Bokeh talks about the damage of X-Ray on film with a complete practical illustration: where, how many time, which film, and the actual images. Just an example of what can happen.
Personally I just avoid as much as I can traveling with film.
Arkadiusz Podniesinski, a Polish photographer, has a photoessay on Fukushima and the exclusion zone around the nuclear power plant disaster.
Petapixel has Daniel Lachman tell us how much you can over expose colour negative film:
â€œWhat I took away from this is that film basically canâ€™t be overexposed, it can just be too dense for the scanner to be able to shoot through the negative. But the information will always be there.â€
My quick take is that you can shoot it at +2 and it will be more tolerant to under exposure error.