Nuclear Database Research Articles

Bullying in the Nuclear Medicine Department and During Clinical Nuclear Medicine Education

Workplace bullying (WPB) in the medical field is a significant occupational hazard and health-care safety concern, though many cases go unreported. Often regarded as a rite of passage to desensitize and toughen new employees and students, WPB causes psychologic harm and creates an unsafe working environment resulting in health complications, anxiety, depression, low self-esteem, difficulty concentrating, and self-harm. Decreased productivity, increased absenteeism, high turnover rates, and inappropriate patient care are linked to WPB, perpetrating organizational dysfunction. This research study evaluated WPB (prevalence, frequency, and behaviors; associated characteristics; effects on patient care; and awareness and enforcement of antibullying protocols) in nuclear medicine (NM) departments and clinical education. <b>Methods:</b> A quantitative single-group correlational analysis was used to survey certified NM technologists and students in the Nuclear Medicine Technology Certification Board e-mail database (<i>n</i> = 20,389). The highest response rate for any individual question was 836. Data were collected using the short version of the negative-acts questionnaire along with a researcher-created survey and analyzed using χ² testing and central tendencies. <b>Results:</b> WPB existed in varying degrees (46.8%) within the previous 6 mo, predominantly in the form of being ignored, excluded, and subjected to repeated reminders of errors and having information affecting performance withheld. NM professionals are more likely to witness and experience WPB than students and are more likely to be bullied by a fellow technologist. Some characteristics, such as sex, age, and occupation, were statistically significant, whereas others, such as race, height, body type, experience, and education, showed no significant correlation. Attention to patient care decreased (39.6%) when WPB was present. An 8% variation exists between enforcement and nonenforcement of antibullying policies, with 26% of professionals being unaware of whether antibullying policies exist at their workplace. <b>Conclusion:</b> Explanations for underreported WPB include fear of retaliation, nonenforcement and lack of awareness of antibullying policies, organizational complacency, and perceived hierarchic power. Recommendations to minimize WPB include adopting and publicizing a descriptive definition, implementing antibullying policies, using mediation procedures, and imposing noncompliance penalties. A decrease in the incidence of WPB correlates with an increase in employee satisfaction and retention, patient safety, and student success.

Single pencil beam benchmark of a module for Monte Carlo simulation of proton transport in the PENELOPE code.

PENH is a recently coded module for simulation of proton transport in conjunction with the Monte Carlo code PENELOPE. PENELOPE applies class II simulation to all type of interactions, in particular, to elastic collisions. PENH uses calculated differential cross sections for proton elastic collisions that include electron screening effects as well as nuclear structure effects. Proton-induced nuclear reactions are simulated from information in the ENDF-6 database or from alternative nuclear databases in ENDF format. The purpose of this work is to benchmark this module by simulating absorbed dose distributions from a single finite spot size proton pencil beam in water. Monte Carlo simulations with PENH are compared with simulation results from TOPAS Monte Carlo (v3.1p2) and RayStation Monte Carlo (v6). Different beam models are examined in terms of mean energy and energy spread to match the measured profiles. The phase-space file is derived from experimental measurements. Simulated absorbed dose distributions are compared to experimental data obtained with the ionization chamber array MatriXX 2D detector (IBA Dosimetry) in a water tank. The experiments were conducted with a clinical IBA pencil beam scanning dedicated nozzle. In all simulations a Fermi-Eyges phase-space representation of a single finite spot size proton pencil beam is used. In general, there is a good agreement between simulated results and experimental data up to a distance of 3cm from the central axis. In the core region (region where the dose is more than 10% of the maximum dose) PENH shows, overall, the smallest deviations from experimental data, with the largest radial rms (root mean square) smaller than 0.2. The results achieved by TOPAS and RayStation in that region are very close to those of PENH. For the halo region, that is the area of the dose distribution outside the core region reaching down to 0.01% of the maximum intensity, the largest rms achieved by TOPAS is always smaller than 0.5, yielding better results than the rest of the codes. The physics modeling of the PENELOPE/PENH code yields results consistent with measurements in the dose range relevant for proton therapy. The discrepancies between PENH appearing at distances larger than 3cm from the central-beam axis are accountable to the lack of neutron simulation in this code. In contradistinction, TOPAS has a better agreement with experimental data at large distances from the central-beam axis because of the simulation of neutrons.

