Lawrence Livermore National Laboratory



Tashi Parsons-Davis

Overview

Realistic post-detonation surrogate debris reference materials (SDRM) at the sub-milligram to tens of grams quantity per test object are needed to assess process timelines. These materials are also needed to test the robustness, accuracy, and precision of various physicochemical analysis techniques used to identify, quantify, and interpret major, minor, and trace elemental and isotopic constituents of radioactive debris. To enable their use in inter-laboratory comparison exercises, realistic post-detonation SDRMs should be high fidelity, homogeneous, and especially, reproducible.

We evaluated the feasibility of using additive manufacturing techniques to prepare realistic, post-detonation SDRM. A representative sample produced by electrophoretic deposition (EPD)—analyzed by laser ablation inductively coupled plasma mass spectrometry to examine the spatial distribution of trace elements—was found to be homogenous with less than 15% variation across 4 mm for almost all elements. Samples produced via direct ink writing could not maintain physical structure during calcination but may be viable in future work if different solvents are used for the ink. This study showed that EPD offers advantages over conventional methods for control of trace element concentrations and distributions in solid glassy materials. More research is needed to develop methods for preparing homogeneous and heterogeneous standard reference materials with complex chemical and isotopic compositions.

Impact on Mission

This work was the first step in the development of solid-phase SDRMs, which directly support Lawrence Livermore National Laboratory's nuclear threat reduction mission focus area and expand the Laboratory's capabilities in advanced materials and additive manufacturing. The capability for solid SDRM production will strengthen Livermore's role in preparing quality control materials for post-detonation nuclear forensics exercises. The need for reference materials is also widely recognized in the pre-detonation nuclear forensics community, and homogeneous microanalytical standards will support many analytical techniques applied to understanding potentially unique materials.