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Isotopes of uranium
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<h2 id="list-of-isotopes">List of isotopes</h2> <table><tbody><tr><th rowspan="2">Nuclide<a class="footnote-ref" id="fnref:2" href="#fn:2"><sup>2</sup></a></th><th rowspan="2">Historicname</th><th rowspan="1"><a href="/facts/Atomic_number/bgAr581S"><i>Z</i></a></th><th rowspan="1"><a href="/facts/Neutron_number/eNtwGnVL"><i>N</i></a></th><th rowspan="1"><a href="/facts/Atomic_mass/J1FJY9MV">Isotopic mass</a> (<a href="/facts/Dalton_(unit)/IMATU3vf">Da</a>)<a class="footnote-ref" id="fnref:3" href="#fn:3"><sup>3</sup></a><a class="footnote-ref" id="fnref:4" href="#fn:4"><sup>4</sup></a><a class="footnote-ref" id="fnref:5" href="#fn:5"><sup>5</sup></a></th><th rowspan="2"><a href="/facts/Half-life/kGVH8BAB">Half-life</a><a class="footnote-ref" id="fnref:6" href="#fn:6"><sup>6</sup></a></th><th rowspan="2"><a href="/facts/Decay_mode/Ya6FVjt4">Decaymode</a><a class="footnote-ref" id="fnref:7" href="#fn:7"><sup>7</sup></a><a class="footnote-ref" id="fnref:8" href="#fn:8"><sup>8</sup></a></th><th rowspan="2"><a href="/facts/Decay_product/hT0obfLv">Daughterisotope</a><a class="footnote-ref" id="fnref:9" href="#fn:9"><sup>9</sup></a><a class="footnote-ref" id="fnref:10" href="#fn:10"><sup>10</sup></a></th><th rowspan="2"><a href="/facts/Spin_(particle_physics)/4Jvp7e8P">Spin</a> and<a href="/facts/Parity_(physics)/emSbJ4hD">parity</a><a class="footnote-ref" id="fnref:11" href="#fn:11"><sup>11</sup></a><a class="footnote-ref" id="fnref:12" href="#fn:12"><sup>12</sup></a><a class="footnote-ref" id="fnref:13" href="#fn:13"><sup>13</sup></a></th><th colspan="2"><a href="/facts/Natural_abundance/dGjaAwc9">Natural abundance</a> (mole fraction)</th></tr><tr><th colspan="3">Excitation energy<a class="footnote-ref" id="fnref:14" href="#fn:14"><sup>14</sup></a></th><th>Normal proportion<a class="footnote-ref" id="fnref:15" href="#fn:15"><sup>15</sup></a></th><th>Range of variation</th></tr><tr><td>214U<a class="footnote-ref" id="fnref:16" href="#fn:16"><sup>16</sup></a></td><td></td><td>92</td><td>122</td><td></td><td>0.52+0.95−0.21 ms</td><td><a href="/facts/Alpha_decay/rCsHNIUE">α</a></td><td>210Th</td><td>0+</td><td></td><td></td></tr><tr><td rowspan="2">215U</td><td rowspan="2"></td><td rowspan="2">92</td><td rowspan="2">123</td><td rowspan="2">215.026720(11)</td><td rowspan="2">1.4(9) ms</td><td>α</td><td>211Th</td><td rowspan="2">5/2−#</td><td rowspan="2"></td><td rowspan="2"></td></tr><tr><td><a href="/facts/Beta_plus_decay/psWp4bJT">β+</a>?</td><td>215Pa</td></tr><tr><td>216U<a class="footnote-ref" id="fnref:17" href="#fn:17"><sup>17</sup></a></td><td></td><td>92</td><td>124</td><td>216.024760(30)</td><td>2.25+0.63−0.40 ms</td><td>α</td><td>212Th</td><td>0+</td><td></td><td></td></tr><tr><td>216mU</td><td></td><td colspan="3">2206 keV</td><td>0.89+0.24−0.16 ms</td><td>α</td><td>212Th</td><td>8+</td><td></td><td></td></tr><tr><td rowspan="2">217U<a class="footnote-ref" id="fnref:18" href="#fn:18"><sup>18</sup></a></td><td rowspan="2"></td><td rowspan="2">92</td><td rowspan="2">125</td><td rowspan="2">217.024660(86)#</td><td rowspan="2">19.3+13.3−5.6 ms</td><td>α</td><td>213Th</td><td rowspan="2">(1/2−)</td><td rowspan="2"></td><td rowspan="2"></td></tr><tr><td>β+?</td><td>217Pa</td></tr><tr><td>218U<a class="footnote-ref" id="fnref:19" href="#fn:19"><sup>19</sup></a></td><td></td><td>92</td><td>126</td><td>218.023505(15)</td><td>650+80−70 μs</td><td>α</td><td>214Th</td><td>0+</td><td></td><td></td></tr><tr><td rowspan="2">218mU</td><td rowspan="2"></td><td rowspan="2" colspan="3">2117 keV</td><td rowspan="2">390+60−50 μs</td><td>α</td><td>214Th</td><td rowspan="2">8+</td><td rowspan="2"></td><td rowspan="2"></td></tr><tr><td>IT?</td><td>218U</td></tr><tr><td rowspan="2">219U</td><td rowspan="2"></td><td rowspan="2">92</td><td rowspan="2">127</td><td rowspan="2">219.025009(14)</td><td rowspan="2">60(7) μs</td><td>α</td><td>215Th</td><td rowspan="2">(9/2+)</td><td rowspan="2"></td><td rowspan="2"></td></tr><tr><td>β+?</td><td>219Pa</td></tr><tr><td rowspan="2">221U</td><td rowspan="2"></td><td rowspan="2">92</td><td rowspan="2">129</td><td rowspan="2">221.026323(77)</td><td rowspan="2">0.66(14) μs</td><td>α</td><td>217Th</td><td rowspan="2">(9/2+)</td><td rowspan="2"></td><td rowspan="2"></td></tr><tr><td>β+?</td><td>221Pa</td></tr><tr><td rowspan="2">222U</td><td rowspan="2"></td><td rowspan="2">92</td><td rowspan="2">130</td><td rowspan="2">222.026058(56)</td><td rowspan="2">4.7(7) μs</td><td>α</td><td>218Th</td><td rowspan="2">0+</td><td rowspan="2"></td><td rowspan="2"></td></tr><tr><td>β+?</td><td>222Pa</td></tr><tr><td rowspan="2">223U</td><td rowspan="2"></td><td rowspan="2">92</td><td rowspan="2">131</td><td rowspan="2">223.027961(63)</td><td rowspan="2">65(12) μs</td><td>α</td><td>219Th</td><td rowspan="2">7/2+#</td><td rowspan="2"></td><td rowspan="2"></td></tr><tr><td>β+?</td><td>223Pa</td></tr><tr><td rowspan="2">224U</td><td rowspan="2"></td><td rowspan="2">92</td><td rowspan="2">132</td><td rowspan="2">224.027636(16)</td><td rowspan="2">396(17) μs</td><td>α</td><td>220Th</td><td rowspan="2">0+</td><td rowspan="2"></td><td rowspan="2"></td></tr><tr><td>β+?</td><td>224Pa</td></tr><tr><td>225U</td><td></td><td>92</td><td>133</td><td>225.029385(11)</td><td>62(4) ms</td><td>α</td><td>221Th</td><td>5/2+#</td><td></td><td></td></tr><tr><td>226U</td><td></td><td>92</td><td>134</td><td>226.029339(12)</td><td>269(6) ms</td><td>α</td><td>222Th</td><td>0+</td><td></td><td></td></tr><tr><td rowspan="2">227U</td><td rowspan="2"></td><td rowspan="2">92</td><td rowspan="2">135</td><td rowspan="2">227.0311811(91)</td><td rowspan="2">1.1(1) min</td><td>α</td><td>223Th</td><td rowspan="2">(3/2+)</td><td rowspan="2"></td><td rowspan="2"></td></tr><tr><td>β+?</td><td>227Pa</td></tr><tr><td rowspan="2">228U</td><td rowspan="2"></td><td rowspan="2">92</td><td rowspan="2">136</td><td rowspan="2">228.031369(14)</td><td rowspan="2">9.1(2) min</td><td>α (97.5%)</td><td>224Th</td><td rowspan="2">0+</td><td rowspan="2"></td><td rowspan="2"></td></tr><tr><td><a href="/facts/Electron_capture/EIccoV1u">EC</a> (2.5%)</td><td>228Pa</td></tr><tr><td rowspan="2">229U</td><td rowspan="2"></td><td rowspan="2">92</td><td rowspan="2">137</td><td rowspan="2">229.0335060(64)</td><td rowspan="2">57.8(5) min</td><td>β+ (80%)</td><td>229Pa</td><td rowspan="2">(3/2+)</td><td rowspan="2"></td><td rowspan="2"></td></tr><tr><td>α (20%)</td><td>225Th</td></tr><tr><td rowspan="3">230U</td><td rowspan="3"></td><td rowspan="3">92</td><td rowspan="3">138</td><td rowspan="3">230.0339401(48)</td><td rowspan="3">20.23(2) d</td><td>α</td><td>226Th</td><td rowspan="3">0+</td><td rowspan="3"></td><td rowspan="3"></td></tr><tr><td><a href="/facts/Spontaneous_fission/0QuJoVKI">SF</a> ?