“For how the energetic cycles of that power the cell emerged, that alone has only entertained many interesting possibilities, hot core and cooler oceans, reducing ocean/sea floor/land and more oxidizing atmosphere, molecules generated by incubation in space and subsequent infall to earth, reacting with terrestrial molecules, photochemistry (from a uv-rich sun), concentration gradients of a wide variety of sorts, reactions of molecules produced by energetic processes involving meteor impact/burnup.”
“An increase in fuel enrichment from 2% to 2.4% to maintain fuel burnup with an increase in neutron absorption (i.e., less reliance on cooling water for this function).”
“Type Composition Origin Use Reactor-grade from high-burnup fuel 55-70% Pu-239, 19% Pu-240, typically about 30% non-fissile Comprises about 1% of spent fuel from normal operation of civil nuclear reactors used for electricity generation As ingredient (c5%) of MOX fuel for normal reactor Weapons-grade Pu-239 with”
“As reactor operators seek to burn fuel harder and longer, increasing burnup from around 30,000 MW days per tonne a few years ago to over 50,000 MWd/t now, MOX use becomes more attractive.”
“Authorisation for enrichment up to 10% was sought - most enrichment plants operate up to 5% U-235 product, which is becoming a serious constraint as reactor fuel burnup increases.”
“All these considerations mean that only RepU from low-enriched, low-burnup used fuel is normally recycled directly through an enrichment plant.”
“The plutonium isotopic composition of used MOX fuel at 45 GWd/tU burnup is about 37% 239Pu, 32% 240Pu, 16% 241Pu, 12% 242Pu and 4% 238Pu.”
“Two or three categories are possible: degraded Pu (e.g., in high-burnup fuel), low-grade Pu (e.g., separated from spent fuel of normal burnup), and high-grade Pu (e.g., from weapons or low-burnup fuel).”
“The reactivity control system is passive, using lithium expansion modules (LEM) which give burnup compensation, partial load operation, and negative reactivity feedback.”
“As well as many passive safety features, the nuclear reactor design is simpler overall and uses high-burnup fuels enriched to 3.54%, giving it refuelling intervals of up to 24 months.”
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