Simultaneous Separation of Protactinium-230 and Uranium-230 Isotopes from a Proton-Irradiated Thorium Matrix.

The use of radioisotopes in cancer therapy is becoming increasingly important. As a potential candidate for targeted alpha therapy, 230U (t1/2 = 20.8 d), the decay daughter of 230Pa (t1/2 = 17.4 d) is currently being investigated for cancer treatment. For radioisotopes to be used in biomedicine, they must be radiochemically pure and free from carrier interference. This can be challenging given their short half-life. Thus, radiological separation methods for harvesting isotopes for use in biomedicine must be simple, fast, and capable of obtaining the required purity levels. Herein, we demonstrate a new rapid method for the separation of 230U and 230Pa from a proton-irradiated 232Th metal target and from coproduced fission products with high recovery and purity. A dual-column approach was used, in which the first column was an anion exchange (AX) column and the second column was a DGA column. The MP-1 AX resin was used for the primary separation of the three major components (U, Pa, and Th, as well as fission products), and the DGA column was used for further purification of the separated 230U. The method is simple and allows for straightforward separation of U, Pa, Th, and fission products; also, the entire process from target dissolution to shipment of 230U could be completed in 3 days with an overall 230U recovery yield of 96 ± 3%. Additionally, separated 230Pa fractions can be used to harvest ingrown 230U after initial separation.

Occurrence and behavior of uranium and thorium series radionuclides in the Permian shale hydraulic fracturing wastes.

Over the last decade, there has been a rapid growth in the use of hydraulic fracturing (fracking) to recover unconventional oil and gas in the Permian Basin of southeastern New Mexico (NM) and western Texas. Fracking generates enormous quantities of wastes that contain technologically enhanced naturally occurring radioactive materials (TENORM), which poses risks to human health and the environment because of the relatively high doses of radioactivity. However, very little is known about the chemical composition and radioactivity levels of Permian Basin fracking wastes. Here, we report chemical as well as radiochemical compositions of hydraulic fracking wastes from the Permian Basin. Radium, the major TENORM of interest in unconventional drilling wastes, varied from 19.1 ± 1.2 to 35.9 ± 3.2 Bq/L for 226Ra, 10.3 ± 0.5 to 21.5 ± 1.2 Bq/L for 228Ra, and 2.0 ± 0.05 to 3.7 ± 0.07 Bq/L for 224Ra. In addition to elevated concentrations of radium, these wastewaters also contain elevated concentrations of dissolved salts and divalent cations such as Na+ (31,856-43,000 mg/L), Ca2+ (668-4123 mg/L), Mg2+ (202-2430 mg/L), K+ (148-780 mg/L), Sr2+ (101-260 mg/L), Cl- (5160-66,700 mg/L), SO42- (291-1980 mg/L), Br- (315-596 mg/L), SiO2 (20-32 mg/L), and high total dissolved solid (TDS) of 5000-173,000 mg/L compared to background waters. These elevated levels are of radiological significance and represent a major source of Ra in the environment. The recent discovery of large deposits of recoverable oil and gas in the Permian Basin will lead to more fracking, TENORM generation, and radium releases to the environment. This paper evaluates the potential radiation risks associated with TENORM wastes generated by the oil and gas recovery industry in the Permian Basin.

Optimal methods for preparation, separation, and determination of radium isotopes in environmental and biological samples.

In recent years, radium has attracted considerable attention primarily because of the rapid increase in unconventional (fracking) drilling technology in the United States and around the world. One of the major radionuclides of interest in unconventional drilling wastes is radium isotopes (224Ra, 226Ra, 228Ra). To access long-term risks associated with radium isotopes entering into the environment, accurate measurements of radium isotopes in environmental and biological samples are crucial. This article reviews many aspects of radium chemistry, which includes recent developments in radiochemical separations methods, advancements in analytical techniques followed by a more detailed discussion on the recent trends in radium determination.

