Review of the role of nuclear analytical chemistry in the Canadian nuclear fuel waste management program

The Canadian Nuclear Fuel Waste Management Program involves both field and laboratory research, to assess the concept of disposal of nuclear fuel wastes at depths of up to 1000 m in plutonic rocks. This research program is multifaceted and requires data from a large number of disciplines, such as geology, geochemistry, hydrogeology, civil and mining engineering, chemistry, solid state science, environmental science, and meteorology. In many of these disciplines, nuclear analytical chemistry plays a major role. Examples of the application of nuclear analytical chemistry, including radiochemical separation and instrumental neutron activation analysis, will be discussed.Issued as AECL-8748.     

Hairs,criminals, moonrocks,metals diseases,polluters! Where next for nuclear analytical chemistry?

Nuclear methods of analysis have advanced dramatically in recent years, and in many ways, techniques that once were viewed as a scientific curiosity and the toys of a few scientists working in large nuclear research establishments, are now semi-routine and can be applied even by young students. Large amounts of good analytical data are outputted from instruments having sophisticated embedded software. It is interesting to speculate on the directions that nuclear analytical techniques may take next: whether more multielement; more automation for vastly larger sample suites; extension to minor and major components of samples as well as trace components; coupling of nuclear methods to hyphenated methods. However, in some respects the resources needed to continue to develop and apply radioanalytical methods are on the wane: reactors and accelerators are being closed and fewer radiochemical specialists are being trained. The open question, is whether instrumental analysis techniques will offer more and better results with less effort, or be less equipment intensive? In this paper some personal reflections on nuclear actcivation methods and their trends are presented and discussed. Some mileposts in the development of the field and some unique and interesting applications (as implied by the paper title) are cited and discussed.     

Rheo-NMR in food science—Recent opportunities

For over 25 years, nuclear magnetic resonance (NMR) and magnetic resonance imaging (MRI) techniques have been used to study materials under mechanical deformation. Collectively, these methods are referred to as Rheo-NMR. In many cases, it provides spatially and temporally resolved maps of NMR spectra, intrinsic NMR parameters (such as relaxation times), or motion (such as diffusion or flow). Therefore, Rheo-NMR is complementary to conventional rheological measurements. This review will briefly summarize current capabilities and limitations of Rheo-NMR in the context of material science and food science in particular. It will report on recent advances such as the incorporation of torque sensors or the implementation of large amplitude oscillatory shear and point out future opportunities for Rheo-NMR in food science.     

Photodesorption of diatomic molecules from surfaces: A theoretical approach based on first principles

Photodesorption of small molecules from surfaces is one of the most fundamental processes in surface photochemistry. Despite its apparent simplicity, a microscopic understanding beyond a qualitative picture still poses a true challenge for theory. While the dynamics of nuclear motion can be treated on various levels of sophistication, all approaches suffer from the lack of sufficiently accurate potential energy surfaces, in particular for electronically excited states involved in the desorption scenario.In the last decade, a systematic and accurate methodology has been developed which allows a reliable calculation of accurate ground and excited state potential energy surfaces (PES) for different adsorbate–substrate systems. These potential energy surfaces serve as a prerequisite for subsequent quantum dynamical wave packet calculations, which allow for a direct simulation of experimentally observable quantities such as quantum state resolved velocity distributions.In the first part of this review, we will focus on scalar properties of desorbing diatomic molecules from insulating surfaces, where we also present a recently developed strategy of obtaining accurate potential energy surfaces using quantum chemical approaches. In general, diatomic molecules on large band gap materials such as oxide surfaces are studied which allows the use of sufficiently large cluster models and accurate ab initio methods beyond density functional theory (DFT). In the second part, we will focus on the vectorial aspects of the dynamics of nuclear motion and present simulations of experimentally accessible observables such as velocity distributions, Doppler profiles and alignment parameters. For each system, the microscopic mechanism of photodesorption is elucidated. We will demonstrate that the driving force of surface photochemistry is strongly dependent on details of the electronic structure of the adsorbate–substrate systems. This implies that great caution is advisable if experimental results are interpreted using empirical or semi-empirical models.     

