Talk:Nuclear weapon yield/@comment-79.78.77.58-20170629125124

       Estimate of the yield of the Nagasaki bomb.

Oak Ridge National Laboratory ORNL data, critical mass versus natural uranium reflector thickness ( dr ) for 93% U 235 sphere.

The following is an empirical formula to a few % accuracy:-

Rc(dr) = [ 0.92 +{ 0.48 / (1+ dr/4.25) } ] Rc(dr => 21.6 cm.)

Fat Boy ( Nagasaki ) Uranium tamper 2.5” thick, 6.35 cm, estimate 115 Kg Aluminium Pusher 4.5”, 11.43 cm, “ 118 Kg Plutonium 6.2 Kg Mt approx.. 240 Kg

ORNL Plutonium 16.5 gm/cm3 critical bare mass 16.25 Kg, infinite reflector 5.8 Kg.

Rc(dr = 0) = 6.17 cm, Rc(dr = infin.) = 4.37 cm. R at 6.2 Kg = 4.47 cm.

Rc (dr = 6.35 cm) = 4.87 cm, Mc(dr) = 8.0 Kg.

ORNL compression factor Kc_ “twice ”and “2.5 possibly somewhat less”. The numerical mean is 2.25 and the phrase “possibly somewhat less” would put this figure in the region of 2.2 to 2.1.

Pu fission MFP = 14.2 cm giving t = 8.5 x 10^-9 sec. Neutron yield n = 3.

E = Mt/2 { [R Kc^2/3 – Rc][1- ( Rc/(R Kcom^2/3))^2 ][n – 1 ]/4t }^2 ergs.**

Energy equivalent 4.2×10^16 ergs/ton TNT.

It is estimated that 10% of the energy released was due to the fission of the tamper.

Kc = 2.1 yield 18,584 x 10/9 = 20,644 tons TNT 2.15 21,398 23,766 2.2 24,405 27,116

Dr Penney observed the Nagasaki explosion from an escort plane and estimated from an on the ground survey a yield of 22+- 2 Kilo tons TNT.

** Based on a lecture given by Werner Heisenberg 1945.

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