New experimental data on excitation functions of He3 -induced nuclear reactions on Ta up to 27 MeV

Excitation functions of $^{3}\mathrm{He}$-induced nuclear reactions on $^{\mathrm{nat}}\mathrm{Ta}$ were measured utilizing the MGC-20E cyclotron, stacked-foils activation technique, and high-resolution gamma-ray spectrometry. From their threshold energies up to 27 MeV, cross sections for $^{\mathrm{nat}}\mathrm{Ta}(^{3}\mathrm{He},xn)^{182}\mathrm{Re}^{\mathrm{m}}, ^{182}\mathrm{Re}^{\mathrm{g}}, ^{181}\mathrm{Re}$, and $^{\mathrm{nat}}\mathrm{Ta}(^{3}\mathrm{He},\ensuremath{\alpha}xn)^{178}\mathrm{Ta}^{\mathrm{A}}, ^{180}\mathrm{Ta}^{\mathrm{g}}$ reactions were measured. The half-life of the radionuclide $^{181}\mathrm{Re}$ was checked experimentally. The intensity of the energy line 360.7 keV, in the radionuclide $^{181}\mathrm{Re}$ decay scheme, was revised experimentally. The new experimental intensity represents about half the reported value in the different nuclear structure databases. The nuclear reaction codes TALYS-1.9 and EMPIRE-3.2.3 were used to predict the formation of these products. The isomeric cross-section ratio for the $^{182}\mathrm{Re}^{\mathrm{m},\mathrm{g}}$ was also calculated. The ratio indicates that the pre-equilibrium mechanism is dominant at energies over 19 MeV. Various combinations of the models' parameters implemented in EMPIRE such as nuclear level density models, optical model, and pre-equilibrium parameters were used to reproduce the experimental excitation functions. For TALYS calculations, the TENDL-2019 nuclear data library based on TALYS-1.9 was used. The present data were compared to theoretical results and the available experimental data. Integral yields for the produced radioisotopes were determined.

The p(20)+Be reaction as a source of fusion relevant neutrons

The p(20)+Be neutron source reaction was investigated at the Nuclear Physics Institute of the Czech Academy of Sciences using the 20 MeV proton beam on thick beryllium target (thickness of 8 mm). Neutron field in close source-to-sample distances was determined by means of the activation foils technique; set of ten activation foils (Al, Ti, Co, Fe, Ni, Y, In, Nb, Lu, Au) was utilized. Neutron spectrum reconstruction from reaction rates obtained using the gamma-spectroscopy method (semiconductor HPGe detectors) was performed utilizing the modified version of SAND-II unfolding code and relevant activation cross-sections from the EAF-2010 nuclear database. Determined neutron energy spectra were validated against the MCNPX calculations. Developed p(20)+Be neutron field with broad spectrum represents a useful tool for the cross-section data validation within the ITER and IFMIF-DONES research programs (≥ 12 MeV), neutron-hardness tests of microelectronics, study of material damage, and calibration of new detection systems.

Analysis of rice nuclear-localized seed-expressed proteins and their database (RSNP-DB)

Nuclear proteins are primarily regulatory factors governing gene expression. Multiple factors determine the localization of a protein in the nucleus. An upright identification of nuclear proteins is way far from accuracy. We have attempted to combine information from subcellular prediction tools, experimental evidence, and nuclear proteome data to identify a reliable list of seed-expressed nuclear proteins in rice. Depending upon the number of prediction tools calling a protein nuclear, we could sort 19,441 seed expressed proteins into five categories. Of which, half of the seed-expressed proteins were called nuclear by at least one out of four prediction tools. Further, gene ontology (GO) enrichment and transcription factor composition analysis showed that 6116 seed-expressed proteins could be called nuclear with a greater assertion. Localization evidence from experimental data was available for 1360 proteins. Their analysis showed that a 92.04% accuracy of a nuclear call is valid for proteins predicted nuclear by at least three tools. Distribution of nuclear localization signals and nuclear export signals showed that the majority of category four members were nuclear resident proteins, whereas other categories have a low fraction of nuclear resident proteins and significantly higher constitution of shuttling proteins. We compiled all the above information for the seed-expressed genes in the form of a searchable database named Rice Seed Nuclear Protein DataBase (RSNP-DB) https://pmb.du.ac.in/rsnpdb. This information will be useful for comprehending the role of seed nuclear proteome in rice.

