Fission product yield

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Main article: Fission product
Long-lived
fission products
Prop:
Unit:
t½
(Ma)
Yield
(%)
Q *
(keV)
βγ
*
99Tc 0.211 6.1385 294 β
126Sn 0.230 0.1084 4050 βγ
79Se 0.327 0.0447 151 β
93Zr 1.53 5.4575 91 βγ
135Cs 2.3  6.9110 269 β
107Pd 6.5  1.2499 33 β
129I 15.7  0.8410 194 βγ
Hover underlined: more info

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 halflife 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% to 0.4% of fissions, also produces a third light nucleus such as helium-4 (90%) or tritium (7%).

Medium-lived
fission products
Prop:
Unit:
t½
(a)
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 96.6 0.5314 77 β

Mass vs. yield curve[edit]

From Fluoride volatility: 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-85Rb, Sr-90Zr, Ru-106Pd, Sb-125Te, Cs-137Ba, Ce-144Nd, Sm-151Eu, Eu-155Gd visible.
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 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).

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 gives yields for notable radioactive (with halflife 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].

The yields in the table sum to only 45.5522%, including 34.8401% which have halflife 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 halflife less than one year into nonradioactive nuclei.

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

  • 135Xe capturing a neutron and becoming nonradioactive 136Xe, rather than decaying to 135Cs which is radioactive with a halflife of 2.3 million years
  • Nonradioactive 133Cs capturing a neutron and becoming 134Cs which is radioactive with a halflife of 2 years
  • Many of the fission products with mass 147 or greater such as Promethium-147, Samarium-149, Samarium-151, Europium-155 have significant cross sections for neutron capture, so that one heavy fission product atom can undergo multiple successive neutron captures.

Besides fission products, the other types of radioactive products are

Cumulative Fission Yields[edit]