</td><td>(various)</td></tr><tr><td><a href="/facts/Cluster_decay/sIelGo3t">CD</a> (4.8×10−12%)</td><td>208<a href="/facts/Lead/EYljasJN">Pb</a>22<a href="/facts/Neon/5bF1FwGL">Ne</a></td></tr><tr><td rowspan="2">231U</td><td rowspan="2"></td><td rowspan="2">92</td><td rowspan="2">139</td><td rowspan="2">231.0362922(29)</td><td rowspan="2">4.2(1) d</td><td>EC</td><td>231Pa</td><td rowspan="2">5/2+#</td><td rowspan="2"></td><td rowspan="2"></td></tr><tr><td>α (.004%)</td><td>227Th</td></tr><tr><td rowspan="4"><a href="/facts/Uranium-232/9sPn8oCm">232U</a></td><td rowspan="4"></td><td rowspan="4">92</td><td rowspan="4">140</td><td rowspan="4">232.0371548(19)</td><td rowspan="4">68.9(4) y</td><td>α</td><td>228Th</td><td rowspan="4">0+</td><td rowspan="4"></td><td rowspan="4"></td></tr><tr><td>CD (8.9×10−10%)</td><td>208Pb24Ne</td></tr><tr><td>SF (10−12%)</td><td>(various)</td></tr><tr><td>CD?</td><td>204Hg28Mg</td></tr><tr><td rowspan="4"><a href="/facts/Uranium-233/a6sMrk07">233U</a></td><td rowspan="4"></td><td rowspan="4">92</td><td rowspan="4">141</td><td rowspan="4">233.0396343(24)</td><td rowspan="4">1.592(2)×105 y</td><td>α</td><td>229Th</td><td rowspan="4">5/2+</td><td rowspan="4">Trace<a class="footnote-ref" id="fnref:20" href="#fn:20"><sup>20</sup></a></td><td rowspan="4"></td></tr><tr><td>CD (≤7.2×10−11%)</td><td>209Pb24Ne</td></tr><tr><td>SF ?</td><td>(various)</td></tr><tr><td>CD ?</td><td>205Hg28Mg</td></tr><tr><td rowspan="5"><a href="/facts/Uranium-234/nKrs059u">234U</a><a class="footnote-ref" id="fnref:21" href="#fn:21"><sup>21</sup></a><a class="footnote-ref" id="fnref:22" href="#fn:22"><sup>22</sup></a></td><td rowspan="5">Uranium II</td><td rowspan="5">92</td><td rowspan="5">142</td><td rowspan="5">234.0409503(12)</td><td rowspan="5">2.455(6)×105 y</td><td>α</td><td>230Th</td><td rowspan="5">0+</td><td rowspan="5">[0.000054(5)]<a class="footnote-ref" id="fnref:23" href="#fn:23"><sup>23</sup></a></td><td rowspan="5">0.000050–0.000059</td></tr><tr><td>SF (1.64×10−9%)</td><td>(various)</td></tr><tr><td>CD (1.4×10−11%)</td><td>206Hg28Mg</td></tr><tr><td>CD (≤9×10−12%)</td><td>208Pb26Ne</td></tr><tr><td>CD (≤9×10−12%)</td><td>210Pb24Ne</td></tr><tr><td>234mU</td><td></td><td colspan="3">1421.257(17) keV</td><td>33.5(20) ms</td><td><a href="/facts/Isomeric_transition/L8DHcqnk">IT</a></td><td>234U</td><td>6−</td><td></td><td></td></tr><tr><td rowspan="5"><a href="/facts/Uranium-235/pe0RznDM">235U</a><a class="footnote-ref" id="fnref:24" href="#fn:24"><sup>24</sup></a><a class="footnote-ref" id="fnref:25" href="#fn:25"><sup>25</sup></a><a class="footnote-ref" id="fnref:26" href="#fn:26"><sup>26</sup></a></td><td rowspan="5">Actin UraniumActino-Uranium</td><td rowspan="5">92</td><td rowspan="5">143</td><td rowspan="5">235.0439281(12)</td><td rowspan="5">7.038(1)×108 y</td><td>α</td><td>231Th</td><td rowspan="5">7/2−</td><td rowspan="5">[0.007204(6)]</td><td rowspan="5">0.007198–0.007207</td></tr><tr><td>SF (7×10−9%)</td><td>(various)</td></tr><tr><td>CD (8×10−10%)</td><td>215Pb20Ne</td></tr><tr><td>CD (8×10−10%)</td><td>210Pb25Ne</td></tr><tr><td>CD (8×10−10%)</td><td>207Hg28Mg</td></tr><tr><td>235m1U</td><td></td><td colspan="3">0.076737(18) keV</td><td>25.7(1) min</td><td>IT</td><td><i>235U</i></td><td>1/2+</td><td></td><td></td></tr><tr><td>235m2U</td><td></td><td colspan="3">2500(300) keV</td><td>3.6(18) ms</td><td>SF</td><td>(various)</td><td></td><td></td><td></td></tr><tr><td rowspan="4"><a href="/facts/Uranium-236/1JepNWSb">236U</a></td><td rowspan="4">Thoruranium<a class="footnote-ref" id="fnref:27" href="#fn:27"><sup>27</sup></a></td><td rowspan="4">92</td><td rowspan="4">144</td><td rowspan="4">236.0455661(12)</td><td rowspan="4">2.342(3)×107 y</td><td>α</td><td><i>232Th</i></td><td rowspan="4">0+</td><td rowspan="4">Trace<a class="footnote-ref" id="fnref:28" href="#fn:28"><sup>28</sup></a></td><td rowspan="4"></td></tr><tr><td>SF (9.6×10−8%)</td><td>(various)</td></tr><tr><td>CD (≤2.0×10−11%)<a class="footnote-ref" id="fnref:29" href="#fn:29"><sup>29</sup></a></td><td>208Hg28Mg</td></tr><tr><td>CD (≤2.0×10−11%)<a class="footnote-ref" id="fnref:30" href="#fn:30"><sup>30</sup></a></td><td>206Hg30Mg</td></tr><tr><td>236m1U</td><td></td><td colspan="3">1052.5(6) keV</td><td>100(4) ns</td><td>IT</td><td>236U</td><td>4−</td><td></td><td></td></tr><tr><td rowspan="2">236m2U</td><td rowspan="2"></td><td rowspan="2" colspan="3">2750(3) keV</td><td rowspan="2">120(2) ns</td><td>IT (87%)</td><td>236U</td><td rowspan="2">(0+)</td><td rowspan="2"></td><td rowspan="2"></td></tr><tr><td>SF (13%)</td><td>(various)</td></tr><tr><td>237U</td><td></td><td>92</td><td>145</td><td>237.0487283(13)</td><td>6.752(2) d</td><td><a href="/facts/Beta_minus_decay/vxTBlckp">β−</a></td><td>237Np</td><td>1/2+</td><td>Trace<a class="footnote-ref" id="fnref:31" href="#fn:31"><sup>31</sup></a></td><td></td></tr><tr><td>237mU</td><td></td><td colspan="3">274.0(10) keV</td><td>155(6) ns</td><td>IT</td><td>237U</td><td>7/2−</td><td></td><td></td></tr><tr><td rowspan="3"><a href="/facts/Uranium-238/QhcHm6q8">238U</a><a class="footnote-ref" id="fnref:32" href="#fn:32"><sup>32</sup></a><a class="footnote-ref" id="fnref:33" href="#fn:33"><sup>33</sup></a><a class="footnote-ref" id="fnref:34" href="#fn:34"><sup>34</sup></a></td><td rowspan="3">Uranium I</td><td rowspan="3">92</td><td rowspan="3">146</td><td rowspan="3">238.050787618(15)<a class="footnote-ref" id="fnref:35" href="#fn:35"><sup>35</sup></a></td><td rowspan="3">4.468(3)×109 y</td><td>α</td><td>234Th</td><td rowspan="3">0+</td><td rowspan="3">[0.992742(10)]</td><td rowspan="3">0.992739–0.992752</td></tr><tr><td>SF (5.44×10−5%)</td><td>(various)</td></tr><tr><td><a href="/facts/Double_beta_decay/ILmpbfqS">β−β−</a> (2.2×10−10%)</td><td>238Pu</td></tr><tr><td rowspan="2">238mU</td><td rowspan="2"></td><td rowspan="2" colspan="3">2557.9(5) keV</td><td rowspan="2">280(6) ns</td><td>IT (97.4%)</td><td><i>238U</i></td><td rowspan="2">0+</td><td rowspan="2"></td><td rowspan="2"></td></tr><tr><td>SF (2.6%)</td><td>(various)</td></tr><tr><td>239U</td><td></td><td>92</td><td>147</td><td>239.0542920(16)</td><td>23.45(2) min</td><td>β−</td><td>239Np</td><td>5/2+</td><td>Trace<a class="footnote-ref" id="fnref:36" href="#fn:36"><sup>36</sup></a></td><td></td></tr><tr><td>239m1U</td><td></td><td colspan="3">133.7991(10) keV</td><td>780(40) ns</td><td>IT</td><td>239U</td><td>1/2+</td><td></td><td></td></tr><tr><td rowspan="2">239m2U</td><td rowspan="2"></td><td rowspan="2" colspan="3">2500(900)# keV</td><td rowspan="2">>250 ns</td><td>SF?