Strengthening Pacific Rim marine radioactive pollution governance: from nuclear data legal regulatory cooperative aspect.

The late Sol Pearlstein was a pioneer and leading figure in the field of nuclear physics data, a field that is fundamental to progress in both applied nuclear technology and basic nuclear physics research. As the first director of the United States National Nuclear Data Center, he was responsible for organizing the United States nuclear data evaluation work and the production of the Evaluated Nuclear Data File (ENDF). Sol was a strong supporter of collaboration in science, both nationally and internationally. He was the driving force behind the development of international collaborations to compile nuclear reaction data and to evaluate nuclear structure and radioactivity data, activities that continue to this day to be crucial components of the world’s nuclear data effort.

The Nuclear Data Centers Network is a world-wide cooperation of nuclear data centers under the auspices of the International Atomic Energy Agency. The Network organizes the task of collecting, compiling, standardizing, storing, assessing, and distributing the nuclear data on an international scale. Information available at the Centers includes bibliographic, experimental, and evaluated databases for nuclear reaction data and for nuclear structure and radioactive decay data. The objective of the Network is to provide the information to users in a convenient, readily-available form. To this end, online data services have been established at three of the centers: the National Nuclear Data Center (NNDC), the Nuclear Data Section of the International Atomic Energy Agency (NDS), and the OECD Nuclear Energy Agency Data Bank (NEADB). Some information is also available at the NNDC and NEADB World Wide Web sites.

Nuclear data in general, and neutron-induced reaction cross sections in particular, are important for a wide variety of research fields. They play a key role in the safety and criticality assessment of nuclear technology, not only for existing power reactors but also for radiation dosimetry, medical applications, the transmutation of nuclear waste, accelerator-driven systems, fuel cycle investigations and future reactor systems as in Generation IV. Applications of nuclear data are also related to research fields as the study of nuclear level densities and stellar nucleosynthesis. Simulations and calculations of nuclear technology applications largely rely on evaluated nuclear data libraries. The evaluations in these libraries are based both on experimental data and theoretical models. Experimental nuclear reaction data are compiled on a worldwide basis by the international network of Nuclear Reaction Data Centres (NRDC) in the EXFOR database. The EXFOR database forms an important link between nuclear data measurements and the evaluated data libraries. CERN's neutron time-of-flight facility n_TOF has produced a considerable amount of experimental data since it has become fully operational with the start of the scientific measurement programme in 2001. While for a long period a single measurement station (EAR1) located at 185 m from the neutron production target was available, the construction of a second beam line at 20 m (EAR2) in 2014 has substantially increased the measurement capabilities of the facility. An outline of the experimental nuclear data activities at CERN's neutron time-of-flight facility n_TOF will be presented.

The types of nuclear data and their quality required in the production and application of diagnostic radionuclides are outlined. The radioactive decay data determine the suitability of a radioisotope forin vivotracer studies, both from the imaging and internal radiation dose considerations. The nuclear reaction cross section data allow optimisation of production routes. Both reactors and cyclotrons are used for production purposes. The nuclear data needed in the two cases and their present status are discussed. Special attention is paid to radionuclides suitable for emission tomography (PET and SPECT). The controversy aboutreactorvscyclotronproduction of the widely used99Mo/99mTc generator system is discussed. Some special considerations in cyclotron production of radionuclides are outlined. The need of accurate data near reaction thresholds, the constraint of available particles and their energies at a small cyclotron, the influence of increasing incident particle energy, and the formation of isomeric impurities are discussed in detail. The role of nuclear model calculations in predicting unknown data is considered.

A brief introduction to nuclear data in medicine is given. The choice of a radioisotope for medical application demands an accurate knowledge of radioactive decay data. Short-lived single photon and β+-emitters are preferred for diagnostic investigations, and longer-lived corpuscular radiation emitting radioisotopes for endoradiotherapy. The nuclear reaction cross section data, on the other hand, are needed for optimising the production routes. Besides radioactive isotopes, the use of ionising radiation in therapy is discussed. External radiation therapy has achieved an important place in medicine. The role of nuclear data is briefly discussed; they are needed for radiation dose calculations. The hitherto rather neglected activation products in proton therapy are considered. The methodology of development of a nuclear data file for medical applications is outlined

