Uranium Target Research Articles

Locating New Uranium Occurrence by Integrated Weighted Analysis in Kaladgi Basin, Karnataka

Interpretation of airborne geophysical data especially gamma ray spectrometric data is important for mineral exploration, specifically radioactive elements and to identify uranium targets. Exploration was carried out in MesoNeoproterozoic Kaladgi basin for five decades to target different types of uranium mineralisation. The first sizable sub-surface uranium mineralisation was intercepted at Deshnur within Badami arenites close to unconformity contact along the southern margin of the basin (Shobhita et al., 2011). Heliborne geophysical surveys were carried out in western part of the basin from Kadgaon to Ramdurg to acquire Time Domain Electromagnetic, Magnetic and Radiometric data. The radiometric data was collected using Exploranium GR820 airborne (256-channel recording) spectrometer system mounted in a helicopter with four 4.2L downward looking crystals and one 4.2L upward looking crystal for a total effective volume of 16.8L downwards and 4.2L upwards. The raw radiometric data was processed for corrections (background, radon, stripping, height attenuation etc) and counts were converted to ground concentration of %K, eU ppm, and eTh ppm, and their grid maps were prepared (Sridhar et al, 2012) . Kaladgi basin is an irregular E-W trending area in the northern part of Dharwar craton. In the study area, Kaladgi basin sediments are exposed as unconformably overlying the basement crystallines in the south and are covered by Deccan traps in the north. The crystalline basement of the Kaladgi Supergroup is represented by NNW trending Meso to Neoarchaean peninsular gneiss, greenstone belts and Closepet granite. The sedimentary sequence in the Kaladgi Supergroup has been divided along an angular unconformity surface into two groups: the lower Bagalkot Group, and the overlying Badami Group. The sediments of Bagalkot Group comprises of arenaceous, argillaceous and carbonate sequences which are folded into a series of anticlines and synclines. The sediments of Badami Group are undeformed and rest unconformably over the Archaean basement rocks as well as the Bagalkot Group. The Badami Group comprises of horizontal to gently dipping beds of arenite, shale and limestones (Jayaprakash et al., 1987). This study aims at identifying uranium potential zones by integrated analysis of thematic layer interpreted and derived from airborne radiometric and magnetic data, satellite data along with available ground geochemical data in western part of Kaladgi basin. Integrated weighted analysis of spatial datasets which included airborne radiometric data (eU, eTh & % K conc.), litho-structural map, hydrogeochemical U conc., and geomorphological data pertaining to study area, was attempted. The weightage analysis was done in GIS environment where different spatial dataset were brought on to a single platform and were analyzed by integration (Fig.1). The processed radiometric database was taken up for quantitative analysis to identify radiometric uranium anomalies. The database was clipped by using exposed and inferred lithological contacts of Badami Group to separate out data over sediments of Badami Group only. The analysis was carried out in two methods - 1 st the whole block and 2 nd Badami Group exclusive. Statistical analysis was applied to the airborne spectrometric data for separation of uranium anomalies from background. The statistics of the databases for uranium, thorium, ratio of uranium to thorium and uranium squared by thorium were calculated. The anomalies were extracted by applying cutoff threshold values for uranium, uranium by thorium and uranium squared by thorium channels in both methods. These anomalies were plotted spatially and they were classified as cluster anomalies and point anomalies depending upon their nature. Weightages were assigned based on nature of anomalies and cluster anomalies were given more weightage as they are more significant compared to point anomalies. The anomalies extracted from the

Numerical research on the ion-beam-driven hydrodynamic motion of fissile targets for nuclear safety studies

AbstractAs a method to evaluate high-temperature equation of state (EOS) data of fissile materials precisely and safely, we numerically examined an experimental setup based on a sub-range fissile target and a high-intensity short-pulsed heavy-ion beam. As an example, we calculated one-dimensional hydrodynamic motion of a uranium target with ρ = 0.03ρsolid(ρsolid ≡ solid density = 19.05 g/cm3) induced by a pulsed23Na+beam with a duration of 2 ns and a peak power of 5 GW/mm2. The projectile stopping power was calculated using a density- and temperature-dependent dielectric response function. To heat the target uniformly, we optimized the experimental condition so that the energy deposition could occur almost at the top of the Bragg peak. The energy deposition inhomogeneity could be reduced to ±5% by adjusting the incident energy and the target thickness to be 2.02 MeV/u and 180 μm, respectively. The target could be heated homogeneously up tokT=7 eV well before the arrival of the rarefaction waves at the center of the target. In principle, the EOS data can be evaluated by iteratively adjusting the data embedded in the hydro code until the measured hydrodynamic motion is reproduced by the calculation. This method is consistent with the conditions of nuclear nonproliferation, because a very small amount of fissile material is enough to perform the experiment, and no shock compression occurs in the target.

