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.