[arethuza]

The epilogue of the show makes it very clear that the three survived and at the time of broadcast two were still alive.

Also, I believe the Soviet authorities at the time may have incorrectly believed that a large explosion was possible - in that respect the show may be correctly repeating a mistake that was made at the time.

[unicornfinder]

If memory serves this is confirmed in the podcast - i.e. the soviet engineers at the time believed it, even if we now know that it was unlikely.