Talk:Fission product yield

Totals

The total sum of isotope yield is 45.5522% in all shown tables. Why is that-where is the rest 54.4478% gone? 81.173.168.31 (talk) 07:15, 5 June 2008 (UTC)

The tables from IAEA are yield/fission, so should add up to about %200. But they are cumulative yield, so some decay to stable nuclides, and, it seems, don't count anymore. Gah4 (talk) 00:29, 17 November 2016 (UTC)

I agree the lack of summing to 100% (or 200% as in the above comment) seems dissatisfying. The table "Ordered by mass number (thermal fission)" has a nice way of presenting the neutron-capture transmutations & decays temporally into columns; maybe this could be expanded upon? (Also in this table shouldn't the 136Xe yield in particular be shown based on its significant yield from neutron capture)? -RJS

Put four ~ at the end of your post, and it will automatically get your user name and data and such. Gah4 (talk) 13:45, 15 June 2019 (UTC)

IAEA has both immediate and cummulative yield tables. Changes due to neutron capture would be in the cumulative yield case. I believe that is, what you get in a continuously, more or less, running reactor. Gah4 (talk) 13:45, 15 June 2019 (UTC)

The table "Ordered by Yield" doesn't sort meaningfully by column Halflife. I tried experimenting with the approach documented in http://meta.wikimedia.org/wiki/Help:Sorting#Sorting_with_hidden_sortkey but without success. Any offers? Simon Marchese (talk) 22:57, 19 April 2011 (UTC)

I just added new IAEA tables, which don't have sort keys yet. Well, not the half life table yet. Gah4 (talk) 00:29, 17 November 2016 (UTC)

Hmm, that is a tough one, not sure.

These tables were some of the first I wrote on this subject in Wikipedia and are not complete. --JWB (talk) 06:09, 20 April 2011 (UTC)

"A few isotopes can be produced directly by fission, but not by beta decay because the would-be precursor with atomic number one greater is stable". Electron emission means the precursor has an atomic number one less. Is positron emission or electron absorption significant here? RTBoyce (talk) 13:06, 11 August 2011 (UTC)

(Comment on immediate and cumulative fission moved down below.)

Today the table sums to 51.9%. It would be interesting to see what the remaining products are, if the sum of everything should reach 100% or 200%, and factors affecting the yields (fissile material, neutron spectrum, time), in particular it would be interesting to see the yield very shortly after fission.150.227.15.253 (talk) 00:01, 8 February 2022 (UTC)

Some of these tables I converted from HTML from IAEA tables. (And I asked to be sure it is allowed.) There are tables called immediate and cumulative yield. I believe cumulative is what you get in a continuously running reactor, in steady state conditions. I didn't figure out why they don't add to 200%, but I suspect it is that there is a long tail. There is are a large number of nuclides each produced with very small yield, as the tail of an exponential. I believe stable nuclides also don't appear in the table. Gah4 (talk) 01:29, 8 February 2022 (UTC)

Multiple tables

Why are there multiple tables? Shouldn't we have a single table that's sortable by multiple columns? OrangeDog (τ • ε) 12:54, 8 April 2014 (UTC)

It seems that there are multiple tables, sortable by multiple columns, some duplicated, some not. There is at least some redundancy left. Gah4 (talk) 23:43, 10 November 2016 (UTC)

But OK, there should be multiple tables. Seems to me that yields of U-235 and Pu-239 should have their own tables. Do we need both immediate and cumulative yield tables? Gah4 (talk) 06:04, 11 November 2016 (UTC)

Update data and reference

The fission yields are apparently sourced from [1], an unreferenced graph, and [2] a 1956 paper. It would be better to use values from a current compilation. I propose to update the data to IAEA cumulative yield tables from https://www-nds.iaea.org/sgnucdat/c3.htm for thermal fission of U-235. Gierszep (talk) 02:25, 2 June 2015 (UTC)

Sounds good to me. Try to make one table with all the data, sortable by user selectable column. I came here interested in the source data for decay heat. It seems that these tables aren't so useful for that. Gah4 (talk) 23:46, 10 November 2016 (UTC)

OK, cumulative yields tables from IAEA for U-235 and Pu-239 are in. Does anyone want the independent yield tables? Or the tables for Th232, U-233, U-238, or Pu-241?

(And the IAEA Activation Product table is on the appropriate article for that one.)

Gah4 (talk) 23:58, 16 November 2016 (UTC)

If someone is interested in more tables, please ask before I forget how to do it. I have an AWK program to convert from IAEA form to Wiki form. Gah4 (talk) 01:57, 23 November 2017 (UTC)

References

independent or cumulative?

