Isotope Separation Program Research Articles

Production of stable isotopes utilizing the plasma separation process

A plasma separation process (PSP) is being operated at Theragenics Corporation’s®, Oak Ridge, TN, facility for the enrichment of stable isotopes. The PSP utilizes ion cyclotron mass discrimination to separate isotopes on a relatively large scale. With a few exceptions, nearly any metallic element could be processed with PSP. Output isotope enrichment factor depends on natural abundance and mass separation and can be fairly high in some cases. The Theragenics™ PSP facility is believed to be the only such process currently in operation. This system was developed and formerly operated under the US Department of Energy Advanced Isotope Separation program. Theragenics™ also has a laboratory at the PSP site capable of harvesting the isotopes from the process and a mass spectrometer system for analyzing enrichment and product purity. Since becoming operational in 2002, Theragenics™ has utilized the PSP to separate isotopes of several elements including: dysprosium, erbium, gadolinium, molybdenum and nickel. Currently, Theragenics™ is using the PSP for the separation of 102Pd, which is used as precursor for the production of 103Pd. The 103Pd radioisotope is the active ingredient in TheraSeed®, which is used in the treatment of early stage prostate cancer and being investigated for other medical applications. New industrial, medical and research applications are being investigated for isotopes that can be enriched on the PSP. Pre-enrichment of accelerator or reactor targets offers improved radioisotope production. Theragenics operates 14 cyclotrons for proton activation and has access to HFIR at ORNL for neutron activation of radioisotopes.

The Livermore experience: Contributions of J H Eberly to laser excitation theory

This article summarizes the developing understanding of coherent atomic excitation, as gained through a collaboration of J. H. Eberly with the Laser Isotope Separation Program of the Lawrence Livermore National Laboratory, particularly aspects of coherence, population trapping, multilevel multiphoton excitation sequences, analytic solutions to multistate excitation chains, the quasicontinuum, pulse propagation, and noise. In addition to the discovery of several curious and unexpected properties of coherent excitation, mentioned here, the collaboration provided an excellent example of unexpected benefits from investment into basic research.

Sodium-layer laser-guide-star experimental results

We describe a series of experiments to characterize the sodium-layer guide star that was formed with the high-power laser developed for the Lawrence Livermore National Laboratory Atomic Vapor Laser Isotope Separation program. An emission spot size of 3.0 m was measured, with an implied laser irradiance spot diameter of 2.0 m. The rms spot motion at the higher laser powers, with active beam-pointing control, was less than 0.5 arcsec and had little effect on the observed spot size under these conditions. We measured the resonant backscatter from the sodium layer as a function of laser power to obtain a saturation curve. With a transmitted power of 1100 W and an atmospheric transmission of 0.6, the irradiance from the guide star at the ground was 10 (photons/cm2)/ms, corresponding to a visual magnitude of 5.1. The implications for the performance of wave-front sensors with a laser guide star of this magnitude and resulting closed-loop adaptive-optics performance are discussed.

Design, layout, and early results of a feasibility experiment for sodium-layer laser-guide-star adaptive optics

We describe the design and the early results of a feasibility experiment for sodium-layer laser-guide-star adaptive optics. Copper-vapor-laser-pumped dye lasers from Lawrence Livermore National Laboratory’s Atomic Vapor Laser Isotope Separation program are used to create the guide star. The laser beam is projected upward from a beam director that is located ~5 m from a 0.5-m telescope and forms an irradiance spot ~2 m in diameter at the atmospheric-sodium layer (at an altitude of 95 km). The laser guide star is approximately fifth magnitude and is visible to the naked eye at the top of the Rayleigh-scattered laser beam. To date, we have made photometric measurements and open-loop wave-front-sensor measurements of the laser guide star. We give an overview of the experiment’s design and the laser systems, describe the experimental setup, show preliminary photometric and open-loop wave-front-sensor data on the guide star, and present predictions of closed-loop adaptive-optics performance based on these experimental data. The long-term goal of this effort is to develop laser guide stars and adaptive optics for use with large astronomical telescopes.

Isotope separation program — present and future

The availability of a broad spectrum of highly enriched isotopes is vitally important for the fabrication of nuclear targets used in basic and applied research. The Isotope Separation Program at the Oak Ridge National Laboratory prepares and distributes electromagnetically enriched stable isotopes on a worldwide basis to the scientific community. Topics discussed include: a brief review of the separation facility, a description of each production step, and future enrichment efforts. Current technology being applied in the electromagnetic isotope process to minimize stable isotope depletion rate and methods to achieve specific isotope requirements are emphasized. The availability of the Plasma Separation Process (PSP) equipment to augment the present stable isotope separation capability is addressed. The basic principles of the PSP are discussed, and its applicability to the isotopic enrichment of calutron feed-material and to the selective production of isotopes is examined.

Some reminiscences of mass spectrometry and the Manhattan Project

The need of the petroleum industry to find better means for analyzing complex hydrocarbon mixtures and the uranium isotope separation and atomic bomb production program (known as the Manhattan Project) stimulated the design and construction of new improved mass spectrometers.

Stable isotope enrichment techniques and ORNL separation status

The isotope separation program is described, emphasizing present state-of-the-art techniques utilized to achieve specific isotopic requirements. An interesting problem addressed here is the calutron enrichment of rare-earth isotopes where small quantities of feed (< 5 g) are available, and the unresolved feed is to be recovered and recycled. Conventional ion-source units using graphite and stainless steel deteriorate in the halogenating atmosphere or are permeable to rare-earth compounds, reducing the process efficiency. An ion source has been developed using boron nitride for containing the halogenating agent and rare-earth compounds. Tests have been successfully conducted using Lu 2O 3 and the in situ chlorinating technique with CCl 4. Collectively, 166 mg of 176Lu were recovered from two runs using 2.95 and 1.10 g of 44.5% 176Lu. Process efficiency of 10.5% was achieved, and 1.2 g of the unresolved feed were recovered. Material compatibility of the boron nitride, carbon tetrachloride, and lutetium compounds has been established.

The electromagnetic isotope separation program at the oak ridge national laboratory

The isotope separation program at the Oak Ridge National Laboratory prepares and distributes electromagnetically enriched stable isotopes to the worldwide scientific community. Among the topics discussed in the present paper are the methods of enriching isotopes, the limitations that apply to the quantity and final assay of the separation products, and a generalized production flowsheet indicating the capability of the facility. A brief description of each of the production steps, from the selection and preparation of the initial feedstock to the recovery and distribution of the isotropically enriched material, is presented. The future of the facility, the continued supply of the enriched isotopes, and the response of the program to new and changing requirements is emphasized.

The isotope separator program at the Princeton-Pennsylvania accelerator

The initial isotope separation program at the Princeton-Pennsylvania Accelerator is outlined. The procedures used for the mass dispersion of mercury and thallium radioisotopes produced in lead targets irradiated with 3 GeV protons are described. Some preliminary nuclear spectroscopic results for the 190, 192 and 194 mass chains are given.

Enriching Stable Isotopes Electromagnetically

The natural stable isotopes of forty-three elements, comprising 177 different nuclides, have been enriched; the goal is to enrich 257 isotopes of fifty-nine elements. The isotopic enrichments, the operation of the production mass spectrographs including a listing of best charge materials, a brief review of the chemical and analytical problems, a tabulation of the best compounds of the separated isotopes for mass spectrometer analyses, and a listing of some of the major uses of separated isotopes have been included in this survey of the electromagnetic isotope separation program.