</td><td>(various)</td><td rowspan="2">0+</td><td rowspan="2"></td><td rowspan="2"></td></tr><tr><td>IT?</td><td>239U</td></tr><tr><td rowspan="2">240U</td><td rowspan="2"></td><td rowspan="2">92</td><td rowspan="2">148</td><td rowspan="2">240.0565924(27)</td><td rowspan="2">14.1(1) h</td><td>β−</td><td>240Np</td><td rowspan="2">0+</td><td rowspan="2">Trace<a class="footnote-ref" id="fnref:37" href="#fn:37"><sup>37</sup></a></td><td rowspan="2"></td></tr><tr><td>α?</td><td>236Th</td></tr><tr><td>241U<a class="footnote-ref" id="fnref:38" href="#fn:38"><sup>38</sup></a></td><td></td><td>92</td><td>149</td><td>241.06031(5)</td><td>~40 min<a class="footnote-ref" id="fnref:39" href="#fn:39"><sup>39</sup></a><a class="footnote-ref" id="fnref:40" href="#fn:40"><sup>40</sup></a></td><td>β−</td><td>241Np</td><td>7/2+#</td><td></td></tr><tr><td>242U</td><td></td><td>92</td><td>150</td><td>242.06296(10)<a class="footnote-ref" id="fnref:41" href="#fn:41"><sup>41</sup></a></td><td>16.8(5) min</td><td>β−</td><td>242Np</td><td>0+</td><td></td><td></td></tr><tr><th colspan="20"><i>This table header & footer:</i> <ul><li>view</li></ul></th></tr></tbody></table> <h2 id="actinides-vs-fission-products">Actinides vs fission products</h2> <table><tbody><tr><th colspan="9">Actinides and fission products by half-life <ul><li>v</li><li>t</li><li>e</li></ul></th></tr><tr><th colspan="4"><a href="/facts/Actinide/kHC4lxJV">Actinides</a><a class="footnote-ref" id="fnref:42" href="#fn:42"><sup>42</sup></a> by <a href="/facts/Decay_chain/JvTwPNBn">decay chain</a></th><th rowspan="2"><a href="/facts/Half-life/kGVH8BAB">Half-life</a> range (<a href="/facts/Year/51V242hh">a</a>)</th><th colspan="4"><a href="/facts/Fission_product/xJd9MXXH">Fission products</a> of <a href="/facts/Uranium-235/pe0RznDM">235U</a> by <a href="/facts/Fission_product_yield/5t9htHpQ">yield</a><a class="footnote-ref" id="fnref:43" href="#fn:43"><sup>43</sup></a></th></tr><tr><th><a href="/facts/Thorium_series/JvTwPNBn">4<i>n</i></a></th><th><a href="/facts/Neptunium_series/JvTwPNBn">4<i>n</i> + 1</a></th><th><a href="/facts/Uranium_series/JvTwPNBn">4<i>n</i> + 2</a></th><th><a href="/facts/Actinium_series/JvTwPNBn">4<i>n</i> + 3</a></th><th>4.5–7%</th><th>0.04–1.25%</th><th><0.001%</th></tr><tr><td><a href="/facts/Radium-228/T0SlGtRH">228</a>Ra№</td><td></td><td></td><td></td><th><a href="/facts/Medium-lived_fission_product/wxe6qNIp">4–6 a</a></th><td></td><td><a href="/facts/Europium-155/IUWzfhMI">155</a>Euþ</td><td></td></tr><tr><td><a href="/facts/Berkelium-248/RnvnlKK4">248</a>Bk<a class="footnote-ref" id="fnref:44" href="#fn:44"><sup>44</sup></a></td><td></td><td></td><td></td><th><a href="/facts/Medium-lived_fission_product/wxe6qNIp">> 9 a</a></th><td></td><td></td><td></td></tr><tr><td><a href="/facts/Curium-244/WnMh6VLE">244</a>Cmƒ</td><td><a href="/facts/Plutonium-241/vUyJGFrs">241</a>Puƒ</td><td><a href="/facts/Californium-250/tX06MlFX">250</a>Cf</td><td><a href="/facts/Actinium-227/vnv59EsB">227</a>Ac№</td><th><a href="/facts/Medium-lived_fission_product/wxe6qNIp">10–29 a</a></th><td><a href="/facts/Strontium-90/VJNoC5eR">90</a>Sr</td><td><a href="/facts/Krypton-85/c32MkhnV">85</a>Kr</td><td><a href="/facts/Cadmium-113m/2F42oNDz">113m</a>Cdþ</td></tr><tr><td><a href="/facts/Uranium-232/9sPn8oCm">232</a>Uƒ</td><td></td><td><a href="/facts/Plutonium-238/JzY7TPFE">238</a>Puƒ</td><td><a href="/facts/Curium-243/WnMh6VLE">243</a>Cmƒ</td><th><a href="/facts/Medium-lived_fission_product/wxe6qNIp">29–97 a</a></th><td><a href="/facts/Cs-137/NrY5Tb6j">137</a>Cs</td><td><a href="/facts/Samarium-151/e5wQw5B0">151</a>Smþ</td><td><a href="/facts/Tin-121m/C3yupbqu">121m</a>Sn</td></tr><tr><td></td><td><a href="/facts/Californium-249/tX06MlFX">249</a>Cfƒ</td><td><a href="/facts/Americium-242m/aqoWt39B">242m</a>Amƒ</td><td></td><th>141–351 a</th><td rowspan="7" colspan="3"><p>No fission products have a half-lifein the range of 100 a–210 ka ...</p></td></tr><tr><td></td><td><a href="/facts/Americium-241/HnXXm1nx">241</a>Amƒ</td><td></td><td><a href="/facts/Californium-251/tX06MlFX">251</a>Cfƒ<a class="footnote-ref" id="fnref:45" href="#fn:45"><sup>45</sup></a></td><th>430–900 a</th></tr><tr><td></td><td></td><td><a href="/facts/Radium-226/T0SlGtRH">226</a>Ra№</td><td><a href="/facts/Berkelium-247/RnvnlKK4">247</a>Bk</td><th>1.3–1.6 ka</th></tr><tr><td><a href="/facts/Plutonium-240/kIWwdLkI">240</a>Pu</td><td><a href="/facts/Thorium-229/lRb3opzg">229</a>Th</td><td><a href="/facts/Curium-246/WnMh6VLE">246</a>Cmƒ</td><td><a href="/facts/Americium-243/aqoWt39B">243</a>Amƒ</td><th>4.7–7.4 ka</th></tr><tr><td></td><td><a href="/facts/Curium-245/WnMh6VLE">245</a>Cmƒ</td><td><a href="/facts/Curium-250/WnMh6VLE">250</a>Cm</td><td></td><th>8.3–8.5 ka</th></tr><tr><td></td><td></td><td></td><td><a href="/facts/Plutonium-239/eRobTXos">239</a>Puƒ</td><th>24.1 ka</th></tr><tr><td></td><td></td><td><a href="/facts/Thorium-230/lRb3opzg">230</a>Th№</td><td><a href="/facts/Protactinium-231/AVGw4A8U">231</a>Pa№</td><th>32–76 ka</th></tr><tr><td><a href="/facts/Neptunium-236/X3bPWwX1">236</a>Npƒ</td><td><a href="/facts/Uranium-233/a6sMrk07">233</a>Uƒ</td><td><a href="/facts/Uranium-234/nKrs059u">234</a>U№</td><td></td><th><a href="/facts/Long-lived_fission_product/wxe6qNIp">150–250 ka</a></th><td><a href="/facts/Technetium-99/0w2EE0G2">99</a>Tc₡</td><td><a href="/facts/Tin-126/C3yupbqu">126</a>Sn</td></tr><tr><td><a href="/facts/Curium-248/WnMh6VLE">248</a>Cm</td><td></td><td><a href="/facts/Plutonium-242/o1fg0sBh">242</a>Pu</td><td></td><th><a href="/facts/Long-lived_fission_product/wxe6qNIp">327–375 ka</a></th><td></td><td><a href="/facts/Selenium-79/3TDcPNTR">79</a>Se₡</td></tr><tr><td></td><td></td><td></td><td></td><th><a href="/facts/Long-lived_fission_product/wxe6qNIp">1.33 Ma</a></th><td><a href="/facts/Caesium-135/m5AYV9tp">135</a>Cs₡</td></tr><tr><td></td><td><a href="/facts/Neptunium-237/X3bPWwX1">237</a>Npƒ</td><td></td><td></td><th><a href="/facts/Long-lived_fission_product/wxe6qNIp">1.61–6.5 Ma</a></th><td><a href="/facts/Zirconium-93/NzDqkTRf">93</a>Zr</td><td><a href="/facts/Palladium-107/deN3NNeY">107</a>Pd</td></tr><tr><td><a href="/facts/Uranium-236/1JepNWSb">236</a>U</td><td></td><td></td><td><a href="/facts/Curium-247/WnMh6VLE">247</a>Cmƒ</td><th><a href="/facts/Long-lived_fission_product/wxe6qNIp">15–24 Ma</a></th><td></td><td><a href="/facts/Iodine-129/oJDlGf5H">129</a>I₡</td></tr><tr><td><a href="/facts/Plutonium-244/XGtUVghF">244</a>Pu</td><td></td><td></td><td></td><th>80 