Template talk:Actinides vs fission products

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early comment[edit]

What is this template supposed to show? A list of actinide isotopes by half-life on the left-hand-side, fine. But why ordered by the number of nucleotides modulo 4 (?) in each line, with arbitrary delimiting values? Also, the explanations should not be inside the table, but below or above. --Roentgenium111 (talk) 13:07, 27 July 2009 (UTC)

They are decay series if you click on the 4n+x links. --JWB (talk) 17:37, 2 August 2009 (UTC)

Too compact?[edit]

Nice table! I wonder if it'd be clearer if the keys were pulled out to the bottom.

Actinides Halflife Fission products
244Cm 241Pu 250Cf 243Cm 10–30 y 137Cs 90Sr 85Kr
232U 238Pu 69–90 y 151Sm nc➔
249Cf 242Am 141–351 No fission product
has halflife 102
to 2×105 years
241Am 251Cf 431–898
240Pu 229Th 246Cm 243Am 5–7 ky
4n 245Cm 250Cm 239Pu 8–24 ky
233U 230Th 231Pa 32–160
4n+1 234U 4n+3 211–290 99Tc 126Sn 79Se
248Cm 242Pu 340–373 Long-lived fission products
237Np 4n+2 1–2 my 93Zr 135Cs nc➔
236U 247Cm 6–23 107Pd 129I
244Pu Fissile:bold 80 my >7% >5% >1% >.1%
232Th 238U 235U .7–12by Fission product yield
Actinides Halflife Fission products

244Cm 241Pu 250Cf 243Cm 10–30 y 137Cs 90Sr 85Kr
232U 238Pu 69–90 y 151Sm nc➔
249Cf 242Am 141–351 No fission product
has halflife
102– 2×105 years
241Am 251Cf 431–898
240Pu 229Th 246Cm 243Am 5–7 ky
245Cm 250Cm 239Pu 8–24 ky
233U 230Th 231Pa 32–160
234U 211–290 99Tc 126Sn 79Se
248Cm 242Pu 340–373 Long-lived fission products
237Np 1–2 my 93Zr 135Cs nc➔
236U Fissile:
247Cm 6–23 107Pd 129I
244Pu 80 my
232Th 238U 235U .7–12 by

4n 4n+1 4n+2 4n+3 >7% >5% >1% >.1%
Decay series Fission product yield

—WWoods (talk) 14:21, 14 August 2009 (UTC)

Thanks. I really like compact, have put a lot of effort into making it that way, and continue to look for more ways to put more information in the same space. I think I have used color, borders, typeface etc. to avoid visual monotony and thereby give it good intelligibility. Compactness may look unfamiliar at first but I think it makes best use of limited screen real estate. Most often the template will be used as a reference for adjacent article text mentioning actinides or fission products, and it is much easier to use it this way when both are on the screen at once, instead of some items being pushed off by sparser layout. --JWB (talk) 16:02, 14 August 2009 (UTC)

I did not understand what this table meant until I searched and found the non-compact version here. The compact one really defies the rules for how tables are supposed to be read--I mean, the keys are actual items on the table... (talk) 07:08, 15 May 2010 (UTC)

Wwoods; I think your version is more accessible. While I understand the desire that the table be compact, I think most readers would be better served by your version. Walter Siegmund (talk) 21:39, 29 March 2011 (UTC)

Color unreadble[edit]

Something should be done with the colors and alternatively the layout of this template; the lower isotopes are barely readable. What is the inspiration for the color scheme? Spiff (talk) 03:37, 31 July 2010 (UTC)

Most confused template anywhere[edit]

The template is extremely confused, I would discourage its usage anywhere. My objections are:

  • The title boxes of the radioactive series are chaotically dispersed inside the table, at columns 6, 8, 10, 10 – it is hard to realize that these boxes actually contains title boxes – by convention title boxes are either at the top or at the left,
  • The legend for ƒ, ₡, №, m is chaotically dispersed in the table, it is virtually impossible to understand that it is a legend,
  • If the actinide serieses are represented as columns in the table, why is it that the nuclides are sorted in the order of half-life, rather than the order of decay, which would be natural if representing radioactive serieses?
  • using the order of half-life, why are the half-life intervals uneven and chosen arbitrarily rather than say order of 101—103 seconds, then 103—105 seconds?
  • I believe the letter a should be used instead of y for years,
This suggestion has now been implemented. -- Limulus (talk) 22:15, 15 June 2013 (UTC)
  • What is the meaning? Why use this template?