Recycling the Actinides,The Cornerstone of Any Sustainable Nuclear Fuel Cycles

The sustainability of the current nuclear fuel cycles is not completely achieved since they do not optimise the consumption of natural resource (only a very small part of uranium is burnt) and they do not ensure a complete and efficient recycling of the potential energetic material like the actinides. Promoting nuclear energy as a future energy source requires proposing new nuclear systems that could meet the criteria of sustainability in terms of durability, bearability and liveability. In particular, it requires shifting towards more efficient fuel cycles, in which natural resources are saved, nuclear waste are minimised, efficiently confined and safely disposed of, in which safety and proliferation-resistance are more than ever ensured. Such evolution will require (i) as a mandatory step, evolutionary recycling of the major actinides U and Pu up to their optimized use as energetic materials using fast neutron spectra, (ii) as an optional step, the implementation of the recycling of minor actinides which are the main contributors to the long term heat power and radiotoxicity of nuclear waste. Both options will require fast neutrons reactors to ensure an efficient consumption of actinides. In such a context, the back-end of the fuel cycle will be significantly modified: implementation of advanced treatment/recycling processes, minor-actinides recovery and transmutation, production of lighter final waste requiring lower repository space. In view of the 2012 French milestones in the framework of the 2006 Waste Management Act, this paper will depict the current state of development with regards with these perspectives and will enlighten the consequences for the subsequent nuclear waste management.     

Nuclear forensics education at the University of Texas at Austin

Nuclear forensics continues to be an integral part of the Domestic Nuclear Detection Office, the Defense Threat Reduction Agency and the National Nuclear Security Administration. As with our previous three-year Nuclear Forensics Education Award Program we will continue to offer a comprehensive educational program and closely collaborate with national laboratories to pursue common research. Our research will primarily focus on analysis of radioactive debris following a nuclear or radiological dispersive device event or the investigation of the pedigree of nuclear materials in nonproliferation. This research will include using Compton suppression and gamma coincidence low-level gamma ray counting, investigation of nuclear fuel cycles for nonproliferation, on-site inspection within the context of the Comprehensive Nuclear-Test-Ban Treaty and radioxenon detection physics. We also offer a graduate program in nuclear robotics, an interdisciplinary program in the automation of handling special nuclear materials. To better equip our students who are entering the workforce at the national laboratories and government agencies we are also proposing the development of several new laboratory modules for non-destructive identification of fission products in environmental samples and irradiated uranium specimens at various enrichments and characterizing naturally occurring radioactive material. Collaboration with Florida Memorial University a Historically Black Colleges and Universities will continue for training and collaborative research.     

Quantitative NMR for bioanalysis and metabolomics

Over the last several decades, significant technical and experimental advances have made quantitative nuclear magnetic resonance (qNMR) a valuable analytical tool for quantitative measurements on a wide variety of samples. In particular, qNMR has emerged as an important method for metabolomics studies where it is used for interrogation of large sets of biological samples and the resulting spectra are treated with multivariate statistical analysis methods. In this review, recent developments in instrumentation and pulse sequences will be discussed as well as the practical considerations necessary for acquisition of quantitative NMR experiments with an emphasis on their use for bioanalysis. Recent examples of the application of qNMR for metabolomics/metabonomics studies, the characterization of biologicals such as heparin, antibodies, and vaccines, and the analysis of botanical natural products will be presented and the future directions of qNMR discussed.     