Ma</th><td colspan="3" rowspan="2"><p>... nor beyond 15.7 Ma<a class="footnote-ref" id="fnref:46" href="#fn:46"><sup>46</sup></a></p></td></tr><tr><td><a href="/facts/Thorium-232/lRb3opzg">232</a>Th№</td><td></td><td><a href="/facts/Uranium-238/QhcHm6q8">238</a>U№</td><td><a href="/facts/Uranium-235/pe0RznDM">235</a>Uƒ№</td><th>0.7–14.1 Ga</th></tr><tr><td colspan="9"><ul><li>₡, has thermal <a href="/facts/Neutron_capture/elsFpM12">neutron capture</a> cross section in the range of 8–50 barns</li><li>ƒ, <a href="/facts/Fissile/XJR9qoxW">fissile</a></li><li>№, primarily a <a href="/facts/Naturally_occurring_radioactive_material/oUbIxWlg">naturally occurring radioactive material</a> (NORM)</li><li>þ, <a href="/facts/Neutron_poison/bkruR3yz">neutron poison</a> (thermal neutron capture cross section greater than 3k barns)</li></ul></td></tr></tbody></table> <h2 id="uranium-214">Uranium-214</h2> <p> Uranium-214 is the lightest known isotope of uranium. It was discovered at the Spectrometer for Heavy Atoms and Nuclear Structure (SHANS) at the Heavy Ion Research Facility in <a href="/facts/Lanzhou/RkUtPsSM">Lanzhou</a>, <a href="/facts/China/lTjIXY5p">China</a> in 2021, produced by firing argon-36 at tungsten-182. It alpha-decays with a half-life of 0.5 ms.<a class="footnote-ref" id="fnref:47" href="#fn:47"><sup>47</sup></a><a class="footnote-ref" id="fnref:48" href="#fn:48"><sup>48</sup></a><a class="footnote-ref" id="fnref:49" href="#fn:49"><sup>49</sup></a><a class="footnote-ref" id="fnref:50" href="#fn:50"><sup>50</sup></a> </p> <h2 id="uranium-232">Uranium-232</h2> <p class="note">Main article: <a href="/facts/Uranium-232/9sPn8oCm">Uranium-232</a></p> <p>Uranium-232 has a half-life of 68.9 years and is a side product in the <a href="/facts/Thorium_cycle/mohxxkx3">thorium cycle</a>. It has been cited as an obstacle to <a href="/facts/Nuclear_proliferation/f8dSJyAR">nuclear proliferation</a> using 233U, because the intense <a href="/facts/Gamma_radiation/5Drf913J">gamma radiation</a> from <a href="/facts/Thallium-208/7BEwqp8j">208Tl</a> (a daughter of 232U, produced relatively quickly) makes 233U contaminated with it more difficult to handle. Uranium-232 is a rare example of an <a href="/facts/Even_and_odd_atomic_nuclei/x1A0CaB9">even-even isotope</a> that is <a href="/facts/Fissile/XJR9qoxW">fissile</a> with both thermal and fast neutrons.<a class="footnote-ref" id="fnref:51" href="#fn:51"><sup>51</sup></a><a class="footnote-ref" id="fnref:52" href="#fn:52"><sup>52</sup></a> </p> <h2 id="uranium-233">Uranium-233</h2> <p class="note">Main article: <a href="/facts/Uranium-233/a6sMrk07">Uranium-233</a></p> <p>Uranium-233 is a fissile isotope that is bred from <a href="/facts/Thorium-232/lRb3opzg">thorium-232</a> as part of the thorium fuel cycle. 233U was investigated for use in nuclear weapons and as a reactor fuel. It was occasionally tested but never deployed in nuclear weapons and has not been used commercially as a nuclear fuel.<a class="footnote-ref" id="fnref:53" href="#fn:53"><sup>53</sup></a> It has been used successfully in experimental nuclear reactors and has been proposed for much wider use as a nuclear fuel. It has a half-life of around 160,000 years. </p><p>Uranium-233 is produced by neutron irradiation of thorium-232. When thorium-232 absorbs a <a href="/facts/Neutron/oRCM1geb">neutron</a>, it becomes <a href="/facts/Thorium-233/lRb3opzg">thorium-233</a>, which has a half-life of only 22 minutes. Thorium-233 <a href="/facts/Beta_decay/vxTBlckp">beta decays</a> into <a href="/facts/Protactinium-233/AVGw4A8U">protactinium-233</a>. Protactinium-233 has a half-life of 27 days and beta decays into uranium-233; some proposed molten salt reactor designs attempt to physically isolate the protactinium from further neutron capture before beta decay can occur. </p><p>Uranium-233 usually fissions on neutron absorption but sometimes retains the neutron, becoming <a href="/facts/Uranium-234/nKrs059u">uranium-234</a>. The capture-to-fission ratio is smaller than the other two major fissile fuels, <a href="/facts/Uranium-235/pe0RznDM">uranium-235</a> and <a href="/facts/Plutonium-239/eRobTXos">plutonium-239</a>; it is also lower than that of short-lived <a href="/facts/Plutonium-241/vUyJGFrs">plutonium-241</a>, but bested by very difficult-to-produce <a href="/facts/Neptunium-236/X3bPWwX1">neptunium-236</a>. </p> <h2 id="uranium-234">Uranium-234</h2> <p class="note">Main article: <a href="/facts/Uranium-234/nKrs059u">Uranium-234</a></p> <p>234U occurs in natural uranium as an indirect decay product of uranium-238, but makes up only 55 parts per <a href="/facts/Million/RMGVIm1j">million</a> of the uranium because its <a href="/facts/Half-life/kGVH8BAB">half-life</a> of 245,500 years is only about 1/18,000 that of 238U. The path of production of 234U is this: 238U <a href="/facts/Alpha_decay/rCsHNIUE">alpha decays</a> to <a href="/facts/Thorium-234/lRb3opzg">thorium-234</a>. Next, with a short <a href="/facts/Half-life/kGVH8BAB">half-life</a>, 234Th <a href="/facts/Beta_decay/vxTBlckp">beta decays</a> to <a href="/facts/Protactinium-234/AVGw4A8U">protactinium-234</a>. Finally, 234Pa beta decays to 234U.<a class="footnote-ref" id="fnref:54" href="#fn:54"><sup>54</sup></a><a class="footnote-ref" id="fnref:55" href="#fn:55"><sup>55</sup></a> </p><p>234U <a href="/facts/Alpha_decay/rCsHNIUE">alpha decays</a> to <a href="/facts/Thorium-230/lRb3opzg">thorium-230</a>, except for a small percentage of nuclei that undergo <a href="/facts/Spontaneous_fission/0QuJoVKI">spontaneous fission</a>. </p><p>Extraction of small amounts of 234U from natural uranium could be done using <a href="/facts/Isotope_separation/07rvF6NA">isotope separation</a>, similar to normal uranium-enrichment. However, there is no real demand in <a href="/facts/Chemistry/SrNqkGVm">chemistry</a>, <a href="/facts/Physics/a7aH2y08">physics</a>, or engineering for isolating 234U. Very small pure samples of 234U can be extracted via the chemical <a href="/facts/Ion-exchange/C2DPoGqg">ion-exchange</a> process, from samples of <a href="/facts/Plutonium-238/JzY7TPFE">plutonium-238</a> that have aged somewhat to allow some alpha decay to 234U. </p><p><a href="/facts/Enriched_uranium/vSb2Tcsb">Enriched uranium</a> contains more 234U than natural uranium as a byproduct of the uranium enrichment process aimed at obtaining <a href="/facts/Uranium-235/pe0RznDM">uranium-235</a>, which concentrates lighter isotopes even more strongly than it does 235U. The increased percentage of 234U in enriched natural uranium is acceptable in current nuclear reactors, but (re-enriched) <a href="/facts/Reprocessed_uranium/xNEHPzNQ">reprocessed uranium</a> might contain even higher fractions of 234U, which is undesirable.