Reply #89: #4. The isotope Cs-135 has a very long half-life. [View All]

[NNadir]

One cesium isotope, Cs-135, is extremely long lived relative to most fission products. Its half-life is 2.3 million years. Even I, a proponent of the rapid expansion of nuclear power, cannot be absolutely (as in perfectly or 100%) certain that cesium-135 can be stabilized for millions of years, especially given its chemical properties. Cesium-135 is one of three radioisotopes produced as fission products in nuclear reactors that can be expected to actually persist for millions of years barring an intervention like transmutation. (The other two are Iodine-129 and Technetium-99.)