The first people there certainly knew what they were facing, and they knew the risks. The rest - not so much. People were gathered from the streets, from their homes and their workplaces. None were told what they were about to face, none were allowed to talk to anyone back home, and none were allowed to leave when they got there.
All in all, there was a handful of people who really knew the risks and who truly, heroically sacrificed themselves. Then there were some volunteers, and then there were masses of involuntary laborers who were told that they should take a few charcoal tablets a day and they'll be fine.
About 600 000 people were involved in the liquidation effort. Surely you cannot believe that they were all Soviet heroes, or volunteers for a cause no one actually was told about at the time. You don't need to hope for volunteers in a totalitarian regime if you can just gather any able-bodied man you can find.
Grabbed in the streets and thrown into radiation-glowing ruines? Not to much to believe only for someone who hates Soviet from the very depth of his heart, I suspect, sorry :)
As any dramaticals events you had stupidy , petty arrangements, manipulations and heroism.
Still glad for the heroism of the first people on this event.