<a class="footnote-ref" id="fnref:56" href="#fn:56"><sup>56</sup></a> This is because 234U is not <a href="/facts/Fissile/XJR9qoxW">fissile</a>, and tends to absorb slow <a href="/facts/Neutrons/oRCM1geb">neutrons</a> in a <a href="/facts/Nuclear_reactor/8xqjIbge">nuclear reactor</a>—becoming 235U.<a class="footnote-ref" id="fnref:57" href="#fn:57"><sup>57</sup></a><a class="footnote-ref" id="fnref:58" href="#fn:58"><sup>58</sup></a> </p><p>234U has a <a href="/facts/Neutron_capture/elsFpM12">neutron capture</a> cross section of about 100 <a href="/facts/Barn_(unit)/0yCEtKJ9">barns</a> for <a href="/facts/Thermal_neutrons/UMKR4XgJ">thermal neutrons</a>, and about 700 barns for its <a href="/facts/Resonance_integral/elsFpM12">resonance integral</a>—the average over neutrons having various intermediate energies. In a nuclear reactor, non-fissile isotopes capture a neutron breeding fissile isotopes. 234U is converted to 235U more easily and therefore at a greater rate than <a href="/facts/Uranium-238/QhcHm6q8">uranium-238</a> is to <a href="/facts/Plutonium-239/eRobTXos">plutonium-239</a> (via <a href="/facts/Neptunium-239/X3bPWwX1">neptunium-239</a>), because 238U has a much smaller neutron-capture <a href="/facts/Cross_section_(physics)/lo014h2D">cross section</a> of just 2.7 barns. </p> <h2 id="uranium-235">Uranium-235</h2> <p class="note">Main article: <a href="/facts/Uranium-235/pe0RznDM">Uranium-235</a></p> <p>Uranium-235 makes up about 0.72% of natural uranium. Unlike the predominant isotope <a href="/facts/Uranium-238/QhcHm6q8">uranium-238</a>, it is <a href="/facts/Fissile/XJR9qoxW">fissile</a>, i.e., it can sustain a <a href="/facts/Nuclear_fission/LfkIylvm">fission</a> <a href="/facts/Chain_reaction/5UwHTKXS">chain reaction</a>. It is the only <a href="/facts/Fissile_isotope/XJR9qoxW">fissile isotope</a> that is a <a href="/facts/Primordial_nuclide/lFAUqHDv">primordial nuclide</a> or found in significant quantity in nature. </p><p>Uranium-235 has a <a href="/facts/Half-life/kGVH8BAB">half-life</a> of 703.8 <a href="/facts/Million_years/DXcnXuAw">million years</a>. It was discovered in 1935 by <a href="/facts/Arthur_Jeffrey_Dempster/Ts6YYDM6">Arthur Jeffrey Dempster</a>. Its (fission) nuclear <a href="/facts/Fission_cross_section/AtghNytD">cross section</a> for slow <a href="/facts/Thermal_neutron/UMKR4XgJ">thermal neutron</a> is about 504.81 <a href="/facts/Barn_(unit)/0yCEtKJ9">barns</a>. For fast <a href="/facts/Neutrons/oRCM1geb">neutrons</a> it is on the order of 1 barn. At thermal energy levels, about 5 of 6 neutron absorptions result in fission and 1 of 6 result in neutron capture forming <a href="/facts/Uranium-236/1JepNWSb">uranium-236</a>.<a class="footnote-ref" id="fnref:59" href="#fn:59"><sup>59</sup></a> The fission-to-capture ratio improves for faster neutrons. </p> <h2 id="uranium-236">Uranium-236</h2> <p class="note">Main article: <a href="/facts/Uranium-236/1JepNWSb">Uranium-236</a></p> <p>Uranium-236 has a half-life of about 23 million years; and is neither fissile with thermal neutrons, nor very good fertile material, but is generally considered a nuisance and long-lived <a href="/facts/Radioactive_waste/MjYh5tlu">radioactive waste</a>. It is found in spent <a href="/facts/Nuclear_fuel/8RhAomlJ">nuclear fuel</a> and in the reprocessed uranium made from spent nuclear fuel. </p> <h2 id="uranium-237">Uranium-237</h2> <p>Uranium-237 has a half-life of about 6.75 days. It decays into <a href="/facts/Neptunium-237/X3bPWwX1">neptunium-237</a> by <a href="/facts/Beta_decay/vxTBlckp">beta decay</a>. It was discovered by Japanese physicist <a href="/facts/Yoshio_Nishina/SsFIQfRg">Yoshio Nishina</a> in 1940, who in a near-miss discovery, inferred the creation of element 93, but was unable to isolate the then-unknown element or measure its decay properties.<a class="footnote-ref" id="fnref:60" href="#fn:60"><sup>60</sup></a> </p> <h2 id="uranium-238">Uranium-238</h2> <p class="note">Main article: <a href="/facts/Uranium-238/QhcHm6q8">Uranium-238</a></p> <p>Uranium-238 (238U or U-238) is the most common <a href="/facts/Isotope/KD9B1y6o">isotope</a> of <a href="/facts/Uranium/n2sGWBzU">uranium</a> in nature. It is not <a href="/facts/Fissile/XJR9qoxW">fissile</a>, but is <a href="/facts/Fertile_material/Gt9u52G8">fertile</a>: it can capture a slow <a href="/facts/Neutron/oRCM1geb">neutron</a> and after two <a href="/facts/Beta_decays/vxTBlckp">beta decays</a> become fissile <a href="/facts/Plutonium-239/eRobTXos">plutonium-239</a>. Uranium-238 is fissionable by fast neutrons, but cannot support a chain reaction because inelastic scattering reduces <a href="/facts/Neutron_energy/UMKR4XgJ">neutron energy</a> below the range where fast fission of one or more next-generation nuclei is probable. Doppler broadening of 238U's neutron absorption resonances, increasing absorption as fuel temperature increases, is also an essential negative feedback mechanism for reactor control. </p><p>About 99.284% of natural uranium is uranium-238, which has a half-life of 1.41×1017 seconds (4.468×109 years). Depleted uranium has an even higher concentration of 238U, and even low-enriched uranium (LEU) is still mostly 238U. Reprocessed uranium is also mainly 238U, with about as much uranium-235 as natural uranium, a comparable proportion of uranium-236, and much smaller amounts of other isotopes of uranium such as <a href="/facts/Uranium-234/nKrs059u">uranium-234</a>, <a href="/facts/Uranium-233/a6sMrk07">uranium-233</a>, and <a href="/facts/Uranium-232/9sPn8oCm">uranium-232</a>. </p> <h2 id="uranium-239">Uranium-239</h2> <p>Uranium-239 is usually produced by exposing 238U to <a href="/facts/Neutron_radiation/LVJhCcwL">neutron radiation</a> in a nuclear reactor. 239U has a half-life of about 23.45 minutes and <a href="/facts/Beta_decay/vxTBlckp">beta decays</a> into <a href="/facts/Neptunium-239/X3bPWwX1">neptunium-239</a>, with a total decay energy of about 1.29 MeV.<a class="footnote-ref" id="fnref:61" href="#fn:61"><sup>61</sup></a> The most common gamma decay at 74.660 keV accounts for the difference in the two major channels of beta emission energy, at 1.28 and 1.21 MeV.<a class="footnote-ref" id="fnref:62" href="#fn:62"><sup>62</sup></a> </p><p>239Np then, with a half-life of about 2.356 days, beta-decays to <a href="/facts/Plutonium-239/eRobTXos">plutonium-239</a>. </p> <h2 id="uranium-241">Uranium-241</h2> <p>In 2023, in a paper published in <i><a href="/facts/Physical_Review_Letters/rNP3XvYq">Physical Review Letters</a></i>, a group of researchers based in South Korea reported that they had found uranium-241 in an experiment involving 238U+198Pt multinucleon transfer reactions.