[ RadSafe ] Curiosity query

[KARAM, PHILIP]

Well...quick-and-dirty check:

- 1 gram of Ra-226 (half-life 1600 yrs) is about 1 Ci
- Half-life of U-235 is about 700 million years - about 437,000 times as long as Ra-226
- Specific activity ratios with both half-life and atomic weight
- The atomic weights are pretty close, so we can approximate the specific activity as being proportional to the half-life - the specific activity of Ra-226 should be about 437,000 times as high as U-235, so 1 gram of ra-226 should have about as much activity as 437,000 grams of U-235
- 437,000 grams is 437 kg

Enrichment will also concentrate U-234 (short half-life) and any fission products from recycled materials, so the actual activity of a kg of "real" HEU can be higher than this. On the other hand, there would have been no fission products in the first batch of HEU manufactured (no opportunity to recycle fuel). I'm not sure how much U-234 adds to this (or how much it would have added in 1945), but the specific activity for pure U-235 should be pretty close.

Andy



-----Original Message-----
From: radsafe-bounces at health.phys.iit.edu [mailto:radsafe-bounces at health.phys.iit.edu] On Behalf Of JPreisig at aol.com
Sent: Monday, August 05, 2013 3:59 PM
To: radsafe at health.phys.iit.edu
Subject: Re: [ RadSafe ] Curiosity query

Hmmmmm,  
 
    450 kg of HEU???? sounds like much too much.  Try  again.
 
    Joe Preisig
 
 
 
 
In a message dated 8/5/2013 2:50:05 P.M. Eastern Daylight Time,  
PHILIP.KARAM at nypd.org writes:

If I got  the math right, about 450 kg of HEU is 1 Ci (37 GBq) with a dose 
rate of less  than 70 mR/hr (0.7 mGy/hr) at 1 meter. So from a radiation 
safety standpoint,  not that big a deal.

Andy


-----Original  Message-----
From: radsafe-bounces at health.phys.iit.edu  
[mailto:radsafe-bounces at health.phys.iit.edu] On Behalf Of Maury
Sent:  Monday, August 05, 2013 12:17 PM
To: The International Radiation Protection  (Health Physics) Mailing List
Subject: [ RadSafe ] Curiosity  query

Can anyone tell me or suggest a link to description of the size  and 
weight of the radioactive components of the Hiroshima bomb?  Also  would 
like to know weight and size of the shielding required to handle  this 
material.  How did they load this material onto the USS  Indianapolis 
without lethal irradiation of handlers?  Am wondering if  these answers 
would shed any light on what would be required to attempt a  practicable 
so-called dirty bomb if not a practicable nuclear  weapon.

Seems to me that terrorist groups would be hard pressed to  handle a 
nuclear weapon even if any of our opponents saw fit to give them  one 
...?  The implication to me is that a dirty bomb of any serious  yield 
would not be feasible?

Thanks for  comments.
Maury&Dog
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