Radiochemistry at the University of Missouri-Columbia: A joint venture with chemistry,nuclear engineering,molecular biology,biochemistry, and the Missouri University Research Reactor (MURR)

Summary The United States, the Department of Energy (DOE) and its National Laboratories, including the Pacific Northwest National Laboratory (PNNL), are facing a serious attrition of nuclear scientists and engineers and their capabilities through the effects of aging staff. Within the DOE laboratories, 75% of nuclear personnel will be eligible to retire by 2010. It is expected that there will be a significant loss of senior nuclear science and technology staff at PNNL within five years. PNNL's nuclear legacy is firmly rooted in the DOE Hanford site, the World War II Manhattan Project, and subsequent programs. Historically, PNNL was a laboratory where 70% of its activities were nuclear/radiological, and now just under 50% of its current business science and technology are nuclear and radiologically oriented. Programs in the areas of nuclear legacies, global security, nonproliferation, homeland security and national defense, radiobiology and nuclear energy still involve more than 1,000 of the 3,800 current laboratory staff, and these include more than 420 staff who are certified as nuclear/radiological scientists and engineers. This paper presents the current challenges faced by PNNL that require an emerging strategy to solve the nuclear staffing issues through the maintenance and replenishment of the human nuclear capital needed to support PNNL nuclear science and technology programs.     

NUCLEAR SPIN-SPIN COUPLING CONSTANT AND MOLECULAR STRUCTURE——Ⅰ. The Relationship between Coupling Constants and Bond Lengths (Internuclear Distances)

<正> A discussion on the relationship between nuclear spin-spin coupling constants and bond lengths (internuclear distances) will be presented in this paper. The discussion will be focussed on the R-3 rule, the limit of its application and its influencing factors. Specifically, the causes for two long-existing puzzles in NMR coupling constants will be discussed: (a) the abnormal values of the coupling constants in ethylene and acetylene and (b) the "methyl-substitution rule". It will be pointed out that in solution the coupling of intramolecular nuclear spins is affected by many factors and thus will not strictly obey the R-3rule in general. However, in practice, the R-3 rule will still be valid when various influencing factors are carefully taken into consideration.     

Implementation of radionuclide measurements for the Comprehensive Nuclear-Test-Ban Treaty and associated on-site inspections

The Comprehensive Nuclear-Test-Ban Treaty (CTBT) plans the installation of an International Monitoring System (IMS) based upon four global networks. Seismic, hydroacoustic and infrasound waves will help detect underground, underwater and atmospheric nuclear tests and will permit their discrimination from natural events. 80 particulate stations will detect radioactive aerosols, this network being completed with a sub-set of 40 stations which will measure rare gases, typically xenon isotopes. 16 IMS laboratories will perform additional analysis mainly by gamma-spectrometry, using the most sensitive methods such as particulate analysis. In order to have the most effective network, modeling was performed by using an inverse method in which the radioactive tracer is transported back from detectors. Examples will be given, regarding the maps of detection probability, background effects of existing xenon or radon, or the decoupling effects. All these tools and means are anticipated to have a complete process of certification, authentication of the data and discrimination capabilities between nuclear test and releases from civilian nuclear industry (reactors, reprocessing plants,). If a State Party identifies events that it feels could be a nuclear explosion, it can ask for clarification and finally it may send a request for an On-Site Inspection. The rights of the State Party and the constraints for the Inspection Team are defined in the Treaty. That leads to limited time, to limited number of inspectors on the site and to precise methods to be authorized. The means and resulting data have to be blinded in order to make sure the confidentiality is observed. Examples of restricting measurements will be given regarding airborne or vehicle mounted spectrometry as well as laboratory analysis. Cooperation with international organizations (WMO, WHO) will be discussed, depending on confidentiality issues.     

Assessment of non-traditional isotopic ratios by mass spectrometry for analysis of nuclear activities

This work provides an assessment of suitable forensic indicators that may be measured by portable mass spectrometry systems. Traditional assessments of nuclear fuel cycle manipulation or other nuclear activities often depend upon analyses of uranium and plutonium isotopes in the nuclear fuel. Any entity engaging in shortened fuel cycle activity will recover U and Pu during reprocessing. Fission, capture, and activation products are less valuable and generally regarded as waste products. This work determined isotopic ratios that distinguish nuclear weapons and shortened nuclear fuel cycles from commercial nuclear reactors. Modeling of fuel cycles was conducted via ORIGEN-S, MCNPX, and through custom calculations.     

