Long-lived fission products
Nuclide t1⁄2 Yield Q[a 1] βγ
(Ma) (%)[a 2] (keV)
99Tc 0.211 6.1385 294 β
126Sn 0.230 0.1084 4050[a 3] βγ
79Se 0.327 0.0447 151 β
135Cs 1.33  6.9110[a 4] 269 β
93Zr 1.53  5.4575 91 βγ
107Pd 6.5   1.2499 33 β
129I 15.7   0.8410 194 βγ
  1. ^ Decay energy is split among β, neutrino, and γ if any.
  2. ^ Per 65 thermal neutron fissions of 235U and 35 of 239Pu.
  3. ^ Has decay energy 380 keV, but its decay product 126Sb has decay energy 3.67 MeV.
  4. ^ Lower in thermal reactors because 135Xe, its predecessor, readily absorbs neutrons.
Medium-lived
fission products [further explanation needed]
t½
(year) 		Yield
(%) 		Q
(keV) 		βγ
155Eu  4.76 0.0803  252 βγ
85Kr 10.76 0.2180  687 βγ
113mCd 14.1  0.0008  316 β
90Sr 28.9  4.505   2826 β
137Cs 30.23 6.337   1176 βγ
121mSn 43.9  0.00005 390 βγ
151Sm 88.8  0.5314  77 β

Nuclear fission splits a heavy nucleus such as uranium or plutonium into two lighter nuclei, which are called fission products. Yield refers to the fraction of a fission product produced per fission.

Yield can be broken down by:

  1. Individual isotope
  2. Chemical element spanning several isotopes of different mass number but same atomic number.
  3. Nuclei of a given mass number regardless of atomic number. Known as "chain yield" because it represents a decay chain of beta decay.

Isotope and element yields will change as the fission products undergo beta decay, while chain yields do not change after completion of neutron emission by a few neutron-rich initial fission products (delayed neutrons), with half-life measured in seconds.

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 and does not decay. Chain yields do not account for these "shadowed" isotopes; however, they have very low yields (less than a millionth as much as common fission products) because they are far less neutron-rich than the original heavy nuclei.

Yield is usually stated as percentage per fission, so that the total yield percentages sum to 200%. Less often, it is stated as percentage of all fission products, so that the percentages sum to 100%. Ternary fission, about 0.2–0.4% of fissions, also produces a third light nucleus such as helium-4 (90%) or tritium (7%).

Mass vs. yield curve

Fission product yields by mass for thermal neutron fission of U-235, Pu-239, a combination of the two typical of current nuclear power reactors, and U-233 used in the thorium fuel cycle

If a graph of the mass or mole yield of fission products against the atomic number of the fragments is drawn then it has two peaks, one in the area zirconium through to palladium and one at xenon through to neodymium. This is because the fission event causes the nucleus to split in an asymmetric manner,[1] as nuclei closer to magic numbers are more stable.[2]

Yield vs. Z - This is a typical distribution for the fission of uranium. Note that in the calculations used to make this graph the activation of fission products was ignored and the fission was assumed to occur in a single moment rather than a length of time. In this bar chart results are shown for different cooling times (time after fission).

Yield vs Z. Colors indicate fluoride volatility, which is important in nuclear reprocessing: Blue elements have volatile fluorides or are already volatile; green elements do not but have volatile chlorides; red elements have neither, but the elements themselves are volatile at very high temperatures. Yields at 100,1,2,3 years after fission, not considering later neutron capture, fraction of 100% not 200%. Beta decay Kr-85→Rb, Sr-90→Zr, Ru-106→Pd, Sb-125→Te, Cs-137→Ba, Ce-144→Nd, Sm-151→Eu, Eu-155→Gd visible.

Because of the stability of nuclei with even numbers of protons and/or neutrons the curve of yield against element is not a smooth curve. It tends to alternate.

