[ RadSafe ] Californium vs. Americium

Sun Jul 8 20:37:41 CDT 2007

I bit the bullet and did some research.  Californium-252 is used in sources for simple neutron well logging quite successfully, but the relatively short half-life is a potential problem.  It's spontaneous fission neutron generation is greater than three orders of magnitude more efficient than the alpha-Be AmBe reaction, so there is little reason to worry about the Californium alphas.

Since I get many enquiries on AmBe source availability, I threw this page together this morning:
www.logwell.com/tech/nuclear/Californium-252.html

This page is intended primarily for independent well loggers needing information about alternatives to AmBe sealed sources.

If anybody sees any mistakes, inaccuracies, or omissions, I sure would appreciate input.

Syd H. Levine
AnaLog Services, Inc.
Phone:  (270) 276-5671
Telefax:  (270) 276-5588
E-mail:  analog at logwell.com
Web URL:  www.logwell.com

----- Original Message ----- 
From: "Doug Aitken" <jdaitken at sugar-land.oilfield.slb.com>
To: "Brennan, Mike (DOH)" <Mike.Brennan at DOH.WA.GOV>; "radsafe" <radsafe at radlab.nl>
Sent: Thursday, June 28, 2007 2:02 PM
Subject: RE: [ RadSafe ] Californium vs. Americium

> There have been a number of geophysical logging tools that used straight Cf 
> (SF) neutron sources, which were found to be more applicable to stimulating 
> specific reactions due to their lower energy spectrum compared with 
> alpha-Be sources, but the current interest is in using the Cf alphas due to 
> the drying up of Americium supplies.
> 
> Unfortunately, even the best manufactured alpha-Be sources have relatively 
> low efficiency/yield. So a material such as DU would not be practical....
> Besides this, such a source would be a PR disaster, as WE KNOW that DU is 
> the most dangerous substance on earth..........
> ;~)
> Doug
> 
> At 01:37 PM 6/28/2007, Brennan, Mike  (DOH) wrote:
>>I admit to not knowing much about these kinds of neutron sources (in my
>>program, if you wanted to expose something to neutrons you ran it into
>>the reactor), but I was under the impression that the reason for using
>>CF was the SF neutrons.  My source says that CF-252 decays via SF about
>>11% of the time.  I have no idea of what percentage of the alpha decays
>>cause an "alpha + Be => n" reaction, but I suspect it is a function of
>>the energy of the alpha and the abundance of Be atoms to encounter.
>>
>>I realize there are non-trivial drawbacks, but it is a shame that they
>>can't use some of the DU to make DUBE sources.  In addition to a cool
>>name, you could calibrate your logging equipment once, and you'd be good
>>to go for your lifetime.
>>
>>-----Original Message-----
>>From: radsafe-bounces at radlab.nl [mailto:radsafe-bounces at radlab.nl] On
>>Behalf Of Doug Aitken
>>Sent: Thursday, June 28, 2007 10:08 AM
>>To: Syd H. Levine; radsafe
>>Subject: Re: [ RadSafe ] Californium vs. Americium
>>
>>Ahhhh. The Americium crunch....
>>
>>AFAIK (and Bob of NSSI can confirm) the neutron yield of any "Xx"-Be
>>source depends as much on the way you mix the two elements as it does
>>the activity of your alpha source. But the mean neutron energy of a
>>Cf-Be and Am-Be should be similar, given that this is the result of
>>ejection of the neutron from the C13. Don't forget the small (lower
>>energy) neutron yield from spontaneous fission of the Cf itself (~3% of
>>the alpha production of the
>>Cf) which, given the low efficiency of the Cf-Be neutron production, may
>>change the overall energy spectrum vs an Am-Be source. and this may make
>>any characterization of tool response based on Am-Be sources invalid....
>>
>>But, as Bob of NSSI says,  the short half life, that forces a very
>>frequent re-calibration of the logging equipment, and a short effective
>>life of the source are probably the overriding reason that these sources
>>are not often used.
>>
>>(personal observations only: not in any way the opinion or
>>recommendation of the company I consult for!) Regards Doug At 10:47 AM
>>6/28/2007, Syd H. Levine wrote:
>> >Aside from half-life considerations, what are the technical issues with
>>
>> >using Californium in place of Americium in Be based neutron sources
>> >(for well logging)?  Are the neutrons of the same energy?
>> >
>> >My understaning is the half-life is 2.64 years and that the well
>> >logging sources are made up with about 30 Ci initially so that you wind
>>
>> >up with around 15 Ci at the end of that time period.  I am guessing one
>>
>> >might be able to log with them for five years maybe, then they could
>> >still be used for tools that only need 3 Ci or so for awhile?
>> >
>> >TIA
>> >
>> >Syd H. Levine
>> >AnaLog Services, Inc.
>> >Phone:  (270) 276-5671
>> >Telefax:  (270) 276-5588
>> >E-mail:  analog at logwell.com
>> >Web URL:  www.logwell.com
>> >
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>>Doug Aitken                     Office Phone Use Cell phone!
>>QHSE Advisor                    Home Phone 713 797-0919
>>D&M Operations Support  Cell Phone    713 562-8585
>>Schlumberger Technology Corporation
>>
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> 
> Doug Aitken                     Office Phone Use Cell phone!
> QHSE Advisor                    Home Phone 713 797-0919
> D&M Operations Support  Cell Phone    713 562-8585
> Schlumberger Technology Corporation 
> 
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