Separation and recovery of exotic radiolanthanides from irradiated tantalum targets for half-life measurements.

The current knowledge of the half-lives (T1/2) of several radiolanthanides is either affected by a high uncertainty or is still awaiting confirmation. The scientific information deriving from this imprecise T1/2 data has a significant impact on a variety of research fields, e.g., astrophysics, fundamental nuclear sciences, and nuclear energy and safety. The main reason for these shortcomings in the nuclear databases is the limited availability of suitable sample material together with the difficulties in performing accurate activity measurements with low uncertainties. In reaction to the urgent need to improve the current nuclear databases, the long-term project “ERAWAST” (Exotic Radionuclides from Accelerator Waste for Science and Technology) was launched at Paul Scherrer Institute (PSI). In this context, we present a wet radiochemical separation procedure for the extraction and purification of dysprosium (Dy), terbium (Tb), gadolinium (Gd), and samarium (Sm) fractions from highly radioactive tantalum specimens, in order to obtain 154Dy, 157-158Tb, 148,150Gd, and 146Sm samples, needed for T1/2 determination studies. Ion-exchange chromatography was successfully applied for the separation of individual lanthanides. All separations were conducted in aqueous phase. The separation process was monitored via γ-spectrometry using suitable radioactive tracers. Both the purity and the quantification of the desired radiolanthanides were assessed by inductively coupled plasma mass spectrometry. Test experiments revealed that, prior to the Dy, Tb, Gd, and Sm separation, the removal of hafnium, lutetium, and barium from the irradiated tantalum material was necessary to minimize the overall dose rate exposure (in the mSv/h range), as well to obtain pure lanthanide fractions. With the herein proposed separation method, exotic 154Dy, 157-158Tb, 148,150Gd, and 146Sm radionuclides were obtained in sufficient amounts and purity for the preparation of samples for envisaged half-life measurements. During the separation process, fractions containing holmium, europium, and promethium radionuclides were collected and stored for further use.

Updated deterministic radiation transport for future deep space missions

NASA's deterministic transport code HZETRN, and its three-dimensional (3D) counterpart, 3DHZETRN, are being used to characterize the space radiation environment over a wide range of scenarios, including future planned missions to the moon or Mars. Combined with available spaceflight measurements, these tools provide the fundamental input for risk models used to quantify possible astronaut health decrements and satisfy agency limits in support of exploration initiatives. Further research is therefore needed to improve radiation transport and nuclear physics models while at the same time continuing to expand the available measurement database (ground-based and spaceflight) to validate such efforts. In this work, significant updates to the deterministic radiation transport models are presented. Charged muons and pions are fully coupled with the existing solutions developed for neutron and light ion (Z ≤ 2) transport. This update includes the 3D nature of pion production as well as the pion interactions, resulting in further production of energetic nucleons within shielding. Additional updates related to low energy proton recoils in hydrogenous materials and capture/decay processes associated with charged pions at rest are also described. Included in this work is the coupling of single and double-differential cross sections from Geant4 into HZETRN and 3DHZETRN. This enables a direct comparison of deterministic and Monte Carlo transport methodologies using the same nuclear databases for specific interactions. Comparisons between Geant4 and 3DHZETRN are shown and establish that the transport methodologies are in excellent agreement when the same cross sections are used. The deterministic codes are also compared to ISS data, and it is found that the updated 3D procedures are within measurement uncertainty (±5%) at cutoff rigidities below 1 GV, which approaches free space conditions.