Calculations of ADS with deep subcritical uranium active cores – comparison with experiments and predictions

The main characteristics of the neutron field formed within the massive (512 kg) natural uranium target assembly (TA) QUINTA irradiated by deuteron beam of JINR Nuclotron with energies 1,2,4, and 8 GeV as well as the spatial distributions and the integral numbers of (n,f), (n,γ) and (n,xn)- reactions were calculated and compared with experimental data [1] . The MCNPX 27e code with ISABEL/ABLA/FLUKA and INCL4/ABLA models of intra-nuclear cascade (INC) and experimental cross-sections of the corresponding reactions were used. Special attention was paid to the elucidation of the role of charged particles (protons and pions) in the fission of natural uranium of TA QUINTA. Extensive calculations have been done for quasi-infinite (with very small neutron leakage) depleted uranium TA BURAN having mass about 20 t which are intended to be used in experiments at Nuclotron in 2014-2016. As in the case of TA QUINTA which really models the central zone of TA BURAN the total numbers of fissions, produced 239Pu nuclei and total neutron multiplicities are predicted to be proportional to proton or deuteron energy up to 12 GeV. But obtained values of beam power gain are practically constant in studied incident energy range and are approximately four. These values are in contradiction with the experimental result [2] obtained for the depleted uranium core weighting three tons at incident proton energy 0.66 GeV.

Design optimization of a new homogeneous reactor for medical radioisotope Mo-99/Tc-99m production

To partly solve the global and regional shortages of Mo-99/Tc-99m supply, a conceptual design of a homogeneous solution reactor for Mo-99/Tc-99m medical radioisotope production is proposed. Some basic characteristics and features of the design are discussed. The new homogeneous solution reactor is designed by taking into account the matured technology for chemically extracting the Mo-99 from the low enriched uranium (LEU) targets (the modified LEU Cintichem process) that has been acquired, demonstrated and licensed commercially for decades by the Center for Radioisotope Production of the National Nuclear Energy Agency of Indonesia (BATAN). Design optimization for obtaining the minimum critical U-235 mass and the maximum reactor power (proportional to Mo-99 production capacity) is presented.

Investigation of Active Background From Photofission in Depleted Uranium Using Cherenkov Detectors and Gamma Ray Time-of-Flight Analysis

Prompt gammas from induced fission could potentially be a valuable fission signature to use for detection of special nuclear materials like highly enriched uranium. Detectability requires an understanding of both signal and background, and the background from highly enriched uranium can be understood using depleted uranium as a surrogate. In order to study the prompt gamma active backgrounds from special nuclear materials induced through photofission, a combination of measurements using the Idaho Accelerator Center 44 MeV Electron Linear Accelerator and Monte Carlo N-Particle simulations were used. In this paper, we discuss the prompt, time-gated glass Cherenkov detector response to gamma emissions resulting from short pulse 6, 10, and 25 MeV bremsstrahlung beams incident on a depleted uranium target. Considering any threshold used with the Cherenkov detectors, the prompt gamma signal from depleted uranium is buried in the active background from the interrogating photon source. This paper describes the contributions to this prominent prompt active background observed in our measurements.

Production of Fission Product 99Mo using High-Enriched Uranium Plates in Polish Nuclear Research Reactor MARIA: Technology and Neutronic Analysis

