Probable nuclear reactions to produce proton rich rhenium radionuclides

The crux of the present work is to explore the various channels leading to the production of proton rich rhenium radionuclides, ^181–186Re, for different applications. The possible production routes encompass both light and heavy ion induced reactions up to a maximum 100 MeV projectile energy starting from threshold. The nuclear reaction model codes ALICE91 and PACE-II were employed in this endeavour. Excitation functions of the rhenium radionuclides have been calculated using the aforesaid nuclear reaction model codes and compared with the measured data wherever available. The contributions of preequilibrium and equilibrium reaction mechanisms to the total reaction cross section were analysed. For the first time, this study talks about the possibility of light-heavy ion (^6,7Li and ⁹Be) induced production of proton rich rhenium radionuclides.     

New ultra-sensitive radioanalytical technologies for new science

Recent developments in radiometric and mass spectrometry technologies have been associated in the radiometric sector mainly with underground operations of large volume Ge detectors, while the mass-spectrometry sector, represented mainly by accelerator mass spectrometry and inductively coupled plasma mass spectrometry has become the most sensitive technique for ultra-low-level analyses of long-lived radionuclides. These new developments have had great impact on investigations of rare nuclear processes and applications of radionuclides in environmental, life and space sciences. New scientific investigations have been carried out therefore which have not been possible before either because of lack of sensitivity or required large sample size.     

Proton activation analysis for chromium,nickel and copper

Proton activation analysis has been applied to develop a procedure for the simultaneous determination of chromium, nickel and copper. The procedure involves the bombardment of the sample with protons to induce⁵²Cr(p, n)^52mMn,⁶⁰Ni(p, n)⁶⁰Cu and⁶³Cu(p, n)⁶³Zn reactions. These reactions have been studied for proton energies from 11 MeV to 15 MeV. Thick target yields for the production of the indicator radionuclides as well as the sensitivities of the determination have been measured in this energy region and are compared with results obtained for other charged particle induced reactions. Detailed data are given on nuclear and instrumental interferences. The trace elements have been determined nondestructively and simultaneously in cobalt with a relative precision of 8 to 15%.     

Field testing of collection and measurement of radioxenon for the Comprehensive Test Ban Treaty

Pacific Northwest National Laboratory, with guidance and support from the U.S. Department of Energy's NN-20 Comprehensive Test Ban Treaty (CTBT) Research and Development program, has developed and demonstrated a fully automatic sampler-analyzer (ARSA) for the collection and quantitative measurement of the four xenon radionuclides,^131mXe (11.9 d),^133mXe (2.19 d),¹³³Xe (5.24 d), and¹³⁵Xe (9.10 h), in the atmosphere. These radionuclides are important signatures in monitoring for compliance to a CTBT, and may have applications in stack monitoring and other areas where xenon radionuclides are present. The activity ratios between certain of these radionuclides permit discrimination between radioxenon originating from nuclear detonations and that from nuclear reactor operations, nuclear fuel reprocessing, or from medical isotope production and usage. With the ARSA system, xenon is continuously and automatically separated from the atmosphere at flow rates of about 100 lpm by sorption-bed techniques. Samples collected in 8 hours are automatically analyzed by electron-photon coincidence spectrometry to provide detection sensitivities as low as 100 μBq/m³ of air. This sensitivity is about 10-fold better than achieved with reported laboratory-based procedures¹ for the short time collection intervals of interest. Gamma-ray energy spectra and gas analysis data are automatically collected.     

Radiochemical determination of nuclear data for theory and applications

A vast knowledge of nuclear data is available and is grouped under three headings, namely, nuclear structure, nuclear decay and nuclear reaction data. Still newer aspects are under continuous investigation. Data measurements are done using a large number of techniques, including the radiochemical method, which has been extensively worked out at Jülich. This method entails preparation of high-quality sample for irradiation, isolation of the desired radioactive product from the strong matrix activity, and preparation of thin source suitable for accurate measurement of the radioactivity. It is especially useful for fundamental studies on light complex particle emission reactions and formation of low-lying isomeric states, both of which are rather difficult to describe by nuclear model calculations. The neutron induced reaction cross section data are of practical application in fusion reactor technology, particularly for calculations on tritium breeding, gas production in structural materials and activation of reactor components. The charged particle induced reaction cross section data, on the other hand, are of significance in medicine, especially for developing new production routes of novel positron emitters and therapeutic radionuclides at a cyclotron. Both neutron and charged particle data also find application in radiation therapy. A brief overview of advances made in all those areas is given, with major emphasis on nuclear reaction cross section data.     

