Not sure about this but I know a few sites around this area

http://www.walesonline.co.uk/news/wales-news/hundreds-thousands-tonnes-radioactive-mud-13673203

That's one solution to badly lit wam scenes, make the models glow in the dark!

Interesting, but sadly pathetic article and writing/reporting skills. They never once mention any specific level or radiation... only 'higher than currently believed' and/or '5 times deeper = 5 times higher radiation'. They even put 'radioactive' in quotes for the headline?!?

So what is the level 'believed' to be? The natural background? twice the natural background? the level of a banana? https://en.wikipedia.org/wiki/Banana_equivalent_dose they never say!