development of the design basis earthquake for the uranium … · 2016-11-15 · development of the...

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Development of the Design Basis Earthquake for the Uranium Processing Facility

Albert Kottke, Chih-Cheng Chin, Farhang Ostadan, James Marrone, Lisa Anderson, Nan Deng, Nick Gregor, Thomas Ma

2016 DOE Natural Phenomena Hazards Meeting

This document has been reviewed by a Y-12 DC / UCNI-RO and has been determined to be UNCLASSIFIED and contains no UCNI. This review does not constitute clearance for Public Release. Name:________________________ Date:__________

09/07/16

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TIO#: 42243

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Introduction

Uranium Processing Facility• To be constructed at the Y-12 National Security Complex in Oak Ridge, TN

‒ Currently in design (all structures are SDC-1 or SDC-2)

• Will support enriched uranium operations that relate to nuclear security

Seismic Summit• Numerous industry experts assessed the current status of seismic analysis

and design

• Recommended a reassessment of the current seismic hazard

• Prompted the development of the updated Design Basis Earthquake (DBE)


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Development of the DBE

Sequence• Hard Rock (HR) Probabilistic Seismic Hazard Assessment (PSHA)

• Geological Assessment of Site-Specific Data

• Design Site Profiles

• Two-Dimensional Site Response Analysis

• Site Profile Simulation

• One-Dimensional Site Response Analysis

• Code-Based Design Response Spectrum

• Horizontal and Vertical Site-Specific Spectra


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Hard Rock Probabilistic Seismic Hazard Assessment

• Clinch River Nuclear Power Plant horizontal HR PSHA results‒ HR seismic hazard curves for 7 response

spectral frequencies‒ PSHA deaggregation information on

controlling earthquakes

• Additional Deaggregation information from USGS National Seismic Hazard Maps‒ Used to interpolate and extrapolate beyond

the 7 point Uniform Hazard Response Spectra (UHRS)

• HR UHRS are developed for 8 Mean Annual Frequency of Exceedance levels

• Results in 38-point High Frequency and Low Frequency UHRS for each MAFE


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Site-Specific Geological Assessment

• Deep site profile developed that extends to HR horizon (sustained Vs > 9200 fps) ‒ 11,500 ft below grade

• Based on provisional maps, seismic reflection profiles, core hole data, seismic field data, and published active fault information

• Location of stratigraphic units are defined‒ Mostly shale with some limestone

and sandstone

• Geologic section is defined in terms of thickness, dip angle and strike‒ Average of 54-degrees

• Qualitative assessment of rock properties


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Design Site Profiles

• Compilation of subsurface properties gathered from various references‒ Shear Wave Velocity‒ Poisson’s Ratio‒ Unit Weight‒ Linear Damping‒ Strain-Dependent Shear Modulus‒ Strain-Dependent Damping

• Best Estimate (BE) values summarized

• Applicable range of data‒ Aleatory and epistemic uncertainty

• Damping of deep unweathered rock‒ Based on assessment of kappa‒ Recommended as 0.5%


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Two-Dimensional Site Response Analysis

• 1D site response is augmented with 2D site response to capture effect of dipping rock formations‒ 2D SASSI2010 model with plane-strain elements representing the soil/rock properties‒ 21,125’ x 11,825’ with 25’ element widths‒ BE, Upper Bound, and Lower Bound soil/rock properties considered‒ Compared with multiple 1D analyses of sections throughout the model

• Results indicate higher 2D response in the 1 Hz to 5 Hz range ~84%‒ All other ranges show lower 2D response

• Only the effect of increased 2D response is considered in the soil profiles simulation


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Site Profile Simulation

• Based on BE site properties and assigned variability, 12 base profiles are assigned‒ 4 upper zone, 3 lower zone

• 60 simulated site profiles, resulting in 720 profile realizations


Nonlinear Curves

Vs

Upper Zone Thickness

Lower Zone Thickness

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One-Dimensional Site Response Analysis

• 720 site profiles; 9 MAFE levels; HF and LF UHRS

• Total of 12,960 site response analyses using P-SHAKE

• 2D ratio (where > 1) is applied to the results

• App2BEC used for Approach 3 calculation of site-specific hazard curves‒ Input spectra, geometric mean site amplification function, logarithmic standard deviation


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Code-Based Design Response Spectrum

• DOE 1020-2010 for SDC-1/2 requires use of ASCE 7-10‒ Site Class B; TL = 12 sec; S1 = 0.121 g; SS = 0.373 g


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Site-Specific Design Response Spectra


• Process 38 site-specific hazard curves to develop 38-point horizontal ASCE 7 maximum considered earthquake and corresponding DBE

• Vertical DBE generated using V/H ratios (Approach A) and NEHRP FEMA P-1050-1 (Approach B)

HR Input is also considered

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Selection of the DBE

• Approach A selected for low frequency content (strictly code-based)‒ Provides additional margin over the minimum 80% code requirement in low frequency where

amplifications are observed in the site response analysis

• HR input selected for high frequency content‒ Code-based alone may not be adequate for equipment qualification and testing


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Summary

• Dipping rock formations at UPF induce amplifications in the low frequency range

• Site response analyses indicate a large de-amplification from the HR input motion in the high frequency range (> 10 Hz)‒ Not typical for Central and Eastern United States‒ Attributable to accumulation of damping throughout ~12,000 ft column despite very low assigned

damping of 0.5%‒ This is consistently observed in the 1D analysis in almost every hazard level and range of inputs

• Project is obligated to follow commercial building code only (ASCE 7)‒ In-Structure Response Spectra will be required for equipment qualification and seismic shake table

testing‒ For this reason, conservatism is warranted in the high frequency range

• UPF updated DBE consists of the full code-based response spectrum in addition to the HR input motion


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Questions?

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