Remote Americium Detection Using an Optical Sensor: A D-Optimal Strategy for Efficient PLS-Based Modeling.

Area of Science:

• Nuclear Chemistry and Engineering
• Analytical Chemistry
• Spectroscopy

Background:

• Accurate monitoring of actinide solutions is crucial for nuclear process safety and control.
• Traditional methods for analyzing actinide concentrations can be invasive and time-consuming.
• Developing noninvasive, real-time monitoring techniques is essential for advanced nuclear applications.

Purpose of the Study:

• To demonstrate a fiber-optic spectroscopy system for remote quantification of Am(III) and HNO3.
• To validate the use of neodymium (Nd(III)) as an optical surrogate for Am(III) in process monitoring.
• To establish a flexible calibration strategy using D-optimal design for multivariate models.

Main Methods:

• Development of a fiber-optic visible-near-infrared absorption spectroscopy system within a glove box.
• Application of partial least squares regression (PLSR) models (PLS1 and PLS2) for quantification.
• Utilized a D-optimal design, initially developed for Nd(III), extended to an Am(III) system.

Main Results:

• The system successfully quantified Am(III) (0-500 µM) and HNO3 (0.1-9 M) with high accuracy.
• Nd(III) demonstrated strong spectral similarities to Am(III), validating its role as an effective optical surrogate.
• PLS1 models for Am(III) and HNO3 showed superior performance over PLS2, even with interfering U(VI) presence.

Conclusions:

• The demonstrated fiber-optic spectroscopy system offers a noninvasive, real-time solution for monitoring actinide process solutions.
• The D-optimal design approach is effective for minimizing sample size while maintaining robust model performance.
• This technology provides a flexible, scalable, and safe approach for process monitoring in nuclear applications.