An upgrade of the UoA nuclear electromagnetic moments database

A web–based database of nuclear electromagnetic moments data has been created and hosted online at the University of Athens since 2012. In this work, we report on an update which has focused on syncing spectroscopic information, electric quadrupole and magnetic dipole moments with the ENSDF database and literature values. A new feature is the incorporation of nuclear charge radii values obtained after 2015. Additionally, instructions of how to use the database, alongside with annonations and abbreviations, are presented.

Perspectives on nuclear data for advanced reactor design and analysis

Nuclear reaction cross section and other neutron physics data are basic inputs to reactor design and analysis. The physical constants such as reaction cross section and other physical constants are usually generated in labs with neutrons as probes, are then coded and subject to detailed evaluation and qualification and finally are made ready for use for potential reactor applications. The nuclear data measurement requires cutting edge technologies from generation of mono-energetic source of neutrons to developing pure targets and covering the entire range of neutron energies and reaction channels. The evaluated data which are created from a best fit of several experiments are then processed to a reactor-specific dataset which again is a multi-parametric and required different treatment in different energy regimes and is also for different target isotopes. The life cycle of these physical constants from lab to the user is very large, sometimes spans over a few decades. This field of nuclear data physics, which entails multi-physics covering the entire gamut from experiments to processing, is an exciting branch of reactor design. This paper attempts to give an overview of the importance of these cross-section data for design studies, safety and operation of reactors. Emphasis is mainly in the condensed nuclear datasets used of design simulations. Advanced reactor designs use newer materials, are optimized for better fuel utilization and are required to model more complex phenomenon. All these require that the uncertainties in the basic nuclear data be minimized. The deviations in core parameters due to the variations in basic nuclear cross sections are estimated as sensitivity or uncertainty coefficient, which are then accounted for in the design margins. This paper will cover the various aspects of the nuclear data, i.e., experiments to reactor-specific data, its use in reactors, the influence on operational parameters and sensitivity studies.

Theoretical Cross-Section Calculations for the ($$\mathbf{\alpha}$$, $$\boldsymbol{n}$$) and ($$\mathbf{\alpha}$$, $$\boldsymbol{2n}$$) Reactions on $${}^{\mathbf{46}}$$Ti, $${}^{\mathbf{50}}$$Cr, $${}^{\mathbf{54}}$$Fe, and $${}^{93}$$Nb Isotopes

The employment of the fusion mechanism for the energy production is a promising solution to the continuously growing global energy demand. The correct material selection for this cutting edge technology is just as important as the efforts to understand the related nuclear reaction mechanisms. A value which is relevant to nuclear reactions and is of considerable importance is the cross-section of the reaction. Among many parameters, which affect the theoretical calculations of this quantity, level density models and alpha optical model potentials have played an important role, due to their direct effects on the calculations. By considering the importance of the materials used in the fusion technology and the aforementioned parameters, the aim of this work is to study the effects of level density models, alpha optical model potentials and their combinational usage in the cross-section theoretical calculations on the alpha particle induced reactions for $${}^{46}$$ Ti, $${}^{50}$$ Cr, $${}^{54}$$ Fe and $${}^{93}$$ Nb isotopes. The examined reaction routes are limited to the alpha particle induced single and double neutron emitting reactions. All calculations were performed by using the 1.9 version of the TALYS code, in which six level density models and eight alpha optical model potentials are available. The results of the present work are compared with the existing literature data, taken from the Experimental Nuclear Reaction Database (EXFOR) library, by performing a mean weighted deviation analysis calculation. The more consistent results in comparison with the experimental data were obtained with the combinational use of the models.

