WTP Final Seismic Design Criteria

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• WTP Final Seismic Design Criteria
• John Eschenberg
• Project Manager, WTP
• Office of River Protection,
• and Deep Boreholes Project Staff

Presented to the Defense Nuclear Facilities
Safety Board July 24, 2007
U.S. Department of Energy
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Presentation Outline Introductions

• Purpose and Background Lew Miller, DOE-ORP
• Deep Boreholes Project Tom Brouns, PNNL
• Velocity Models Alan Rohay, PNNL
• 
  Ken Stokoe, University
  of Texas at Austin
• Revised Seismic Analyses Bob Youngs, Geomatrix
• Derivation of WSGM Bob Youngs, Geomatrix
• 
  Carl Costantino, CJCA
• Future Plans John Eschenberg, DOE-ORP

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Purpose and Background

• Purpose
• Update the DNFSB on the final WTP seismic design
  criteria
• Background
• Project seismic design basis ground motion and
  spectra issued in May 1999
• Criteria revised in February 2005 to accommodate
  uncertainty in interbed velocity contrasts
• Deep Boreholes Project initiated in 2005 to
• Obtain direct seismic velocity data and reduce
  this uncertainty
• Revise the WTP seismic analyses and produce a
  final WTP site-specific ground motion design
  response spectra (WSGM)

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Background (cont.)

• The horizontal ground motion design response
  spectrum for WTP developed in 2005 is shown in
  the graph to the right (RGM-2005)
• The spectrum represents a conservative envelope
  of the range of the mean results

• No direct measured data existed for seismic shear
  wave velocities of the sediments interbedded with
  the basalt underneath the WTP a source of
  uncertainty contributing to the increased seismic
  acceleration envelope (shown in green above)
• Ground motion at WTP is strongly influenced by
  interbed shear wave velocity contrast. If
  interbeds are more rocklike, ground motion is
  increased.
• Limited data on suprabasalt sediments

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Deep Boreholes Project Fieldwork

• Drill three deep boreholes and one corehole
  adjacent to the WTP HLW and Pretreatment
  facilities
• Collect subsurface velocity and geophysical data
  in-situ and on extracted core samples
• Schedule and Cost
• 14 months
• 18M

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Deep Boreholes Project Participants
Project Team
Drilling Partners
Geophysics Partners
Pacific Northwest National LaboratoryProject
Management and Technical Lead Energy
SolutionsField Oversight and Site
Operations Fluor HanfordWell Site Geology,
Radiological Controls, and Waste Management US
Army Corps of EngineersDrilling/Data Collection
Oversight, Sediment Physical and Dynamic
Properties Testing
BlueStar Enterprises NorthWest, Inc. Layne
Christensen Company WDC Exploration and Wells
GEOVision Redpath Geophysics University of Texas
at Austin Micro-g LaCoste COLOG
Site Response Analysis Partners
Geomatrix Consultants, Inc. Logic Tree Expert
Panel (various)
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Boreholes Design and Installation

• Four steel-cased entry holes (9-5/8 in) to top of
  basalt
• One wireline corehole (3-1/2 in) to 1400 ft
• Three deep mud rotary boreholes
• (7-7/8 in) to 1400 ft through four interbeds

bgs below ground surface
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Geologic Characterization

• Interbeds
• Basalt Breccia
• Vesicular Basalt
• Basalt interiors

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Boreholes Data Collection
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Drilling and Data Collection

• Initiated drilling 6/12/06
• All three boreholes and corehole drilled to depth
  10/12/06
• Suspension (p-s) logging completed 10/17/06
• Geophysical logging completed 10/28/06
• Gravity-density logging completed 12/11/06
• Deep downhole seismic logging completed 12/20/06
• Shallow sediment logging completed 2/09/07 after
  casing Hanford and Ringold formations

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Downhole Logging
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Velocity Data

• Velocity data collected using an impulsive
  seismic source in suprabasalt sediments and upper
  two basalt and interbed units
• Data from three boreholes comparable

Shear wave velocity measurements in borehole
C4993 using an impulsive seismic source
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Downhole Signals
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Velocity Data

• Velocity data collected using a vibratory seismic
  source in the basalt and interbed units
• Data from three boreholes comparable

