[ RadSafe ] Re:U-238 spontaneous fission

Peter Bossew peter.bossew at jrc.it
Wed Jun 18 12:25:03 CDT 2008

A short calculation:
The effective  SF decay rate of 238U is lambda=2.678e-24 s-1.
1 mol = 238 g of 238U contains A=6e23 atoms with an activity of 
lambda*A=1.6 SF decays per second
I did not find a nu value for spontaneous fission of 238U; for fast 
fission it is 2.819 (http://www-nds.iaea.org/sgnucdat/a6.htm ), which is 
a conservative estimate for SF (I think). Thus we find 1.6*2.819=4.51 
n/s per mol due to SF, or 0.019 n/s = 68 n/h per g 238U. For 1 ug this 
is about 1 neutron every 609 days. Wow.
68 agrees well with the quoted number 59.5.


Geo>K0FF wrote:
> Sorry, in my haste, I left the tittle intact, with no intention to 
> equate spontaneous fission with any sort of effect whatsoever.  We 
> treat the few
> neutrons present as being only a scientific curiosity and a nucleonic 
> metrology measurement challenge.
> Personally I remain neutral concerning *low dose* radiation as being 
> either helpful or harmful, as there seems to be no overwhelmingly 
> clear correlation either way.
> Maybe I'm lucky, but I grew up playing in lead mine tailing piles as 
> if they were sand piles, lived around and
> worked chemical plants all my life, and  no doubt received more than 
> my fair share of neurton irradiation, and certainly gamma radiation 
> over a
> long period of time with no ill effects.
> ALARA makes sense, and most professionals follow it with caution but 
> not paranoia.
> George Dowell
> New London Nucleonics Lab
> ----- Original Message ----- From: "Geo>K0FF" 
> <GEOelectronics at netscape.com>
> To: "Brennan, Mike (DOH)" <Mike.Brennan at DOH.WA.GOV>; <radsafe at radlab.nl>
> Sent: Wednesday, June 18, 2008 10:48 AM
> Subject: Re: [ RadSafe ] [DU-WATCH] Re:U-238 spontaneous fission
>> From: "Brennan, Mike (DOH)" <Mike.Brennan at DOH.WA.GOV>
>> To: <radsafe at radlab.nl>
>> Sent: Wednesday, June 18, 2008 10:39 AM
>> Subject: RE: [ RadSafe ] [DU-WATCH] Re:U-238 spontaneous fission=
>> The "59.5 neutrons/g/hr" rate (I neither confirm nor dispute its
>> validity) "
>> Mike, there is indeed some SF going on in DU as I show being tested 
>> and measured here:
>> http://www.qsl.net/k0ff/Fission%20in%20the%20Home%20Rad%20Lab/
>> George Dowell
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Peter Bossew 

European Commission (EC) 
Joint Research Centre (JRC) 
Institute for Environment and Sustainability (IES) 

TP 441, Via Fermi 1 
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Tel. +39 0332 78 9109 
Fax. +39 0332 78 5466 
Email: peter.bossew at jrc.it 

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