Orville T. Farmer

Extraction chromatographic separations and analysis of actinides using sequential injection techniques with on-line inductively coupled plasma mass spectrometry (ICP MS) detection

A sequential injection (SI) separation system has been developed for separation and analysis of Am, Pu, and Np isotopes using on-line inductively coupled plasma mass spectrometry (ICP MS) detection. On-line actinide separations were carried out using an actinide-specific extraction chromatographic material (TRU-resin, Eichrom Industries, Inc. USA). Separations are demonstrated and characterized that are compatible with on-line ICP MS detection and address isobaric (241Am/241Pu, 244Pu/244Cm, 238U/238Pu), molecular (238UH/239Pu), and spectral (238U/237Np) interferences encountered in the analysis of Am, Pu and Np isotopic composition using ICP MS. The effects of reductive sample treatment on the extent of U matrix removal were investigated. Uranium separation factors were limited by the formation of U(IV) species, which exhibited separation behaviors similar to that of Pu(IV) and Np(IV). Nevertheless, separation factors as high as 3.0 × 105 can be achieved at the 0.1 mg ml−1 U concentration levels using Fe(II) sulfamate as a reductant. The sequential injection (SI) ICP MS technique has been applied towards analysis of Am, Pu, and Np isotopes in a dissolved vitrified nuclear waste sample. Results obtained using the automated separation technique with ICP MS detection were in satisfactory agreement with results obtained using standard analytical methodologies.

Nuclear archeology in a bottle: evidence of pre-Trinity U.S. weapons activities from a waste burial site.

During World War II, the Hanford Site in Washington became the location for U.S. plutonium production. In 2004, a bottle containing a sample of plutonium was recovered from a Hanford waste trench. Here, state-of-the-art instrumental analyses, reactor model simulations, and investigative science techniques were used to provide insights as to the origin of this unknown sample, a process collectively termed as nuclear archeology. Isotopic age dating conducted on the sample in 2007 indicated the sample was separated from the spent fuel 61.6 +/- 4.5 years earlier. The isotope (22)Na, a detectable product of a secondary nuclear reaction, proved useful as a powerful tool for nuclear forensic analysis as (1) an easily detectable signifier of the presence of alpha emitting actinides, (2) an indicator of sample splitting, and (3) a measure of the time since sample splitting. Analytical results of minor actinide isotopes and reactor model simulations confirmed the material originated from the X-10 reactor in Oak Ridge, TN. Corroborated by historical documents, we concluded this sample was part of the first batch of Pu separated at T-Plant, Hanford, the worlds first industrial-scale reprocessing facility, on December 9, 1944. This sample represents the oldest known collection of man-made (239)Pu in the world.

Determination of129I in ambient air by inductively coupled plasma mass spectrometry (ICP/MS)

The detection of129I by Inductively Coupled Plasma Mass Spectrometry (ICP/MS) in environmental samples can be used to determine anthropogenic release of this long-lived radionuclide, which is a definitive indicator of certain nuclear activities. By using selective precipitation techniques with on-line ICP/MS detection, low levels of129I can be detected. The major interference for the ICP/MS detection of129I is due the presence of natural129Xe found in water samples at a concentration of about 1 ng/ml. This work will demonstrate a instrument detection of less than 50 fg129I from environmental air samples and shows promise for a rugged ICP/MS technique to monitor129I levels in ambient air for nonproliferation monitoring purposes.

Anionic Forensic Signatures for Sample Matching of Potassium Cyanide Using High Performance Ion Chromatography and Chemometrics

Potassium cyanide was used as a model toxicant to determine the feasibility of using anionic impurities as a forensic signature for matching cyanide salts back to their source. In this study, portions of eight KCN stocks originating from four countries were separately dissolved in water and analyzed by high performance ion chromatography (HPIC) using an anion exchange column and conductivity detection. Sixty KCN aqueous samples were produced from the eight stocks and analyzed for 11 anionic impurities. Hierarchal cluster analysis and principal component analysis were used to demonstrate that KCN samples cluster according to source based on the concentrations of their anionic impurities. The Fisher-ratio method and degree-of-class separation (DCS) were used for feature selection on a training set of KCN samples in order to optimize sample clustering. The optimal subset of anions needed for sample classification was determined to be sulfate, oxalate, phosphate, and an unknown anion named unk5. Using K-nearest neighbors (KNN) and the optimal subset of anions, KCN test samples from different KCN stocks were correctly determined to be manufactured in the United States. In addition, KCN samples from stocks manufactured in Belgium, Germany, and the Czech Republic were all correctly matched back to their original stocks because each stock had a unique anionic impurity profile. The application of the Fisher-ratio method and DCS for feature selection improved the accuracy and confidence of sample classification by KNN.

