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Plutonium oxide is substantially more toxic than uranium oxide, making fuel manufacture more difficult and expensive. As plutonium isotopes absorb more neutrons than uranium fuels, reactor control systems may need modification. MOX fuel tends to run hotter because of lower thermal conductivity, which may be an issue in some reactor designs.
A typical 5.3% reactor-grade plutonium MOX fuel bundle, is transmutated when it itself is again burnt, a practice that is typical in French thermal reactors, to a twice-through reactor-grade plutonium, with an isotopic composition of 40.8% 239 Pu and 30.6% 240 Pu at the end of cycle (EOC).
Fission product yields by mass for thermal neutron fission of U-235 and Pu-239 (the two typical of current nuclear power reactors) and U-233 (used in the thorium cycle). This page discusses each of the main elements in the mixture of fission products produced by nuclear fission of the common nuclear fuels uranium and plutonium.
A comparison of the activity associated to U-233 for three different SNF types can be seen in the figure on the top right. The burnt fuels are Thorium with Reactor-Grade Plutonium (RGPu), Thorium with Weapons-Grade Plutonium (WGPu) and Mixed Oxide fuel (MOX, no thorium). For RGPu and WGPu, the initial amount of U-233 and its decay around a ...
Plutonium is graded by proportion of 240 Pu: weapons grade (<7%), fuel grade (7–19%) and reactor grade (>19%). Lower grades are less suited for bombs and thermal reactors but can fuel fast reactors. Plutonium-241 is fissile, but beta decays with a half-life of 14 years to americium-241.
Reprocessing of spent nuclear fuel by the PUREX method, first developed in the 1940s to produce plutonium for nuclear weapons, [1] was demonstrated commercially in Belgium to partially re-fuel a LWR in the 1960s. [2] This aqueous chemical process continues to be used commercially to separate reactor grade plutonium (RGPu) for reuse as MOX fuel ...
Apr. 14—It's been almost 80 years since the first atomic bomb was detonated, and scientists say there's still much to learn about how nuclear devices function as they reach the point of exploding.
Plutonium recovered from LWR spent fuel, while not weapons grade, can be used to produce nuclear weapons at all levels of sophistication, [25] though in simple designs it may produce only a fizzle yield. [26] Weapons made with reactor-grade plutonium would require special cooling to keep them in storage and ready for use. [27]