An Evaluation of the Plutonium Denaturing Concept as an Effective Safeguards Method

The effectiveness of denaturing plutonium with a ²³⁸Pu heat spike was evaluated as a safeguards deterrent for light water reactor (LWR) fuel. The following aspects were examined:

1. the percentage of ²³⁸Pu denaturant required to sufficiently protect reactor-grade plutonium from national and subnational diversion attempts
2. the production rate of denaturant in LWRs
3. logistics requirements.

Calculations were also performed to determine the impact of ²³⁸Pu precursors on fuel reactivity and economics. Results indicate that a 5% by weight denaturant is sufficient to produce desired safeguards effects in reactor-grade plutonium. Reactivity calculations show that a maximum increase in uranium enrichment from 3.2 to 3.7% is required to compensate for additions of ²³⁷Np and ²³⁶U in first-cycle fuel. Required modifications of a standard PUREX plant are estimated to result in an overall increase in reprocessing costs of ∼5%, which does not have a significant impact on reprocessing economics.