1. The effect of radiation damage by fission fragments on dissolution of spent nuclear fuel Aleksej Popel, PhD candidate Supervisor: Dr Ian Farnan Department of Earth Sciences University of Cambridge 1

2. Content Introduction into my project Key results Relevance of the work 2

3. Introduction Several countries, including the UK, decided or considering direct disposal of Spent Nuclear Fuel using Geological Disposal Facilities 3

4. Geological Disposal It is expected that: ground water will enter the repository fuel containers and fuel cladding will be breached spent nuclear fuel will start to dissolve and radioactive nuclides will start to migrate into biosphere 4

5. Geological Disposal Need to know spent fuel solubility and dissolution rate to assess the extent of possible radioactive contamination: extensive research in this area but very little work on the effect of radiation damage on dissolution of spent nuclear fuel 5

6. My Project Aim: to study the effect of radiation damage by fission fragments on dissolution of spent nuclear fuel 6

7. ( J. Somers) (Z. Hiezl) i) structural effects: ↑ surface area ↑ lattice strain ii) chemical effects: U(IV) → U(V) & U(VI) ? vs Fresh fuel Spent Fuel Motivation: expect ↑ of solubility: 7

8. Approach Use simulant fuel made out of depleted UO2 Simulate the effect of fission damage by ion irradiation at an accelerator Characterise the samples Conduct dissolution experiments 8

9. Key results: replication of the real spent fuel microstructure Real Spent Fuel Our effort ( J. Somers) 9

10. Key results: the effect of radiation damage on solubility of UO2 10

11. Applications Direct: supports the safety case for a UK Geological Disposal Facility Indirect: i) general better understanding of nuclear fuel dissolution in the cases of the fuel failure in: - working reactors - reactor accidents - fuel ponds ii) extension of the fuel operating life (burn-up) 11

12. Aleksej Popel+44 1223 768357 ap499@cam.ac.uk Thanks for your attention! Department of Earth Sciences, University of Cambridge, Downing Street, Cambridge, Cambridgeshire, CB2 3EQ, United Kingdom 12

13. References http://www.noldus.com/events/mb98/logo-cup1.gif - Cambridge University logohttp://www.noldus.com/events/mb98/logo-cup1.gif http://www.esc.cam.ac.uk/ - Earth Sciences logohttp://www.esc.cam.ac.uk/ http://www.theecologist.org/News/news_analysis/1235798/battlelines_drawn_as_cumbrian_reside nts_square_up_over_nuclear_waste_site.html - NGR diagramhttp://www.theecologist.org/News/news_analysis/1235798/battlelines_drawn_as_cumbrian_reside nts_square_up_over_nuclear_waste_site.html http://www.zmescience.com/science/physics/fission-tectonic-18072011/ - fission diagramhttp://www.zmescience.com/science/physics/fission-tectonic-18072011/ J. Somers F-BRIDGE presentation – HBS photo Z. Hiezl – fresh UO2 photo 13