Cumulative Fission Yields for U-235 (% per fission)[3]
Product Thermal Fission Yield Fast Fission Yield 14-MeV Fission Yield
1
1
H
0.00171 ± 0.00018 0.00269 ± 0.00044 0.00264 ± 0.00045
2
1
H
0.00084 ± 0.00015 0.00082 ± 0.00012 0.00081 ± 0.00012
3
1
H
0.0108 ± 0.0004 0.0108 ± 0.0004 0.0174 ± 0.0036
3
2
He
0.0108 ± 0.0004 0.0108 ± 0.0004 0.0174 ± 0.0036
4
2
He
0.1702 ± 0.0049 0.17 ± 0.0049 0.1667 ± 0.0088
85
35
Br
1.304 ± 0.012 1.309 ± 0.043 1.64 ± 0.31
82
36
Kr
0.000285 ± 0.000076 0.00044 ± 0.00016 0.038 ± 0.012
85
36
Kr
0.286 ± 0.021 0.286 ± 0.026 0.47 ± 0.1
85m
36
Kr
1.303 ± 0.012 1.307 ± 0.043 1.65 ± 0.31
90
38
Sr
5.73 ± 0.13 5.22 ± 0.18 4.41 ± 0.18
95
40
Zr
6.502 ± 0.072 6.349 ± 0.083 5.07 ± 0.19
94
41
Nb
0.00000042 ± 0.00000011 2.90 x 10-8 ± 7.70 x 10-9 0.00004 ± 0.000015
95
41
Nb
6.498 ± 0.072 6.345 ± 0.083 5.07 ± 0.19
95m
41
Nb
0.0702 ± 0.0067 0.0686 ± 0.0071 0.0548 ± 0.0072
92
42
Mo
0 ± 0 0 ± 0 0 ± 0
94
42
Mo
8.70 x 10-10 ± 3.20 x 10-10 0 ± 0 6.20 x 10-8 ± 2.50 x 10-8
96
42
Mo
0.00042 ± 0.00015 0.000069 ± 0.000025 0.0033 ± 0.0015
99
42
Mo
6.132 ± 0.092 5.8 ± 0.13 5.02 ± 0.13
99
43
Tc
6.132 ± 0.092 5.8 ± 0.13 5.02 ± 0.13
103
44
Ru
3.103 ± 0.084 3.248 ± 0.042 3.14 ± 0.11
106
44
Ru
0.41 ± 0.011 0.469 ± 0.036 2.15 ± 0.59
106
45
Rh
0.41 ± 0.011 0.469 ± 0.036 2.15 ± 0.59
121m
50
Sn
0.00106 ± 0.00011 0.0039 ± 0.00091 0.142 ± 0.023
122
51
Sb
0.000000366 ± 0.000000098 0.0000004 ± 0.00000014 0.00193 ± 0.00068
124
51
Sb
0.000089 ± 0.000021 0.000112 ± 0.000034 0.027 ± 0.01
125
51
Sb
0.026 ± 0.0014 0.067 ± 0.011 1.42 ± 0.42
132
52
Te
4.276 ± 0.043 4.639 ± 0.065 3.85 ± 0.16
129
53
I
0.706 ± 0.032 1.03 ± 0.26 1.59 ± 0.18
131
53
I
2.878 ± 0.032 3.365 ± 0.054 4.11 ± 0.14
133
53
I
6.59 ± 0.11 6.61 ± 0.13 5.42 ± 0.4
135
53
I
6.39 ± 0.22 6.01 ± 0.18 4.8 ± 1.4
128
54
Xe
0 ± 0 0 ± 0 0.00108 ± 0.00048
130
54
Xe
0.000038 ± 0.0000098 0.000152 ± 0.000055 0.038 ± 0.014
131m
54
Xe
0.0313 ± 0.003 0.0365 ± 0.0031 0.047 ± 0.0049
133
54
Xe
6.6 ± 0.11 6.61 ± 0.13 5.57 ± 0.41
133m
54
Xe
0.189 ± 0.015 0.19 ± 0.015 0.281 ± 0.049
135
54
Xe
6.61 ± 0.22 6.32 ± 0.18 6.4 ± 1.8
135m
54
Xe
1.22 ± 0.12 1.23 ± 0.13 2.17 ± 0.66
134
55
Cs
0.0000121 ± 0.0000032 0.0000279 ± 0.0000073 0.0132 ± 0.0035
137
55
Cs
6.221 ± 0.069 5.889 ± 0.096 5.6 ± 1.3
140
56
Ba
6.314 ± 0.095 5.959 ± 0.048 4.474 ± 0.081
140
57
La
6.315 ± 0.095 5.96 ± 0.048 4.508 ± 0.081
141
58
Ce
5.86 ± 0.15 5.795 ± 0.081 4.44 ± 0.2
144
58
Ce
5.474 ± 0.055 5.094 ± 0.076 3.154 ± 0.038
144
59
Pr
5.474 ± 0.055 5.094 ± 0.076 3.155 ± 0.038
142
60
Nd
6.30 x 10-9 ± 1.70 x 10-9 1.70 x 10-9 ± 4.80 x 10-10 0.0000137 ± 0.0000049
144
60
Nd
5.475 ± 0.055 5.094 ± 0.076 3.155 ± 0.038
147
60
Nd
2.232 ± 0.04 2.148 ± 0.028 1.657 ± 0.045
147
61
Pm
2.232 ± 0.04 2.148 ± 0.028 1.657 ± 0.045
148
61
Pm
5.00 x 10-8 ± 1.70 x 10-8 7.40 x 10-9 ± 2.50 x 10-9 0.0000013 ± 0.00000042
148m
61
Pm
0.000000104 ± 0.000000039 1.78 x 10-8 ± 6.60 x 10-9 0.0000048 ± 0.0000018
149
61
Pm
1.053 ± 0.021 1.064 ± 0.03 0.557 ± 0.09
151
61
Pm
0.4204 ± 0.0071 0.431 ± 0.015 0.388 ± 0.061
148
62
Sm
0.000000149 ± 0.000000041 2.43 x 10-8 ± 6.80 x 10-9 0.0000058 ± 0.0000018
150
62
Sm
0.000061 ± 0.000022 0.0000201 ± 0.0000077 0.00045 ± 0.00018
151
62
Sm
0.4204 ± 0.0071 0.431 ± 0.015 0.388 ± 0.061
153
62
Sm
0.1477 ± 0.0071 0.1512 ± 0.0097 0.23 ± 0.015
151
63
Eu
0.4204 ± 0.0071 0.431 ± 0.015 0.388 ± 0.061
152
63
Eu
3.24 x 10-10 ± 8.50 x 10-11 0 ± 0 3.30 x 10-8 ± 1.10 x 10-8
154
63
Eu
0.000000195 ± 0.000000064 4.00 x 10-8 ± 1.10 x 10-8 0.0000033 ± 0.0000011
155
63
Eu
0.0308 ± 0.0013 0.044 ± 0.01 0.088 ± 0.014