Assessment of neutron kerma coefficients and its calculation methodologies using recent basic ENDF-6 libraries

The generation of heat due to interaction of neutrons with matter is an important aspect in the designing of nuclear reactors. The estimation of neutron heating depends profoundly on the evaluated nuclear reaction parameters. Hence, within the purview of radiation damage of materials, it is necessary to investigate the effects of improvements in nuclear databases on the neutron heating rates under various neutron spectra. There are two well established methods to quantify the neutron kerma coefficients in matter: energy balance method and direct method. The well established code like NJOY21 gives the energy balance neutron kerma. In this study, the importance and performance of the direct method has been investigated, as the recent general purpose basic evaluated nuclear data files provide more complete database. Though both the methods predict closely the reported measured values of neutron kerma coefficients for structural elements, significant differences are observed between these two methods at higher energies where contributions from charged particle emitting reactions become important. The direct method is found to be more meaningful as it always ensures positive kerma coefficients and helps to separately identify the contributions from light charged particles and recoil nucleus. The neutron spectrum dependence of neutron kerma from both the methods are also investigated. Further, the nuclear data uncertainties in neutron heating are quantified by the Total Monte Carlo (TMC) methodology using the random ENDF-6 files in TENDL-2015 and the results show that the nuclear data uncertainties are in the range of 9–29%.

SPECT myocardial perfusion imaging in liver transplantation candidates

BackgroundThe optimal cardiovascular evaluation prior to liver transplantation remains controversial and includes stress echocardiography, stress MPI, cardiac CTA, and coronary angiography. This study summarizes our experience of the past decade using SPECT MPI in patients with end-stage liver disease, including patient characteristics, stress testing protocols, test results, the need for repeat testing, and downstream testing. MethodsAll patients who underwent a clinically indicated stress SPECT MPI study as part of their pre-liver transplant evaluation from 2004 to 2014 were reviewed from the Nuclear Cardiology database. Results of perfusion imaging, repeat testing, subsequent angiography, and need for revascularization were reviewed. ResultsA total of 2500 patients were referred for SPECT MPI, of those 111 had known CAD and 271 underwent more than one MPI study. Compared to other patients undergoing stress MPI, pre-liver transplant patients were younger, had fewer cardiac risk factors and lower prevalence of prior cardiac history, and used pharmacologic stress more often. During the study decade, patient age increased, prevalence of hypertension increased and smoking decreased, prevalence of known CAD increased, and the number of abnormal studies decreased. Abnormal perfusion results were present in 7.8% of pre-liver transplant patients compared to 34.3% of all other patients. In a multivariate model, age and lower ejection fraction were associated with an abnormal MPI result. Of the 64 patients who underwent subsequent invasive or non-invasive coronary angiography after an abnormal MPI, obstructive CAD was diagnosed in 25 patients (1.0%), non-obstructive CAD was diagnosed in 23 patients (0.9%), and normal coronaries found in 16 patients (0.6%); a total of 18 (0.7%) of these underwent coronary revascularization. The average time to repeat testing was 27.2 ± 17.9 months. In a multivariate model, younger age and exercise stress were associated with repeat testing. In only 17 patients out of 271 with a normal initial perfusion, the repeat study became abnormal. The use of stress-first imaging was successful in 80% of patients with a reduction in Tc-99m dose from 39.1 to 18.3 mCi. ConclusionAbnormal SPECT MPI results in candidates for liver transplantation are infrequent compared to non-liver transplant patients and the incidence of obstructive CAD on subsequent angiography even less. Repeat testing in those on the transplant waiting list after initial normal test results appears to be of limited value. Stress-first protocols may be considered for the majority of these patients to reduce testing time and radiation exposure.

Notes on the Motion of Celestial Bodies

A novel method for the computation of the motion of multi-body systems is proposed against the traditional one, based on the dynamic exchange of attraction forces or using complex field equations, that hardly face two-body problems. The Newton gravitational model is interpreted as the emission of neutrino/gravitons from celestial bodies that combine to yield a cumulative flux that interacts with single bodies through a momentum balance. The neutrino was first found by Fermi to justify the energy conservation in β decay and, using his model; we found that the emission of neutrino from matter is almost constant independently from the nuclides involved. This flux can be correlated to Gauss constant G, allowing the rebuilding of Newton law on the basis of nuclear data, the neutrino weight and the speed of light. Similarly to nature, we can therefore separate in the calculations the neutrino flux, that represents the gravitational field, is dependent on masses and is not bound to the number of bodies involved, from the motion of each body that, given the field, is independent of the mass of bodies themselves. The conflict between exchanges of forces is avoided, the mathematics is simplified, the computational time is reduced to seconds and the stability of result is guaranteed. The example of computation of the solar system including the Sun and eight planets over a period of one to one hundred years is reported, together with the evolution of the shape of the orbits.

