Cleaning up residential areas after a nuclear accident – Accident scenario Michael Ammann, STUK
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
Precautionary evacuation of the 5-km zone
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
Loviisa is evacuated
Second day Hydrogen combustion occurs and the containment fails 80 % of noble gases and 1 % of iodine and caesium were released, presumably
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
The dose from the 1 st week Cloud, inhalation, 7 days ground exposure Effective, normal living, adults
It was raining Wet deposition of 137 Cs
137 Cs deposition
131 I deposition
Measured and predicted dose- rates
Key nuclides … as percentages of the total effective dose after 70 years
Data aggregation Let us use the contour bands of the 137 Cs deposition map for data aggregation
Zone 0 - Characteristics
Zone 1 - Characteristics
Zone 2 - Characteristics
Zone 3 - Characteristics
Zone 1 – Relocation of different duration
Zone 1 – Clean-up actions
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
Consequence table