AW: C-14 production

[Franz Schönhofer <franz.schoenhofer@CHELLO.AT>]

Franz Schoenhofer

PhD, MR iR

Habicherg. 31/7

A-1160 Vienna

AUSTRIA

phone -43-0699-1168-1319





-----Ursprüngliche Nachricht-----

Von: owner-radsafe@list.vanderbilt.edu

[mailto:owner-radsafe@list.vanderbilt.edu] Im Auftrag von

daleboyce@charter.net

Gesendet: Freitag, 27. August 2004 18:11

An: radsafe@list.vanderbilt.edu

Betreff: C-14 production



Hi All,



I've received a few similar questions about the C-14 calculation I

posted.

In trying to keep it short I left some confusion. I used the C-12

capture

cross section to determine the mean path length for removal of neutrons

in

graphite since it is the dominant nuclide.  I did not mean for people to

infer that I was calculating double neutron capture.  In my calculation

I

went back and calculated the number C-13(n, gamma)C-14 reactions based

on

the C-13 abundance and cross section.



This calculation was in no way meant to be exact, as there is a lot

going on

that I didn't have a good way to treat.  It was meant soley as an

estimate

of the scale of C-14 production in the graphite.  One should also

remember

that the N14(n,p)C14 and  and O-17(n,alpha)C14 reactions were excluded

as

well.



----------------------------



Dale,



Thanks for the calculations, how accurate or inaccurate they might be.

They confirm my comment, that production of C-14 (and tritium) is very

low in a reactor and therefore it is clear, that no elevations for those

radionuclides were found in precipitation and aerosols in Europe, not

even in the most affected countries, like Austria was. I know, what I am

talking about, because we have done the measurements in my laboratory

for Austria. Some laboratories reported elevated tritium values, but it

was found, that they misinterpreted I-131 contamination for tritium

and/or C-14. 



I remember from a seminar a long time ago a comparison of C-14 and T in

different reactor types, found in the containment air. They were

significantly different in PWR and BWR, but I do not remember any

numbers. When I asked the presenter for the reason he said that he did

not know. 



I do not believe, that the nitrogen and oxygen reactions are of much

importance - first of all, because there would not be nitrogen present,

secondly I wonder about the isotopic abundance of O-17. 



Best regards,



Franz









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