and Rivers - PMF NUREG/CR-7046 Section 3.3 (Reference 1) states that "The PMF is defined by ANSI/ANS-2.8-1992 (ANS 1992) as ' ...the hypothetical flood (peak discharge, volume, and hydrograph shape) that is considered to be the most severe reasonably possible, based on comprehensive hydrometeorological application of PMP and other hydrologic factors favorable for maximum flood runoff such as sequential storms and snowmelt."'

SGS is located near the confluence of the Delaware Bay and Delaware River. The potential for site flooding exists from a combined event scenario with storm surge and astronomic tide being the main contributors to flooding. NUREG/CR-7046 and ANS-2.8 (Reference 3) detail the methodology for performing a combined event analysis using a series of alternatives. Specifically, Section 9.2.2.2 of ANS-2.8 describes the four alternatives that include PMF events, Alternatives I, II, Ill, and IV. These alternatives are appropriate for streamside locations on an open and semi-closed body of water.

None of these alternatives include the consideration of snowpack or snowmelt, which is more appropriately considered for sites located on inland streams (Sections 9.2.1 and 9.2.1.1 of ANS-2.8).

PMP events augmented by snowpack or snowmelt would potentially occur in winter or early spring. Major storm surge events in the Delaware Bay would be associated with tropical or post-tropical systems, which could occur in the summer and fall months.

2 of 4

LR-N15-0101 Therefore, the effects of snowpack and snowmelt should not be combined with a storm surge event. PMP-based flooding in the upper Delaware River Basin alone does not have a significant effect on the water levels at the site (see Reference 4, Section 2.2).

In addition, existing SGS Technical Specifications specify the flood levels at which (1) watertight integrity will be established (at which time flood protection procedures will be initiated on a site-wide basis to protect the plant from flood waters) and (2) plant shutdown will be initiated. Closure of protective doors is required by Technical Specifications (References 5 and 6) at nominal site grade elevation of 10.5 feet Mean Sea Level USGS Datum (99.5 feet PSE&G Datum) and is performed by procedure when the river water level exceeds 97.5 feet PSE&G Datum (see Reference 4, Section 1.5).

RAI 3: Comparison of Reevaluated Flood Hazard with Current Design Basis The FHRR for Salem Generating Station Unit Nos. 1 and 2 provides a comparison of the reevaluated flood hazards with the current licensing basis (CLB). For the purposes of the FHRR, the parameter of interest is the current design basis (COB). Provide clarification for the inconsistencies identified in the FHRR with regard to the comparison of the reevaluated flood hazard to the current design basis and submit a revised hazard comparison consistent with the instructions provided in the 50.54(f) letter.

Response to RAI 3: Comparison of Reevaluated Flood Hazard with Current Design Basis The SGS FHRR (Reference 4) uses the terminology "current design basis" anct "current licensing basis" interchangeably. The FHRR is in all cases comparing the reevaluated flood hazards with the current design basis as documented in the Salem Generating Station UFSAR (Reference 7).

References:

1. NUREG/CR-7046, Design-Basis Flood Estimation for Site Characterization at Nuclear Power Plants in the United States of America, November 2011

2. NOAA Hydrometerological Report No. 52 (HMR-52), Application of Probable Maximum Precipitation Estimates- United States East of the 1osth Meridian, U.S.

Department of Commerce, National Oceanic and Atmospheric Administration, and U.S. Department of the Army Corps of Engineers

3. ANSI/ANS-2.8-1992, Determining Design Basis Flooding at Power Reactor Sites

4. LR-N14-0042, "PSEG Nuclear LLC's Response to Request for Information Regarding Flooding Aspects of Recommendation 2. 1 of the Near-Term Task Force Review of Insights from the Fukushima Dai-ichi Accident- Salem Generating Station Flood Hazard Reevaluation", dated March 11, 2014 3 of 4

LR-N15-0101

5. Salem Unit 1 Technical Specifications, Section 3/4.7.5, "Flood Protection"

6. Salem Unit 2 Technical Specifications, Section 3/4.7.5, "Flood Protection"

7. PSEG Nuclear LLC, "Salem Generating Station Updated Final Safety Analysis Report", Revision 27, 2013 4 of4