Experimentally measured isotopic concentrations of well characterized spent nuclear fuel (SNF) samples have been collected and analyzed by previous researchers. These sets of experimental data have been used extensively to validate the accuracy of depletion code predictions for given sets of burnups, initial enrichments, and varying power histories for different reactor types. The purpose of this report is to present the diversity of data in a concise manner and summarize the current accuracy of depletion modeling. All calculations performed for this report were done using the Oak Ridge Isotope GENeration (ORIGEN) code, an internationally used irradiation and decay code solver within the SCALE comprehensive modeling and simulation code. The diversity of data given in this report includes key actinides, stable fission products, and radioactive fission products. In general, when using the current ENDF/B-VII.0 nuclear data libraries in SCALE, the major actinides are predicted to within 5% of the measured values. Large improvements were seen for several of the curium isotopes when using improved cross section data found in evaluated nuclear data file ENDF/B-VII.0 as compared to ENDF/B-V-based results. The impact of the flux spectrum on the plutonium isotope concentrations as a function of burnup was also shown. The general accuracymore » noted for the actinide samples for reactor types with burnups greater than 5,000 MWd/MTU was not observed for the low-burnup Hanford B samples. More work is needed in understanding these large discrepancies. The stable neodymium and samarium isotopes were predicted to within a few percent of the measured values. Large improvements were seen in prediction for a few of the samarium isotopes when using the ENDF/B-VII.0 libraries compared to results obtained with ENDF/B-V libraries. Very accurate predictions were obtained for 133Cs and 153Eu. However, the predicted values for the stable ruthenium and rhodium isotopes varied as much as 10% of the measured values, and 109Ag was consistently over-predicted by as much as 170%. In general, there is a larger uncertainty for modeling radioactive fission products when compared to either the actinides or the stable fission products in SNF. The relative C/E ratios ranged from a few percent for 137Cs up to 60% and 100% for 106Ru and 125Sb, respectively. Limited or no radioactive fission products data exist in the current data sets for reactor types other than PWRs and BWRs. More work is needed in obtaining a greater diversity of radioactive fission product data. While performing this survey, issues leading to inconsistencies in nuclear fission yield data were discovered that specifically impacted the fission product noble gases. Emphasis was given to this legacy data, and corrective actions were taken as described in this report. After the fission yield data were corrected, the stable xenon and krypton fission products were predicted to within 5% of their measurements. However, preliminary results not explicitly given in this report indicate that the relative C/E ratio for the radioactive isotope 85Kr varied as much as 10%. Due to the complex migration and the difficulty in measuring noble gases in the fuel, a more thorough investigation is needed to understand how accurately depletion codes can calculate these gas concentrations.« less

A study on the gaseous radionuclide dispersion in the highway across urban blocks: Effects of the urban morphology, roadside vegetation and leakage location

Radioactive waste has to undergo a process of quality checking in order to check its conformance with national regulations prior to its transport, intermediate storage and final disposal. Within the quality checking of radioactive waste packages non-destructive assays are required to characterize their radio-toxic and chemo-toxic contents. The Institute of Energy and Climate Research - Nuclear Waste Management and Reactor Safety of the Forschungszentrum Jülich develops in the framework of cooperation nondestructive analytical techniques for the routine characterization of radioactive waste packages at industrial-scale. During the phase of research and development Monte Carlo techniques are used to simulate the transport of particle, especially photons, electrons and neutrons, through matter and to obtain the response of detection systems. The radiological characterization of low and intermediate level radioactive waste drums is performed by segmented γ-scanning (SGS). To precisely and accurately reconstruct the isotope specific activity content in waste drums by SGS measurement, an innovative method called SGSreco was developed. The Geant4 code was used to simulate the response of the collimated detection system for waste drums with different activity and matrix configurations. These simulations allow a far more detailed optimization, validation and benchmark of SGSreco, since the construction of test drums covering a broad range of activity and matrix properties is time consuming and cost intensive. The MEDINA (Multi Element Detection based on Instrumental Neutron Activation) test facility was developed to identify and quantify non-radioactive elements and substances in radioactive waste drums. MEDINA is based on prompt and delayed gamma neutron activation analysis (P&DGNAA) using a 14 MeV neutron generator. MCNP simulations were carried out to study the response of the MEDINA facility in terms of gamma spectra, time dependence of the neutron energy spectrum, neutron flux distribution. The validation of the measurements simulations with Mont-Carlo transport codes for the design, optimization and data analysis of further P&DGNAA facilities is performed in collaboration with LMN CEA Cadarache. The performance of the prompt gamma neutron activation analysis (PGNAA) for the nondestructive determination of actinides in small samples is investigated. The quantitative determination of actinides relies on the precise knowledge of partial neutron capture cross sections. Up to today these cross sections are not very accurate for analytical purpose. The goal of the TANDEM (Trans-uranium Actinides’ Nuclear Data – Evaluation and Measurement) Collaboration is the evaluation of these cross sections. Cross sections are measured using prompt gamma activation analysis facilities in Budapest and Munich. Geant4 is used to optimally design the detection system with Compton suppression. Furthermore, for the evaluation of the cross sections it is strongly needed to correct the results to the self-attenuation of the prompt gammas within the sample. In the framework of cooperation RWTH Aachen University, Forschungszentrum Jülich and the Siemens AG will study the feasibility of a compact Neutron Imaging System for Radioactive waste Analysis (NISRA). The system is based on a 14 MeV neutron source and an advanced detector system (a-Si flat panel) linked to an exclusive converter/scintillator for fast neutrons. For shielding and radioprotection studies the codes MCNPX and Geant4 were used. The two codes were benchmarked in processing time and accuracy in the neutron and gamma fluxes. Also the detector response was simulated with Geant4 to optimize components of the system.