The Nuclear Fuel Cycle Back-End after Fukushima

The impact of the Fukushima accident on the nuclear fuel cycle back-end is obvious. In the present paper the various back-end options and their impact on the environment will be presented in view of this new perspective. The partitioning and transmutation (P&T) concept and the direct disposal of nuclear fuel including a very long intermediate storage will certainly be revisited with respect to safety considerations; here the instant release fraction (IRF) and the long-term stability of the fuel matrix under real repository conditions are highly relevant. Furthermore the impact of released radionuclides to the environment will have a higher attention.     

The quadrupole moment of the 3/2+ nuclear ground state of 197Au from electric field gradient relativistic coupled cluster and density-functional theory of small molecules and the solid state

An attempt is made to improve the currently accepted muonic value for the 197Au nuclear quadrupole moment [+0.547(16)x10(-28) m2] for the 3/2+ nuclear ground state obtained by Powers et al. [Nucl. Phys. A230, 413 (1974)]. From both measured Mossbauer electric quadrupole splittings and solid-state density-functional calculations for a large number of gold compounds a nuclear quadrupole moment of +0.60x10(-28) m2 is obtained. Recent Fourier transform microwave measurements for gas-phase AuF, AuCl, AuBr, and AuI give accurate bond distances and nuclear quadrupole coupling constants for the 197Au isotope. However, four-component relativistic density-functional calculations for these molecules yield unreliable results for the 197Au nuclear quadrupole moment. Relativistic singles-doubles coupled cluster calculations including perturbative triples [CCSD(T) level of theory] for these diatomic systems are also inaccurate because of large cancellation effects between different field gradient contributions subsequently leading to very small field gradients. Here one needs very large basis sets and has to go beyond the standard CCSD(T) procedure to obtain any reliable field gradients for gold. From recent microwave experiments by Gerry and co-workers [Inorg. Chem. 40, 6123 (2001)] a significantly enhanced (197)Au nuclear quadrupole coupling constant in (CO)AuF compared to free AuF is observed. Here, these cancellation effects are less important, and relativistic CCSD(T) calculations finally give a nuclear quadrupole moment of +0.64x10(-28) m2 for 197Au. It is argued that it is currently very difficult to improve on the already published muonic value for the 197Au nuclear quadrupole moment.     

Metallic radionuclides in the development of diagnostic and therapeutic radiopharmaceuticals

Metallic radionuclides are the mainstay of both diagnostic and therapeutic radiopharmaceuticals. Therapeutic nuclear medicine is less advanced but has tremendous potential if the radionuclide is accurately targeted. Great interest exists in the field of inorganic chemistry for developing target specific radiopharmaceuticals based on radiometals for non-invasive disease detection and cancer radiotherapy. This perspective will focus on the nuclear properties of a few important radiometals and their recent applications to developing radiopharmaceuticals for imaging and therapy. Other topics for discussion will include imaging techniques, radiotherapy, analytical techniques, and radiation safety. The ultimate goal of this perspective is to introduce inorganic chemists to the field of nuclear medicine and radiopharmaceutical development, where many applications of fundamental inorganic chemistry can be found.     

Chemical Aspects of Fusion Technology

Managing thermally controlled nuclear fusion will certainly be regarded one day as one of the most successful accomplishments in nuclear physics. At the same time, however, it will represent a technical achievement unparalleled in the history of science and engineering. This in turn would mean, in retrospect, that decisive contributions had to come from a number of disciplines as diverse as materials and engineering sciences and classical chemistry, and that the same collaboration will have to continue in the future in order to reach the ultimate goal, to construct a reactor capable of producing energy from almost inexhaustible source materials (fuels), such as deuterium and lithium. What is the chemist's role in this development? Similarly as in the development of fission reactors, i.e., the nuclear power plants currently in operation, chemists will have to ensure the existence of a reliable fuel cycle–starting from the availability, storage and reprocessing of the fuel through to the provision for safe storage of the waste. In this review article an attempt will be made to outline the problems associated with these tasks and the approaches to be made by the chemist in solving them.     

