IAEA Technical Meeting on Future Human Actions at Disposal Sites IAEA, Vienna, Austria September...
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Transcript of IAEA Technical Meeting on Future Human Actions at Disposal Sites IAEA, Vienna, Austria September...
IAEA Technical Meeting on Future Human Actions at Disposal Sites
IAEA, Vienna, Austria
September 24-28, 2012
Overview of NRC Approach to Human Intrusion
at LLW Shallow Land Disposal Facilities
Boby Abu-Eid, Ph.D.
Division of Waste Management and Environmental Protection
Office of Federal and State Materials and Environmental Management ProgramsU.S. Nuclear Regulatory Commission
10 CFR Part 61 LLW Disposal Concept
Near-surface (<30 m depth) land disposal with specific technical requirements, performance objectives, and procedural requirements
Cornerstone of safe disposal is stability:• Stable wastes, design• Reliance on natural system isolation • Reduced exposure to intruders• Stability of waste form & packaging
Graded stability requirements using waste classes A, B, and C
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10 CFR Part 61.7 LLW Disposal Conceptfor Intruder Protection
(3) ……Protection of such intruders can involve two principal controls: (a) institutional control over the site after operations by the site owner to ensure that no such occupation or improper use of the site occurs; (b) or, designating which waste could present an unacceptable risk to an intruder, and disposing of this waste in a manner that provides some form of intruder barrier that is intended to prevent contact with the waste. This regulation incorporates both types of protective controls.
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LLW Timeframe and Performance Period
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NUREG-1573
Waste Classification Table 1 Long-Lived Radionuclide (§61.55)
Radionuclide Concentration Ci/M3
C-14 8
C-14 in activated metal 80
Ni-59 in activated metal 220
NB-94 in activated metal 0.2
Tc-99 3
I-129 0.08
Alpha-emitting transuranic nuclides (t1/2 > 5yr), nCi/g 100
Pu-241, nCi/g 3,500
Cm-242, nCi/g
(If Concentration <0.1 of column value, Class A; if >0.1 and <1.0 of column value, Class C.
20,000
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A LLW Disposal Design Concept
7NUREG-1573
Intruder Scenarios for Part 61 LLW & for Incidental Waste
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Cap
Waste
Inhalation of dust
Direct radiation from dust cloud
Direct radiation from waste volume
Intruder Construction
10 CFR Part 61 LLW Disposal Concept
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Cap
Waste
Inhalation of dust
Direct radiation from dust cloud
Direct radiation from waste volume
Deposition of dust
Soil to root transfer
Plant-to-animal-to-human
Plant-to-animal product-to-human
NOTE: Includes modified food pathways to account for non-equilibrium deposition and subsequent root uptake: (i) plant-human; (ii) plant-animal-human; and (iii) plant-animal product-human
Intruder Agriculture
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Schematic Illustration of Examples of Exposure Scenarios for DU Disposal
PA Approach: Representation of LLW System, Conceptual & Mathematical Models, and Estimated Performance
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An Approach to Uncertainty Analysis
Intruder & Human Activity Issues
• How to treat future site conditions, processes, events, & climate change• Intruder exposure scenarios assumptions, probability, and safety case (SC)
stylized specific scenarios and realistic exposure pathways• Timeframe for LLW performance assessment, Intruder dose criteria,
compliance period & SR-SSR-5 Para 2.15 dose band optimization • Performance of covers, engineered barriers & as a safty function to protect
intruder • Treatment of sensitivity and uncertainty and integration of uncertainties for
intruder analysis & human activities• Role of monitoring & safety functions during operational and post- closure
periods;• Passive & active institutional controls issues• Source term assumptions, waste stability, and waste classification • Overall integration of safety functions based on site characterization, facility
design, scenario assumptions, and safety analysis during facility life cycle and update of the safety case
• Bench-marking and QA/QC issues• Stakeholders Inputs
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