In general, the higher the energy of the state that undergoes nuclear fission, the more likely a symmetric fission is, hence as the neutron energy increases and/or the energy of the fissile atom increases, the valley between the two peaks becomes more shallow; for instance, the curve of yield against mass for Pu-239 has a more shallow valley than that observed for U-235, when the neutrons are thermal neutrons. The curves for the fission of the later actinides tend to make even more shallow valleys. In extreme cases such as 259Fm, only one peak is seen.

Yield is usually expressed relative to number of fissioning nuclei, not the number of fission product nuclei, that is, yields should sum to 200%.

The table in the next section ("Ordered by yield") gives yields for notable radioactive (with half-lives greater than one year, plus iodine-131) fission products, and (the few most absorptive) neutron poison fission products, from thermal neutron fission of U-235 (typical of nuclear power reactors), computed from [1][permanent dead link].

The yields in the table sum to only 45.5522%, including 34.8401% which have half-lives greater than one year:

t½ in years Yield
1 to 5 2.7252%
10 to 100 12.5340%
2 to 300,000 6.1251%
1.5 to 16 million 13.4494%

The remainder and the unlisted 54.4478% decay with half-lives less than one year into nonradioactive nuclei.

This is before accounting for the effects of any subsequent neutron capture; e.g.:

Besides fission products, the other types of radioactive products are

Fission products from U-235

Yield Element Isotope Halflife Comment
6.7896% Caesium 133Cs → 134Cs 2.065 y Neutron capture (29 barns) slowly converts stable 133Cs to 134Cs, which itself is low-yield because beta decay stops at 134Xe; can be further converted (140 barns) to 135Cs.
6.3333% Iodine, xenon 135I → 135Xe 6.57 h Most important neutron poison; neutron capture converts 10–50% of 135Xe to 136Xe; remainder decays (9.14h) to 135Cs (2.3 My).
6.2956% Zirconium 93Zr 1.53 My Long-lived fission product also produced by neutron activation in zircalloy cladding.
6.1% Molybdenum 99Mo 65.94 h Its daughter nuclide 99mTc is important in medical diagnosing.
6.0899% Caesium 137Cs 30.17 y Source of most of the decay heat from years to decades after irradiation, together with 90
Sr.
6.0507% Technetium 99Tc 211 ky Candidate for disposal by nuclear transmutation.
5.7518% Strontium 90Sr 28.9 y Source of much of the decay heat together with 137
Cs on the timespan of years to decades after irradiation. Formerly used in radioisotope thermoelectric generators.
2.8336% Iodine 131I 8.02 d Reason for the use of potassium iodide tablets after nuclear accidents or nuclear bomb explosions.
2.2713% Promethium 147Pm 2.62 y beta decays to very long lived Samarium-147 (half life>age of the universe); has seen some use in radioisotope thermoelectric generators
1.0888% Samarium 149Sm Observationally stable 2nd most significant neutron poison.
0.9%[3] Iodine 129I 15.7 My Long-lived fission product. Candidate for disposal by nuclear transmutation.
0.4203% Samarium 151Sm 90 y Neutron poison; most will be converted to stable 152Sm.
0.3912% Ruthenium 106Ru 373.6 d ruthenium tetroxide is volatile and chemically aggressive; daughter nuclide 106
Rh decays quickly to stable 106
Pd
0.2717% Krypton 85Kr 10.78 y noble gas; has some uses in industry to detect fine cracks in materials via autoradiography
0.1629% Palladium 107Pd 6.5 My Long-lived fission product; hampers extraction of stable isotopes of platinum group metals for use due to chemical similarity.
0.0508% Selenium 79Se 327 ky
0.0330% Europium, gadolinium 155Eu → 155Gd 4.76 y Both neutron poisons, most will be destroyed while fuel still in use.
0.0297% Antimony 125Sb 2.76 y
0.0236% Tin 126Sn 230 ky
0.0065% Gadolinium 157Gd stable Neutron poison.
0.0003% Cadmium 113mCd 14.1 y Neutron poison, most will be destroyed while fuel still in use.
Yields at 100,1,2,3 years after fission, probably of Pu-239 not U-235 because left hump is shifted right, not considering later neutron capture, fraction of 100% not 200%. Beta decay Kr-85→Rb, Sr-90→Zr, Ru-106→Pd, Sb-125→Te, Cs-137→Ba, Ce-144→Nd, Sm-151→Eu, Eu-155→Gd visible.