Abstract The main objective of 235U irradiation is to obtain the 99mTc isotope, which is widely used in the domain of medical diagnostics. The decisive factor determining its availability, despite its short lifetime, is a reaction of radioactive decay of 99Mo into 99mTc. One of the possible sources of molybdenum can be achieved in course of the 235U fission reaction. The paper presents activities and the calculation results obtained upon the feasibility study on irradiation of 235U targets for production of 99Mo in the MARIA research reactor. Neutronic calculations and analyses were performed to estimate the fission products activity for uranium plates irradiated in the reactor. Results of dummy targets irradiation as well as irradiation uranium plates have been presented. The new technology obtaining 99Mo is based on irradiation of high-enriched uranium plates in standard reactor fuel channel and calculation of the current fission power generation. Measurements of temperatures and the coolant flow in the molybdenum installation carried out in reactor SAREMA system give online information about the current fission power generated in uranium targets. The corrective factors were taken into account as the heat generation from gamma radiation from neighbouring fuel elements as well as heat exchange between channels and the reactor pool. The factors were determined by calibration measurements conducted with aluminium mock-up of uranium plates. Calculations of fuel channel by means of REBUS code with fine mesh structure and libraries calculated by means of WIMS-ANL code were performed.

Evaluation of characteristics of molybdenum-technetium generators prepared from regenerated uranium at the VVR-ts reactor

The problem of uranium regeneration from uranium-containing residues after irradiating a uranium target and isolating from it 99Mo for use in nuclear medicine is considered. It is shown to be possible to produce 99Mo of quality required for charging a 99mTc generator from the regenerated 235U. The service characteristics of the 99mTc generator based on secondary 99Mo fully meet the Technical Specifications for the standard 99mTc generator, and the quantitative characteristics of sodium pertechnetate meet the requirements of Russian and international pharmacopoeias.

Measurement of Gamma Energy Distributions and Multiplicities Using STEFF

Prompt gamma-ray energy distributions and multiplicities released during thermally induced fission of 235U have been measured using STEFF (SpecTrometer for Exotic Fission Fragments). Thermal neutrons are provided by the high-flux reactor at the ILL, Grenoble. STEFF is a unique 2E2v device that uses a coincidence timing method to measure the emission of prompt gamma rays as a function of the fragment mass and energy. Following scission, the fission fragments contain excitation energy that is released via prompt neutron and gamma-ray emission as the fragment decays to the ground state. STEFF contains an array of 11 NaI detectors surrounding the uranium target providing a 6.8% photopeak detection efficiency for gamma rays released within 1 ns of the scission time. STEFF also consists of 7 NE213 detectors, which detect the emission of prompt neutrons, the release of which is associated with reduction of fragment energy and, to a lesser extent, fragment spin. This experiment acts as a direct response to the NEA high priority demand which requires more accurate knowledge of heating caused by gamma emission in the next generation of nuclear reactors.

Implementation of Multi-Curie Production of (99m)Tc by Conventional Medical Cyclotrons.

(99m)Tc is currently produced by an aging fleet of nuclear reactors, which require enriched uranium and generate nuclear waste. We report the development of a comprehensive solution to produce (99m)Tc in sufficient quantities to supply a large urban area using a single medical cyclotron. A new target system was designed for (99m)Tc production. Target plates made of tantalum were coated with a layer of (100)Mo by electrophoretic deposition followed by high-temperature sintering. The targets were irradiated with 18-MeV protons for up to 6 h, using a medical cyclotron. The targets were automatically retrieved and dissolved in 30% H2O2. (99m)Tc was purified by solid-phase extraction or biphasic exchange chromatography. Between 1.04 and 1.5 g of (100)Mo were deposited on the tantalum plates. After high-temperature sintering, the (100)Mo formed a hard, adherent layer that bonded well with the backing surface. The targets were irradiated for 1-6.9 h at 20-240 μA of proton beam current, producing up to 348 GBq (9.4 Ci) of (99m)Tc. The resulting pertechnetate passed all standard quality control procedures and could be used to reconstitute typical anionic, cationic, and neutral technetium radiopharmaceutical kits. The direct production of (99m)Tc via proton bombardment of (100)Mo can be practically achieved in high yields using conventional medical cyclotrons. With some modifications of existing cyclotron infrastructure, this approach can be used to implement a decentralized medical isotope production model. This method eliminates the need for enriched uranium and the radioactive waste associated with the processing of uranium targets.

