RE: Mo-99 from fission

[John Jacobus <crispy_bird@YAHOO.COM>]

Does anyone know if there is an on-line Chart of the

Nuclides that has this information?  Those that I use,

such as http://www2.bnl.gov/ton/, which does not have

information of fission products.



--- Dr Christoph Hofmeyr <chofmeyr@nnr.co.za> wrote:

> Jaro,

> The 6.1% per fission of U-235 is the figure for the

> mass 99 beta chain (see chart of the nuclides). If I

> am not mistaken, ORIGEN will calculate the result

> after a certain specified operational time at given

> neutronic conditions in the core, taking into

> account decay (2.75 day halflife in the case of

> Mo-99), neutron capture, etc.  For Mo-99 producers

> it is necessary to optimise the effective yield. 

> The fact that capture could give an improved yield

> at higher neutron energies is certainly interesting.

> Chris Hofmeyr

> chofmeyr@nnr.co.za

> 

> -----Original Message-----

> From: Franta, Jaroslav [mailto:frantaj@AECL.CA]

> Sent: 12 August 2003 08:41

> To: 'Read, Jacques'; Radsafe (E-mail)

> Subject: RE: Mo-99 from fission

> 

> 

> Hi Jacques,

>  

> Please forgive me for doubting your figures, but

> could you please cite a reference or two for that 6%

> yield ?

> The tables of ORIGEN results I've seen give a yield

> of about 0.13% for Mo-99 

> (the highest yield of all appears to be I-138, at

> some 2.76% - only - but this has a T½ of just 6½

> sec).

> Maybe I'm looking at the wrong table ?

> Thank you.

> Jaro 

> -----Original Message-----

> From: Read, Jacques [mailto:Jacques.Read@eh.doe.gov]

> Sent: Tuesday August 12, 2003 1:48 PM

> To: 'radsafe@list.vanderbilt.edu'

> Subject: Mo-99 from fission

> 

> 

> 

> Ms. Hamrick asked "...can someone explain 

> why it is more efficient to irradiate HEU to produce

> Mo-99, than it would be to 

> irradiate a single target nuclide? " 

> 

> Mo-98 is only 24% of stable Mo, and has a very small

> neutron capture cross section for producing Mo-99. 

> 6% of uranium fissions result in Mo99, and the

> fission cross section is orders of magnitude bigger

> than the Mo capture croos-section.  If you just put

> uranium into a reactor for just a little while,

> Mo-99 is a great deal of the radioactivity you'll

> find in the target.

> 

> Jacques 

> 

> 





=====

-- John

John Jacobus, MS

Certified Health Physicist

e-mail:  crispy_bird@yahoo.com



__________________________________

Do you Yahoo!?

Yahoo! SiteBuilder - Free, easy-to-use web site design software

http://sitebuilder.yahoo.com

************************************************************************

You are currently subscribed to the Radsafe mailing list. To unsubscribe,

send an e-mail to Majordomo@list.vanderbilt.edu  Put the text "unsubscribe

radsafe" (no quote marks) in the body of the e-mail, with no subject line.

You can view the Radsafe archives at http://www.vanderbilt.edu/radsafe/