Cumulative fission yields

Cumulative fission yields give the amounts of nuclides produced either directly in the fission or by decay of other nuclides.

Cumulative fission yields per fission for U-235 (%)[4]
Product Thermal fission yield Fast fission yield 14-MeV fission yield
1
1H
 0.00171 ± 0.00018 0.00269 ± 0.00044 0.00264 ± 0.00045
2
1H
 0.00084 ± 0.00015 0.00082 ± 0.00012 0.00081 ± 0.00012
3
1H
 0.0108 ± 0.0004 0.0108 ± 0.0004 0.0174 ± 0.0036
3
2He
 0.0108 ± 0.0004 0.0108 ± 0.0004 0.0174 ± 0.0036
4
2He
 0.1702 ± 0.0049 0.17 ± 0.0049 0.1667 ± 0.0088
85
35Br
 1.304 ± 0.012 1.309 ± 0.043 1.64 ± 0.31
82
36Kr
 0.000285 ± 0.000076 0.00044 ± 0.00016 0.038 ± 0.012
85
36Kr
 0.286 ± 0.021 0.286 ± 0.026 0.47 ± 0.1
85m
36Kr
 1.303 ± 0.012 1.307 ± 0.043 1.65 ± 0.31
90
38Sr
 5.73 ± 0.13 5.22 ± 0.18 4.41 ± 0.18
95
40Zr
 6.502 ± 0.072 6.349 ± 0.083 5.07 ± 0.19
94
41Nb
 0.00000042 ± 0.00000011 2.90±0.770 × 10−8 0.00004 ± 0.000015
95
41Nb
 6.498 ± 0.072 6.345 ± 0.083 5.07 ± 0.19
95m
41Nb
 0.0702 ± 0.0067 0.0686 ± 0.0071 0.0548 ± 0.0072
92
42Mo
 0 ± 0 0 ± 0 0 ± 0
94
42Mo
 8.70 × 10−10 ± 3.20 × 10−10 0 ± 0 6.20 × 10−8 ± 2.50 × 10−8
96
42Mo
 0.00042 ± 0.00015 0.000069 ± 0.000025 0.0033 ± 0.0015
99
42Mo
 6.132 ± 0.092 5.8 ± 0.13 5.02 ± 0.13
99
43Tc
 6.132 ± 0.092 5.8 ± 0.13 5.02 ± 0.13
103
44Ru
 3.103 ± 0.084 3.248 ± 0.042 3.14 ± 0.11
106
44Ru
 0.41 ± 0.011 0.469 ± 0.036 2.15 ± 0.59
106
45Rh
 0.41 ± 0.011 0.469 ± 0.036 2.15 ± 0.59
121m
50Sn
 0.00106 ± 0.00011 0.0039 ± 0.00091 0.142 ± 0.023
122
51Sb
 0.000000366 ± 0.000000098 0.0000004 ± 0.00000014 0.00193 ± 0.00068
124
51Sb
 0.000089 ± 0.000021 0.000112 ± 0.000034 0.027 ± 0.01
125
51Sb
 0.026 ± 0.0014 0.067 ± 0.011 1.42 ± 0.42
132
52Te
 4.276 ± 0.043 4.639 ± 0.065 3.85 ± 0.16
129
53I
 0.706 ± 0.032 1.03 ± 0.26 1.59 ± 0.18
131
53I
 2.878 ± 0.032 3.365 ± 0.054 4.11 ± 0.14
133
53I
 6.59 ± 0.11 6.61 ± 0.13 5.42 ± 0.4
135
53I
 6.39 ± 0.22 6.01 ± 0.18 4.8 ± 1.4
128
54Xe
 0 ± 0 0 ± 0 0.00108 ± 0.00048
130
54Xe
 0.000038 ± 0.0000098 0.000152 ± 0.000055 0.038 ± 0.014
131m
54Xe
 0.0313 ± 0.003 0.0365 ± 0.0031 0.047 ± 0.0049
133
54Xe
 6.6 ± 0.11 6.61 ± 0.13 5.57 ± 0.41
133m
