1. Handling of Future Human Actions in the safety assessment SR-Site
Eva Andersson

2. Outline The Swedish system and SR-Site
Methodology for handling FHA at SKB
Calculation cases for FHA covered in SR-Site
Results of FHA assessment in SR-Site

3. The Swedish system

4. Spent fuel repository according to KBS-3 at Forsmark
SR-Site: safety assessment for a deep repository for spent nuclear fuel. SKB’s licence application march
Spent fuel repository according to KBS-3 at Forsmark
Backfill
Rock
Djup 400–700 meter, Undermarksanläggning 2–4 km2 Cirka kapslar
Buffer
Canister

5. Strategy and results of Future human actions reported in TR-10-53
General considerations of FHA
Methodology applied
Representative cases
The report can be downloaded from

6. Development of the methodology used at SKB
SKB has worked with FHA since late 1990ies.
The methodology is based to on the conclusion of the NEA working group assessment of future human actions at radioactive waste disposal sites (NEA 1995) and three SKB workshop in1997 and 1998
Provide a comprehensive picture – involved people from different field of knowledge
Methodology used in a number of safety assessments at SKB: SR97, SAFE, SR-Can and now in SR-Site. Inputs from the authorities on each safety assessment has been used to update the methodology and calculation cases

7. General considerations
Potential for exposure inescapable consequence of deposition in a final repository
Main focus of FHA assessment is a time period when institutional control has ceased to be effective (300 y or more after repository closure)
Restricted to global pollution and actions that:
take place at or close to the repository site,
impair the safety functions of the repository’s barriers.
are carried out after the sealing of the repository,
are unintentional, i.e. are carried out when the location of the repository is unknown, its purpose forgotten or the consequences of the action are unknown, Future generations are responsible for their own actions if they are aware of the consequences
In line with guidelines from Swedish authorities Future human actions are evaluated separately and not included in base scenarios and risk summations in the safety assessment.

8. The following systematic approach has been used:
Technical analysis: Identify human actions that may impact the safety functions of the repository and describe and, in technical terms, justify that such actions may occur.
Analysis of societal factors: Identify framework scenarios (framework conditions) that describe feasible societal contexts for future human actions that can affect the radiological safety of a deep repository.
Choice of representative cases: The results of the technical and societal analyses are put together and one or several illustrative cases of future human activities are chosen.
Scenario description and consequence analysis of the chosen cases.

9. Technical analysis: Actions divided into the categories
Thermal (heat stores, extract energy etc)
Hydrological (well construction, dams, drainage systems etc)
Mechanical (drilling, build rock caverns, shafts, mining etc)
Chemical (dispose hazardous waste, acidification, chemical accidents)
Conclusions from the technical analysis
Actions including drilling or construction in the rock have the greatest potential to impair safety functions
The site is more favourable for heat extraction than other similar sites
Someone or something must cover the costs for the action
The conclusion from the technical analysis is that actions including drilling or construction in the rock are of greatest potential to influence the repository

10. societal analysis

11. Conclusion from societal analysis
It is difficult to imagine inadvertent intrusion given a continuous development of society and knowledge
However, owing to the long time horizon it is not possible to rule out the possibility that the repository and its purpose will be forgotten, even if both society and knowledge make gradual progress

12. A set of representative cases
Representative cases for a sealed repository:
Canister penetration by drilling
Rock facility in the vicinity of the repository
Mine in the vicinity of the Forsmark site
In addition:
Complementary analysis for an incompletely sealed repository

13. Rock facility in the vicinity of the repository
Very high water conductivity in the tectonic lens in the upper 150 meter of the bedrock above the repository
Unfavorable site for tunnel or rock
Analysis also show that a tunnel at this depth would not affect the ground water flow at repository depth

14. Mine in the vicinity of the Forsmark site
The ore potential has been investigated in Forsmark. Siting of the repository has been chosen after this
An area south west of the repository have potential for iron oxide mineralisation
No influence on repository safety functions

15. Deep drilling
Technology available but knowledge of repository lost, 300 years or longer. Drilling angel is 85 degrees and cuttings are according to present day practise left on the ground. One month after the drilling a family moves in, uses the drillhole as a well, and use the cuttings on the field were they grow all their food.

16. Canister penetration by drilling- dose to drilling personnel
130 mSV/h if drilling occur 300 y after closure. After 5000 years dose is 1 m Si/h Mainly due to cautious assumption of amount of Ag-108 m brought to surface

17. Canister penetration by drilling – dose from well
The dose from welk is 0.24 mSi/y which is somewhat higher

18. Canister penetration by drilling – dose from using the contaminated soil for agriculture
7 Sv /

19. Incompletely sealed repository
Repository is left without backfilling and sealing of all parts of the repository
Results imply that backfill in the deposition tunnels may be lost and that the safety functions in the deposition holes close to the entrance are violated
If corrosion breakthrough in canisters occur during the next glaciation radionuclides are calculated to reach the surface systems and give rise to dose.

20. Conclusions
The calculation cases illustrate that drilling a deep borehole into a canister could give high doses both to drilling personnel and humans settling on the site afterwards
Leaving the repository without complete backfilling and sealing could violate the safety functions of deposition holes close to the entrance of the repository
A set of cases illustrating the consequences of Future human actions have been identified and consequences has been estimated and discussed.
Drilling of deep boreholes at the site will cause high doses if a canister is penetrated and the borehole is abandoned without further measures
If the borehole is used as a well the dose limit is exceeded but the background radiation is not
The cuttings left on the ground may cause very high doses
With the exception of drilling deep boreholes the site can be freely utilized for the identified future human actions