Installation of a Shielded SIMS for the Analysis of Irradiated Nuclear Fuels

A CAMECA IMS 6F secondary ion mass spectrometer (SIMS) for the analysis of irradiated nuclear fuel has been installed in the Microbeam Analysis Laboratory of the Institute for Transuranium Elements (ITU). This device is specially equipped with heavy metal shielding to enable the safe examination of irradiated nuclear fuel samples with activities up to 75 GBq. At ITU the shielded SIMS will be used in conjunction with EPMA taking advantage of the complementary nature of the two techniques and will make important contributions to ongoing research programmes such as the safety of nuclear fuels, the partitioning and transmutation programme and the characterisation of spent fuels. The paper describes the shielded SIMS installation and presents a selection of results from the commissioning tests.     

Nuclear forensics—metrological basis for legal defensibility

The admissibility of nuclear forensics measurements and opinions derived from them in US Federal and State courts are based on criteria established by the US Supreme Court in the case of Daubert v. Merrell Dow and the 2000 Amendment of Rule 702 of the Federal Rules of Evidence. These criteria are being addressed by new efforts that include the development of certified reference materials (CRMs) to provide the basis for analytical method development, optimization, calibration, validation, quality control, testing, readiness, and declaration of measurement uncertainties. Quality data is crucial for all stages of the program, from R&D, and database development, to actual casework. Weakness at any point in the program can propagate to reduce the confidence of final conclusions. The new certified reference materials will provide the necessary means to demonstrate a high level of metrological rigor for nuclear forensics evidence and will form a foundation for legally defensible nuclear chemical analysis. The CRMs will allow scientists to devise validated analytical methods, which can be corroborated by independent analytical laboratories. CRMs are required for ISO accreditation of many different analytical techniques which may be employed in the analysis of interdicted nuclear materials.     

Nuclear, chemical, and physical characterization of nuclear materials

The goal of nuclear forensics is to establish an unambiguous link between illicitly trafficked nuclear material and its origin. The Los Alamos National Laboratory (LANL) Nuclear Materials Signatures Program has implemented a graded “conduct of operations” type analysis flow path approach for determining the key nuclear, chemical, and physical signatures needed to identify the manufacturing process, intended use, and origin of interdicted nuclear material. This analysis flow path includes both destructive and non-destructive characterization techniques and has been exercized against different nuclear materials from LANL’s special nuclear materials archive. Results obtained from the case study will be presented to highlight analytical techniques that offer the critical attribution information.     

Contribution of rotational diffusion to pulsed field gradient diffusion measurements

NMR diffusion experiments employing pulsed field gradients are well established as sensitive probes of the displacement of individual nuclear spins in a sample. Conventionally such measurements are used as a measure of translational diffusion, but here we demonstrate that under certain conditions rotational motion will contribute very significantly to the experimental data. This situation occurs when at least one spatial dimension of the species under study exceeds the root mean square displacement associated with translational diffusion, and leads to anomalously large apparent diffusion coefficients when conventional analytical procedures are employed. We show that in such a situation the effective diffusion coefficient is a function of the duration of the diffusion delay used, and that this dependence provides a means of characterizing the dimensions of the species under investigation.     

The Living Textbook of Nuclear Chemistry

Summary A Summer School in Nuclear Chemistry sponsored by the U. S. Department of Energy and the American Chemical Society has been held at San Jos&eacute; State University for the past 20 years. The intent of the program is to introduce outstanding college students to the field of nuclear and radiochemistry with the goal that some of these students will consider careers on nuclear science. The program features radiochemistry experiments along with radiation safety training, guest lectures by well known nuclear scientists and field trips to nuclear chemistry facilities in the San Francisco area.