ML13275A225

9/24/13 Meeting Slides from Meeting with Duke Energy Carolinas, LLC, Oconee Nuclear Station Units 1, 2, and 3, Jocassee Dam Seismic Analysis

ML13275A225
Person / Time
Site:	Oconee
Issue date:	09/24/2013
From:	Hubbard D Duke Energy Carolinas
To:	Office of Nuclear Reactor Regulation
Guzman R
References
Download: ML13275A225 (13)

Text

Oconee Nuclear Station Jocassee Seismic Analysis, September 24, 2013 Fukushima - External Flooding For Information Only

Duke Participants Ray McCoy, Principal Engineer - Civil, Oconee Nuclear Station Lee Kanipe, Senior PRA Analyst Ed Luttrell, PE, Hydro Director, HDR Inc Greg Hardy, Senior Principal, Simpson Gumpertz & Heger Dean Hubbard, Licensing Manager, Oconee Nuclear Station For Information Only 2

Agenda Overview Opening Remarks - Dean Hubbard Jocassee Seismic Analysis - Ray McCoy Jocassee Fragility Analysis - Lee Kanipe NRC Questions -

For Information Only 3

Regional Geology for Jocassee Regional Geology for Jocassee The Jocassee Development is located on the western edge of the Piedmont Physiographic Province (a spatial entity with common geologic attributes)

The site is located within the Inner Piedmont Block (crust), bounded on the west by the Brevard Fault Zone and the east by the Lowndesville and the Kings Mountain Shear Zones.

Specific to the site, and within this Block is the Henderson Gneiss, a plutonic rock of medium gray, augen gneiss.

This tectonic province highest historical seismicity is noted to be Intensity VII MM.

(Modified Mercalli VII. Damage negligible in buildings of good design and construction; slight to moderate in well-built ordinary structures; considerable damage in poorly built or badly designed structures; some chimneys broken. )

For Information Only 4

Local Foundation Conditions Local Foundation Conditions The foundation for the core of Jocassee Dam was excavated to "sound" rock.

This rock foundation was treated with dental concrete and consolidation grouting.

(providing potential seepage cutoffs for the dam).

The foundations for the shells were excavated to firm soil or partially weathered rock. Upper Abutment areas were founded on residual soil over weathered rock.

For Information Only 5

Local Foundation Conditions For Information Only 6

Jocassee Seismic Analysis Discussion will be focused on the Jocassee Dam.

Saddle Dikes Saddle Dikes are independent of the main dam.

Saddle Dikes are low in height and impound a very shallow depth of water.

The loss of any one or all saddle dikes would not cause flooding for the nuclear site.

Spillway/Intake Both the spillway and the intake (penstock) are independent of the main dam.

Both the spillway and the intake are cut into rock. The loss of any one of these could be managed by the spillway capacities at Keowee and no nuclear site flooding would occur.

For Information Only 7

Jocassee Seismic Analysis Jocassee Seismic Assessment History related to Oconee and FERC May 25, 1967 - Safety Analysis Report, Supplement No. 4, Question 12.3 states Duke will design the Jocassee Dam for the Maximum Hypothetical Earthquake. (.10g)

June 17, 1970 - provided NRC with results of seismic analysis demonstrating adequate factors of safety for seismic assessments using an acceleration of .10g.

January 21, 1977 - Duke provided Law Engineering seismic re-analysis demonstrating adequate factors of safety for seismic assessments using an acceleration of .12g.

October 5, 1990 - Jocassee seismic stability analysis for FERC demonstrates factors of safety in excess of required values for an acceleration of .12g.

Jocassee Dam Five-Year Safety Inspection Reports for FERC re-demonstrate factors of safety in excess of required values for an acceleration of .12g.

For Information Only 8

Jocassee Seismic Analysis Current Jocassee Dam Analysis Seismic Load Cases Earthquake: Horizontal acceleration of 0.12g with full pond condition. (check both upstream and downstream slopes.)

Earthquake with Rapid Drawdown: Horizontal acceleration of 0.12g with 33ft rapid drawdown from elevation 1110 ft msl (full pond) on the upstream slope.

Methodology 1990 Assessment. Used computer code SB-SLOPE for Earthquake evaluation. Slope stability Factors of Safety computed using Bishops Simplified Method of Slices.

Earthquake and Rapid Drawdown analyzed using computer code UTEXAS3 (a three-stage analysis procedure). Slope stability Factors of Safety computed using Spencers Method.

1993 supplemental seismic stability analysis work used computer code UTEXAS3 and Spencers Method. Both 1993 and 1990 assessments utilized the same model geometry for the dam.

For Information Only 9

Jocassee Seismic Analysis Current Jocassee Dam Analysis Results FERC seismic requirements met and exceeded.

UFSAR commitment met and exceeded.

Seismic Margin (reserve) demonstrated.

For Information Only 10

Jocassee Seismic Analysis Probabilistic Analysis Jocassee Seismic Fragility Analysis was updated for the Oconee PRA in 2007 (ARES Report)

Updated to apply improved analytical and computational capabilities Free-field ground motion based on 1989 EPRI hard rock hazard for ONS Results:

Median fragility value is 1.64 g characterized by the fragility of the downstream embankment slope.

Equivalent High Confidence of a Low Probability of Failure (HCLPF) = 0.305 g.

For Information Only 11

Jocassee Seismic Analysis Questions For Information Only 12

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