This has always been 'the worst fear' of people knowledgeable about Chernobyl. Everything for miles, in all directions, around the power plant is radioactive: the trees, plants, dirt, insects, animals (deer herds, wild pigs, birds, fish)...you name it. It's ALL radioactive.
A forest fire could send TONS of highly radioactive ash into the atmosphere where it would spiral in a counterclockwise direction, covering first eastern Europe, then Scandinavia and Great Britain before plunging south towards France and the Mediterranean region.