Sorbent extraction behavior of a nonionic surfactant,Triton X-100, onto commercial charcoal from low level radioactive waste

In nuclear power plants and nuclear laboratories, laundry wastewater is generated from decontaminating polluted instruments, worker’s clothes and taking shower after work. Laundry wastewater contains radionuclides and surfactants. The surfactants included in laundry wastewater affect the extraction of radionuclides. Therefore, surfactants should be removed before extraction of radionuclides. The objective of the present work is to assess the ability of commercial charcoal for the removal of nonionic surfactants, where, commercial charcoal is a commonly available adsorbent for treatment. Charcoal was characterized using different analytical techniques. The isotherm models and thermodynamic parameters were evaluated. Charcoal was applied to the removal of surfactant from liquid radioactive waste. The data obtained can be used for designing a plant for treatment of surfactant rich water and wastewater economically.     

Production and separation of 111In: an important radionuclide in life sciences: a mini review

¹¹¹In is amongst the frequently used radionuclides in diagnostic nuclear medicine. Therefore its production and subsequent separation chemistry have been widely investigated since late 40s. ¹¹¹In is commonly produced in proton or α-particle induced reactions on cadmium or silver targets. However, in recent past, various heavy ion (⁷Li, ¹¹B, ¹²C etc.) activation routes have been proposed for its production. In this mini review, we have tried to portray the production routes of ¹¹¹In and chemical separation methodologies reported so far in the literature in a concise form. A critical analysis presented in this review will be helpful to select suitable nuclear reaction and radiochemical method to produce high purity ¹¹¹In for applications.     

An anion exchange technique for separation of Na and K for neutron activation analysis of W-Ti alloy

Anthropogenic radioactivity is being measured in near-real time by an international monitoring system designed to verify the Comprehensive Nuclear Test Ban Treaty. Airborne radioactivity measurements are conducted in-situ by stations that are linked to a central data processing and analysis facility. Aerosols are separated by high-volume air sampling with high-efficiency particulate filters. Radio-xenon is separated from other gases through cryogenic methods. Gamma-spectrometry is performed by high purity germanium detectors and the raw spectral data is immediately transmitted to the central facility via Internet, satellite, or modem. These highly sensitive sensors, combined with the automated data processing at the central facility, result in a system capable of measuring environmental radioactivity on the microbeequerel scale where the data is available to scientists within minutes of the field measurement. During the past year, anthropogenic radioactivity has been measured at approximately half of the stations in the current network. Sources of these measured radionuclides include nuclear power plant emissions, Chernobyl resuspension, and isotope production facilities. The ability to thoroughly characterize site-specific radionuclides, which contribute to the radioactivity of the ambient environment, will be necessary to reduce the number of false positive events. This is especially true of anthropogenic radionuclides that could lead to ambiguous analysis.     

Radionuclide-rich spruce twigs and needles as analytical reference materials

Black spruce /Picea mariana/ twigs and needles have been collected from a uraniferous area of northern Saskatchewan and characterized for their content of some radionuclides and trace elements in an interlaboratory program. These materials, rich in uranium, are available as reference materials, for estimating accuracy in the analysis of vegetation, from the Canadian Certified Reference Materials Project in Ottawa, Canada.     

Neutron transport simulation (selected topics)

Neutron transport simulation is usually performed for criticality, power distribution, activation, scattering, dosimetry and shielding problems, among others. During the last fifteen years, innovative technological applications have been proposed (Accelerator Driven Systems, Energy Amplifiers, Spallation Neutron Sources, etc.), involving the utilization of intermediate energies (hundreds of MeV) and high-intensity (tens of mA) proton accelerators impinging in targets of high Z elements. Additionally, the use of protons, neutrons and light ions for medical applications (hadrontherapy) impose requirements on neutron dosimetry-related quantities (such as kerma factors) for biologically relevant materials, in the energy range starting at several tens of MeV. Shielding and activation related problems associated to the operation of high-energy proton accelerators, emerging space-related applications and aircrew dosimetry-related topics are also fields of intense activity requiring as accurate as possible medium- and high-energy neutron (and other hadrons) transport simulation. These applications impose specific requirements on cross-section data for structural materials, targets, actinides and biologically relevant materials.Emerging nuclear energy systems and next generation nuclear reactors also impose requirements on accurate neutron transport calculations and on cross-section data needs for structural materials, coolants and nuclear fuel materials, aiming at improved safety and detailed thermal-hydraulics and radiation damage studies.In this review paper, the state-of-the-art in the computational tools and methodologies available to perform neutron transport simulation is presented. Proton- and neutron-induced cross-section data needs and requirements are discussed. Hot topics are pinpointed, prospective views are provided and future trends identified.     