54Xe
 0.189 ± 0.015 0.19 ± 0.015 0.281 ± 0.049
135
54Xe
 6.61 ± 0.22 6.32 ± 0.18 6.4 ± 1.8
135m
54Xe
 1.22 ± 0.12 1.23 ± 0.13 2.17 ± 0.66
134
55Cs
 0.0000121 ± 0.0000032 0.0000279 ± 0.0000073 0.0132 ± 0.0035
137
55Cs
 6.221 ± 0.069 5.889 ± 0.096 5.6 ± 1.3
140
56Ba
 6.314 ± 0.095 5.959 ± 0.048 4.474 ± 0.081
140
57La
 6.315 ± 0.095 5.96 ± 0.048 4.508 ± 0.081
141
58Ce
 5.86 ± 0.15 5.795 ± 0.081 4.44 ± 0.2
144
58Ce
 5.474 ± 0.055 5.094 ± 0.076 3.154 ± 0.038
144
59Pr
 5.474 ± 0.055 5.094 ± 0.076 3.155 ± 0.038
142
60Nd
 6.30 × 10−9 ± 1.70 × 10−9 1.70 × 10−9 ± 4.80 × 10−10 0.0000137 ± 0.0000049
144
60Nd
 5.475 ± 0.055 5.094 ± 0.076 3.155 ± 0.038
147
60Nd
 2.232 ± 0.04 2.148 ± 0.028 1.657 ± 0.045
147
61Pm
 2.232 ± 0.04 2.148 ± 0.028 1.657 ± 0.045
148
61Pm
 5.00 × 10−8 ± 1.70 × 10−8 7.40 × 10−9 ± 2.50 × 10−9 0.0000013 ± 0.00000042
148m
61Pm
 0.000000104 ± 0.000000039 1.78 × 10−8 ± 6.60 × 10−9 0.0000048 ± 0.0000018
149
61Pm
 1.053 ± 0.021 1.064 ± 0.03 0.557 ± 0.09
151
61Pm
 0.4204 ± 0.0071 0.431 ± 0.015 0.388 ± 0.061
148
62Sm
 0.000000149 ± 0.000000041 2.43 × 10−8 ± 6.80 × 10−9 0.0000058 ± 0.0000018
150
62Sm
 0.000061 ± 0.000022 0.0000201 ± 0.0000077 0.00045 ± 0.00018
151
62Sm
 0.4204 ± 0.0071 0.431 ± 0.015 0.388 ± 0.061
153
62Sm
 0.1477 ± 0.0071 0.1512 ± 0.0097 0.23 ± 0.015
151
63Eu
 0.4204 ± 0.0071 0.431 ± 0.015 0.388 ± 0.061
152
63Eu
 3.24 × 10−10 ± 8.50 × 10−11 0 ± 0 3.30 × 10−8 ± 1.10 × 10−8
154
63Eu
 0.000000195 ± 0.000000064 4.00 × 10−8 ± 1.10 × 10−8 0.0000033 ± 0.0000011
155
63Eu
 0.0308 ± 0.0013 0.044 ± 0.01 0.088 ± 0.014
Cumulative fission yield per fission for Pu-239 (%)[4]
Product Thermal fission yield Fast fission yield 14-MeV fission yield
1
1H
 0.00408 ± 0.00041 0.00346 ± 0.00057 -
2
1H
 0.00135 ± 0.00019 0.00106 ± 0.00016 -
3
1H
 0.0142 ± 0.0007 0.0142 ± 0.0007 -
3
2He
 0.0142 ± 0.0007 0.0142 ± 0.0007 -
4
2He
 0.2192 ± 0.009 0.219 ± 0.009 -
85
35Br
 0.574 ± 0.026 0.617 ± 0.049 -
82
36Kr
 0.00175 ± 0.0006 0.00055 ± 0.0002 -
85
36Kr
 0.136 ± 0.014 0.138 ± 0.017 -
85m
36Kr
 0.576 ± 0.026 0.617 ± 0.049 -
90
38Sr
 2.013 ± 0.054 2.031 ± 0.057 -
95
40Zr
 4.949 ± 0.099 4.682 ± 0.098 -
94
41Nb