<a class="footnote-ref" id="fnref:63" href="#fn:63"><sup>63</sup></a><a class="footnote-ref" id="fnref:64" href="#fn:64"><sup>64</sup></a> Its half-life is about 40 minutes.<a class="footnote-ref" id="fnref:65" href="#fn:65"><sup>65</sup></a> </p> <h2 id="references">References</h2> <ol> <li id="fn:1"><p>"Uranium Isotopes". GlobalSecurity.org. Retrieved 14 March 2012. <a href="http://www.globalsecurity.org/wmd/intro/u-isotopes.htm" target="_blank">http://www.globalsecurity.org/wmd/intro/u-isotopes.htm</a> <a href="#fnref:1" class="footnote-back-ref">↩</a></p></li> <li id="fn:2"><p>mU – Excited nuclear isomer. <a href="/wiki/Nuclear_isomer" target="_blank">/wiki/Nuclear_isomer</a> <a href="#fnref:2" class="footnote-back-ref">↩</a></p></li> <li id="fn:3"><p>Wang, Meng; Huang, W.J.; Kondev, F.G.; Audi, G.; Naimi, S. (2021). "The AME 2020 atomic mass evaluation (II). Tables, graphs and references*". Chinese Physics C. 45 (3): 030003. doi:10.1088/1674-1137/abddaf. <a href="/wiki/Doi_(identifier)" target="_blank">/wiki/Doi_(identifier)</a> <a href="#fnref:3" class="footnote-back-ref">↩</a></p></li> <li id="fn:4"><p>( ) – Uncertainty (1σ) is given in concise form in parentheses after the corresponding last digits. <a href="#fnref:4" class="footnote-back-ref">↩</a></p></li> <li id="fn:5"><p># – Atomic mass marked #: value and uncertainty derived not from purely experimental data, but at least partly from trends from the Mass Surface (TMS). <a href="#fnref:5" class="footnote-back-ref">↩</a></p></li> <li id="fn:6"><p>Kondev, F. G.; Wang, M.; Huang, W. J.; Naimi, S.; Audi, G. (2021). "The NUBASE2020 evaluation of nuclear properties" (PDF). Chinese Physics C. 45 (3): 030001. doi:10.1088/1674-1137/abddae. <a href="https://www-nds.iaea.org/amdc/ame2020/NUBASE2020.pdf" target="_blank">https://www-nds.iaea.org/amdc/ame2020/NUBASE2020.pdf</a> <a href="#fnref:6" class="footnote-back-ref">↩</a></p></li> <li id="fn:7"><p>Kondev, F. G.; Wang, M.; Huang, W. J.; Naimi, S.; Audi, G. (2021). "The NUBASE2020 evaluation of nuclear properties" (PDF). Chinese Physics C. 45 (3): 030001. doi:10.1088/1674-1137/abddae. <a href="https://www-nds.iaea.org/amdc/ame2020/NUBASE2020.pdf" target="_blank">https://www-nds.iaea.org/amdc/ame2020/NUBASE2020.pdf</a> <a href="#fnref:7" class="footnote-back-ref">↩</a></p></li> <li id="fn:8"><p>Modes of decay: EC:Electron captureCD:Cluster decaySF:Spontaneous fission <a href="/wiki/Electron_capture" target="_blank">/wiki/Electron_capture</a> <a href="#fnref:8" class="footnote-back-ref">↩</a></p></li> <li id="fn:9"><p>Bold italics symbol as daughter – Daughter product is nearly stable. <a href="#fnref:9" class="footnote-back-ref">↩</a></p></li> <li id="fn:10"><p>Bold symbol as daughter – Daughter product is stable. <a href="#fnref:10" class="footnote-back-ref">↩</a></p></li> <li id="fn:11"><p>Kondev, F. G.; Wang, M.; Huang, W. J.; Naimi, S.; Audi, G. (2021). "The NUBASE2020 evaluation of nuclear properties" (PDF). Chinese Physics C. 45 (3): 030001. doi:10.1088/1674-1137/abddae. <a href="https://www-nds.iaea.org/amdc/ame2020/NUBASE2020.pdf" target="_blank">https://www-nds.iaea.org/amdc/ame2020/NUBASE2020.pdf</a> <a href="#fnref:11" class="footnote-back-ref">↩</a></p></li> <li id="fn:12"><p>( ) spin value – Indicates spin with weak assignment arguments. <a href="#fnref:12" class="footnote-back-ref">↩</a></p></li> <li id="fn:13"><p># – Values marked # are not purely derived from experimental data, but at least partly from trends of neighboring nuclides (TNN). <a href="#fnref:13" class="footnote-back-ref">↩</a></p></li> <li id="fn:14"><p># – Values marked # are not purely derived from experimental data, but at least partly from trends of neighboring nuclides (TNN). <a href="#fnref:14" class="footnote-back-ref">↩</a></p></li> <li id="fn:15"><p>Kondev, F. G.; Wang, M.; Huang, W. J.; Naimi, S.; Audi, G. (2021). "The NUBASE2020 evaluation of nuclear properties" (PDF). Chinese Physics C. 45 (3): 030001. doi:10.1088/1674-1137/abddae. <a href="https://www-nds.iaea.org/amdc/ame2020/NUBASE2020.pdf" target="_blank">https://www-nds.iaea.org/amdc/ame2020/NUBASE2020.pdf</a> <a href="#fnref:15" class="footnote-back-ref">↩</a></p></li> <li id="fn:16"><p>Zhang, Z. Y.; Yang, H. B.; Huang, M. H.; Gan, Z. G.; Yuan, C. X.; Qi, C.; Andreyev, A. N.; Liu, M. L.; Ma, L.; Zhang, M. M.; Tian, Y. L.; Wang, Y. S.; Wang, J. G.; Yang, C. L.; Li, G. S.; Qiang, Y. H.; Yang, W. Q.; Chen, R. F.; Zhang, H. B.; Lu, Z. W.; Xu, X. X.; Duan, L. M.; Yang, H. R.; Huang, W. X.; Liu, Z.; Zhou, X. H.; Zhang, Y. H.; Xu, H. S.; Wang, N.; Zhou, H. B.; Wen, X. J.; Huang, S.; Hua, W.; Zhu, L.; Wang, X.; Mao, Y. C.; He, X. T.; Wang, S. Y.; Xu, W. Z.; Li, H. W.; Ren, Z. Z.; Zhou, S. G. (2021). "New α-Emitting Isotope U214 and Abnormal Enhancement of α-Particle Clustering in Lightest Uranium Isotopes". Physical Review Letters. 126 (15): 152502. arXiv:2101.06023. Bibcode:2021PhRvL.126o2502Z. doi:10.1103/PhysRevLett.126.152502. PMID 33929212. S2CID 231627674. <a href="/wiki/ArXiv_(identifier)" target="_blank">/wiki/ArXiv_(identifier)</a> <a href="#fnref:16" class="footnote-back-ref">↩</a></p></li> <li id="fn:17"><p>Zhang, M. M.; Tian, Y. L.; Wang, Y. S.; Zhang, Z. Y.; Gan, Z. G.; Yang, H. B.; Huang, M. H.; Ma, L.; Yang, C. L.; Wang, J. G.; Yuan, C. X.; Qi, C.; Andreyev, A. N.; Huang, X. Y.; Xu, S. Y.; Zhao, Z.; Chen, L. X.; Wang, J. Y.; Liu, M. L.; Qiang, Y. H.; Li, G. S.; Yang, W. Q.; Chen, R. F.; Zhang, H. B.; Lu, Z. W.; Xu, X. X.; Duan, L. M.; Yang, H. R.; Huang, W. X.; Liu, Z.; Zhou, X. H.; Zhang, Y. H.; Xu, H. S.; Wang, N.; Zhou, H. B.; Wen, X. J.; Huang, S.; Hua, W.; Zhu, L.; Wang, X.; Mao, Y. C.; He, X. T.; Wang, S. Y.; Xu, W. Z.; Li, H. W.; Niu, Y. F.; Guo, L.; Ren, Z. Z.; Zhou, S. G. (4 August 2022). "Fine structure in the α decay of the 8+ isomer in 216, 218U". Physical Review C. 106 (2): 024305. doi:10.1103/PhysRevC.106.024305. ISSN 2469-9985. S2CID 251359451. <a href="/wiki/Doi_(identifier)" target="_blank">/wiki/Doi_(identifier)</a> <a href="#fnref:17" class="footnote-back-ref">↩</a></p></li> <li id="fn:18"><p>Gan, ZaiGuo; Jiang, Jian; Yang, HuaBin; Zhang, ZhiYuan; Ma, Long; Yu, Lin; Wang, JianGuo; Tian, YuLin; Ding, Bing; Huang, TianHeng; Wang, YongSheng; Guo, Song; Sun, MingDao; Wang, KaiLong; Zhou, ShanGui; Ren, ZhongZhou; Zhou, XiaoHong; Xu, HuShan (1 August 2016). "α decay studies of the neutron-deficient uranium isotopes 215-217U". Chinese Science Bulletin. 