Longitudinal study of iodine in market milk and infant formula via epiboron neutron activation analysis

A global radionuclide monitoring system is being engineered as part of a multi-technology verification system for the Comprehensive Nuclear Test Ban Treaty. The system detects airborne radioactive aerosols and gases that can indicate nuclear weapons test debris. The backbone of the system is a network of 80 remote detection stations that utilize high-volume air sampling and high-resolution gamma spectrometry to provide in-situ assay and near-real time reporting. These stations are linked to the International Data Centre, which is a central data processing hub where raw spectral data is automatically processed, analyzed, and disseminated to the states parties. Measurements are categorized based on spectral content to determine which contain anomalous anthropogenic radionuclides that require intensive radiochemical analysis at a certified laboratory. The resulting system has the capability to measure microbecquerel concentrations of radionuclides and provide accessible data products within minutes of field measurements. During the past year of international operations, the minimum detectable concentrations and spectroscopy processing statistics were recorded as a function of geographical location and time. The results show that this system is an effective tool for nuclear test monitoring, as well as other applications such as radiological emergency response, public health monitoring, and scientific research.     

The possible discovery of neutron activation in 1910

One-hundred-two years ago, on 21 April 1910, the Austrian chemist Carl Auer von Welsbach published a short comment on a fundamental discovery he had made in the field of nuclear sciences. He reported that “jonium” (²³⁰Th) was able to induce radioactivity in other materials if stored in contact with the ionium sample. He was well aware that this observation was “not quite in agreement with current theories”, because, as a basic principle, a radioactive substance cannot activate an inactive substance. Since he could not remove any superficial contamination, he concluded that the previously inactive materials had become radioactive themselves. Auer von Welsbach predicted that this observation “might be of importance for the mysterious field of radioactivity research”. In fact, we believe that in this experiment he incidentally discovered neutron activation and the production of artificial radionuclides (24 years before I. Curie and F. Joliot) or even induced nuclear fission. The neutron source in his experiments is yet unknown and shall be identified in this project. The neutrons could have been produced from nuclear reactions with impurities of beryllium in the sample. Auer von Welsbach may even have observed nuclear fission 29 years before O. Hahn, F. Straßmann, L. Meitner and O. R. Frisch. In any case, he may have noticed the effects of neutron radiation—22 years before its discovery by J. Chadwick. The main aim of this interdisciplinary project (of which preliminary results are presented herein) is to repeat the 1910-experiment and to identify the source of the neutrons. It will be equally important to investigate the historical reasons and circumstances why Auer’s report remained mostly uncommented in the scientific community. The hypothetical consequences are worth discussion: Auer’s publication could have started the “nuclear age” much earlier than it finally began, with all the consequences for mankind.     

Activation rates and chemical recovery of67Cu produced with low energy proton irradiation of enriched70Zn targets

Copper-67 is a radioisotope with significant potential for diagnostic and therapeutic applications in nuclear medicine. Despite its promise,⁶⁷Cu has failed to make an impact in clinical nuclear medicine, primarily because it is available sporadically, and in limited quantities. Common methods of production rely on high energy proton irradiation of natural zinc targets or on induced reactions using high energy neutrons at nuclear reactors. We have evaluated alternative production methods that could provide year-round adequate supply of this isotope. Using a low energy accelerator, we have studied the production of⁶⁷Cu by proton reactions on enriched⁷⁰Zn. Our results indicate that it is possible to produce useful quantities of⁶⁷Cu from the irradiation of enriched⁷⁰Zn with protons that have energies of less than 20 MeV. Production rates are higher than currently used methods at high energy accelerators or reactors. This isotope can be made available throughout the year as a result of this research.     

