Ralf Sudowe

Effects of urban debris material on the extraction chromatographic separation of strontium—part I: steel

An incident involving a radiation dispersal device (RDD) would most likely occur in an urban or metropolitan area. However, the majority of radiochemical separation schemes available have been developed for environmental samples that are not necessarily representative of those found in an urban environment. 90Sr is one of the possible radioisotopes that could be used in an RDD. It is therefore important to find efficient and accurate ways to separate it from debris in the area of deployment. This research demonstrates that the presence of steel in dissolved samples shows no appreciable interference with extraction chromatographic separations. Instead, it indicates that the separation could actually be improved by the presence of the steel constituents.

Development of a standardized sequential extraction protocol for simultaneous extraction of multiple actinide elements

Sequential extraction is a useful technique for assessing the potential to leach actinides from soils; however, current literature lacks uniformity in experimental details, making direct comparison of results impossible. This work continued development toward a standardized five-step sequential extraction protocol by analyzing extraction behaviors of 232Th, 238U, 239,240Pu and 241Am from lake and ocean sediment reference materials. Results produced a standardized procedure after creating more defined reaction conditions to improve method repeatability. A NaOH fusion procedure is recommended following sequential leaching for the complete dissolution of insoluble species.

Using Sr Resin with mixed acid matrices

The quantification of radioactive material dispersed following the release of 90Sr, whether accidental or intentional, would be of high importance. Depending on the circumstances, it is possible that the contaminated materials would need to be completely digested prior to quantification. Many sample matrices require a mixture of different acids be employed to achieve total dissolution. Unfortunately, one the most common approaches for the separation of strontium, extraction chromatography with Sr Resin, has only been fully characterized in pure mineral acid solutions (Filosofov et al. in Solv Extr Ion Exch 33(5): 496–509, 2015; Horwitz et al. in Solv Extr Ion Exch 10(2): 313–336, 1992). This work shows that Sr Resin can be used effectively with high concentration mixtures of nitric and hydrochloric acids in the presence or absence of hydrofluoric acid, thereby potentially negating the need for conversion to a pure mineral acid matrix.

Rapid method to determine plutonium, neptunium, americium and curium in granite samples

A fast method for determination of plutonium, neptunium, americium and curium isotopes in granite has been developed for use following a radiological event. Granite samples are fused with sodium hydroxide to achieve complete dissolution, critical if refractory particles are present. Rapid precipitation steps are utilized to preconcentrate the actinide isotopes and remove sample matrix interferences. Plutonium, neptunium, and americium/curium are separated using innovative extraction chromatography and measured by alpha spectrometry. The sample preparation time is less than four hours.

Effects of urban debris material on the extraction chromatographic separation of strontium: Part II: cement and concrete

The majority of radiochemical separation schemes available have been developed for environmental samples that are not necessarily representative of those found in an urban environment. However, it is much more likely that an incident involving a radiation dispersal device (RDD) would occur in an urban or metropolitan area. It is unclear if the currently available separation schemes would be effective in such an event. It is therefore important to determine if the current schemes would be adequate, or to find efficient and accurate ways to separate radiological material from urban debris. One important radiological material that could be used in an RDD is 90Sr. Part I of this work investigated the effects steel had on strontium separations, while this work investigates cement and concrete. This research demonstrates that the individual elements present in a cement and concrete sample matrix can give rise to significant interferences with extraction chromatographic separations. Solutions of the constituents mixed in representative ratios; however, show fewer problems.

A Rapid Method for Quantification OF 242Pu in Urine Using Extraction Chromatography and ICP-MS

Abstract Occupational exposure to plutonium is generally monitored through analysis of urine samples. Typically, plutonium is separated from the sample and other actinides, and the concentration is determined using alpha spectroscopy. Current methods for separations and analysis are lengthy and require long count times. A new method for monitoring occupational exposure levels of plutonium has been developed, which requires fewer steps and overall less time than the alpha spectroscopy method. In this method, the urine is acidified, and a 239Pu internal standard is added. The urine is digested in a microwave oven, and plutonium is separated using an Eichrom TRU Resin column. The plutonium is eluted, and the eluant is injected directly into the Inductively Coupled Plasma–Mass Spectrometer (ICP-MS). Compared to a direct “dilute and shoot” method, a 30-fold improvement in sensitivity is achieved. This method was validated by analyzing several batches of spiked samples. Based on these analyses, a combined standard uncertainty plot, which relates uncertainty to concentration, was produced. The MDA95 was calculated to be 7.0 × 10−7 &mgr;g L−1, and the Lc95 was calculated to be 3.5 × 10−7 &mgr;g L−1 for this method.