R-Matrix Analysis of the Total and Inelastic Scattering Cross Section of 23Na

Resonance parameters characterizing the interaction of neutrons with 23Na in the energy range from 0.3 to 2 MeV were obtained. These parameters describe the total and inelastic cross section. They were obtained from an analysis of data reported by Märten et al. for inelastic and elastic scattering and by D.C. Larson et al. for the total cross section. The data analysis and deduced resonance parameters are presented in some detail. This report serves to clarify the resonance parameters delivered to CEA/Cadarache.JRC.D.4-Nuclear physic

Comparison of resonance integrals of cross sections from JEFF-3.2 library for some problematic reactions

The quality of the capture cross sections in JEFF-3.2 for a selection of nuclides has been assessed in comparison to other evaluated nuclear data libraries (ENDF/B-VII.1, JENDL-4.0, TENDL-2014 and IRDFF v1.05). The incident neutron capture reactions of this nuclides have been compared to experimental data from the EXFOR database in terms of resonance integrals and, where available, energy dependent data. Recommendations for next version of the JEFF library have been given. For 55Mn, JEFF-3.2 is strongly recommended. For 58Fe and 176,178Hf, JEFF-3.2 is recommended. For 93Nb and 148Nd, JEFF-3.2 is not recommended. For those two nuclides, the capture cross section from JENDL-4.0 is recommended.JRC.D.4-Standards for Nuclear Safety, Security and Safeguard

Gamma-rays from a 241AmO2 Source in an Al2O3 Matrix

Americium is a minor actinide making an important component of high level nuclear waste. A considerable number of studies have been performed or are ongoing to determine cross sections for neutron-induced reactions on 241Am. Recently, two measurements of the neutron-induced capture reaction on 241Am were performed at the n_TOF facility of CERN. One of these measurements used the C6D6 detectors, the other used the BaF2 calorimeter. In both cases, a sample from IRMM was used that had been prepared at ITU [1]. This sample consisted of 241AmO2 which was dispersed in a matrix of Al2O3. The material was pressed into a disk, calcined and enclosed in an aluminium container. It contained about 40 mg of 241Am. The samples had been prepared for measurements of the 241Am(n,2n)240Am reaction cross section [2]. Further details about the sample and these measurements may be found in [1,2]. During the measurements at CERN it was noted that several high energy gamma-rays were emitted by the sample. This presented the question as to the exact energies and origin of these gamma-rays. For this purpose the sample was returned to IRMM and gamma-ray spectroscopy with a high purity germanium (HPGe) detector was performed. The energy and origin of most gamma-rays was determined in this way. Here we report about these measurements paying attention only to gamma-rays that are not known from the decay of 241Am [3] and to the gamma-ray energy range from 844 keV to 13 MeV. There are two mechanisms leading to gamma-ray emission. First there is the natural activity of 241Am and the three known actinide impurities: 237Np (0.021), 233-236,238U (0.000094) and 239,240Pu (0.0017; fractions by weight). Of these 241Am dominates the spectrum, even after applying absorbers to completely stop the 59 keV transition. From the main impurity, 237Np, no gammas are found but there are those of its daughter, 233Pa. For the other actinide impurities and their descendants no gamma-rays were found in the measurement. The second source of gamma-rays are alpha-induced reactions. For energies below the maximum alpha energy of 5.485 MeV, Q-values, thresholds and main characteristic gamma-rays are given in table 1 for the likely candidate reactions. Reactions conclusively identified are 27Al(alpha,alpha’gamma)27Al, and 27Al(alpha,p)30Si and these explain nearly everything besides the 241Am and 233Pa gammas already discussed. There is a clear indication for the 27Al(alpha,n)30P reaction, but for the 27Al(alpha,gamma)31P reaction the evidence is not conclusive due to an overlap with gammas from 30Si. No evidence was found for alpha-induced reactions on the isotopes of oxygen. The measurements are described in the section Experiment. A table with gamma-ray energies and figures with the gamma-ray spectra are given in the section Results. The origin of these gammas is indicated there as well. Only three gamma-rays remain unattributed. A spectrum taken at CERN with a germanium detector showing many additional lines cannot be confirmed. Most likely this was taken under very poor background conditions.JRC.DG.D.5-Nuclear physic