Cumulative Fission Yields for Pu-239 (% per fission)[3]
Product Thermal Fission Yield Fast Fission Yield 14-MeV Fission Yield
1
1
H
0.00408 ± 0.00041 0.00346 ± 0.00057 -
2
1
H
0.00135 ± 0.00019 0.00106 ± 0.00016 -
3
1
H
0.0142 ± 0.0007 0.0142 ± 0.0007 -
3
2
He
0.0142 ± 0.0007 0.0142 ± 0.0007 -
4
2
He
0.2192 ± 0.009 0.219 ± 0.009 -
85
35
Br
0.574 ± 0.026 0.617 ± 0.049 -
82
36
Kr
0.00175 ± 0.0006 0.00055 ± 0.0002 -
85
36
Kr
0.136 ± 0.014 0.138 ± 0.017 -
85m
36
Kr
0.576 ± 0.026 0.617 ± 0.049 -
90
38
Sr
2.013 ± 0.054 2.031 ± 0.057 -
95
40
Zr
4.949 ± 0.099 4.682 ± 0.098 -
94
41
Nb
0.0000168 ± 0.0000045 0.00000255 ± 0.00000069 -
95
41
Nb
4.946 ± 0.099 4.68 ± 0.098 -
95m
41
Nb
0.0535 ± 0.0066 0.0506 ± 0.0062 -
92
42
Mo
0 ± 0 0 ± 0 -
94
42
Mo
3.60 x 10-8 ± 1.30 x 10-8 4.80 x 10-9 ± 1.70 x 10-9 -
96
42
Mo
0.0051 ± 0.0018 0.0017 ± 0.00062 -
99
42
Mo
6.185 ± 0.056 5.82 ± 0.13 -
99
43
Tc
6.184 ± 0.056 5.82 ± 0.13 -
103
44
Ru
6.948 ± 0.083 6.59 ± 0.16 -
106
44
Ru
4.188 ± 0.092 4.13 ± 0.24 -
106
45
Rh
4.188 ± 0.092 4.13 ± 0.24 -
121m
50
Sn
0.0052 ± 0.0011 0.0053 ± 0.0012 -
122
51
Sb
0.000024 ± 0.0000063 0.0000153 ± 0.000005 -
124
51
Sb
0.00228 ± 0.00049 0.00154 ± 0.00043 -
125
51
Sb
0.117 ± 0.015 0.138 ± 0.022 -
132
52
Te
5.095 ± 0.094 4.92 ± 0.32 -
129
53
I
1.407 ± 0.086 1.31 ± 0.13 -
131
53
I
3.724 ± 0.078 4.09 ± 0.12 -
133
53
I
6.97 ± 0.13 6.99 ± 0.33 -
135
53
I
6.33 ± 0.23 6.24 ± 0.22 -
128
54
Xe
0.00000234 ± 0.00000085 0.0000025 ± 0.0000012 -
130
54
Xe
0.00166 ± 0.00056 0.00231 ± 0.00085 -
131m
54
Xe
0.0405 ± 0.004 0.0444 ± 0.0044 -
133
54
Xe
6.99 ± 0.13 7.03 ± 0.33 -
133m
54
Xe
0.216 ± 0.016 0.223 ± 0.021 -
135
54
Xe
7.36 ± 0.24 7.5 ± 0.23 -
135m
54
Xe
1.78 ± 0.21 1.97 ± 0.25 -
134
55
Cs
0.00067 ± 0.00018 0.00115 ± 0.0003 -
137
55
Cs
6.588 ± 0.08 6.35 ± 0.12 -
140
56
Ba
5.322 ± 0.059 5.303 ± 0.074 -
140
57
La
5.333 ± 0.059 5.324 ± 0.075 -
141
58
Ce
5.205 ± 0.073 5.01 ± 0.16 -
144
58
Ce
3.755 ± 0.03 3.504 ± 0.053 -
144
59
Pr
3.756 ± 0.03 3.505 ± 0.053 -
142
60
Nd
0.00000145 ± 0.0000004 0.00000251 ± 0.00000072 -
144
60
Nd
3.756 ± 0.03 3.505 ± 0.053 -
147
60
Nd
2.044 ± 0.039 1.929 ± 0.046 -
147
61
Pm
2.044 ± 0.039 1.929 ± 0.046 -
148
61
Pm
0.0000056 ± 0.0000019 0.000012 ± 0.000004 -
148m
61
Pm
0.0000118 ± 0.0000044 0.000029 ± 0.000011 -
149
61
Pm
1.263 ± 0.032 1.275 ± 0.056 -
151
61
Pm
0.776 ± 0.018 0.796 ± 0.037 -
148
62
Sm
0.0000168 ± 0.0000046 0.000039 ± 0.000011 -
150
62
Sm
0.00227 ± 0.00078 0.0051 ± 0.0019 -
151
62
Sm
0.776 ± 0.018 0.797 ± 0.037 -
153
62
Sm
0.38 ± 0.03 0.4 ± 0.18 -
151
63
Eu
0.776 ± 0.018 0.797 ± 0.037 -
152
63
Eu
0.000000195 ± 0.00000005 0.00000048 ± 0.00000014 -
154
63
Eu
0.000049 ± 0.000012 0.000127 ± 0.000043 -
155
63
Eu
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-85Rb, Sr-90Zr, Ru-106Pd, Sb-125Te, Cs-137Ba, Ce-144Nd, Sm-151Eu, Eu-155Gd visible.