 0.0000168 ± 0.0000045 0.00000255 ± 0.00000069 -
95
41Nb
 4.946 ± 0.099 4.68 ± 0.098 -
95m
41Nb
 0.0535 ± 0.0066 0.0506 ± 0.0062 -
92
42Mo
 0 ± 0 0 ± 0 -
94
42Mo
 3.60 × 10−8 ± 1.30 × 10−8 4.80 × 10−9 ± 1.70 × 10−9 -
96
42Mo
 0.0051 ± 0.0018 0.0017 ± 0.00062 -
99
42Mo
 6.185 ± 0.056 5.82 ± 0.13 -
99
43Tc
 6.184 ± 0.056 5.82 ± 0.13 -
103
44Ru
 6.948 ± 0.083 6.59 ± 0.16 -
106
44Ru
 4.188 ± 0.092 4.13 ± 0.24 -
106
45Rh
 4.188 ± 0.092 4.13 ± 0.24 -
121m
50Sn
 0.0052 ± 0.0011 0.0053 ± 0.0012 -
122
51Sb
 0.000024 ± 0.0000063 0.0000153 ± 0.000005 -
124
51Sb
 0.00228 ± 0.00049 0.00154 ± 0.00043 -
125
51Sb
 0.117 ± 0.015 0.138 ± 0.022 -
132
52Te
 5.095 ± 0.094 4.92 ± 0.32 -
129
53I
 1.407 ± 0.086 1.31 ± 0.13 -
131
53I
 3.724 ± 0.078 4.09 ± 0.12 -
133
53I
 6.97 ± 0.13 6.99 ± 0.33 -
135
53I
 6.33 ± 0.23 6.24 ± 0.22 -
128
54Xe
 0.00000234 ± 0.00000085 0.0000025 ± 0.0000012 -
130
54Xe
 0.00166 ± 0.00056 0.00231 ± 0.00085 -
131m
54Xe
 0.0405 ± 0.004 0.0444 ± 0.0044 -
133
54Xe
 6.99 ± 0.13 7.03 ± 0.33 -
133m
54Xe
 0.216 ± 0.016 0.223 ± 0.021 -
135
54Xe
 7.36 ± 0.24 7.5 ± 0.23 -
135m
54Xe
 1.78 ± 0.21 1.97 ± 0.25 -
134
55Cs
 0.00067 ± 0.00018 0.00115 ± 0.0003 -
137
55Cs
 6.588 ± 0.08 6.35 ± 0.12 -
140
56Ba
 5.322 ± 0.059 5.303 ± 0.074 -
140
57La
 5.333 ± 0.059 5.324 ± 0.075 -
141
58Ce
 5.205 ± 0.073 5.01 ± 0.16 -
144
58Ce
 3.755 ± 0.03 3.504 ± 0.053 -
144
59Pr
 3.756 ± 0.03 3.505 ± 0.053 -
142
60Nd
 0.00000145 ± 0.0000004 0.00000251 ± 0.00000072 -
144
60Nd
 3.756 ± 0.03 3.505 ± 0.053 -
147
60Nd
 2.044 ± 0.039 1.929 ± 0.046 -
147
61Pm
 2.044 ± 0.039 1.929 ± 0.046 -
148
61Pm
 0.0000056 ± 0.0000019 0.000012 ± 0.000004 -
148m
61Pm
 0.0000118 ± 0.0000044 0.000029 ± 0.000011 -
149
61Pm
 1.263 ± 0.032 1.275 ± 0.056 -
151
61Pm
 0.776 ± 0.018 0.796 ± 0.037 -
148
62Sm
 0.0000168 ± 0.0000046 0.000039 ± 0.000011 -
150
62Sm
 0.00227 ± 0.00078 0.0051 ± 0.0019 -
151
62Sm
 0.776 ± 0.018 0.797 ± 0.037 -
153
62Sm
 0.38 ± 0.03 0.4 ± 0.18 -
151
63Eu
 0.776 ± 0.018 0.797 ± 0.037 -
152
63Eu
 0.000000195 ± 0.00000005 0.00000048 ± 0.00000014 -
154
63Eu
 0.000049 ± 0.000012 0.000127 ± 0.000043 -
155
63Eu
 0.174 ± 0.03 0.171 ± 0.054 -
JEFF-3.1

