Nuclear Fission Yields

I'm looking for the most common thermal fission products for U-233, U-235, Pu-239 and Pu-241. As far as I understand it there are two quantities of interest, the cumulative fission yield and the independent fission yield. The latter being "number of atoms of a specific nuclide produced directly by a fission event (not via radioactive decay of the precursors)," whilst the former does include the precursors. This is defined http://www-nds.iaea.org/sgnucdat/safeg2008.pdf" [Broken].

I have found some values http://www-nds.iaea.org/sgnucdat/c3.htm" [Broken]. Unless I've misunderstood both the cumulative fission yield and the independent fission yield columns should add up to 100% yet the cumulative fission yield sums to considerably more than that and the independent fission yield less than that.

Wikipedia gives a list of products in order of yield for U-235 http://en.wikipedia.org/wiki/Fission_product_yield" [Broken]. This is apparently based on the link above but the two don't seem to correspond and I don't know where the numbers have come from.

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arivero
Gold Member
I think the independent yields should add to 200%. No idea about the cumulative, and in fact I am rescuing this thread to ask what is exactly the definition of cummulative... Should not be only the final stable nuclei?

Astronuc
Staff Emeritus
Cumulative yield for a given nuclide includes it's yield from fission, from decay and from transmutation, since fission products absorbs neutrons, e.g., Te-134 > I-134 > Xe-134 > Cs-134 > Ba-134 . . . and e.g., I-133 + n => I-134, Xe-133 + n => Xe-134, . . . .

arivero
arivero
Gold Member
Ok, to fix it:

independent yields are the immediate yields
cumulative yields are all the possible nuclei during the reaction process
chain yields are the final stable nuclei, or very long term.

I guess cumulative is for radatiation in the reactor and chain for the nuclear waste.

Astronuc
Staff Emeritus