Production of radionuclides for nuclear therapy and environmental studies

This work is devoted to the production of the radionuclides used in nuclear medicine and as radiotracers for environmental research. Production methods for high LET radionuclides (⁶⁷Ga, ⁷⁷Br, ¹¹¹In, ²¹¹At) that are promising for radioimmunotherapy are proposed. Production techniques for short-lived analogues of highly radiotoxic long-lived fission products (Tc, Se, Sr) are developed. The techniques are based on extraction and chromatographic separation from a cyclotron target irradiated by α-particles and deuteron beams.     

A study of the indium and germanium photopeaks in the background spectra of Ge spectrometers with a passive shield

Cosmic ray neutron interactions with indium, used as electrical contact within a Ge diode, the diode itself and the surrounding materials can give rise to a large number of photopeaks in the 50 to 1300 keV region of background spectra of Ge spectrometers with a passive shield. The nuclear processes and decays involved in the production of these photopeaks are discussed. These cosmic ray produced photopeaks are compared with those due to primordial radionuclides. Some useful information can be drawn from these measurements on the contribution of the cosmic rays on the background of Ge detectors with a passive shield.     

Cyclotron production and quality control of “high specific activity' radionuclides in “no-carrier-added” form for radioanalytical applications in the life sciences

Radionuclides of very high specific activity A _S(t) have great relevance for applications in the life sciences. Updated definitions of A _S are given. The real A _S(t) must be measured by analytical and radioanalytical techniques. No-carrier-added (NCA) radionuclides have A _S(NCA) sometimes close to the carrier-free (CF) value A _S(CF). The accurate knowledge of excitation functions of nuclear reactions vs. ion beam energy is mandatory to maximize A _S(NCA); the minimization of isotopic dilution factor IDF(t) has been achieved too. A range of accelerator production and radioanalytical QC methods for A _S(NCA) optimization and determination is presented. This revised version was published online in August 2006 with corrections to the Cover Date.     

Nanoscale Chemical Imaging Using Tip‐Enhanced Raman Spectroscopy: A Critical Review

Methods for chemical analysis at the nanometer scale are crucial for understanding and characterizing nanostructures of modern materials and biological systems. Tip‐enhanced Raman spectroscopy (TERS) combines the chemical information provided by Raman spectroscopy with the signal enhancement known from surface‐enhanced Raman scattering (SERS) and the high spatial resolution of atomic force microscopy (AFM) or scanning tunneling microscopy (STM). A metallic or metallized tip is illuminated by a focused laser beam and the resulting strongly enhanced electromagnetic field at the tip apex acts as a highly confined light source for Raman spectroscopic measurements. This Review focuses on the prerequisites for the efficient coupling of light to the tip as well as the shortcomings and pitfalls that have to be considered for TERS imaging, a fascinating but still challenging way to look at the nanoworld. Finally, examples from recent publications have been selected to demonstrate the potential of this technique for chemical imaging with a spatial resolution of approximately 10 nm and sensitivity down to the single‐molecule level for applications ranging from materials sciences to life sciences.     

Distribution and dynamics of radionuclides and stable elements in the coastal waters off Rokkasho Village, Japan, prior to the opening of a nuclear reprocessing facility

The suspended particles floating in the seawater have the ability to biologically, as well as physically adsorb radionuclides and other elements dissolved in seawater. We have studied the distribution and composition of suspended particles, as well as the state of eluted of radionuclides in the decomposition process, in the coastal waters off Rokkasho Village, where radionuclides will be discharged from a nuclear fuel reprocessing plant in the near future.     

Radionuclide release from high-level nuclear-waste packages

The engineered barrier subsystem (EBS) in an important component in limiting the release of radionuclides from a geologic repository for disposal of high-level nuclear waste. The purpose of this paper is to identify and discuss the key processes that affect the release of radionuclides from nuclear waste forms and migration of these radionuclides through the nuclear-waste packages of the EBS to the geologic setting (i.e., far-field). Previous studies of release have focused on laboratory testing and modelling of the waste-form dissolution (leaching). Mass-transfer analyses, using realistic chemical-reaction-rate boundary conditions, confirm that radionuclide release from the EBS will be controlled by solubilitylimited, mass transport, rather than by waste-form leaching. Based on these well-established and laboratory-validated models, key data necessary for reliable predictions of the long-term performance of an EBS are identified. These data include the local chemistry at the wasteform surface, radionuclide solubilities and sorption behavior in contact with engineered materials, and characteristics of radionuclide-bearing colloids.