You wouldn’t want to drink reactor coolant water (mostly because of the chemistry additives) but water in a tank that just stays between the people and the hot stuff would mostly just get warm.
Most of what you’d get at that kind of distance is neutrons, and they are more likely to bounce off the hydrogen than to do something like activate the oxygen into N16 which dies off pretty fast anyway.
“All we’re missing is the single hardest piece, which we have been failing to make work in cars for years”