1. Cleaning up residential areas after a nuclear accident – Accident scenario Michael Ammann, STUK

2. Imagine a serious accident at the Loviisa NPP … A fire in the electrical cabinet of reactor 1 Core cooling fails Containment is isolated Site emergency is declared 5-km zone is evacuated according to emergency plans

3. Precautionary evacuation of the 5-km zone

4. Some hours later Core is heating up General emergency declared Vessel breaches at high pressure Large amounts of hydrogen and carbon monoxide have been produced Risk of uncontrollable hydrogen combustion Precautionary evacuation

5. Loviisa is evacuated

6. Second day Hydrogen combustion occurs and the containment fails 80 % of noble gases and 1 % of iodine and caesium were released, presumably

7. Imagine now a week later Radiological situation has been monitored and modelled Deposition is known to some extent Received and future doses have been estimated

8. The dose from the 1 st week Cloud, inhalation, 7 days ground exposure Effective, normal living, adults

9. It was raining Wet deposition of 137 Cs

10. 137 Cs deposition

11. 131 I deposition

12. Measured and predicted dose- rates

13. Key nuclides … as percentages of the total effective dose after 70 years

14. Data aggregation Let us use the contour bands of the 137 Cs deposition map for data aggregation

15. Zone 0 - Characteristics

16. Zone 1 - Characteristics

17. Zone 2 - Characteristics

18. Zone 3 - Characteristics

19. Zone 1 – Relocation of different duration

20. Zone 1 – Clean-up actions

21. Strategies Zone 1Zone 2Zone 3 1Relocate 1 week Cut grass 2Relocate 3 weeks Cut grass 3Relocate 1 year Cut grass Hosing roofs and walls Sweeping pavement Cut grass 4 Hosing roofs Cut grass Hosing roofs 5Cut grass Hosing roofs Cut grass 6 Hosing roofs and walls Sweeping pavement Cut grass

22. Consequence table