Transcript Near Surface Disposal Facilities

Near Surface Disposal Facilities
• Evaluation of the Dominant Ecological Processes Impacting the
Performance of NSDFs (Clarke, Burger, Kosson and Ph.D.
graduate Brooke Traynham)
• Incorporation of Episodic Events and Anticipated Climate Change
Impacts on Cover Performance(Clarke, Abkowitz, Benson and
Ph.D. Candidate Roneisha Worthy).
• A Systems Approach to Performance Assessment for NSDFs
(Clarke, Kosson, Benson and Ph.D. Candidate Joe Rustick).
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Evaluation of the Dominant Ecological Processes Impacting
the Performance of NSDFs
• Importance to the DOE
 Current PAs are deficient from the standpoint of
incorporation of ecological processes that are critical to
long-term performance, especially for evapotranspiration
(ET) or water balance designs that rely on ET for
performance.
• Work products
 Ph.D. Thesis (Dr. Brooke Traynham)
 One book chapter (Traynham, Burger, Clarke)
 Two peer reviewed publications in review (Traynham,
Burger, Waugh, Clarke)
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Incorporation of Episodic Events
and Anticipated Climate Change Impacts on Cover
Performance
• Increased confidence is needed in the predictive nature of longterm cover performance models.
• These covers must be able to perform over long periods of time and
accommodate potential impacts due to climate change and
episodic events
• The above considerations are especially important to the evaluation
of evapotranspiration or water balance covers.
• Model selection featured analysis of three models ending HELP was
selected based on a great deal of experience with it within the DOE
and contractor community.
• A probabilistic approach will enable consideration of uncertainties
associated with long term estimates.
• Performance metric: percolation into the waste is less than 3mm/yr
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Evapotranspiration
Alternative to Conventional Cover =
Evapotranspiration (ET) Covers
Precipitation (P)
“Sponge”
(S)
L
Infiltration (I)
Factors Affecting Storage & Percolation
Water retention characteristics of soils
(loam vs. sand)
Meteorological conditions
- amount of precipitation
- distribution of precipitation
- form of precipitation
Type of vegetation
Layering of soils
Percolation if I > S
Work Products and Deliverables
• Conference presentations and peer-reviewed
publications
 WM 10 and 11
 ANS 2011 Winter Meeting
• Manuscripts in preparation:
Cover Performance Under Precipitation and Temperature
Extremes at the Monticello UMT Disposal Facility
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A Systems Approach to
Performance Assessment for NSDFs
• Importance to the DOE
 A systems approach is needed.
Current evaluations and potential
decision-making lack a systems
approach (e.g., liners vs. no liners)
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Our Challenge:
• To develop a standardized risk-informed and performance
based decision-making tool that can be used to:
– Improve consistency in performance assessment (PA)
methodology
– Evaluate proposed low level radioactive waste (LLW) near
surface disposal facilities (NSDFs) using a systems design
approach
– Take into account potentially important waste-specific and sitespecific differences
– Provide information over various timeframes (e.g., less than
100 yrs., 300-500 yrs., greater than 500 yrs.) to identify
influence of time-dependent processes
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Performance Assessment
Components
• Site Conceptual Models:
– Link sources of
contamination to
potential receptors
through environmental
transport pathways and
exposure routes
• Performance Evaluation
Scenarios:
– Examine how the disposal
facility could evolve over
the life-cycle of the facility
• Event Tree Analysis:
– Can be used to select
performance evaluation
scenarios
(Figure from the Ph.D. dissertation of Kevin Brown)
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Examples of Sub-Components For a Broad Systems Approach
• Design specific considerations:
– Type of engineered barriers to
be used
• Waste-specific considerations:
– Waste form
– Waste package
• Site-specific considerations:
– Climate
– Geology
– Ecology
Class A trench in 2008 –
Barnwell LLW site
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Performance Metrics for the Decision-Making Tool
The desired decision-making tool will have the ability to:
– Assess the influence of each disposal facility component on modes
of disposal facility change, both individually and in connection with
other components.
– Provide guidance on NSDF life-cycle risks for specific combinations
of site attributes and waste characteristics.
– Support decisions about performance monitoring locations and
parameters to monitor.
– Provide a standardized methodology for selecting appropriate
disposal facility components applicable for any site across the DOE
complex, in a manner that is transparent, defensible, and
quantitative.
• Example: Site-specific, and waste-specific guidance to site
engineering staff on whether or not a liner system is needed
for a future disposal facility and what type of liner would be
needed (if any)
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Work Products and Deliverables
• Presentations and Peer-Reviewed Papers to MW 10
and WM11
• Presentation to the WA Ecology Barriers Workshop
(February 2012)
• Presentation Proposal in to ANS 2012 Semi-Annual
Meeting in Chicago (June 2012).
• Manuscripts in Preparation:
– Conceptual Model Framework for Performance Evaluation
– Use of Site- and Waste-Specific Event Trees in Post Closure
Performance Assessment
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A Systems Approach to Determining Design Requirements for
Near Surface Disposal
Joseph H. Rustick
James H. Clarke
Vanderbilt University/CRESP
Craig H. Benson
University of Wisconsin – Madison/CRESP
February 1st, 2012
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Other CRESP Projects
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Development of a Risk-Informed Project Prioritization
Tool for the Oak Ridge Reservation (Powers, Kosson, Burger,
Brown, Krahn, Mayer, Gochfeld, Clarke)
Review of RI/FS Documents for the Hanford River Corridor
(Powers, Clarke)
Development of a Risk-Informed Approach to D&D Priority
Setting (Powers, Kosson, Mayer, Clarke)
Manuscript(s) in preparation that will integrate conceptual
models, event tree analyses and performance assessments
(Brown, Kosson, Powers, Clarke and Traynham, Rustick)
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