It's just that - if you are unlucky enough to look at the source, the interaction of high intensity radiation with your eyes is perceived as blue. You wouldn't see it looking at objects within the shine without being in it yourself. You wouldn't see it with sufficient clear shielding, though that's not possible with any materials we know of, except water perhaps.

As a side note, high radiation levels degrade regular glass transparency quite quickly. When we used to specify remote cameras, everything had to be nuclear grade and have particularly pure glass so the lenses wouldn't cloud.

Both are useful nuggets for sci fi on radiation I would think.