Re: Fission Efficiency

[Bernard L Cohen <blc+@pitt.edu>]

On Wed, 4 Oct 2000 Jacques.Read@eh.doe.gov wrote:

> One kiloton of TNT is 4 E12 Joules, or the energy given off by 2.5E24 atoms of
> Pu fissioning. That's about 950 grams of Pu per kiloton

	--I calculate
4.2E12joules x (239 Kg / 6E26 atoms) / (200 MeV/atom x 1.6E-13 joules/MeV)
	=0.05 Kg = 50 grams of Pu fission per kiloton, not 950 grams

> The 14 KT of the
> Nagaski bomb fissioned about 13 Kg pf Pu.

	--Using my calculation above, the 14 kiloton yield would mean
50 x 14 = 700 grams = 0.7 Kg of plutonium fissioned.. My understanding is
that the Nagasaki bomb contained 15 lb = 6.8 Kg of plutonium (Someone
might check this with the Smythe Report) which means that just over 10% of
the plutonium (0.7 / 6.8) was consumed by fission.
	At the time of the Plowshares Project, information released
indicated that modern bombs around 1970 consumed about 20% of the
plutonium by fission.

Bernard L. Cohen
Physics Dept.
University of Pittsburgh
Pittsburgh, PA 15260
Tel: (412)624-9245
Fax: (412)624-9163
e-mail: blc+@pitt.edu


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