How many B.T.U. per Hour did the atom bomb generate over Hiroshima or Nagasaki?

Question

Require details about the amount of heat that was generated when U.S.A. droped an atom bomb over Hiroshima & Nagasaki in Japan during world war II.
Thanks

Answer 1

Assuming a total yield of 15 kilotons, that's 63 x 10^12 joules or about 60 billion BTUs. Figure somewhere between 30 and 50% of the energy is thermal, that's 18 to 30 billion BTUs. I don't know a time profile for the energy release, but it all happens pretty quickly, so the peak hourly rate is immense.

Answer 2

On the ground, beneath the explosion center(hypocenter), the temperature rose to approximately 7,000 degree F. On the stairway of the entrance to a bank, which was 1/8 mile from the explosion center, a man was sitting waiting for its opening. The surface of the stone stairway was changed by the immense heat. The part where the man was sitting remained unchanged because his body absorbed the heat.
Roof (ceramic) tiles on houses within 1/3 mile radius from the explosion center melted, and gray stones which contained silicon particles became white. The clothes which people wore were burnt by the heat within 1 1/4 mile radius from the explosion center.

Bomb blast
An ultra high pressure was generated by the explosion. The wind velocity on the ground beneath the explosion center was 980 miles/hr, which is five times stronger than the wind generated by strong hurricanes. The pressure was 3.5 kg per square centi-meter which is equivalent to 8,600 pound per square feet.
At a point that was 1/3 mile from the explosion center, the wind velocity was 620 miles/hr; the pressure was 4,600 pound per square feet. Most of concrete buildings inside this range were completely destroyed.

Even a mile from the explosion center, where the wind velocity was 190 miles/hr and the pressure was 1,180 pound per square feet, all brick buildings were completely destroyed.

Answer 3

Foregoing answer is good. The fission reaction lasts for only a few microseconds before the bomb disintegrates, so the power production is indeed immense.