Joint Evaluated Fission and Fusion File, Incident-neutron data, http://www-nds.iaea.org/exfor/endf00.htm, 2 October 2006; see also A. Koning, R. Forrest, M. Kellett, R. Mills, H. Henriksson, Y. Rugama, The JEFF-3.1 Nuclear Data Library, JEFF Report 21, OECD/NEA, Paris, France, 2006, ISBN 92-64-02314-3.

Yields at 100,1,2,3 years after fission, probably of Pu-239 not U-235 because left hump is shifted right, not considering later neutron capture, fraction of 100% not 200%. Beta decay Kr-85→Rb, Sr-90→Zr, Ru-106→Pd, Sb-125→Te, Cs-137→Ba, Ce-144→Nd, Sm-151→Eu, Eu-155→Gd visible.

Ordered by mass number

Decays, even if lengthy, are given down to the stable nuclide.

Decays with half lives longer than a century are marked with a single asterisk (*), while decays with a half life longer than a hundred million years are marked with two asterisks (**).

Yield Isotope
0.0508% selenium-79→* bromine-79
0.2717% krypton-85→ rubidium-85
5.7518% strontium-90 → yttrium-90→ zirconium-90
6.2956% zirconium-93 →* niobium-93
6.0507% technetium-99→* ruthenium-99
0.3912% ruthenium-106→ rhodium-106→ palladium-106
0.1629% palladium-107→* silver-107
0.0003% cadmium-113m→ cadmium-113 (essentially stable)→** indium-113
0.0297% antimony-125→ tellurium-125m→ tellurium-125
0.0236% tin-126 →* antimony-126→ tellurium-126
0.9% iodine-129→* xenon-129
2.8336% iodine-131→ xenon-131
6.7896% caesium-133 → caesium-134→ barium-134
6.3333% iodine-135 → xenon-135 → caesium-135→* barium-135
6.3333% iodine-135 → xenon-135 → xenon-136 (essentially stable)→** barium-136
6.0899% caesium-137→ barium-137
2.2713% promethium-147→ samarium-147→* neodymium-143
1.0888% samarium-149
0.4203% samarium-151
0.0330% europium-155 → gadolinium-155
0.0065% gadolinium-157

