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
The world record attempt will raise money for the foundation set up in memory of the Olympic gold medallist, who died in May 2013.
In today's Newsweek, Carl talks about what the 'No' vote in the Scottish Referendum could mean for Wales and the impact of legal highs.
England manager talent spotting at Swansea City v Southampton at the Liberty Stadium