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
It will stay largely cloudy tonight and there will be some further rain around, with central parts perhaps staying driest.
ITV Wales understands the reason for the inquiry call stems from concerns raised at the end of 2016 over a former healthcare support worker.
Plaid Cymru says the Welsh Government must 'show stronger leadership' over fire safety at Welsh tower blocks.