Samarium-151

¹⁵¹Sm is an radioisotope of samarium with a halflife of 90 years, decaying with low-energy beta emission, and a fission product yield of 0.4203%, about 39% of Sm-149's yield.

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Its neutron absorption cross section is high at 15200 Barn (unit)s, about 38% of samarium-149's absorption cross section. Since the percentages are almost equal, the two isotopes should reach similar equilibrium concentrations. Since ¹⁴⁹Sm reaches equilibrium in about 500 hours (20 days), ¹⁵¹Sm should reach equilibrium in about 50 days.

Since nuclear fuel is used for several years in a power reactor, (burnup) the final amount of ¹⁵¹Sm in the spent nuclear fuel at discharge may be only a fraction of the total ¹⁵¹Sm produced during the use of the fuel. This and the isotope's low-level radioactivity mean that Sm-151 has insignificant nuclear waste impact compared to the two main medium-lived fission products Cs-137 and Sr-90.

See also

• Isotopes of samarium
• ANL factsheet