FECSG-ML: Feature Engineering for Nuclear Reaction Cross Sections Generation Using Machine Learning

OECD

Neutronics simulation of nuclear systems relies on the availability of nuclear data to provide accurate numerical representations of the underlying physical processes. Essential nuclear data include energy-dependent reaction cross-sections, the energy and angular distributions of reaction products for various combinations of incident particles and targets, and the atomic and nuclear properties of excited states as well as their radioactive decay data. Fusion neutronics calculations cover particles transport, nuclear transmutation and activation, neutron radiation damage, radiation dose, biological safety, etc. These calculations require nuclear data that include transport nuclear data, transmutation and activation nuclear data, radiation damage nuclear data, etc. This chapter introduces these nuclear data libraries.

This paper describes basic plans for the development of a radioactive waste disposal facility with the introduction of Nuclear Power Plants (NPPs) for Kenya. The specific objective of this study was to estimate the total projected waste volumes of low- and intermediate-level radioactive waste (LILW) expected to be generated from the Kenyan nuclear power programme. The facility is expected to accommodate LILW to be generated from operation and decommissioning of nuclear power plants for a period of 50 years. An on-site storage capacity of 700 <TEX>$m^3$</TEX> at nuclear power plant sites and a final disposal repository facility of more than 7,000 <TEX>$m^3$</TEX> capacity were derived by considering Korean nuclear power programme radioactive waste generation data, including Kori, Hanbit, and APR 1400 nuclear reactor data. The repository program is best suited to be introduced roughly 10 years after reactor operation. This study is important as an initial implementation of a national LILW disposal program for Kenya and other newcomer countries interested in nuclear power technology.

The caterpillars of Gonimbrasia belina, commonly known as mopane worms, are intensively harvested for human consumption in southern Africa. Concerns over the sustainability of the species have been raised for the last two decades due to increasing demand, habitat erosion, and climate change. Despite its cultural, economic, and nutritional significance, genetic data for G. belina was largely unavailable. We used a multi-marker approach including mitochondrial sequences and nuclear ddRADseq data to assess the genetic diversity, phylogeographical structure and demographic history of G. belina in Namibia and the Limpopo River Basin (South Africa and Botswana). Mitochondrial sequences revealed strong phylogeographical structure at the broad scale separating Namibia and Limpopo River Basin populations. Within the Limpopo River Basin, populations are separated by the Limpopo River, with haplotype sharing only at the border between South Africa and Botswana. Mitochondrial genetic diversity varies between sampling areas but overall is highest in South Africa and lowest in Botswana, while historical demography points to population expansion in Namibia but not in South Africa and Botswana. Nuclear data in the Limpopo River Basin revealed some connectivity among populations albeit with significant genetic differentiation and unique gene pools in some sampling areas. All sampling areas show low genetic diversity, alarmingly small effective population size, and signs of recent bottlenecks. We generated the first baseline data for the genetic monitoring of G. belina populations and conclude that concerns over the sustainability of the species are presently justified in Botswana and South Africa.

Nuclear data for accelerator driven systems: Nuclear models, experiments and data libraries

A detailed simulation study on radionuclide dispersion under spent fuel road transportation conditions: Effects of vessel type and coniferous vegetation growth