61 (22): 2502–2511. doi:10.1360/N972015-01316. Retrieved 24 June 2023. <a href="https://www.researchgate.net/publication/312030836" target="_blank">https://www.researchgate.net/publication/312030836</a> <a href="#fnref:18" class="footnote-back-ref">↩</a></p></li> <li id="fn:19"><p>Zhang, M. M.; Tian, Y. L.; Wang, Y. S.; Zhang, Z. Y.; Gan, Z. G.; Yang, H. B.; Huang, M. H.; Ma, L.; Yang, C. L.; Wang, J. G.; Yuan, C. X.; Qi, C.; Andreyev, A. N.; Huang, X. Y.; Xu, S. Y.; Zhao, Z.; Chen, L. X.; Wang, J. Y.; Liu, M. L.; Qiang, Y. H.; Li, G. S.; Yang, W. Q.; Chen, R. F.; Zhang, H. B.; Lu, Z. W.; Xu, X. X.; Duan, L. M.; Yang, H. R.; Huang, W. X.; Liu, Z.; Zhou, X. H.; Zhang, Y. H.; Xu, H. S.; Wang, N.; Zhou, H. B.; Wen, X. J.; Huang, S.; Hua, W.; Zhu, L.; Wang, X.; Mao, Y. C.; He, X. T.; Wang, S. Y.; Xu, W. Z.; Li, H. W.; Niu, Y. F.; Guo, L.; Ren, Z. Z.; Zhou, S. G. (4 August 2022). "Fine structure in the α decay of the 8+ isomer in 216, 218U". Physical Review C. 106 (2): 024305. doi:10.1103/PhysRevC.106.024305. ISSN 2469-9985. S2CID 251359451. <a href="/wiki/Doi_(identifier)" target="_blank">/wiki/Doi_(identifier)</a> <a href="#fnref:19" class="footnote-back-ref">↩</a></p></li> <li id="fn:20"><p>Intermediate decay product of 237Np <a href="/wiki/Neptunium-237" target="_blank">/wiki/Neptunium-237</a> <a href="#fnref:20" class="footnote-back-ref">↩</a></p></li> <li id="fn:21"><p>Used in uranium–thorium dating <a href="/wiki/Uranium%E2%80%93thorium_dating" target="_blank">/wiki/Uranium%E2%80%93thorium_dating</a> <a href="#fnref:21" class="footnote-back-ref">↩</a></p></li> <li id="fn:22"><p>Used in uranium–uranium dating <a href="/wiki/Uranium%E2%80%93uranium_dating" target="_blank">/wiki/Uranium%E2%80%93uranium_dating</a> <a href="#fnref:22" class="footnote-back-ref">↩</a></p></li> <li id="fn:23"><p>Intermediate decay product of 238U <a href="/wiki/Decay_product" target="_blank">/wiki/Decay_product</a> <a href="#fnref:23" class="footnote-back-ref">↩</a></p></li> <li id="fn:24"><p>Primordial radionuclide <a href="/wiki/Radionuclide" target="_blank">/wiki/Radionuclide</a> <a href="#fnref:24" class="footnote-back-ref">↩</a></p></li> <li id="fn:25"><p>Used in Uranium–lead dating <a href="/wiki/Uranium%E2%80%93lead_dating" target="_blank">/wiki/Uranium%E2%80%93lead_dating</a> <a href="#fnref:25" class="footnote-back-ref">↩</a></p></li> <li id="fn:26"><p>Important in nuclear reactors <a href="#fnref:26" class="footnote-back-ref">↩</a></p></li> <li id="fn:27"><p>Trenn, Thaddeus J. (1978). "Thoruranium (U-236) as the extinct natural parent of thorium: The premature falsification of an essentially correct theory". Annals of Science. 35 (6): 581–97. doi:10.1080/00033797800200441. <a href="/wiki/Doi_(identifier)" target="_blank">/wiki/Doi_(identifier)</a> <a href="#fnref:27" class="footnote-back-ref">↩</a></p></li> <li id="fn:28"><p>Intermediate decay product of 244Pu, also produced by neutron capture of 235U <a href="/wiki/Plutonium-244" target="_blank">/wiki/Plutonium-244</a> <a href="#fnref:28" class="footnote-back-ref">↩</a></p></li> <li id="fn:29"><p>Bonetti, R.; Guglielmetti, A. (2007). "Cluster radioactivity: an overview after twenty years" (PDF). Romanian Reports in Physics. 59: 301–310. Archived from the original (PDF) on 19 September 2016. <a href="https://web.archive.org/web/20160919014152/http://www.rrp.infim.ro/2007_59_2/10_bonetti.pdf" target="_blank">https://web.archive.org/web/20160919014152/http://www.rrp.infim.ro/2007_59_2/10_bonetti.pdf</a> <a href="#fnref:29" class="footnote-back-ref">↩</a></p></li> <li id="fn:30"><p>Bonetti, R.; Guglielmetti, A. (2007). "Cluster radioactivity: an overview after twenty years" (PDF). Romanian Reports in Physics. 59: 301–310. Archived from the original (PDF) on 19 September 2016. <a href="https://web.archive.org/web/20160919014152/http://www.rrp.infim.ro/2007_59_2/10_bonetti.pdf" target="_blank">https://web.archive.org/web/20160919014152/http://www.rrp.infim.ro/2007_59_2/10_bonetti.pdf</a> <a href="#fnref:30" class="footnote-back-ref">↩</a></p></li> <li id="fn:31"><p>Neutron capture product, parent of trace quantities of 237Np <a href="/wiki/Neptunium-237" target="_blank">/wiki/Neptunium-237</a> <a href="#fnref:31" class="footnote-back-ref">↩</a></p></li> <li id="fn:32"><p>Used in uranium–uranium dating <a href="/wiki/Uranium%E2%80%93uranium_dating" target="_blank">/wiki/Uranium%E2%80%93uranium_dating</a> <a href="#fnref:32" class="footnote-back-ref">↩</a></p></li> <li id="fn:33"><p>Primordial radionuclide <a href="/wiki/Radionuclide" target="_blank">/wiki/Radionuclide</a> <a href="#fnref:33" class="footnote-back-ref">↩</a></p></li> <li id="fn:34"><p>Used in Uranium–lead dating <a href="/wiki/Uranium%E2%80%93lead_dating" target="_blank">/wiki/Uranium%E2%80%93lead_dating</a> <a href="#fnref:34" class="footnote-back-ref">↩</a></p></li> <li id="fn:35"><p>Kromer, Kathrin; Lyu, Chunhai; Bieroń, Jacek; Door, Menno; Enzmann, Lucia; Filianin, Pavel; Gaigalas, Gediminas; Harman, Zoltán; Herkenhoff, Jost; Huang, Wenjia; Keitel, Christoph H.; Eliseev, Sergey; Blaum, Klaus (2024-02-06). "Atomic mass determination of uranium-238". Physical Review C. 109 (2). American Physical Society (APS). arXiv:2312.17041. doi:10.1103/physrevc.109.l021301. ISSN 2469-9985. <a href="/wiki/ArXiv_(identifier)" target="_blank">/wiki/ArXiv_(identifier)</a> <a href="#fnref:35" class="footnote-back-ref">↩</a></p></li> <li id="fn:36"><p>Neutron capture product; parent of trace quantities of 239Pu <a href="#fnref:36" class="footnote-back-ref">↩</a></p></li> <li id="fn:37"><p>Intermediate decay product of 244Pu <a href="#fnref:37" class="footnote-back-ref">↩</a></p></li> <li id="fn:38"><p>Niwase, T.; Watanabe, Y. X.; Hirayama, Y.; et al. (2023). "Discovery of New Isotope 241U and Systematic High-Precision Atomic Mass Measurements of Neutron-Rich Pa-Pu Nuclei Produced via Multinucleon Transfer Reactions" (PDF). Physical Review Letters. 130 (13): 132502-1 – 132502-6. doi:10.1103/PhysRevLett.130.132502. PMID 37067317. S2CID 257976576. <a href="https://eprints.whiterose.ac.uk/197980/1/PhysRevLett.130.132502.pdf" target="_blank">https://eprints.whiterose.ac.uk/197980/1/PhysRevLett.130.132502.pdf</a> <a href="#fnref:38" class="footnote-back-ref">↩</a></p></li> <li id="fn:39"><p>Mukunth, Vasudevan (2023-04-05). "In pursuit of a 'magic number', physicists discover new uranium isotope". The Hindu. ISSN 0971-751X. Retrieved 2023-04-12. <a href="https://www.thehindu.com/sci-tech/science/in-pursuit-of-a-magic-number-physicists-discover-new-uranium-isotope/article66699249.ece" target="_blank">https://www.thehindu.com/sci-tech/science/in-pursuit-of-a-magic-number-physicists-discover-new-uranium-isotope/article66699249.ece</a> <a href="#fnref:39" class="footnote-back-ref">↩</a></p></li> <li id="fn:40"><p>Yirka, Bob (April 5, 2023). "Previously unknown isotope of uranium discovered". Phys.org. Retrieved 2023-04-12. <a href="https://phys.org/news/2023-04-previously-unknown-isotope-uranium.html" target="_blank">https://phys.org/news/2023-04-previously-unknown-isotope-uranium.html</a> <a href="#fnref:40" class="footnote-back-ref">↩</a></p></li> <li id="fn:41"><p>Niwase, T.; Watanabe, Y. X.; Hirayama, Y.; et al. (2023). "Discovery of New Isotope 241U and Systematic High-Precision Atomic Mass Measurements of Neutron-Rich Pa-Pu Nuclei Produced via Multinucleon Transfer Reactions" (PDF). Physical Review Letters. 