Beta-delayed gamma spectra in CENDL-3.2

A new program is developed to compute the beta delayed fission gamma spectrum, and applied to compute the spectra of n+235U, 239Pu and 241Pu fissions wherein the recent nuclear database is adopted. The results show that most spectra are well in agreement with the data from ENDF/B-VII.0 library, and some are quite different, which should be caused by the improvement of the nuclear database.

Present Status of Neutron-, Photo-induced and Spontaneous Fission Yields Experimental Data

Nuclear reaction data collection, evaluation and dissemination have been pioneered at the Brookhaven National Laboratory since the early 50s. These activities gained popularity worldwide, and around 1970 the experimental nuclear reaction data interchange or exchange format (EXFOR) was established. The originalEXFORcompilation scope consisted only of neutron reactions and spontaneous fission data, while many other nuclear data sets were ignored. Due to the high cost of new experiments, it is very important to find and recover the previously disregarded data using scientific publications, data evaluations and nuclear databases comparisons.Fission yields play a very important role in applied and fundamental physics, and such data are essential in many applications. The comparative analysis of Nuclear Science References (NSR) and Experimental Nuclear Reaction (EXFOR) databases shows a large number of unaccounted experiments and provides a guide for the recovery of fission cross sections, yields and covariance data sets. The dedicated fission yields data compilation effort is currently underway in the Nuclear Reaction Data Centers (NRDC) network, and includes identification, compilation, storage and Web dissemination of the recovered data sets.

Measurement and analysis of 155,157Gd(n,γ) from thermal energy to 1 keV

We have measured the capture cross section of the 155Gd and 157Gd isotopes between 0.025 eV and 1 keV. The capture events were recorded by an array of 4 C6D6 detectors, and the capture yield was deduced exploiting the total energy detection system in combination with the Pulse Height Weighting Techniques. Because of the large cross section around thermal neutron energy, 4 metallic samples of different thickness were used to prevent problems related to self-shielding. The samples were isotopically enriched, with a cross contamination of the other isotope of less than 1.14%. The capture yield was analyzed with an R-Matrix code to describe the cross section in terms of resonance parameters. Near thermal energies, the results are significantly different from evaluations and from previous time-of-flight experiments. The data from the present measurement at n_TOF are publicly available in the experimental nuclear reaction database EXFOR.

A cutoff thyroglobulin value suggestive of distant metastases in differentiated thyroid cancer patients.

Serum thyroglobulin is used as part of the early postoperative assessment of differentiated thyroid cancer (DTC) since there is a clear relationship between an increased risk of recurrence and persistent disease after initial treatment and high postoperative stimulated thyroglobulin (ps-Tg) values. Thus, although ps-Tg above 10–30 ng/mL is considered an independent predictor of worse prognosis, the value that is associated with distant metastases is not defined. Thus, this was our objective. We selected 655 DTC patients from a nuclear medicine department database (Irmandade Santa Casa de Misericórdia de São Paulo, Brazil). All patients had received total thyroidectomy and radioactive iodine (RAI) therapy and had ps-Tg values higher than 10 ng/mL with negative anti-thyroglobulin antibodies. Then, we selected patients who presented post-therapy whole-body scan with pulmonary and/or bone uptake but with no mediastinum or cervical uptake. Patients with negative findings on functional imaging or any doubt on lung/bone uptake were submitted to additional exams to exclude another non-thyroid tumor. Of the 655 patients, 14.3% had pulmonary and 4.4% bone metastases. There was a significant difference in ps-Tg levels between patients with and without metastases (P<0.001). The cutoff value of ps-Tg was 117.5 ng/mL (sensitivity: 70.2%; specificity: 71.7%) for those with lung metastasis, and 150.5 ng/mL (sensitivity: 79.3%; specificity: 85%) for those with bone metastasis. The cutoff value for patients with eitherpulmonary or bone metastasis was 117.5 ng/mL (sensitivity: 70.2%; specificity: 83.7%). Our findings demonstrated that ps-Tg could predict distant metastasis in DTC patients. We identified a cutoff of 117.5 ng/mL with a high negative predictive value of 93.7%.