Half lives, decay modes, and branching fractions

Half-lives and decay branching fractions for fission products[5]
Nuclide Half-life Decay mode Branching fraction Source Notes
85
35Br
 2.9 ± 0.06 m β− 1.0 [6] [a]
85
36Kr
 10.752 ± 0.023 y β− 1.0 [7]
85m
36Kr
 4.48 ± 0.008 h IT 0.214 ± 0.005 [6]
β− 0.786 ± 0.005
90
38Sr
 28.8 ± 0.07 y β− 1.0 [8]
95
40Zr
 64.032 ± 0.006 d β− 1.0 [8]
94
41Nb
 (7.3 ± 0.9) × 106 d β− 1.0 [9]
95m
41Nb
 3.61 ± 0.03 d β− 0.025 ± 0.001 [8] [b]
IT 0.975 ± 0.001
95
41Nb
 34.985 ± 0.012 d β− 1.0 [9]
99
43Tc
 (2.111 ± 0.012) × 105 y β− 1.0 [6]
103
44Ru
 39.247 ± 0.013 d β− 1.0 [9]
106
44Ru
 1.018 ± 0.005 y β− 1.0 [9]
106
45Rh
 30.1 ± 0.3 s β− 1.0 [9]
121m
50Sn
 55 ± 5 y β− 0.224 ± 0.02 [6]
IT 0.776 ± 0.02
122
51Sb
 2.7238 ± 0.0002 d EC 0.0241 ± 0.0012 [6]
β− 0.9759 ± 0.0012
124
51Sb
 60.2 ± 0.03 d β− 1.0 [6]
125
51Sb
 2.7584 ± 0.0006 y β− 1.0 [9]
129
53I
 (5.89 ± 0.23) × 109 d β− 1.0 [9]
131
53I
 8.0233 ± 0.0019 d β− 1.0 [7]
133
53I
 20.87 ± 0.08 h β− 1.0 [8] [c]
135
53I
 6.57 ± 0.02 h β− 1.0 [6]
131m
54Xe
 11.930 ± 0.016 d IT 1.0 [7]
133
54Xe
 5.243 ± 0.001 d β− 1.0 [6]
133m
54Xe
 2.19 ± 0.01 d IT 1.0 [6]
135
54Xe
 9.14 ± 0.02 h β− 1.0 [6]
135m
54Xe
 15.29 ± 0.05 m β− 0.003 ± 0.003 [6] [d]
IT 0.997 ± 0.003
134
55Cs
 2.063 ± 0.003 y EC 0.000003 ± 0.000001 [9] [e]
β− 0.999997 ± 0.000001
137
55Cs
 30.05 ± 0.08 y β− 1.0 [9]
140
56Ba
 12.753 ± 0.004 d β− 1.0 [7]
140
57La
 1.67850 ± 0.00017 d β− 1.0 [7]
141
58Ce
 32.508 ± 0.010 d β− 1.0 [8]
144
58Ce
 285.1 ± 0.6 d β− 1.0 [9]
144
59Pr
 17.28 ± 0.05 m β− 1.0 [6]
147
60Nd
 10.98 ± 0.01 d β− 1.0 [6]
147
61Pm
 2.6234 ± 0.0002 y β− 1.0 [6]
148m
61Pm
 41.29 ± 0.11 d IT 0.042 ± 0.007 [6]
β− 0.958 ± 0.007
148
61Pm
 5.368 ± 0.002 d β− 1.0 [6]
149
61Pm
 2.2117 ± 0.0021 d β− 1.0 [6]
151
61Pm
 1.1833 ± 0.0017 d β− 1.0 [6]
151
62Sm
 90 ± 6 y β− 1.0 [6]
153
62Sm
 1.938 ± 0.010 d β− 1.0 [9]
152
63Eu
 (4.941 ± 0.007) × 103 d β− 0.279 ± 0.003 [9] [f]
EC 0.721 ± 0.003
154
63Eu
 (3.1381 ± 0.0014) × 103 d EC 0.00018 ± 0.00013 [9] [f]
β− 0.99982 ± 0.00013
155
63Eu
 4.753 ± 0.016 y β− 1.0 [9]
  1. ^ β− decay branches of 0.9982 ± 0.0002 to Kr-85m and 0.0018 ± 0.0002 to Kr-85.
  2. ^ ENSDF branching fractions: 0.944 ± 0.007 for IT and 0.056 ± 0.007 for β−.
  3. ^ β− decay branch of 0.0288 ± 0.0002 to Xe-133m.
  4. ^ Branching fractions were averaged from ENSDF database.
  5. ^ Branching fractions were adopted from ENSDF database.
  6. ^ a b Branching fractions were adopted from LNHB data.

