There is no such thing as a "radiation suit". What you're referring to is a suit to protect oneself from chemical and biological agents. At least there is no suit that will protect you from receiving a radiation dose in a "HOT" environment.
The best suit available for that is the US Army charcoal (green) that can be found @ surplus stores for about $50-$75.00 each. You still need a gas mask, rubber boots and gloves, worn as described down below.
A suitable gas mask accompanied by the appropriate amount of masking tape in the appropriate locations is required to provide complete protection in the chemical and biological area.
For nuclear protection: Dress for the climate, put a slicker suit over that (with a hood). Wear rubber boots. Don a gas mask and pull the hood up over your head. Don rubber gloves. Use masking tape (or duct tape) to seal all gaps and connections of the slicker suit, rubber boots, rubber gloves, around the hood and the gas mask.
This DOES NOT protect you from radiation!!! This prevents you from ingesting radioactive particles via breathing, the eyes, and/or open cuts in the skin. You will have to have arrangements made beforehand to decontaminate yourself BEFORE you re-enter your shelter or else you will contaminate the shelter interior and everyone/thing inside of it with radioactive particles. Decontamination is a subject for another thread.
Before one goes outside, into a "hot" environment, one should know what the radiation levels are outside, in order to know how long (how much exposure) one can stay outside before getting an overdose.
Approximate Radiation Doses/Effects:
150 rads/hr = radiation sickness
250 rads/hr = military command max dosage
450 rads/hr = death
I strongly suggest you got www.oism.org
and go to the ebook: Nuclear War Survival Skills. It has most of the information that you are looking for, judging from your question.