Effect of target density uncertainties on extracted experimental cross sections for the natTi(α, x)51Cr,46Sc reactions

The production optimization of medical radioisotopes for various applications requires careful analysis of all production parameters. The importance of such radioisotopes in nuclear medicine cannot be overemphasized. During cross section calculations, experimentalist sometimes find more than one reported literature value of a certain parameter, each leading to a different effect on the overall cross sections. In the present work, we considered the effect of slight variations of density values of titanium reported in the literature on the experimental cross sections. Several reported density values (4.50, 4.51 and 4.54 g/cm3) were found in the literature, but only the lowest and highest values (4.50 and 4.54 g/cm3) were considered in this study. The said densities were used to calculate the cross sections of Ti(a, x)51Cr,46Sc radioisotopes. The corresponding trends of the excitation functions of 51Cr and 46Sc were analyzed for the selected density values. The calculated cross sections from the different density values have been analyzed and compared graphically to show the level of variations, as well as comparison with theoretical TALYS code calculated cross sections. About 1 percent variation of the cross sections have been observed. Following the observed slight variation in cross sections effect of the various density values, we recommend that IAEA could update its nuclear data service database to include recommended density values for all metals using reliable sources.

Completeness of neutron-, photo-induced and spontaneous fission yields data

Nuclear data collection, evaluation and dissemination activities have been performed worldwide for many years. They are absolutely essential for the overall progress of science and technology to create the complete collections of experimental data sets and associated publications, and store these data in publicly accessible databases. Due to many historical and technological reasons not all published data have been identified and compiled. These "missing data" manifest themselves via scientific publications, data evaluations and nuclear databases comparisons. The detailed analysis of the Nuclear Science References (NSR) and the Experimental Nuclear Reaction (EXFOR) databases shows thousands of previously missed nuclear reaction experiments and creates a roadmap for the creation of complete data records for fission cross sections, yields and covariances. The National Nuclear Data Center (NNDC) program for identification, compilation and storage of missing fission yields data sets is described, and recommendations for improving the databases completeness are given.

Overview of the OECD-NEA Working Party on International Nuclear Data Evaluation Cooperation (WPEC)

The OECD Nuclear Energy Agency (NEA) Working Party on International Nuclear Data Evaluation Cooperation (WPEC) was established in 1989 to facilitate collaboration in nuclear data activities. Over its thirty year history, different Subgroups have been created to address topics in nearly every aspect of nuclear data, including: experimental measurements, evaluation, validation, model development, quality assurance of databases and the development of software tools.WPEC has recently completed activities on fission yield evaluation, the general nuclear database structure (GNDS) to replace the ENDF-6 format, methods to provide feedback to evaluation, studies of specific capture cross sections, new methods in thermal scattering kernel evaluation and the Collaborative International Evaluated Library Organisation (CIELO) Pilot Project. Ongoing activities in GNDS application programming interface (API) development, methods for covariance evaluation and quality assurance in nuclear data validation using the International Criticality Safety Benchmark Evaluation Project (ICSBEP) database are complemented by the work of two Expert Groups that oversee the High-Priority Request List (HPRL) for Nuclear Data and the continuous development of the GNDS. New activities on the use of integral experiments for nuclear data validation and adjustment, as well as the use of the Shielding Integral Benchmark Archive and Database (SINBAD) for validation have begun and will be coordinated alongside future Subgroups.After three decades we will review the status of WPEC, how it integrates other collections and activities organised by the NEA and how it dovetails with the initiatives of the IAEA and other bodies to effectively coordinate international activities in nuclear data.