Rursus dixit. (mbork3!) 13:15, 10 May 2013 (UTC)

As the individual responsible for most of the recent edits since [1] I should respond; my primary goal was to make the template as compact as possible; the dispersed keys are a holdover that helps with that. It may be more legible to split them out though. The odd timeframes for the grouping also helped compact the chart as the HLs don't line up nicely with round decimal numbers ;) Someone (perhaps even me! ;) should try making the chart with orders of magnitude though to compare to the current version (e.g. to see how much bigger it is). Decay order would jump back and forth in terms of HL, plus the current version omits short (<10y) HLs. This template is used on pages like Radioactive waste, Long-lived fission product, Nuclear fuel cycle, etc. for which chronological ordering is illustrative. -- Limulus (talk) 10:23, 14 June 2013 (UTC)
With so much information to convey, better drop the "compact" goal; use space. Also, all keys should be explained right? -DePiep (talk) 09:09, 18 June 2013 (UTC)
I've documented the color scheme.
It appears to me that the decay chains (4n+ ...) are column related, not just the HL row they are on now. I suggest put then on top or bottom of their column (as was proposed in the top thread here). Also, the dotted border does not add information, so should be gone.
Same for the yield cells (pink colored)? -DePiep (talk) 12:19, 18 June 2013 (UTC)
Just made "4n+..." into column headers. -DePiep (talk) 01:18, 19 June 2013 (UTC)
It's much better now! Thanks a lot! Rursus dixit. (mbork3!) 07:06, 31 July 2013 (UTC)

The primary intention of this table was to inform discussions of nuclear waste lifetimes and effects, and the information design was prioritized with this purpose. Information important for this purpose was made prominent; information of secondary importance was made accessible on examination but less prominent.

Half-life is one of the most important datums for waste evaluation, which is why it is one of the table axes. Decay series is secondary, and making them columns allows searching for decay product only in the same column which is doable, rather than searching the whole actinide table. For organization by full decay chain sequence, which is less relevant to spent fuel and more relevant to natural ore composition, you click through the links to the Decay chain article. Each purpose has its optimized table or article.

The column/row organization was initially motivated by the fission products, visually expressing similarity/difference/clumping of half-lives more than a linear list of nuclides would. The large gap in fission product half-lives is an important fact that can be strongly highlighted with this arrangement. Then, we might as well use the column organization on the actinide side to convey some secondary data, rather than leaving it random conveying nothing. The need to avoid collisions does lead to a larger number of rows and some scattered whitespace, but more rows allow expressing tighter half-life ranges, and whitespace rather than a uniform array adds to visual readability.

The use of tighter ranges than round powers of 10 is also because each row is about a handful of specific spent fuel nuclides whose half-lives vary by a factor of 3 or less, or sometimes very little. The reader is encouraged to click through to learn about specific nuclides, but we can also convey closer estimates in the row caption. Linking only from the mass number and not from the element symbol was a technical difficulty of the nuclide templates that I was unable to easily overcome, and displaying the element symbols as link text might reduce legibility a bit anyway.

The right-superscript symbols are all secondary data as far as spent fuel is concerned. Transmutation potential is significant mostly because transmutation changes abundances while the fuel is still in use in the reactor. Fissile actinides get consumed over use, including secondarily bred fissile actinides like Pu-241 and Cm-245. Sm-151 is a fission product that is mostly transmuted rather than surviving to spent fuel. All neutron absorbers are relevant to overall neutron balance, but most neutron poison nuclides are stable or short-lived and not practical to represent in this table.

--JWB (talk) 15:52, 5 February 2019 (UTC)


There are 47 isotopes in the list; HLs in years, via their respective pages; FP % yield via templates used on Long-lived fission product:

