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
Becoming drier and brighter from the northwest during the day, but with the risk of scattered, locally heavy, showers developing later.
Warren Gatland says he 'feels massively' for the players who didn't make his final squad and said some decisions were 'the toss of a coin.'
Wales' final 31-man Rugby World Cup squad has been announced.