Today's scenario is an incident involving the transportation of radioactive materials.
"It's extremely unlikely that an event like this could happen for real" said a spokesman for Magnox.
"However we can't allow ourselves to be complacent and need to be prepare for such eventualities".
More top news
Wales has been labelled a blackspot for motor crimes after research revealed 172,000 motoring offences were recorded between 2015 and 2016.
Arriva Trains Wales says twelve trains were damaged by hitting fallen trees and services will be affected this morning.
Paul Clement wants to make sure Swansea's battle for Premier League survival does not see them "suffer" at the end of the season.