  • 85Kr 10.776(3) .2180
  • 250Cf 13.08(9) 4n+2
  • 113mCd 14.1(5) .0008
  • 241Pu 14.290(6) 4n+1
  • 244Cm 18.10(2) 4n
  • 227Ac 21.772(3) 4n+3
  • 90Sr 28.90(3) 4.505
  • 243Cm 29.1(1) 4n+3
  • 137Cs 30.1671(13) 6.337
  • 121mSn 43.9(5) .00005
  • 232U 68.9(4) 4n
  • 238Pu 87.7(1) 4n+2
  • 151Sm 96.6(24) .5314
  • 242mAm 141(2) 4n+2
  • 249Cf 351(2) 4n+1
  • 241Am 432.2(7) 4n+1
  • 251Cf 900(40) 4n+3
  • 247Bk 1.38(25)E+3 4n+3
  • 226Ra 1600(7) 4n+2
  • 246Cm 4.76(4)×10^3 4n+2
  • 240Pu 6,561(7) 4n
  • 229Th 7.34(16)×10^3 4n+1
  • 243Am 7,370(40) 4n+3
  • 250Cm 8,300 4n+2
  • 245Cm 8.5(1)×10^3 4n+1
  • 239Pu 2.411(3)×10^4 4n+3
  • 231Pa 3.276(11)×10^4 4n+3
  • 230Th 7.538(30)×10^4 4n+2
  • 236Np 1.54(6)×10^5 4n
  • 233U 1.592(2)×10^5 4n+1
  • 99Tc 2.111(12)×10^5 6.1385
  • 126Sn 2.30(14)×10^5 0.1084
  • 234U 2.455(6)×10^5 4n+2
  • 79Se 3.27(8)×10^5 0.0447
  • 248Cm 3.48(6)×10^5 4n
  • 242Pu 3.75(2)×10^5 4n+2
  • 93Zr 1.53(10)×10^6 5.4575
  • 237Np 2.144(7)×10^6 4n+1
  • 135Cs 2 300 000 6.9110
  • 107Pd 6.5(3)×10^6 1.2499
  • 247Cm 1.56(5)×10^7 4n+3
  • 129I 1.57(4)×10^7 0.8410
  • 236U 2.342(3)×10^7 4n
  • 244Pu 8.00(9)×10^7 4n
  • 235U 7.04(1)×10^8 4n+3
  • 238U 4.468(3)×10^9 4n+2
  • 232Th 1.405(6)×10^10 4n

-- Limulus (talk) 22:14, 15 June 2013 (UTC)

There are 13 isotopes (incl. all 6 med. lived FP of at least a decade) from 10-100y, 4 100-1K, 8 1-10K, 3 10-100K, 8 (incl. 3 long lived FP) 100K-1M, 4 (3 FP) 1-10M, 4 (1 FP) 10-100M, 1 100M-1G, 1 1-10G, 1 10-100G. -- Limulus (talk) 22:43, 15 June 2013 (UTC)

There are 8 4n, 7 4n+1, 10 4n+2, 9 4n+3. -- Limulus (talk) 23:03, 15 June 2013 (UTC)

We could expand the list to include the shortest medium HL FP, which would also add another actinide:

  • 155Eu 4.7611(13) .0803
  • 228Ra 5.75(3) 4n

-- Limulus (talk) 07:51, 18 June 2013 (UTC)

I've been looking at the FP yields and it would convey more info if split into five columns: 6-7%, 4.5-5.5%, 0.5-1.25%, 0.04-0.22% and <0.001% I will implement that later today. -- Limulus (talk) 23:01, 18 June 2013 (UTC)
Will they be column headers? The pink things sure look like a column header. Any other observations you can reply to? -DePiep (talk) 23:58, 18 June 2013 (UTC)
They should be, yes. Focusing on clarity vs compactness is probably best, esp. if it is confusing in its current form. -- Limulus (talk) 04:29, 19 June 2013 (UTC)
We now have two categorisation classes: the half-live in the center column and by the color code/title. I'd say that is OK only if both are commonly used classifications. Otherwise, it is confusing, right? -DePiep (talk) 09:44, 19 June 2013 (UTC)
The isotopes unfortunately don't line up nicely with a series/yield vs power of ten scale (though I've tried to get it pretty close). At the same time, if we do away with the iso color scheme, I think it will be a visually unappealing representation of the data. In my recent edits I've tried to round the numbers used in the ranges a bit, while still demonstrating that there are significant jumps in HL values (e.g. between U235 and U238). -- Limulus (talk) 20:53, 20 June 2013 (UTC)

RE adding more column(s) to the FPs, the trick will be splitting the 0.04–1.25% one. It's fairly easy to do, but results in more whitespace (which I personally don't like). The isotope yield %s are roughly: 1.25, 0.84, 0.53, 0.22, 0.11, 0.08 and 0.045 so splitting in two would have the split either between 0.84 and 0.53, or between 0.53 and 0.22. If in three, between 0.84 and 0.53, and between 0.22 and 0.11 -- Limulus (talk) 21:25, 20 June 2013 (UTC)

I'm previewing the change and it doesn't really do much; the new column has 155Eu, 126Sn and 79Se separated. If we split it to three, that would just separate the medium 85Kr and 151Sm from long 107Pd and 129I without us removing any whitespace via collapsible rows; I think we should keep the FPs at the current total. -- Limulus (talk) 22:44, 20 June 2013 (UTC)
It may even be possible to *combine* the first two FP columns (6-7 + 4.5-5.5)... I will have a look at that in a little bit. -- Limulus (talk) 23:07, 20 June 2013 (UTC)
Ooo... I like it: [2] -- Limulus (talk) 01:44, 21 June 2013 (UTC)


I just noticed that 248Bk is missing. The HL on its page is just listed as ">9 a"; I note [3] states:

"a species of mass 248 in constant abundance in three samples analysed over a period of about 10 months. This was ascribed to an isomer of Bk248 with a half-life greater than 9 y. No growth of Cf248 was detected, and a lower limit for the β− half-life can be set at about 10^4 y. No alpha activity attributable to the new isomer has been detected; the alpha half-life is probably greater than 300 y."

