Nuclear shutdown in Brazil blackout

The two nuclear reactors at Brazil's Angra plant shut down automatically when the country's grid failed late on 10 November. Operator Eletronuclear reported that emergency diesel generators kept plant systems running during the loss of external power and the reactors themselves were put in a state where natural circulation of cooling water maintained nuclear safety. Logged at 10.15 pm as an 'unusual event', the shutdown progressed to an 'alert' after an hour without external power. Some power was restored around 12.30 am and the alert status ended at 12.36 am and 12.55 am at Angra 1 and 2 respectively. The reactors were able to restart once the grid was restored and they were reconnected at 5.50 pm and 6.57 pm. The blackout started after bad weather caused three transmission lines to collapse, leading to the disconnection of the 14 GWe Itaipu hydroelectric dam. Some 60 million people in 800 towns including Rio de Janeiro and Sao Paulo - as well as the whole of neighbouring Paraguay - were plunged into darkness.