It seems that there are tables of both independent and cumulative fission yields. Which one is this article about? Gah4 (talk) 05:08, 11 November 2016 (UTC)

It seems that someone else asked this earlier, moved down from above: Gah4 (talk) 06:10, 11 November 2016 (UTC)

This whole page confuses immediate fission yield (i.e. which nuclei are the result of fragmentation of the original fissile parent) and radioactive decay (i.e. subsequent transmutation by beta, alpha, and electron capture, positron emission, etc) and neutron absorption. These are different processes. Perhaps the introductory paragraph could make that clear and refer readers to other wikipedia pages on those topics? The tables are woefully incomplete and, I fear inaccurate. Also, fission yields are a function of parent nucleus and incident neutron energy. These tables should make clear the particular case, e.g. U-235 fissioned by a 0.025eV (median room temperature) neutron. Cuhlik (talk) —Preceding undated comment added 22:53, 22 January 2013 (UTC)

One thought is separate articles for immediate and cumulative yield. Gah4 (talk) 06:10, 11 November 2016 (UTC)

I agree, the discussion is lagging in clarity and also because for heaver nuclei the Spontaneous Fission can occur without neutron bombardment, it would be useful to indicate how those reactions can occur. Also, a section with the definition of the difference between Cumulative and Intermediate would also IMHO be appropriate for this article. TimeHorse (talk) 16:35, 31 May 2022 (UTC)

References

Peaks or averages

The Nuclear fission page mentions where the two peaks are, though I am not sure where they got the numbers. First, they are different for U235 and Pu239. Second, are they peak (mode), mean, or median? And which should they be? Does anyone have favorite numbers for the two peaks, and for U235 and Pu239? Gah4 (talk) 02:00, 23 November 2017 (UTC)

if you order all fission products by mass number, you'll get more atoms of certain mass numbers produced than of others. That's where the "peaks" are. Hobbitschuster (talk) 09:38, 12 February 2022 (UTC)

Well, the peaks come from magic numbers, and those are from protons and neutrons separately. Gah4 (talk) 18:19, 12 February 2022 (UTC)

In extreme cases such as 259Fm, only one peak is seen.

In extreme cases such as 259Fm, only one peak is seen. Seems to me that there are two things to consider separately. One is that with more energy available, the peaks are less distinct. (More energy for valley nuclides.) But also for increasing mass of parent, the peaks will move up, such that by 259, two nuclides of (about) mass 130, the position of the second peak, should be produced. The paragraph mentions the first reason, but not the second. Gah4 (talk) 21:35, 31 January 2018 (UTC)

new tables?

About two years ago, I replaced the existing tables with the ones from IAEA, converted to wikitable form. (Using an awk program.) There are many more IAEA tables, if they are wanted. There are tables for Th232, U233, U235, U238, Pu239, Pu241. (Some have no thermal neutron fission.) There are also independent and cumulative yields, the latter after some time, and presumably more useful for operating reactors. Recently added tables have an order mentioned in the title, but also seem to be sortable. But also, some numbers, such as Cs134, are very different from the IAEA tables. It would be nice to know why they are so different. Also, are they independent or cumulative yield? Otherwise, I was figuring if the IAEA tables were good enough for IAEA, they should be good enough here. Gah4 (talk) 14:27, 26 September 2018 (UTC)

Just wondering, if anyone has any more thoughts on these tables. I might still remember how to convert them from the HTML tables at IAEA. Specifically, the left column in this table shows the tables available. As far as I know, they haven't changed over the years since I did those. Gah4 (talk) 01:14, 23 June 2021 (UTC)

Neutron capture

Should the section with the yields listed by mass number (which I completed the decay series for and I also hope I colored all elements correctly now, but so check) consider neutron capture reactions? If so, which? Right now it seems a bit inconsistent as Cs-133 is listed but none of the neutron capture reactions in Europium or the likes are - and those have far larger cross sections. Hobbitschuster (talk) 09:36, 12 February 2022 (UTC)

references

Thanks for fixing up the references in some tables. Note that the tables with IAEA references are generated by programs from the IAEA html tables. If I get in the mood to regenerate them, any changes will go away. (The way they were is closer to the IAEA way.) Actually, I might get in the mood to replace them with JAEA tables. Gah4 (talk) 01:55, 7 March 2022 (UTC)

IT

Someone added to the article In this article I did not see a definition (or a reference)to the abbreviation IT for isomeric transition. which seems like it should go here. Maybe there should be an index of all decay mode symbols? Gah4 (talk) 19:50, 17 March 2022 (UTC)

Thermal vs. Fast vs. 14 MeV rates

Because the IAEA speaks of Thermal percentages, Fast percentages, and 14 MeV rates of Spontaneous Fission, I think it would be useful if we add a section which explains the difference between each of these decay ratios. TimeHorse (talk) 16:35, 31 May 2022 (UTC)

Some years ago, I converted IAEA tables to Wikitables. I am considering using the JAEA versions instead. It would be useful to know which things are considered more, and less, useful here. One is do we need both thermal and fast tables? Cumulative or not? Gah4 (talk) 17:29, 31 May 2022 (UTC)

No references for many of the tables.

The only reference for many of the tables no longer exists.

• The table in the next section...computed from[1]

Moreover the meaning of "computed from" cannot be verified. Many puzzles cannot be investigated, such as:

• The yields in the table sum to only 45.5522%,....

Johnjbarton (talk) 17:58, 11 July 2024 (UTC)

The big tables I generated from IAEA tables, and have references. If you want more, I might still know how to generate them. I don't know about the others. Gah4 (talk) 08:31, 12 July 2024 (UTC)