There's no radiation in the subterranean oceans, which is what they are investigating.
(Radiation shielding is an exponential function; a few meters of water is, for most purposes, total shielding [0]. The major radiation source on Europa is solar particles trapped in Jupiter's magnet belts, which bombard Europa's airless surface. The ocean begins multiple tens of kilometers below that surface).
(Radiation shielding is an exponential function; a few meters of water is, for most purposes, total shielding [0]. The major radiation source on Europa is solar particles trapped in Jupiter's magnet belts, which bombard Europa's airless surface. The ocean begins multiple tens of kilometers below that surface).
[0] https://what-if.xkcd.com/29/