Assessing
potential exposures topeople in the post-closure
period of a waste disposal
facility
II. From present to future
conditions

Gerhard Proehl

From present to future conditions
Assessment for present
conditions
Environmental change• Climate• Lifestyle• Technology• Agriculture/soil

Assessment for future
conditions

Can exposure beassessed for longtime frames?

• We don’t know!

What will
people do in
10000 years ?

• But:−They will breathe.
−They will drink.
−They will eat.
−They will stay outdoors orindoors.

How much will
peopleeat,drink,breathe,in 10000 years ?

• We don’t know!
• But:−They need similar amounts of• Energy• Protein• Fat• Minerals−They need similar amounts of drinking
water−They will breathe similar volumes of air

Developed during the evolutionof life over billions of years

Physiologicalandbiologicalprocess

Similar for all species

Biological processes are universal
Similar on allcontinents

Manifestation
Controlleddepends onby the sameenvironmental
mechanisms
factors• Radiation Protection criteria

Assumptions
related toradiation
protection
criteria− Derived for present day΄s populations
based on current knowledge onradiation risks.

• Future progress in medicine may− Modify the radio-sensitivity of people− Modify the biokinetics of radionuclides
in humans− Improve the success of treatment orradiation-related diseases= > Such changes are not anticipatedin the assessment• Subsistence farming− All food consumed is produced on the area with thehighest impact of radionuclides released from thedisposal facility− This is a very conservative assumption:
Any other assumptions regarding food supply will cause
lower exposures via intake of foodBasic
exposure
scenarios• Agricultural practise− Spectrum of crops and domestic to comply with thesite characteristics• Soil properties should allow the cultivation ofcrops• Use of fertilizer to ensure long-term fertility• Sustainability of land use− The scenario should allow a long-term land-use• Salinity of irrigation and drinking water• Availability of waterHow to addressenvironmental changes
when assessing
exposures for the far future ?

Impact on post-closure assessment
ClimateSoilPostclosure
exposure

TechnologyAgriculturalpractiseLifestyle• Food supply

What maychange –Life-style− The basic scenario assumes complete self-supply,
i.e 100% of the food consumed is produced
locally− This is a pessimistic assumption, the degree ofself-supply cannot be higher− Lower degrees of self-supply imply lower
exposures to people• Food intake− Demand for energy, fat and protein will remain
constant(physiological constraint)− Impact of different diets to be explored bysensitivity analyses

Sustainability

What maychange –Agricultural
practise/ soil

• The basic scenario assumes sustainability ofagriculture− Extreme conditions allowing agricultural use of land
only for a short period of time are not considered− Soil cultivation will try to achieve favourable
conditions for plant growth• pH-value: 5.0-7.5, depending on the crop
• Porosity for exchange of air and drainage of water

Consistency with site-specific conditions• The practices assumed should be consistent
with the site-conditions− No irrigation on sites with sufficient precipitation− E.g. Husbandry of sheep in arid climatesWhat maychange –Technology• Changes in technology are notexplicitly taken into consideration• Agricultural activities will ensuresustainability of land
− This is a universal requirement• Crops will be grown on soil, not innutrient solutions

Climate• Temperature− Seasonal and daily variation, days of frost, etc• Precipitation− Seasonal and daily variation

Climate change,a key elementof long-term
safetyassessment

Impact on plant growth• Length of the vegetation period• Crops grown• Yield of crops• Demand for irrigation• Animal husbandry

Impact on the earth’s surface• Hydrology and hydrogeology• Weathering of rocks• Development of soils• Wind and water erosion

How to address climate?

Options to reflect future developments
Present conditions

Option A: Analogue approach

Option B: Dynamic analysis

Use data forpresent day conditionsof neighboring sites* covering
a wide spectrum of climates

Modelling the evolution of thebiosphere in response to the main
environmental change drivers

Future conditions*Neighbouring sites: Selected from a radius of about 3000 km

Future conditions

Option A:Analogueapproach• Use of data for present dayconditions ata range of different sites
with different climate andother characteristics− Sites are considered as suitableanalogues for future development• It is assumed that− this set of analogous biospheresystems adequately captures therelevant range of future systems− => Envelope for future
developments

Option B:
Dynamic analysis
offuture biospheresystems• Modelling the evolution of thebiosphere in response to the main
environmental change drivers− Climate change− Geomorphological changes associated withsea-level change at coastal sites− Erosion in areas of geological uplift.

• Modelling of the interaction of− Climate− Hydrology− Landform− Radionuclide release from the geosphere− Radionuclide migration and accumulation− Land-use

S − Principally, there is an inherent uncertainty to predict futureconditions
U − However:
Biological processes are universal, following the sameM
dependencies now and in the future
M • Climate
is a key driver for environmental changes with
A − Climate
impact on• Agricultural practiseR• Soil development• Life styleY• Safety assessments need to consider future developments• Addressing future conditions− Option A: Using current data from a wide range ofenvironmental conditions to elaborate an envelope for future
conditions− Option B: Dynamic modelling of climate and landscape