Investigation of the optimal material type and dimension for spallation targets using simulation methods

Accelerator-driven systems are extensively developed to generate neutron sources for research, industrial and medical plans. Different heavy elements are utilized as spallation targets to produce spallation neutrons. Computational methods are efficiently utilized to simulate neutronic behavior of a spallation target. MCNPX 2.6.0 is used as a powerful code based on Monte Carlo stochastic techniques for spallation process computation. This code has the ability to transport different particles using different physical models. In this paper, MCNPX has been utilized to calculate the leaked neutron yield from Pb, LBE, W, Ta, Hg, U, Th, Sn and Cu cylindrical heavy targets. Effects of the target thickness and diameter on neutron yield value have been investigated via the thickness and diameter variations between 5–30 and 5–20 cm, respectively. Proton-induced radionuclide production into the targets as well as leaked neutron spectra from the targets has been calculated for the targets of an optimum determined dimension. 1 GeV proton particle has been selected to induce spallation process inside the targets. 2 mm spatial FWHM distribution has been considered for the 1 mA proton beam. Uranium target produced the highest leaked neutron yield with a 1.32–3.7 factor overweigh the others. Dimension of 15 × 60 cm is suggested for all the cylindrical studied spallation targets. Th target experienced the highest alpha-emitter radionuclide production while lighter elements such as Cu and Sn bore the lowest radio-toxicity. LBE liquid spallation target competes with the investigated solid targets in neutronic point of view while has surpass than volatile liquid Hg target.

Structure and properties of uranium oxide thin films deposited by pulsed dc magnetron sputtering

Crystalline uranium oxide thin films were deposited in an unbalanced magnetron sputtering system by sputtering from a depleted uranium target in an Ar+O2 mixture using middle frequency pulsed dc magnetron sputtering. The substrate temperature was constantly maintained at 500°C. Different uranium oxide phases (including UO2−x, UO2, U3O7 and U3O8) were obtained by controlling the percentage of the O2 flow rate to the total gas flow rate (fO2) in the chamber. The crystal structure of the films was characterized using X-ray diffraction and the microstructure of the films was studied using transmission electron microscopy and atom probe tomography. When the fO2 was below 10%, the film contains a mixture of metallic uranium and UO2−x phases. As the fO2 was controlled in the range of 10–13%, UO2 films with a (220) preferential orientation were obtained. The oxide phase rapidly changed to a mixture of U3O7 and U3O8 as the fO2 was increased to the range of 15–18%. Further increasing the fO2 to 20% and above, polycrystalline U3O8 thin films with a (001) preferential orientation were formed. The hardness and Young's modulus of the uranium oxide films were evaluated using nanoindentation. The film containing a single UO2 phase exhibited the maximum hardness of 14.3GPa and a Young's modulus of 195GPa. The UO2 thin film also exhibited good thermal stability in that no phase change was observed after annealing at 600°C in vacuum for 104h.

How Fundamentals of Phase Equilibria and Diffusion Contribute to the RERTR program

One of the oldest programs of the U.S. Department of Energy is the Reduced Enrichment for Research and Test Reactors (RERTR) program. This program develops technology necessary to convert both research and test reactors, including some medical purpose reactors, from using high enriched uranium (HEU) to using low enriched uranium (LEU) fuels and targets. This conversion is related to non-proliferation by making weapons grade nuclear material less available. In order to pursue their goal, the RERTR Program, managed by the Office of Nuclear Material Threat Reduction in the National Nuclear Security Administration, has held annual international conferences since its inception in 1978.

Preparation of thick uranium layers on aluminium and stainless steel backings

The methods of electrodeposition and “molecular plating” were studied for the production of uranium targets with an areal density up to 0.6mgcm−2 on aluminium and up to 1.5mgcm−2 on stainless steel backings from aqueous and organic electrolytes. For characterisation of the deposited material, gamma-ray spectrometry, alpha-particle spectrometry, X-ray fluorescence, X-ray powder diffraction, scanning electron microscopy and autoradiography were applied.

DEVELOPMENT OF HIGH-DENSITY U/AL DISPERSION PLATES FOR MO-99 PRODUCTION USING ATOMIZED URANIUM POWDER

Uranium metal particle dispersion plates have been proposed as targets for Molybdenum-99 (Mo-99) production to improve the radioisotope production efficiency of conventional low enriched uranium targets. In this study, uranium powder was produced by centrifugal atomization, and miniature target plates containing uranium particles in an aluminum matrix with uranium densities up to 9 g-U/cm 3 were fabricated. Additional heat treatment was applied to convert the uranium particles into UAlx compounds by a chemical reaction of the uranium particles and aluminum matrix. Thus, these target plates can be treated with the same alkaline dissolution process that is used for conventional UAl x dispersion targets, while increasing the uranium density in the target plates

