The need to extend light water reactor spent-fuel on-site storage requirements and the future need to relieve resulting stockpiles necessitates the determination of optimal spent-fuel-withdrawal patterns under various end-use scenarios. End-use scenarios include no-economic- return throwaway and uranium recycle with and without plutonium recycle. Results from developing, analyzing, and solving a spent-fuel-withdrawal model are used to recommend specific strategies.

The spent-fuel-withdrawal problem involves the interaction of spent-fuel generation, time and capacity-dependent reprocessing demand, and expected spent-fuel value. Spent-fuel characteristics based upon burnup history and initial composition, are considered along with uranium, separative work, and storage cost projections to realize profitable spent-fuel disposition. Application of the spent-fuel-withdrawal model is done on a per-reactor basis.

Assumptions inherent in the application of the model developed include, 1) unconstrained on-site storage capacity, 2) realizable uranium and plutonium values, and 3) capacity constrained reprocessing demand. Examining supply, demand, and characteristics of spent-fuel during a twenty-year horizon, the model application is developed through, 1) a dynamic programming approach, 2) a Hitchcock problem to be solved similarly to a minimum-cost-flow problem, and 3) a linear program definable as a Transportation problem.

In the model analyses, the dynamic programming formulation proved to be computationally infeasible. The analyses of the Hitchcock and linear program problem is done by the use of the Out-Of-Kilter Algorithm and the proprietary mathematical MPS-III system, respectfully.

Specific results indicate that the economically optimal withdrawal pattern is:

1. for uranium and plutonium recycle, a Last-In-First-Out pattern,

and

1. for uranium recycle only, no discernible pattern.