Decay Energy Spectrometry for Improved Nuclear Material Analysis at the IAEA NML

TL;DR

Decay energy spectrometry (DES) is a new high-precision radiometric technique using cryogenic microcalorimeters, enabling elemental and isotopic analysis of nuclear materials with high accuracy and efficiency, complementing existing mass spectrometry methods.

Contribution

This paper introduces DES as a novel technique for nuclear material analysis, demonstrating its high precision and potential for integration with current methods at the IAEA NML.

Findings

Achieved isotopic ratio precisions of 1 ppm to 1,000 ppm in 12-hour measurements.

Demonstrated DES's capability to analyze low-activity samples without chemical separation.

Discussed DES's systematic biases and its complementarity to mass spectrometry.

Abstract

Decay energy spectrometry (DES) is a novel radiometric technique for high-precision analysis of nuclear materials. DES employs the unique thermal detection physics of cryogenic microcalorimeters with ultra-high energy resolution and 100$\%$ detection efficiency to accomplish high precision decay energy measurements. Low-activity nuclear samples of 1 Bq or less, and without chemical separation, are used to provide elemental and isotopic compositions in a single measurement. Isotopic ratio precisions of 1 ppm - 1,000 ppm (isotope dependent), which is close to that of the mass spectrometry, have been demonstrated in 12-hour DES measurements of ~5 Bq samples of certified reference materials of uranium (U) and plutonium (Pu). DES has very different systematic biases and uncertainties, as well as different sensitivities to nuclides, compared to mass-spectrometry techniques. Therefore, the accuracy and confidence of nuclear material assays can be improved by combining this new technique with existing mass-spectrometry techniques. Commercial-level DES techniques and equipment are being developed for the implementation of DES at the Nuclear Material Laboratory (NML) of International Atomic Energy Agency (IAEA) to provide complementary measurements to the existing technologies. The paper describes details of DES measurement methods, as well as DES precision and accuracy to U and Pu standard sources to discuss its capability in analysis of nuclear safeguards samples.