>>508935371
Industrial dosimeters are designed to find very small leaks of radioactivity long before they become a major health concern.
Good for testing food, bad for trying to figure out which direction you should go at a fork in the road.
You should look at the UPPER level as well as the lower level. Once it saturates, it becomes useless for helping you make split second decisions.

>>508935453
It's not a secret at all. It had like 30 stages, each one serving as an igniter (fission) or booster (fusion) for the previous/next stage. In the test the last 10 stages or so were with "dummy" materials.
It really wasn't that useful. For most scenarios, it would be more efficient to make 20 smaller nukes from the material used to make one Tsar Bomb. With bigger bombs, you're just making a deeper crater in the ground, for a few hundred extra meters radius of destruction.

>>508935614
Still not useful. 1/3 of the blast goes into the ground, and 1/3 goes into the air, and most everything over 5 PSI is overkill for most situations.
You would get MORE explosive power, over a larger area with many smaller nukes detonating apart.