Preparation of uranium targets by electro-deposition method

The uranium targets were prepared by electro-deposition method.A hydrated uranium dioxide films were electrodeposited into stainless steel plates using uranyl nitrate in ammonium oxalate solution.The results show that the deposition efficiency of the uranium depends on many parameters,such as pH,supporting electrolyte,current density,and cell design.The electro-deposition yield was obtained in thick film samples using ultraviolet-spectrometric analysis of the electrolytic solution before and after the electro-deposition process.The optimized parameters were obtained by investigating the depositing temperature,time,concentration and pH of the supporting electrolyte.Electronic deposit was performed at 60℃ with pH=2-3,current density 60mA/cm2.The effect of UO2(NO3)2on uranium depositing shows an increase in efficiency as the electrolyte molarity increases at lower electrolyte concentrations,reaches the maximum at 1.67mg/mL.The uranium films,which are thin,adherent with a yield of 98%at the thickness of near 6mg/cm2 were characterized by infrared spectrum,scanning electron microscope,and X-ray spectrum.Its possible structure composing of uranium target is [UO2(H2O)4-O-UO2(H2O)4-O].XPS analysis shows that there is no elements other than uranium(65.35%),oxygen(27.38%),carbon(5.46%)and Pt(1.81%)being detected.The thickness of uranium films would reach 6-8mg/cm2 if repeated plating was adopted after sintering.

Reexamining the heavy-ion reactions238U+238U and238U+248Cm and actinide production close to the barrier

Recent theoretical work has renewed interest in radiochemically determined isotope distributions in reactions of ${}^{238}$U projectiles with heavy targets that had previously been published only in parts. These data are being reexamined. The cross sections \ensuremath{\sigma}($Z$) below the uranium target have been determined as a function of incident energy in thick-target bombardments. These are compared to predictions by a diffusion model whereby consistency with the experimental data is found in the energy intervals 7.65--8.30 MeV/u and 6.06--7.50 MeV/u. In the energy interval 6.06--6.49 MeV/u, the experimental data are lower by a factor of 5 compared to the diffusion model prediction indicating a threshold behavior for massive charge and mass transfer close to the barrier. For the intermediate energy interval, the missing mass between the primary fragment masses deduced from the generalized ${Q}_{\mathrm{gg}}$ systematics including neutron pair-breaking corrections and the centroid of the experimental isotope distributions as a function of $Z$ have been used to determine the average excitation energy as a function of $Z$. From this, the $Z$ dependence of the average total kinetic-energy loss ($\overline{\mathrm{TKEL}}$) has been determined. This is compared to that measured in a thin-target counter experiment at 7.42 MeV/u. For small charge transfers, the values of $\overline{\mathrm{TKEL}}$ of this work are typically about 30 MeV lower than in the thin-target experiment. This difference is decreasing with increasing charge transfer developing into even slightly larger values in the thick-target experiment for the largest charge transfers. This is the expected behavior which is also found in a comparison of the partial cross sections for quasielastic and deep-inelastic reactions in both experiments. The cross sections for surviving heavy actinides, e.g., ${}_{98}$Cf, ${}_{99}$Es, and ${}_{100}$Fm indicate that these are produced in the low-energy tails of the dissipated energy distributions, however, with a low-energy cutoff at about 35 MeV. Excitation functions show that identical isotope distributions are populated independent of the bombarding energy indicating that the same bins of excitation energy are responsible for the production of these fissile isotopes. A comparison of the survival probabilities of the residues of equal charge and neutron transfers in the reactions of ${}^{238}$U projectiles with either ${}^{238}$U or ${}^{248}$Cm targets is consistent with such a cutoff as evaporation calculations assign the surviving heavy actinides to the 3$n$ and/or 4$n$ evaporation channels.

Sequential Injection Method for Rapid and Simultaneous Determination of 236U, 237Np, and Pu Isotopes in Seawater

An automated analytical method implemented in a novel dual-column tandem sequential injection (SI) system was developed for simultaneous determination of (236)U, (237)Np, (239)Pu, and (240)Pu in seawater samples. A combination of TEVA and UTEVA extraction chromatography was exploited to separate and purify target analytes, whereupon plutonium and neptunium were simultaneously isolated and purified on TEVA, while uranium was collected on UTEVA. The separation behavior of U, Np, and Pu on TEVA-UTEVA columns was investigated in detail in order to achieve high chemical yields and complete purification for the radionuclides of interest. (242)Pu was used as a chemical yield tracer for both plutonium and neptunium. (238)U was quantified in the sample before the separation for deducing the (236)U concentration from the measured (236)U/(238)U atomic ratio in the separated uranium target using accelerator mass spectrometry. Plutonium isotopes and (237)Np were measured using inductively coupled plasma mass spectrometry after separation. The analytical results indicate that the developed method is robust and efficient, providing satisfactory chemical yields (70-100%) of target analytes and relatively short analytical time (8 h/sample).