So until higher precision data is referenced, I'll put it in with the 141–351 group using the ref. -- Limulus (talk) 10:41, 26 January 2014 (UTC)

Reactor or bomb production of berkelium is via beta decay of Isotopes of curium which doesn’t happen until Cm-249, producing Bk-249 which has a half-life of less than 1 year. This was a reason why I didn’t originally prioritize berkelium in a template aimed at discussions of spent reactor fuel radioactivity lifetimes. --JWB (talk) 15:13, 5 February 2019 (UTC)

Fission product thermal neutron capture cross sections[edit]

Arranged by barns, via [4] For comparison, the two fertile isotopes 232Th and 238U are 7.337 and 2.683, respectively.

  • 113mCd (not listed specifically for meta; if the same, 2.072E+4)
  • 151Sm 1.514E+4
  • 155Eu 3.760E+3
  • 79Se 5.002E+1
  • 129I 3.040E+1
  • 99Tc 2.280E+1
  • 135Cs 8.663
  • 107Pd 2.008
  • 85Kr 1.662
  • 93Zr 6.950E-1
  • 137Cs 2.501E-1
  • 126Sn 9.003E-2
  • 90Sr 1.500E-2
  • 121mSn (not listed)

I'm going to mark 135Cs through 79Se with ₡ and 155Eu to 113mCd be listed with þ (note Neutron_poison#Accumulating_fission_product_poisons which mentions 83Kr; the above source lists it at at 1.981E+2). -- Limulus (talk) 21:59, 20 June 2013 (UTC)

I think a criterion I had in mind was whether a given nuclide was more likely to decay first or be transmuted first in a reactor. Iodine-129 for example has a half-life of 8 days and I think is much more likely to decay first. --JWB (talk) 14:56, 5 February 2019 (UTC)


Are you sure the information is correct? The table does NOT mark NP-237 (Neptunium) as fissile, but it is fissile and has reputedly even been use as material for a nuclear bomb (in a US demonstration, for evaluating proliferation risks; if I remember correctly it requires an unusually large critical mass). In contrast, it lists NP-236 as fissile, which I strongly doubt. — Preceding unsigned comment added by (talk) 14:02, 5 September 2014 (UTC)

Both 236Np and 237Np are fissile, though the latter is more important as it is longer-lived and much easier to purify. Double sharp (talk) 05:52, 21 June 2016 (UTC)
BTW, in some respects this marking is only theoretical, since only 233U, 235U, 239Pu, and 241Pu among the fissile nuclides have been produced and purified in large enough quantities to be credible risks. Double sharp (talk) 06:14, 21 June 2016 (UTC)
Pu-240 and 242 currently marked as fissile, which makes no sense; removing. -- Limulus (talk) 16:53, 29 September 2018 (UTC)

Fissile means fissioning by thermal neutrons, which are most commonly nuclides with an odd number of neutrons; fissionable includes nuclides that fission with fast neutrons, which are practically all actinides and thus not a distinction to be labeled individually. --JWB (talk) 14:46, 5 February 2019 (UTC)

I do not understand the color code[edit]

What is the meaning of the different colors? BTW, there is zero explanation in the "description" field. -- Wassermaus (talk) 19:44, 29 April 2018 (UTC)

As I recall, the colors are from Template:Isotope_colour_chart -- Limulus (talk) 16:05, 29 September 2018 (UTC)

Naturally occurring[edit]

I take issue with how the template currently lists some isotopes as "naturally occurring" i.e. in the edit history: "Pu-240 is in the decay chain from Pu-244, so it should also be natural" However, if one were to detect Pu-240 in the environment, it would certainly NOT be from the decay of extremely rare primordial Pu-244, but rather from a reactor or bomb test. Same with the Pu-238. cf. crustal abundances of Ra and Pa [5] and imagine how much lower natural Pu must be! Above Bismuth, the 4n+1 decay chain is extinct in the wild, so none of those isotopes should be tagged № either. I will edit in a minor tweak to the legend that it represents "primarily a naturally occurring radioactive material (NORM)". This will conveniently preserve the Pu-244 as it is not typically formed in nuclear reactors. --Limulus (talk) 16:25, 29 September 2018 (UTC)

Yes, thanks, the design intention was to show most common origin today as reactor-bred vs. present in ore, not the theoretical possibility of a couple of surviving primordial atoms of Pu-244. --JWB (talk) 14:49, 5 February 2019 (UTC)