Engineering topics

Rapko, Brian M.

Publications and source records attributed to Rapko, Brian M..

5 records

DOE OSTI2019

Synthesis of Plutonium Oxide Specimens for a Statistically Designed Nuclear Forensics Study

This report describes the synthesis of plutonium oxide (PuO 2 ) samples at a bench-scale (10 g Pu) to support nuclear forensics research. The key unit operations that were performed included dissolving the PuO 2 feed material, purifying the Pu by ion exchange, precipitating as plutonium (III) oxalate, and reconverting to PuO 2 by calcination of the oxalate compound. Seventy-six PuO 2 synthetic runs were performed in execution of a statistically designed test matrix. The process parameters varied in these synthesis runs included temperature (30 or 50 °C), the Pu concentration in the feed solution (10, 30, or 50 g Pu/L), the HNO 3 concentration in the feed solution (1, 2, or 3 M), the direction of reagent addition (direct or reverse strike), the source of oxalic acid (solid or solution), and the reagent addition rate (as fast as possible, 20, or 40 minutes). This report describes the synthesis of the 76 PuO 2 specimens. The characterization of these specimens will be described in separate reports.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗

DOE OSTI2018

In situ spectroscopic analysis and quantification of [Tc(CO)3]+ in Hanford tank waste

A Pretreatment Protocol is demonstrated for the quantitative conversion and subsequent in situ spectroscopic analysis of non-pertechnetate [Tc(CO)3]+ in tank 241-AN-102 at the Hanford Site. This conversion technique is based on a test method demonstrated using [Re(CO)3]+ in simulated Hanford tank waste. The Protocol entails adding a real waste sample containing the non-pertechnetate [Tc(CO)3]+ species to a developer solution that facilitates the rapid, quantitative conversion of the non-emissive species to a luminescent species which can then be detected spectroscopically. Three AN-102 samples were tested by the standard addition method: (1) a 5 M Na adjusted sample, (2) a sample depleted 137Cs by resin column ion exchange, (3) and an acid-stripped column eluate. The concentrations of non-pertechnetate [Tc(CO)3]+ in these samples were 7.78 × 10-6 M, 6.53 × 10-7 M, and 2.46 × 10-6 M, respectively.

Branch, Shirmir D.↗

DOE OSTI2018

Crystallographic and Spectroscopic Characterization of Americium Complexes Containing the Bis[(phosphino)methyl]pyridine-1-oxide (NOPOPO) Ligand Platform

Abstract The crystal structures of americium species containing a common multi-functional phosphine oxide ligand, reported for its ability to extract f elements from acidic solutions, namely 2,6-[Ph2P(O)CH2]2C5H3-NO, L, have finally been determined after over three decades of separations studies involving these species and their surrogates. The molecular compounds Am(L)(NO3)3, Am 1:1, and [Am(L)2(NO3)][NO3]2, Am 2:1, along with their neodymium and europium analogs were synthesized and characterized using single-crystal X-ray crystallography, attenuated total reflectance Fourier transform infrared (ATR) spectroscopy and luminescence spectroscopy to provide a comprehensive comparison with new and known analogous complexes.

Crystallographic and Spectroscopic Characterizatio↗

DOE OSTI2018

In Situ Quantification of [Re(CO) 3 ] + by Fluorescence Spectroscopy in Simulated Hanford Tank Waste

A pretreatment protocol is presented that allows for the quantitative conversion and subsequent in situ spectroscopic analysis of [Re(CO)3]+ species in simulated Hanford tank waste. The protocol encompasses adding a simulated waste sample containing the non-emissive [Re(CO)3]+ species to a developer solution that enables the rapid, quantitative conversion of the non-emissive species to a luminescent species which can then be detected spectroscopically. The [Re(CO)3]+ species concentration in an alkaline, simulated Hanford tank waste supernatant can be quantified by the standard addition method. In a test case, the [Re(CO)3]+ species was measured to be at a concentration of 38.9 µM, which was a difference of 2.01% from the actual concentration of 39.7 µM.

fluorescence detection↗

DOE OSTI2017

Non-pertechnetate Technetium Sensor Research and Development

Several significant uncertainties remain regarding the understanding and modeling of the fate and speciation of technicium-99 ( 99 Tc) in Hanford waste tanks, glass, and low-temperature waste forms. A significant (2% to 25%) fraction of the 99Tc in the water-soluble portion of the tank waste may be present as one or more non pertechnetate species that have not been identified and to date, cannot be effectively separated from the wastes. This task will provide a sensor specifically tuned to detect the Tc(I)-carbonyl species believed to constitute the main fraction of the non-pertechnetate form of technetium. By direct measurement of the non-pertechnetate species, such a sensor will help reduce the uncertainties in the modeling of the fate and speciation of 99 Tc in Hanford tanks and waste forms. This report summarizes work performed in FY2016 that was sponsored by the Department of Energy’s Office of Environmental Management and demonstrates the protocol for using fluorescent Tc(I)-tricarbonyl complex as a means to detect the non-pertechnetate species within tank waste solutions. The protocol was optimized with respect to ligand concentration, solvent choice, reaction temperature and time. This work culminated in the quantitation of Tc(I)-tricarbonyl within a waste simulant, using a standard addition method for measurement. This report also summarizes the synthesis and high-yield preparation of the low-valence technetium species, [Tc(CO) 3 (H 2 O) 3 ] + , which will be used as the technetium standard material for the demonstration of the non-pertechnetate species in actual wastes.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