IAEAInternational Atomic Energy Agency

Presenter NameSchool of Drafting Regulations for Borehole Disposal of DSRS

2016Vienna, Austria

Environmental andEnvironmental and

Non-radiological ConcernsNon-radiological Concerns

for Borehole Disposal Sitefor Borehole Disposal Site

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Outline of the PresentationOutline of the Presentation

• Overview of Site Selection Regulatory Framework• Definitions• Characteristics of the Preferred Site

• General;• Geology;• Landform evolution/climate change;• Geochemistry;• Hydrology and hydrogeology;• Biosphere, land use and human activity• Non-radiological concerns

• Summary and conclusions.2

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Presentation ResourcesPresentation Resources

• Borehole Disposal Facilities for Radioactive Waste – Specific Safety Guide; IAEA Safety Standards Series No. SSG-1, IAEA Vienna (2009).

• BOSS: Borehole Disposal of Disused Sealed Sources – A Technical Manual, IAEA-TECDOC-1644, Vienna (2011).

 

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Regulatory FrameworkRegulatory Framework

• Basis in national statues• May be based upon IAEA documents

• Protection of the public and the environment

• Examples of typical regulations governing licensing:• Public dose• Worker dose• Training• Isotope limits• Receipt & shipping of radioactive packages

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Regulatory Framework Regulatory Framework for RW sites for RW sites

• Most likely will have more regulatory “interest”• Definitely will have public interest – NIMBY • Protection of the public and the environment• Examples of typical regulations governing RW

site licensing:• Public dose from conditioning• Worker doses near regulatory limits (≈ 20 mSv if not more)• Training specific to processing equipment• Receipt & shipping of waste packages• Contamination limits• Financial assurance• Emergency Planning• Decommissioning Plan

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Regulatory Framework for RW sites Regulatory Framework for RW sites

• What other regulatory bodies are needed?• Is the public health agency separate from the

environmental protection agency.

• Are there other legal and regulatory requirements dictated by national laws?• Surety?• Is there a need for an Emergency Plan and procedures?

• Public involvementFor example, when the license is ready to issue, it is first

sent to the local government for their review and potential public meeting.

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DefinitionsDefinitions

Disposal borehole: a borehole this is specially located, drilled and constructed for the disposal of disused SRS and other small volume wastes.

Geochemistry –the study of the chemical composition of the earth and its rocks and minerals.

Geology – the study of the earth's physical structure and substance.

Geomorphology – the study of the physical features of the surface of the earth and their relation to its geological structures.

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DefinitionsDefinitions

Hydrogeology –Branch of geology concerned with water occurring underground or on the surface of the earth.

Hydrology – Branch of science concerned with the properties of the earth's water, especially its movement in relation to land.

SRS: sealed radioactive source

Timescale of interest: Post-closure modeling timeframe needed for the decay of the radionuclides to levels below public health concerns (e.g., nominally 1,000,000 years is used)

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Environmental CharacteristicsEnvironmental CharacteristicsGeneral

•The overall aim of site characterization is to gain a general understanding of the site in terms of its regional setting, its past evolution and likely future natural evolution over the assessment time frame. •Understanding water at the site is important to ensure post-closure safety of the disposal site.•Need at least one investigatory borehole for:

• Understand site chemistry,• Depth of groundwater and for modeling groundwater,• Gather data relevant to the feasibility of constructing the site.

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Environmental CharacteristicsEnvironmental CharacteristicsGeology

Information from at least one exploratory borehole•Rock samples for examination

• At least every meter• Log entire depth – soil/rock types, color changes

•Penetration rate – indication of rock hardness,•Water strike depth and flow,

• At each encounter with water while drilling

•Blow yield – indication of borehole (water) yield.

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Environmental CharacteristicsEnvironmental CharacteristicsGeology – other important drillings items

• Loss of compressor air (indication of joints or fissures); • Minor or sudden changes in penetration rate (indicates

changes in lithology or structure);• Sharp color changes (lithological changes, or indications of

weathering); • Sharp increase in size of drill chips (indication of fractures);• Fracturing or creep of the host rock – useful guide in

planning the construction of the disposal borehole;• Standard geophysical investigations for recent faults

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Environmental CharacteristicsEnvironmental Characteristics

Landform Evolution/Climate Change

A geomorphological study of the site and its surrounding area should be conducted to examine evidence for erosive processes and past land movements (landslip, faults and earthquakes). The effect of past climate states on landform development may be helpful in assessing the likely impact of any future states.

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Environmental CharacteristicsEnvironmental CharacteristicsGeochemistry

The geochemistry is an important part of the site characterization programme for a number of reasons:•Groundwater/porewater chemistry (redox) can affect the longevity of the stainless steel and concrete near field; •It can provide insights into the origins of sub-surface groundwater; •It can affect the portability of sub-surface waters (which may affect the biosphere model); •It can affect the migration of radionuclides through the geosphere.

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Environmental CharacteristicsEnvironmental CharacteristicsHydrology and Hydrogeology

•The groundwater exposure pathway is very important and can be dominant.•Additional information needed includes:

• Meteorological measurements, especially precipitation; • Estimates of evapotranspiration; • Indications of any previous flooding of the site.

•Disposal zone can be in saturated or unsaturated zone, but should not be at the interface of the zones.•When site is in the saturated zone, need to identify flow characteristics such as direction and amount.

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Environmental CharacteristicsEnvironmental CharacteristicsBiosphere, Land Use, & Human Activities

•Biosphere characterization, including where groundwater from near the facility could discharge in the post-closure period.•Land use needs to be documented, including farming.•Sources of drinking water near the facility.•Nature of current day activities may provide indication of post-closure activities.

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Non-radiological ConcernsNon-radiological Concerns

• Concerns are divided into technical and non-technical factors

• Both sets of factors can be further divided into “suitable” for a borehole disposal site and “unsuitable” for a site

• Many technical factors are related to previous environmental concerns, but there are others.

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Non-radiological ConcernsNon-radiological Concerns

Technical Factors

•Suitable factors include: geological stability, geomorphological stability, arid areas, and absence of natural resources.

•Not suitable factors include: volcanic or tectonic activity, high erosion/steep topography, flood plains, surface salt deposit, minerals, gas, geothermal or water resources (where water is in high demand)

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Non-radiological ConcernsNon-radiological Concerns

Non-technical Factors•Suitable factors include: government owned land, land far from habitation, easy to travel access roads, and sufficient information available.

•Not suitable factors include: land is a national park or nature reserve, land close to disputed boundaries, areas of high population density, or comprehensive lack of information.

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Non-radiological Site SamplingNon-radiological Site Sampling

Other than radionuclide sampling, disposal sites commonly sampled for:•Soil pH,•Depth to groundwater,•Volatile organic compounds (VOC’s) in the vadose zone and in the groundwater,•Metals in the groundwater, and•Contaminants from nearby operations – both government and commercial sources.

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Summary & ConclusionsSummary & Conclusions• Many environmental factors affect the safety and viability

of a potential borehole disposal site.• Of the environmental and non-radiological factors

reviewed, water movement through the vadose zone is the most important for contaminant transport.

• An exploratory well is critical to establishing baseline values for many environmental factors.

• Modelling of the facility environment will need a timescale of nearly 1,000,000 years to accommodate all SRS nuclides and the decay half-lives.

• A critical non-technical factor is nearby population density

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IAEA 21Thank you!