130 (13): 132502-1 – 132502-6. doi:10.1103/PhysRevLett.130.132502. PMID 37067317. S2CID 257976576. <a href="https://eprints.whiterose.ac.uk/197980/1/PhysRevLett.130.132502.pdf" target="_blank">https://eprints.whiterose.ac.uk/197980/1/PhysRevLett.130.132502.pdf</a> <a href="#fnref:41" class="footnote-back-ref">↩</a></p></li> <li id="fn:42"><p>Plus radium (element 88). While actually a sub-actinide, it immediately precedes actinium (89) and follows a three-element gap of instability after polonium (84) where no nuclides have half-lives of at least four years (the longest-lived nuclide in the gap is radon-222 with a half life of less than four days). Radium's longest lived isotope, at 1,600 years, thus merits the element's inclusion here. <a href="/wiki/Polonium" target="_blank">/wiki/Polonium</a> <a href="#fnref:42" class="footnote-back-ref">↩</a></p></li> <li id="fn:43"><p>Specifically from thermal neutron fission of uranium-235, e.g. in a typical nuclear reactor. <a href="/wiki/Thermal_neutron" target="_blank">/wiki/Thermal_neutron</a> <a href="#fnref:43" class="footnote-back-ref">↩</a></p></li> <li id="fn:44"><p>Milsted, J.; Friedman, A. M.; Stevens, C. M. (1965). "The alpha half-life of berkelium-247; a new long-lived isomer of berkelium-248". Nuclear Physics. 71 (2): 299. Bibcode:1965NucPh..71..299M. doi:10.1016/0029-5582(65)90719-4."The isotopic analyses disclosed 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 [years]. No growth of Cf248 was detected, and a lower limit for the β− half-life can be set at about 104 [years]. No alpha activity attributable to the new isomer has been detected; the alpha half-life is probably greater than 300 [years]." <a href="/wiki/Bibcode_(identifier)" target="_blank">/wiki/Bibcode_(identifier)</a> <a href="#fnref:44" class="footnote-back-ref">↩</a></p></li> <li id="fn:45"><p>This is the heaviest nuclide with a half-life of at least four years before the "sea of instability". <a href="/wiki/Sea_of_instability" target="_blank">/wiki/Sea_of_instability</a> <a href="#fnref:45" class="footnote-back-ref">↩</a></p></li> <li id="fn:46"><p>Excluding those "classically stable" nuclides with half-lives significantly in excess of 232Th; e.g., while 113mCd has a half-life of only fourteen years, that of 113Cd is eight quadrillion years. <a href="/wiki/Primordial_nuclide" target="_blank">/wiki/Primordial_nuclide</a> <a href="#fnref:46" class="footnote-back-ref">↩</a></p></li> <li id="fn:47"><p>"Physicists Discover New Uranium Isotope: Uranium-214". Sci-News.com. 14 May 2021. Retrieved 15 May 2021. <a href="http://www.sci-news.com/physics/uranium-214-09658.html" target="_blank">http://www.sci-news.com/physics/uranium-214-09658.html</a> <a href="#fnref:47" class="footnote-back-ref">↩</a></p></li> <li id="fn:48"><p>Zhang, Z. Y.; et al. (2021). "New α -Emitting Isotope 214 U and Abnormal Enhancement of α -Particle Clustering in Lightest Uranium Isotopes". Physical Review Letters. 126 (15): 152502. arXiv:2101.06023. Bibcode:2021PhRvL.126o2502Z. doi:10.1103/PhysRevLett.126.152502. PMID 33929212. S2CID 231627674. Retrieved 15 May 2021. <a href="https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.126.152502" target="_blank">https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.126.152502</a> <a href="#fnref:48" class="footnote-back-ref">↩</a></p></li> <li id="fn:49"><p>"Lightest-known form of uranium created". Live Science. 3 May 2021. Retrieved 15 May 2021. <a href="https://www.livescience.com/lightest-uranium-isotope-discovered.html" target="_blank">https://www.livescience.com/lightest-uranium-isotope-discovered.html</a> <a href="#fnref:49" class="footnote-back-ref">↩</a></p></li> <li id="fn:50"><p>"Physicists have created a new and extremely rare kind of uranium". New Scientist. Retrieved 15 May 2021. <a href="https://www.newscientist.com/article/2274847-physicists-have-created-a-new-and-extremely-rare-kind-of-uranium/" target="_blank">https://www.newscientist.com/article/2274847-physicists-have-created-a-new-and-extremely-rare-kind-of-uranium/</a> <a href="#fnref:50" class="footnote-back-ref">↩</a></p></li> <li id="fn:51"><p>"Uranium 232". Nuclear Power. Archived from the original on 26 February 2019. Retrieved 3 June 2019. <a href="https://www.nuclear-power.net/nuclear-power-plant/nuclear-fuel/uranium/uranium-232/" target="_blank">https://www.nuclear-power.net/nuclear-power-plant/nuclear-fuel/uranium/uranium-232/</a> <a href="#fnref:51" class="footnote-back-ref">↩</a></p></li> <li id="fn:52"><p>"INCIDENT NEUTRON DATA". atom.kaeri.re.kr. 2011-12-14. <a href="http://atom.kaeri.re.kr/nuchart/getEvaf.jsp?mat=9219&lib=endfb7.1" target="_blank">http://atom.kaeri.re.kr/nuchart/getEvaf.jsp?mat=9219&lib=endfb7.1</a> <a href="#fnref:52" class="footnote-back-ref">↩</a></p></li> <li id="fn:53"><p>C. W. Forsburg; L. C. Lewis (1999-09-24). "Uses For Uranium-233: What Should Be Kept for Future Needs?" (PDF). Ornl-6952. Oak Ridge National Laboratory. <a href="http://moltensalt.org/references/static/downloads/pdf/ORNL-6952.pdf" target="_blank">http://moltensalt.org/references/static/downloads/pdf/ORNL-6952.pdf</a> <a href="#fnref:53" class="footnote-back-ref">↩</a></p></li> <li id="fn:54"><p>Audi, G.; Kondev, F. G.; Wang, M.; Huang, W. J.; Naimi, S. (2017). "The NUBASE2016 evaluation of nuclear properties" (PDF). Chinese Physics C. 41 (3): 030001. Bibcode:2017ChPhC..41c0001A. doi:10.1088/1674-1137/41/3/030001. <a href="https://www-nds.iaea.org/amdc/ame2016/NUBASE2016.pdf" target="_blank">https://www-nds.iaea.org/amdc/ame2016/NUBASE2016.pdf</a> <a href="#fnref:54" class="footnote-back-ref">↩</a></p></li> <li id="fn:55"><p>Ronen, Y., ed. (1990). High converting water reactors. CRC Press. p. 212. ISBN 0-8493-6081-1. LCCN 89-25332. <a href="0-8493-6081-1" target="_blank">0-8493-6081-1</a> <a href="#fnref:55" class="footnote-back-ref">↩</a></p></li> <li id="fn:56"><p>Use of Reprocessed Uranium (PDF). 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