Hm. That's strange, because USSR's 57 Megaton Tzar-bomb had a negligible amount of radiation:
"Radioactive contamination of the experimental field with a radius of 2–3 km (1.2–1.9 mi) in the epicenter area was no more than 1 milliroentgen / hour, the testers appeared at the explosion site 2 hours later, radioactive contamination posed practically no danger to the test participants" [1].
"Radioactive contamination of the experimental field with a radius of 2–3 km (1.2–1.9 mi) in the epicenter area was no more than 1 milliroentgen / hour, the testers appeared at the explosion site 2 hours later, radioactive contamination posed practically no danger to the test participants" [1].
[1]: https://en.wikipedia.org/wiki/Tsar_Bomba#Test_results