I would assume the planet Mercury represents a 'worst case' for radiation risk to people. But how bad is it as compared to, say, radiation workers annual dose limit?
According to this NASA Mercury Facts Sheet, Mercury has almost 7 times the Solar Irradiance that Earth receives (9082.7 W/m^2 versus 1361 W/m^2). I'm not certain how this value translates to Sievert Units.
Mercury does have a large magnetosphere though, which should protect anyone on the planet from a large amount of the harmful radiation the Sun puts out (similar to Earth.) I'd wager you'd receive less radiation on Mercury than on the Moon because of the magnetosphere.