Investigation of Isotopic Signatures for Sources of Groundwater Contamination at the Hanford Site

The Hanford Site Groundwater Monitoring Project at Pacific Northwest National Laboratory (PNNL) investigated selected isotopic signature techniques to aid interpretation of contaminant plumes in Hanford Site groundwater. The main approach was to select groundwater samples expected to exhibit a variety of contaminant characteristics and then develop inductively coupled plasma mass spectrometry (ICP-MS) analytical methods for the groundwater matrix. Initial broad scans were used to identify interferences and to focus the method development on isotopes showing the greatest promise of practical application. In addition, earlier work characterizing chlorine-36 in Hanford Site groundwater by accelerator mass spectrometry (AMS) will be discussed.

Precise ruthenium fission product isotopic analysis using dynamic reaction cell inductively coupled plasma mass spectrometry (DRC-ICP-MS)

99 Tc is a contaminant of interest at numerous nuclear facilities because it is quite mobile in sub-surface environments and is a key contributor to long-term risk. However, as a mono-isotopic fission product, 99Tc is limited in its use as a signature to differentiate between different waste disposal pathways that could have contributed to sub-surface contamination at these facilities. Ruthenium fission-product isotopes are attractive analogues for the characterization of 99Tc sources because of their direct similarity to technetium with regard to subsurface mobility, their large fission yields, and low natural background concentrations. We developed an inductively coupled plasma mass spectrometry (ICP-MS) method capable of measuring ruthenium isotopes in groundwater samples and water extracts of vadose zone sediments. Samples were analyzed directly on a PerkinElmer ELAN DRC II ICP-MS after a single pass through a 1-ml bed volume of Dowex AG 50W-X8 100–200 mesh hydronium-based cation exchange resin. Precise ruthenium isotopic ratio measurements were achieved using a low-flow Meinhard-type nebulizer and long sample acquisition times (150000 ms). Relative standard deviations of triplicate replicates were maintained at less than 0.5% when the total ruthenium solution concentration was 0.1 ng ml−1 or higher. Further work was performed to minimize the impact caused by mass interferences using the dynamic reaction cell (DRC) with O2 as the reaction gas. Aqueous concentrations of 96Mo and 96Zr, two potential interferents to the analysis of total ruthenium concentration, were reduced by more than 99.7% in the reaction cell prior to injection of the sample into the mass analyzer quadrupole. The DRC was used in combination with mass correction to quantitatively analyze samples containing up to two orders of magnitude more zirconium and molybdenum than ruthenium. The analytical approach documented herein provides an efficient and cost-effective way to precisely measure ruthenium isotopes and quantitate total ruthenium (natural versus fission-product) in aqueous matrixes.

Analysis of Radioactive Waste Samples by Ion Chromatography-beta-ICP-MS

A comprehensive ion chromatography (IC) with beta-counting (beta) and inductively coupled plasma mass spectrometry (ICP/MS) detection approach has been developed to separate and detect 20 radionuclides in a Hanford waste tank sample. The IC separation was performed using a multi-functional group (anion/cation) resin and eluents of oxalic acid, diglycolic acid, and hydrochloric acid. Shorter-lived radionuclides were detected by a solid-state beta scintillation counter on-line with the IC separation. Mass spectrometry detection using an efficient and robust plasma ionization source provides isotopic discernability for both stable isotopes and long-lived radioactive species. Effective separation of over 47 elements and 160 isotopes was obtained from a single-elution scheme lasting 70 min. Automated IC separations provide the potential for rapid isotopic and radionuclide analysis of complex radioactive waste, using minimal sample and reagent volumes and reducing personnel exposures.

Applications of inductively coupled plasma mass spectrometry to the production control of aerospace and nuclear materials

Inductively coupled plasma source mass spectrometry (ICP-MS) has proved to be a useful practical tool in a high-volume quality control laboratory. The application of this technique to materials produced for the aerospace and nuclear industries is discussed. Techniques employed for uranium isotope ratio determination and elemental determination of gadolinium, samarium and thorium in hafnium and zirconium alloys are described. Strategies employed for a semi-quantitative survey analysis for a wide range of elements are also presented.

RadICalc: a program for estimating radiation intensity of radionuclide mixtures

RadICalc was developed to address the need for a computer program that could calculate the composition, activity, and measurable radiation of arbitrary radionuclide mixtures over time without significant effort from end-users. It provides an interface to perform decay calculations and can search and display the resulting data in graphical or tabular form. RadICalc can also determine radiation expected at specific masses with user-defined molecules in addition to atomic species for use in mass-based isotope separations for radiometric counting applications, a novel method under development at Pacific Northwest National Laboratory.

Ultra-Low-Background Copper Production and Clean Fabrication

Commercial high‐purity copper is an attractive material for constructing ultra‐low‐background radiation measurement devices. When even higher purity is desired, additional electrolytic and chemical purification can be combined with the final fabrication step. This process results in “electroformed” copper parts of extreme purity. Copper electroforming can be done underground, providing a way to eliminate cosmogenic activation products seen in copper that has had above‐ground exposure. A brief summary of the history, cosmogenics, process chemistry, cleaning, and passivation of this material is given. Examples of finished parts illustrate the method. The required infrastructure is summarized.