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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 Eventsand Anticipated Climate Change Impacts on Cover
Performance• Increased confidence is needed in the predictive nature of long-
term 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
Precipitation (P)
L
“Sponge”(S)
Infiltration (I)
Percolation if I > S
Evapotranspiration
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
Alternative to Conventional Cover = Evapotranspiration (ET) Covers
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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 DOEA systems approach is needed.
Current evaluations and potential decision-making lack a systems approach (e.g., liners vs. no liners)
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 site-specific 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)
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
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Class A trench in 2008 – Barnwell LLW site
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. RustickJames H. Clarke
Vanderbilt University/CRESPCraig H. Benson
University of Wisconsin – Madison/CRESPFebruary 1st, 2012
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Other CRESP Projects• 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)