  This paper addresses the particularities of the uranium extraction-scrubbing
operation in a spent nuclear fuel treatment process (PUREX-Plutonium Uranium
Refining by Extraction) through the use of set-point tracking MPC (Model
Predictive Control). The presented controller uses the feed solution flow rate
as the manipulated variable to control the saturation of the solvent at the
extraction step. In addition, it guarantees not to loose uranium in the
raffinates, and ensures equipment limitations during operation time. Simulation
results show that the tracking NMPC effectively ensures accurate set point
tracking and constraints guarantee. As a result, the system can be driven to
its optimal working condition, avoid and recover from constraint violations.
The control performance was compared with PID and openloop controllers.