Shear wave velocity measurements in borehole
C4993 using a vibratory seismic source
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Velocity Models

• Suprabasalt sediments
• Integrated and averaged new borehole Vs data with
  prior seismic cone penetrometer and downhole data
• Used geologists logs to define range of geologic
  unit thicknesses
• Basalts and interbeds
• Integrated and averaged Texas (vibratory) and
  Redpath (impulsive) new borehole Vs data
• Used density and suspension logging Vs data to
  develop model to represent the change in velocity
  within each basalt flow top
• Used geologists logs and geophysical data to
  define range of geologic unit thicknesses

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Velocity Models - Sediments

• 2007 models are comparable to 2005 except
• Sharp Vs contrast from Hanford sand to gravel
  (H2/H3)
• Sharp Vs contrast from Cold Creek Unit to lower
  Ringold Unit A
• High Vs in Ringold Unit A comparable to Vs in
  basalt flow top

Comparison of 2007 Vs Models to 2005 Vs Models
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Velocity Models Basalts/Interbeds

• 2007 models reflect greater Vs contrasts between
  basalts and interbeds
• Vs basalts near 2005 high-range estimate
• Vs interbeds near 2005 low-range estimate
• Basalt flow top gradients
• individually measured
• thinner and stronger
• Includes internal flow structures
• Individual unit and composite Vs alternative
  models used in final analyses

Comparison of 2007 Vs Models to 2005 Vs Models
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Density Models

• Density measured using downhole gamma-gamma, and
  borehole gravity
• No density measurements in Hanford sand/gravel
  and Ringold Unit due to steel casing
• Good agreement between gamma-gamma and borehole
  gravity

Comparison of gamma-gamma and borehole gravity
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Logic Tree - 2005
Sediment Vs and generic dynamic properties
Vp and Vs of basalts and interbeds

• Lack of Vs data for basalts and interbeds led to
  smaller velocity contrasts and higher probability
  of increased ground motion

Weights in ( )
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Logic Tree - 2007
Vs of basalts and interbeds
Vs of sediments
Generic and site-specific dynamic sediment
properties

• Uncertainty in Vs significantly reduced with site
  data
• New sediment data reflects greater damping
  added site-specific soil curves

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Inputs to Site Response Analyses and Relative
Uncertainties and Impact
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2005 Site Response

• Wide range of Vs alternatives for basalts and
  interbeds had greatest impact on site response

Distribution of relative amplification functions
for the WTP site developed by Rohay and Reidel
(2005)
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2007 Site Response

• Lower uncertainty and greater Vs contrasts result
  in lower relative amplification

Distribution of relative amplification functions
for the WTP site developed by Youngs (2007)
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Summary of Key 2005-2007 Model Differences

• Basalt and interbed Vs
• Significantly smaller uncertainty of median Vs
• Significantly greater contrast between basalts
  and interbeds
• Sediment dynamic properties
• More non-linear and greater damping based on
  site-specific data
• Wider range of alternatives

Lower uncertainty
Reduced ground motion
Reduced ground motion
Higher uncertainty
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Derivation of RGM - 2005

• RGM-2005 design response spectra (DRS) developed
  using 84th percentile relative amplification
  function (RAF)
• Increased peak horizontal ground motion by up to
  40 over original design criteria

Development of 2005 interim WTP horizontal design
response spectrum (RGM-2005) compared to the
original horizontal design response spectrum
(1996 DRS)
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Derivation of WSGM - 2007

• WSGM-2007 design response spectra developed using
  new 84th percentile relative amplification
  function
• Decreased peak horizontal ground motion by 25
  from 2005

Development of WSGM-2007 horizontal design
response spectrum. Also shown are the original
design response spectrum (1996 DRS), the original
design response spectrum multiplied by the 2005
84th-percentile RAF, and the RGM-2005
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Future Plans

• Secretarial Certification of Final Criteria
• Restart Construction of PT and HLW
• PT and HLW Structural Summary Reports to be
  issued December 2007
• One year backlog between design and construction
• Use of final seismic criteria (WSGM-2007) limited

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Aerial View of WTP Site
WTP Site, May 2007
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Reports of the Deep Boreholes Project