Neutron Inelastic Scattering Cross Section Measurements for 23Na

In March 2011 the final data from measurements for the 23Na(n,n'gamma) reaction were delivered to the CEA - Commissariat à l'Énergie Atomique, Cadarache, France in the context of the EURATOM-CEA collaboration agreement. This report documents that deliverable. The measurement campaign was initiated in response to a request expressed by the CEA at a meeting of the Joint Evaluated Fission and Fusion nuclear data library project in 2007. This meeting took place under the auspices of the Nuclear Energy Agency (Organisation for Economic Co-operation and Development). The CEA supports research for the advanced, Generation-IV type, sodium cooled fast reactor and is engaged in a project to develop a prototype: ASTRID - the advanced sodium test reactor for industrial development. Inelastic scattering cross sections for sodium are of interest to the development of sodium cooled fast reactors. A recent OECD-NEA subgroup analysed the sensitivity of reactor parameters to cross sections and accordingly determined target uncertainties for the nuclear data [1]. Comparing these target uncertainties with the current status of nuclear data uncertainties and covariance data resulted in a list of target priorities. Among these features sodium inelastic scattering for which a target uncertainty of 4% was established for the average cross section in the energy range from threshold to 1.35 MeV. This is approximately seven times as good as the uncertainty for current evaluated data files for this isotope (see OECD-NEA High Priority Request List [2]). At IRMM, the GAINS gamma-array for inelastic neutron scattering was developed with the purpose of measuring cross sections with uncertainties at or below the target uncertainties for nuclides like 23Na using the (n, n'g)-technique [3,4]. In response to the request, a measurement campaign of the 23Na(n,n¿g) reaction was conducted with the GAINS array during 2009-2010, using metallic Na discs of 99.8% purity. The sample and the measurements were made at the Institute for Reference Materials and Measurements in Geel making use of GELINA, the Geel linear electron accelerator that drives a pulsed white neutron source allowing measurements by the neutron time-of-flight technique. A preliminary report of this work was presented earlier [5]. For the experimental work a careful review was made of the gamma-efficiency calibrations and the flux normalization in order to investigate in detail the corrections and the final uncertainties that may realistically be achieved.JRC.DG.D.5-Nuclear physic

Experimental uncertainty and covariance information in EXFOR library

Compilation of experimental uncertainty and covariance information in the EXFOR Library is discussed. Following the presentation of a brief history of information provided in the EXFOR Library, the current EXFOR Formats and their limitations are reviewed. Proposed extensions for neutron-induced reaction cross sections in the fast neutron region and resonance region are also presented.JRC.D.4-Standards for Nuclear Safety, Security and Safeguard

Neutron transmission and capture of 241Am

A set of neutron transmission and capture experiments based on the Time Of Flight (TOF) technique, were performed in order to determine the 241Am capture cross section in the energy range from 0.01 eV to 1 keV. The GELINA facility of the Institute for Reference Materials and Measurements (IRMM) served as the neutron source. A pair of C6D6 liquid scintillators was used to register the prompt gamma rays emerging from the americium sample, while a Li-glass detector was used in the transmission setup. Results from the capture and transmission data acquired are consistent with each other, but appear to be inconsistent with the evaluated data files. Resonance parameters have been derived for the data up to the energy of 100 eV.JRC.D.4-Standards for Nuclear Safety, Security and Safeguard

JRC data for the Ti-48 standard

A measurement of the 48Ti(n,n’gamma)48Ti reaction was performed at the GELINA neutron source of EC-JRC-IRMM using the GAINS spectrometer with the purpose of establishing a new gamma-ray standard for neutron induced cross section measurements. A natural target was used and the gamma-production cross section was measured for 10 transitions in the neutron energy range 0-18 MeV. The lowest achieved uncertainty was 4.8%.JRC.D.4-Standards for Nuclear Safety, Security and Safeguard

Nuclear Data for Sustainable Nuclear Energy

Final report of a coordinated action on nuclear data for industrial development in Europe (CANDIDE). The successful development of advanced nuclear systems for sustainable energy production depends on high-level modelling capabilities for the reliable and cost-effective design and safety assessment of such systems, and for the interpretation of key benchmark experiments needed for performance and safety evaluations. High-quality nuclear data, in particular complete and accurate information about the nuclear reactions taking place in advanced reactors and the fuel cycle, are an essential component of such modelling capabilities. In the CANDIDE project, nuclear data needs for sustainable nuclear energy production and waste management have been analyzed and categorized, on the basis of preliminary design studies of innovative systems. Meeting those needs will require that the quality of nuclear data files be considerably improved. The CANDIDE project has produced a set of recommendations, or roadmap, for sustainable nuclear data development. In conclusion, a substantial long-term investment in an integrated European nuclear data development program is called for, complemented by some dedicated actions targeting specific issues.JRC.D.5-Neutron physic

Study of (n,xng) reactions on 238U

Prompt-gamma spectroscopy and time-of-flight techniques were used to measure (n,xn gamma) cross-sections on several nuclei of interest for nuclear reactors. Experiments were performed at the GELINA facility which provides a pulsed white neutron beam of maximum energy about 20 MeV. Preliminary results concerning 238U will be presented. This work was supported by PACEN/GEDEPEONand by the European Commission within the Sixth Framework Programme through I3-EFNUDAT (EURATOMcontract no. 036434) and NUDAME (Contract FP6-516487), and within the Seventh Framework Programme through EUFRAT (EURATOM contract no. FP7-211499) and through ANDES (EURATOM contract no. FP7-249671).JRC.D.4-Standards for Nuclear Safety, Security and Safeguard