A generalized plutonium value equation is given which permits corrections for changes in separative work and uranium price:Pu value = AU - 0.16P

(incremental fabrication cost per kg fuel/g of fissile Pu/kg fuel). In this equation, A is the relative worth of 239Pu to 235U as fissile material, U is the cost of 93% enriched uranium, and P is the ratio of 242Pu content to fissile content. The optimum uranium enrichment to be used in plutonium-containing fuel rods is found to be equivalent to that of natural uranium. Incremental plutonium fabrication costs could go from ∼100% over the projected uranium fabrication cost of $44/kg in 1975 to a 35% increase over this figure in 1985. In considering the throwaway cycle, it is found that the reprocessing will cost $56/kg compared with $21/kg for the throwaway. This leaves the cost difference of $35 as the minimum value of plutonium and uranium in discharged fuel. The value of plutonium in 1975 is estimated to be $7.50/g fissile, increasing to $8.50/g fissile by 1985.