Ordered by mass number[edit]

Yield Isotope
0.0508% selenium-79
0.2717% krypton-85
5.7518% strontium-90 Yttrium-90
6.2956% zirconium-93 Niobium-93
6.0507% technetium-99
0.3912% ruthenium-106
0.1629% palladium-107
0.0003% cadmium-113m
0.0297% antimony-125
0.0236% tin-126 antimony-126
0.9% iodine-129
2.8336% iodine-131
6.7896% caesium-133 caesium-134
6.3333% iodine-135 xenon-135 caesium-135
6.0899% caesium-137
2.2713% promethium-147
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[edit]

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


References
BIPM-5 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.

LNHB Laboratoire National Henri Becquerel, Recommended Data,

http://www.nucleide.org/DDEP_WG/DDEPdata.htm, 16 January 2006.

IAEA-CRP-XG 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.

ENSDF Evaluated Nuclear Structure Data File, http://www-nds.iaea.org/ensdf/, 26 January 2006.
Notes
[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] Branching fractions were adopted from LNHB data.


Ordered by thermal neutron neutron absorption cross section[edit]

Barns Yield Isotope t½ Comment
2,650,000 6.3333% iodine-135 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% gadolinium 157Gd neutron poison, but low yield
40,140 1.0888% samarium-149 149Sm 2nd most important neutron poison
20,600 0.0003% cadmium 113mCd 14.1 y most will be destroyed by neutron capture
15,200 0.4203% samarium-151 151Sm 90 y most will be destroyed by neutron capture
3,950
60,900
0.0330% europium 155Eu 155Gd 4.76 y both neutron poisons
96 2.2713% promethium 147Pm 2.62 y
80 2.8336% iodine-131 131I 8.02 d
29
140
6.7896% caesium-133 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% technetium 99Tc 211 ky candidate for disposal by nuclear transmutation
18 0.6576% iodine-129 129I 15.7 My candidate for disposal by nuclear transmutation
2.7 6.2956% zirconium 93Zr 1.53 My transmutation impractical
1.8 0.1629% palladium 107Pd 6.5 My
1.66 0.2717% krypton 85Kr 10.78 y
0.90 5.7518% strontium 90Sr 28.9 y
0.15 0.3912% ruthenium 106Ru 373.6 d
0.11 6.0899% caesium-137 137Cs 30.17 y
0.0297% antimony 125Sb 2.76 y
0.0236% tin 126Sn 230 ky
0.0508% selenium 79Se 327 ky

References[edit]

  1. ^ fissionyield
  2. ^ "Nuclear fission modes and fragment mass asymmetries in a five-dimensional deformation space". Nature. 409: 785–790. 15 February 2001. doi:10.1038/35057204. Retrieved 12 November 2016. 
  3. ^ a b "Cumulative Fission Yields". www-nds.iaea.org. IAEA. Retrieved 11 November 2016. 

External links[edit]