RE: Dirty bomb predictions

[andrew_mcewan@nrl.moh.govt.nz]

For what it is worth, I used the Federal Guidance Report No. 12 at

http://homer.hsr.ornl.gov/VLAB/FedGR12.html.  For 1 Ci of Cs-137 per square

meter on the surface of the ground, the effective dose equivalent (He) rate

is 3.8 mrem/hr.



I wonder how the survivers of Hiroshima and Nagasaki were able to rebuild

their cities and lives.



-- John

________________________

John



At Hiroshima the height of the detonation was such that the fireball remained well above ground level so that there was little local fallout.  Neutron

induced radioactivity in soil and building materials resulted in some minor irradiation of persons who entered the city in the first few days, and

particularly in the first few hours following the explosion (minor compared with the prompt radiation from the detonation).  Most neutron-activated

radionuclides of importance have half-lives of hours rather than days so that after a week this activity would have decayed to a non-significant

level.  Published results of a radiation survey conducted in October 1945 showed the exposure rate near ground level was only about 0.1 mR/h at 500 m

from the hypocentre and approached normal background for the area of about 0.01 mR/h at 3000 m.



Andrew McEwan



_________________________

Andrew C McEwan PhD

National Radiation Laboratory

PO Box 25-099

Christchurch, New Zealand



Ph 64 3 366 5059

Fax 64 3 366 1156

Andrew_McEwan@nrl.moh.govt.nz