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
An engineer has died following a jet that crashed at a RAF Valley airbase on Angelsey earlier this afternoon.
46-year-old Anthony John Lowe has been sentenced to 18 years minimum for the murder of a young mother he met on a dating site.
Frosty tonight. Turning cloudier with patchy rain on Wednesday.