Ordered by thermal neutron absorption cross section

Barns Yield Isotope t½ Comment
2,650,000 6.3333% 135I → 135Xe 6.57 h Most important neutron poison; neutron capture rapidly converts 135Xe to 136Xe; remainder decays (9.14 h) to 135Cs (2.3 My).
254,000 0.0065% 157Gd ∞ Neutron poison, but low yield.
40,140 1.0888% 149Sm ∞ 2nd most important neutron poison.
20,600 0.0003% 113mCd 14.1 y Most will be destroyed by neutron capture.
15,200 0.4203% 151Sm 90 y Most will be destroyed by neutron capture.
3,950
60,900		 0.0330% 155Eu → 155Gd 4.76 y Both neutron poisons.
96 2.2713% 147Pm 2.62 y Suitable for radioisotope thermoelectric generators with annual or semi-annual refueling.
80 2.8336% 131I 8.02 d
29
140		 6.7896% 133Cs → 134Cs ∞
2.065 y		 Neutron capture converts a few percent of nonradioactive 133Cs to 134Cs, which has very low direct yield because beta decay stops at 134Xe; further capture will add to long-lived 135Cs.
20 6.0507% 99Tc 211 ky Candidate for disposal by nuclear transmutation.
18 0.6576% 129I 15.7 My Candidate for disposal by nuclear transmutation.
2.7 6.2956% 93Zr 1.53 My Transmutation impractical.
1.8 0.1629% 107Pd 6.5 My
1.66 0.2717% 85Kr 10.78 y
0.90 5.7518% 90Sr 28.9 y
0.15 0.3912% 106Ru 373.6 d
0.11 6.0899% 137Cs 30.17 y
0.0297% 125Sb 2.76 y
0.0236% 126Sn 230 ky
0.0508% 79Se 327 ky

References

  1. ^ "fissionyield". Archived from the original on 2007-05-28. Retrieved 2007-06-10.
  2. ^ Möller, P; Madland, DG; Sierk, AJ; Iwamoto, A (15 February 2001). "Nuclear fission modes and fragment mass asymmetries in a five-dimensional deformation space". Nature. 409 (6822): 785–790. Bibcode:2001Natur.409..785M. doi:10.1038/35057204. PMID 11236985. S2CID 9754793.
  3. ^ Purkayastha, B. C., and G. R. Martin. "The yields of 129I in natural and in neutron-induced fission of uranium." Canadian Journal of Chemistry 34.3 (1956): 293-300.
  4. ^ a b "Cumulative Fission Yields". www-nds.iaea.org. IAEA. Retrieved 11 November 2016.
  5. ^ "Half-lives and decay branching fractions for activation products". www-nds.iaea.org. IAEA. Retrieved 11 November 2016.
  6. ^ a b c d e f g h i j k l m n o p q r s Evaluated Nuclear Structure Data File, http://www-nds.iaea.org/ensdf/, 26 January 2006.
  7. ^ a b c d e M.-M. Bé, V. Chisté, C. Dulieu, E. Browne, V. Chechev, N. Kuzmenko, R. Helmer, A. Nichols, E. Schönfeld, R. Dersch, Monographie BIPM-5, Table of Radionuclides, Vol. 2 - A = 151 to 242, 2004.
  8. ^ a b c d e Laboratoire National Henri Becquerel, Recommended Data, http://www.nucleide.org/DDEP_WG/DDEPdata.htm, 16 January 2006.
  9. ^ a b c d e f g h i j k l m n M.-M. Bé, V.P. Chechev, R. Dersch, O.A.M. Helene, R.G. Helmer, M. Herman, S. Hlavác, A. Marcinkowski, G.L. Molnár, A.L. Nichols, E. Schönfeld, V.R. Vanin, M.J. Woods, IAEA CRP "Update of X-ray and Gamma-ray Decay Data Standards for Detector Calibration and Other Applications", IAEA Scientific and Technical Information report STI/PUB/1287, May 2007, International Atomic Energy Agency, Vienna, Austria, ISBN 92-0-113606-4.

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