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Dorhout, Jacquelyn Marie

Publications and source records attributed to Dorhout, Jacquelyn Marie.

A Review of Nuclear Forensics: 2016-2020

The study of nuclear forensics harkens back to the Manhattan Project-era, when scientists first started to analyze the debris from the 1945 Trinity test. Political turmoil stemming from the Cold War and the rehabilitation of Germany following WWII has led to new challenges in international security involving nuclear proliferation. Nuclear materials have, on occasion, been lost, misplaced, or stolen from former Soviet countries, and illicit materials have been interdicted all over the world. The National Technical Nuclear Forensics Center (NTNFC) was established in 2006, and has been at the forefront of drive to advance nuclear forensic capabilities in the United States. The ultimate goal of nuclear forensics is to examine nuclear and other radioactive materials using analytical techniques to determine origin and history of the material, particularly in the context of law enforcement investigations. Nuclear forensics can be divided into two parts: predetonation and post-detonation. Pre-detonation forensics, as the name implies, is the investigation of a nuclear material or weapon that has not been detonated or involved in an explosion, whereas postdetonation forensics is the study of activation or fission products in debris or the environment following the use of a nuclear or radiological dispersal device (RDD). Both parts require a number of analytical chemical and radiochemical techniques to determine identification of the material. Many advancements in analytical techniques, including rapidity, sample size, and forensic signatures have been made in recent years. The analytical methods that can be used in a nuclear forensic investigation, such as mass spectrometry and gamma spectroscopy, have been described in detail in previous reviews, including Straub et.al, and will not be explained here. This review will discuss recent publications (from 2016 to present) describing advancements of techniques such as radiochronometry, morphology, development of novel reference materials, and inter-laboratory collaborations for both pre- and post-detonation nuclear forensics.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

NOx speciation from copper dissolution in nitric acid/water solutions using FTIR spectroscopy

The speciation of NO 2 , NO, and N 2 O gases formed from the dissolution of copper in nitric acid is measured and characterized using Fourier-transform infrared (FTIR) spectroscopy. This study describes analysis of the gas phase species formed and ingrowths of their concentrations as a function of time. Acid concentrations range from 14 to 4 M and the NO 2 , NO, and N 2 O are analyzed using FTIR between 1585 and 2209 wavenumbers. The concentrations of the gases range from 0 to 230 ppm and change over time and as a function of acid concentration.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

Characterization of nitrogen-containing species produced from nitric acid/water systems

The speciation of gases formed in the vapor phase above HNO 3 -H 2 O mixtures at room temperature is measured and characterized using Fourier-transform infrared (FTIR) spectroscopy. Although studies of speciation of compounds have been performed in the solution phase, in this study we focus solely on the gas phase species formed over HNO 3 -H 2 O mixtures and their concentrations as a function of time. The nitric acid concentration in the experiments range from 14 to 4 M. The NO 2 , NO, and N 2 O (collectively known at NOx) gases are measured by FTIR at 1585, 1850, and 2208 wavenumbers, respectively. The concentrations of these NOx species ranges from 0 to 3 ppm and change over time as a function of acid concentration. Two purities of commercially available HNO 3 are used to prepare the HNO 3 -H 2 O mixtures. An analysis of thermodynamic data shows that the formation of NOx gases without the presence of a catalyst are thermodynamically favorable.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

Irradiation and isolation of fission products from uranium metal–organic frameworks

Typical fission product formation experiments utilize metal or oxide target materials that must be dissolved prior to product separation. In this study, we report here a novel study using metal–organic frameworks for recovery of fission products into acidic media. We further show that the frameworks are largely preserved, such that this bulk target material could be retained for additional irradiations or characterizations. Through this approach, fission products can be separated from the actinide-based metal–organic framework using 0.01 M HNO 3 without the need to dissolve the framework itself, reducing the amount of acidic waste. Extraction yields of four frameworks with varying pore sizes are compared. In conclusion, the results suggest that it may be possible to use porous frameworks as target materials for the extraction of select fission products.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗

A UO 2 -based salt target for rapid isolation of fission products

Here, we report here an initial isolation study based upon the use of small uranium oxide particles dispersed in a soluble salt matrix to evaluate the relative recovery of fission products into acidic media. We further show that the macrostructures of the uranium microparticles are largely preserved, such that the bulk target material could be retained for additional irradiations or characterizations. Through this approach, fission products can be separated from the actinide-based target using low molarities of acid without the need to dissolve the actinide itself, reducing the amount of acidic waste. Extraction yields using two molarities of HCl and HNO 3 are compared.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗

Synthesis of Actinide Materials for the Study of Basic Actinide Science and Rapid Separation of Fission Products

This dissertation covers several distinct projects relating to the fields of nuclear forensics and basic actinide science. Post-detonation nuclear forensics, in particular, the study of fission products resulting from a nuclear device to determine device attributes and information, often depends on the comparison of fission products to a library of known ratios. The expansion of this library is imperative as technology advances. Rapid separation of fission products from a target material, without the need to dissolve the target, is an important technique to develop to improve the library and provide a means to develop samples and standards for testing separations. Several materials were studied as a proof-of-concept that fission products can be extracted from a solid target, including microparticulate (< 10 μm diameter) dUO 2 , porous metal organic frameworks (MOFs) synthesized from depleted uranium (dU), and other organicbased frameworks containing dU. The targets were irradiated with fast neutrons from one of two different neutron sources, contacted with dilute acids to facilitate the separation of fission products, and analyzed via gamma spectroscopy for separation yields. The results indicate that smaller particle sizes of dUO 2 in contact with the secondary matrix KBr yield higher separation yields than particles without a secondary matrix. It was also discovered that using 0.1 M HNO 3 as a contact acid leads to the dissolution of the target material. Lower concentrations of acid were used for future experiments. In the case of the MOFs, a larger pore size in the framework leads to higher separation yields when contacted with 0.01 M HNO 3 . Different types of frameworks also yield different results.

36 MATERIALS SCIENCE↗

Postdoc Proposal

The goal of this project is to determine whether variables such as the molarity of nitric acid (HNO 3 ), temperature, and surface characteristics of uranium materials have an effect on the fractionation of 15 N between the solution and vapor phases.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

Student Experience at LANL

This is a presentation for the Radiochemistry group at UNLV that describes student programs at LANL.

99 GENERAL AND MISCELLANEOUS↗