Sources and distribution of 241Am in the vicinity of a deep geologic repository.

The detection, distribution, and long-term behavior of 241Am in the terrestrial environment at the Waste Isolation Pilot Plant (WIPP) site were assessed using historical data from an independent monitoring program conducted by the Carlsbad Environmental Monitoring & Research Center (CEMRC), and its predecessor organization the Environmental Evaluation Group (EEG). An analysis of historical data indicates frequent detections of trace levels of 241Am in the WIPP environment. Positive detections and peaks in 241Am concentrations in ambient air samples generally occur during the March to June timeframe, which is when strong and gusty winds in the area frequently give rise to blowing dust. A study of long-term measurements of 241Am in the WIPP environment suggest that the resuspension of previously contaminated soils is likely the primary source of americium in the ambient air samples from WIPP and its vicinity. Furthermore, the 241Am/239 + 240Pu ratio in aerosols and soils was reasonably consistent from year to year and was in agreement with the global fallout ratios. Higher than normal activity concentrations of 241Am and 241Am/239 + 240Pu ratios were measured in aerosol samples during 2014 as a result of February 14, 2014 radiation release event from the WIPP underground. However, after a brief spike, the activity concentrations of 241Am have returned to the normal background levels. The long-term monitoring data suggest there is no persistent contamination and no lasting increase in radiological contaminants in the region that can be considered significant by any health-based standard.

Ongoing environmental monitoring and assessment of the long-term impacts of the February 2014 radiological release from the waste isolation pilot plant.

Three years ago, the Waste Isolation Pilot Plant (WIPP) experienced its first minor accident involving a radiological release. Late in the evening on February 14, 2014, a waste container in the repository underwent a chemical reaction that caused the container to overheat and breach, releasing its contents into the underground. Following a lengthy recovery process, the facility recently resumed waste disposal operations. The accident released significant levels of radioactivity into the disposal room and adjacent exhaust drifts, and although no one was present in the underground at the time of the release, a total of 22 workers tested positive for very low level of radiation, presumably from some of the radioactive material that was released above ground through a small leak in the HEPA filtration system. The dominant radionuclides released were 241Am and 239 + 240Pu in a ratio that matched the content of the drum from Los Alamos National Laboratory (LANL) that was eventually identified as the breached container. From the air particulate monitoring and plume modeling, it was concluded that the dose, at the nearest location accessible to the general public, from this radiation release event would have been less than 0.01 mSv (< 1 mrem/year). This level is well below the 0.1 mSv/year (10 mrem/year) regulatory limit for DOE facilities established by the US Environmental Protection Agency (EPA).While no long-term impacts to public health or the environment are expected as a result of the WIPP radiation release, the limited ventilation and residual contamination levels in the underground are still a concern and pose a major challenge for the full recovery of WIPP. This article provides an up-to-date overview of environmental monitoring results through the WIPP recovery and an estimate of the long-term impacts of the accident on the natural and human environment.

Thermodynamics and the structural aspects of the ternary complexes of Am(III), Cm(III) and Eu(III) with Ox and EDTA + Ox.

The stability constants and the associated thermodynamic parameters of formation of the binary and the ternary complexes of Am(3+), Cm(3+) and Eu(3+) were determined by a solvent extraction to measure the variation in the distribution coefficient with temperature (0-60 degrees C) for aqueous solutions of I = 6.60 m (NaClO(4)). The formation of ternary complexes is favored by both the enthalpy (exothermic) and the entropy (endothermic) values. (13) C NMR, TRLFS and EXAFS spectral data was used to study the coordination modes of the ternary complexes. In the formation of the complex M(EDTA)(Ox)(3-), the EDTA retained all its coordination sites with Ox binding via two carboxylates and with one water of hydration remaining attached to the M(3+). In the complex M(EDTA)(Ox)(2)(5-), one carboxylate, either from EDTA or Ox, is not bounded to M(3+) and there were no water of hydration attached to these cations.