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
A mostly cloudy day with outbreaks of light rain and drizzle at times, mainly over the mountains where it could occasionally turn heavy.
The parents of a young boy from Anglesey say they're determined to find a missing dog that was bought to aid his recovery from surgery.
Sheffield Wednesday secured their place in this season's Championship play-offs with a 3-0 victory over their nearest challengers, Cardiff.