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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