How secure is the radius encryption

Hello, I wonder if the radius encryption between radius client and radius is secure enough if you choose a decent password like the following: 'O([G6krj\9[9FN#GVn(/|9+8h5vq2!W*J:OrA;2Uvk1G&*z~-6'emgQV 2X5iD>a(' Or if someone should always protect the connection between radius client to radius server using ipsec or some other VPN software like for example openvpn? I don't want to do radius over the internet but in a coporate intranet. However I want also to absolutly sure that noone is reading my pap passwords on the wire between radius client and radius server. Cheers, Thomas