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 Pride of Britain Awards are less than a month away, and today we find out who'll represent Wales in the Fundraiser of the Year category.
Police are appealing for information following a sexual assault on a 29 year old woman that took place in Pontllanfraith.
The personal tragedies and triumphs that have shaped his life. Terry Yorath: Life on the Edge, ITV Cymru Wales on Monday, 23 October (8pm).