Non-denaturating isoelectric focusing gel electrophoresis for uranium–protein complexes quantitative analysis with LA-ICP MS

A non-denaturating isoelectric focusing (ND-IEF) gel electrophoresis protocol has been developed to study and identify uranium (U)-protein complexes with laser ablation-inductively coupled plasma mass spectrometry (LA-ICP MS) and electrospray ionization mass spectrometry (ESI-MS). The ND-IEF-LA-ICP MS methodology set-up was initiated using in vitro U-protein complex standards (i.e., U-bovine serum albumin and U-transferrin) allowing the assessment of U recovery to 64.4 ± 0.4 %. This methodology enabled the quantification of U-protein complexes at 9.03 ± 0.23, 15.27 ± 0.36, and 177.31 ± 25.51 nmol U L(-1) in digestive gland cytosols of the crayfish, Procambarus clarkii, exposed respectively to 0, 0.12, and 2.5 μmol of waterborne depleted U L(-1) during 10 days. ND-IEF-LA-ICP MS limit of detection was 19.3 pmol U L(-1). Elemental ICP MS signals obtained both in ND-IEF electropherograms and in size exclusion chromatograms of in vivo U-protein complexes revealed interactions between U- and Fe- and Cu-proteins. Moreover, three proteins (hemocyanin, pseudohemocyanin-2, and arginine kinase) out of 42 were identified as potential uranium targets in waterborne-exposed crayfish cytosols by microbore reversed phase chromatography coupled to molecular mass spectrometry (µRPC-ESI-MS/MS) after ND-IEF separation.

In-source laser spectroscopy developments at TRILIS—towards spectroscopy on actinium and scandium

Resonance Ionization Laser Ion Sources (RILIS) have become a versatile tool for production and study of exotic nuclides at Isotope SeparatorOn-Line (ISOL) facilities such as ISAC at TRIUMF. The recent development and addition of a grating tuned spectroscopy laser to the TRIUMF RILIS solid state laser system allows for wide range spectral scans to investigate atomic structures on short lived isotopes, e.g., those from the element actinium, produced in uranium targets at ISAC. In addition, development of new and improved laser ionization schemes for rare isotope production at ISAC is ongoing. Here spectroscopic studies on bound states, Rydberg states and autoionizing (AI) resonances on scandium using the existing offline capabilities are reported. These results allowed to identify a suitable ionization scheme for scandium via excitation into an autoionizing state at 58,104 cm−1 which has subsequently been used for ionization of on-line produced exotic scandium isotopes.

Sustained Availability of 99mTc: Possible Paths Forward

The availability of (99m)Tc for single-photon imaging in diagnostic nuclear medicine is crucial, and current availability is based on the (99)Mo/(99m)Tc generator fabricated from fission-based molybdenum (F (99)Mo) produced using high enriched uranium (HEU) targets. Because of risks related to nuclear material proliferation, the use of HEU targets is being phased out and alternative strategies for production of both (99)Mo and (99m)Tc are being evaluated intensely. There are evidently no plans for replacement of the limited number of reactors that have primarily provided most of the (99)Mo. The uninterrupted, dependable availability of (99m)Tc is a crucial issue. For these reasons, new options being pursued include both reactor- and accelerator-based strategies to sustain the continued availability of (99m)Tc without the use of HEU. In this paper, the scientific and economic issues for transitioning from HEU to non-HEU are also discussed. In addition, the comparative advantages, disadvantages, technical challenges, present status, future prospects, security concerns, economic viability, and regulatory obstacles are reviewed. The international actions in progress toward evolving possible alternative strategies to produce (99)Mo or (99m)Tc are analyzed as well. The breadth of technologies and new strategies under development to provide (99)Mo and (99m)Tc reflects both the broad interest in and the importance of the pivotal role of (99m)Tc in diagnostic nuclear medicine.