The problem, as I see it, ignoring anything to do with Neil McEvoy et al, is that EDF have no idea how radioactive this mud actually is, as they have only had the top 5cms tested.
Deeper it could still be within limits or it could be massively over accepted limits, no one knows.
It seems that no further testing is going to be taking place & the stakeholders have agreed to have this 300,000 tonnes dumped just off Cardiff.
If it transpires later that beneath this top 5cms the mud is indeed above legal radiation limits then it will be to late as 300,000 tonnes of it will have already been dumped off Cardiff & will be polluting The Bristol Channel with no way of any remedial action being taken as it will have been dispersed over a massive area as The Bristol Channel has the second biggest tidal range in the world.