An exercise is taking place in Romania today to test the international response to a nuclear disaster.
An accident is being simulated at a nuclear power station in the east of the country.
Experts from around 60 countries are taking part in the 36-hour operation organised by the UN's Atomic Energy Agency.
As well as the mass mobilisation of emergency services, contingency plans being put into effect include arranging evacuations and coping with the impact of such an accident on food and water supplies.
Emergency response teams in Romania are tackling the situation, while other countries are tracking nuclear fallout.
Full details are being kept secret to make the simulated accident as real as possible for emergency teams.
