The Fuel Cycle Effect of ²³⁶U in Pressurized Water Reactors

The effect of the introduction of ²³⁶U because of the recycling of nuclear fuel has been determined for a typical pressurized water reactor fuel cycle. It has been estimated that an extra 0.255 g of ²³⁵U is required for each gram of ²³⁶U present at the beginning of exposure. In terms of cost, the additional ²³⁵U translates into an ∼1% increase in the fuel cost for every gram of ²³⁶U. The value of the uranium component of the exposed fuel has also been calculated in terms of the savings in separative work and the feed requirements resulting from the use of recycled uranium. While the exact value depends on the fuel cycle component costs and the relative concentrations of ²³⁵U and ²³⁶U, it is estimated that even after accounting for the presence of ²³⁶U, the use of reprocessed uranium may result in a total saving of ∼14% in ore and enrichment costs. It was also found that upon repeated recycling, ²³⁶U reaches an equilibrium concentration, but only if the recycled fuel ratio in the feed to enrichment plant is limited to about 1 part in 5.