Something to chew on....
I believe the really hard radiation (the stuff to worry about) from solar flares is more ray like so if you see the sun, it sees you. Not through the wall of a crater though.
The thing to get the night sweats over are CME shocks. This is when a strong and fast CME ploughs through the slower solar wind and accelerates the particles to much higher energy (protons) in a large area that travels away from the sun.
There was one of these between Apollos 16 and 17 that showered the Earth-Moon system for about 2-3 days and probably could've killed a crew in transit or on the surface.