GELINA stability program (GESTA)

Technical description of the GESTA application developed at IRMM.JRC.D.4-Standards for Nuclear Safety, Security and Safeguard

Review of capture cross section data in support to WPEC Subgroup 31

This report is the result of the EC-JRC-IRMM support to the OECD-NEA WPEC Subgroup 31, "Meeting Nuclear Data Needs for Advanced Reactor Systems". It summarizes the contribution that is related to capture cross section data. The status of capture cross section measurements based on the detection of prompt gamma rays is discussed and experimental data that are available to evaluate the capture cross section for 28Si, 206Pb, 238U and 241Am for advanced reactor systems are reviewed.JRC.D.4-Standards for Nuclear Safety, Security and Safeguard

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

Measurement of the direct particle transport through stochastic media using neutron resonance transmission analysis

A measurement of the uncollided neutron flux passing through a sample containing a stochastic mixture of tungsten and sulfur grains has been performed using neutron resonance transmission analysis in the 3 - 200 eV energy region. The impact of the heterogeneous characteristic of the sample is shown based on a comparison of the measurement with a calculated transmission spectrum of a homogeneous sample, which was verified by a measurement with a homogeneous metallic disc. By using a single strong resonance of tungsten, the particle self-shielding factor between 0.2 - 0.9 was directly measured. The experimental data have been compared with model calculations using the Markovian Levermore-Pomraning model. The measured transmission has been used to determine the effective characteristic chord length and volume fraction of the tungsten grains within the sample.JRC.D.4-Standards for Nuclear Safety, Security and Safeguard

Neutron resonance spectroscopy for the characterisation of materials and objects

The use of neutron resonance spectroscopy to investigate and study properties of materials and objects is the basis of neutron resonance transmission analysis (NRTA) and neutron resonance capture analysis (NRCA). NRTA and NRCA are non-destructive methods to determine the elemental and isotopic composition without the need of any sample preparation and resulting in a negligible residual activity. The basic principles of NRTA and NRCA are explained. The use of NRTA and NRCA to determine the elemental composition of archaeological objects and to characterise nuclear materials is reviewed. Other applications of neutron resonance spectroscopy such as imaging, detection of explosives and drugs and thermometry are briefly discussed. A combination of NRTA and NRCA, referred to as Neutron Resonance Densitometry (NRD), is presented as a non-destructive method to quantify nuclear material, in particular the amount of special nuclear material in particle-like debris of melted fuel that is formed in severe nuclear accidents. Finally the importance of accurate nuclear resonance parameters for these applications is discussed and the performance of NRTA for the characterization of nuclear material in the presence of matrix material is assessed.JRC.D.4-Standards for Nuclear Safety, Security and Safeguard

Use of a CAEN digitiser for nuclear safeguards and security applications with a scintillator detector

The performance of a CAEN DT5751 digitiser for nuclear safeguards and security applications is discussed. The pulse shape processing firmware embedded in the digitiser was tested with a EJ-309 liquid scintillator, exposed to gamma and neutron radiation from radioactive sources and from a Van de Graaff and cyclotron-based accelerator. Software modules were developed for data acquisition and online analysis, and for more advanced off-line processing of data acquired in list mode. The potential use of a scintillator coupled to the digitiser for the detection of both gamma-rays and neutrons has been demonstrated.JRC.D.4-Standards for Nuclear Safety, Security and Safeguard

ENDF-6 compatible evaluation of neutron induced reaction cross sections for 182,183,184,186W

An ENDF-6 compatible evaluation for neutron induced reactions in the resonance region has been completed for 182,183,184,186W. The parameters are the result of an analysis of experimental data available in the literature together with a parameter adjustment on transmission and capture data obtained at the time-of-flight facility GELINA. Complete evaluated data files in ENDF-6 format have been produced by joining the evaluations in the resonance region with corresponding files from the JEFF-32T1 and ENDF/B-VII.1 library. The evaluated files have been processed with the latest updates of NJOY.99 to test their format and application consistency as well as to produce a continuous-energy data library in ACE format for use in Monte Carlo codes. The evaluated files will be implemented in the next release of the JEFF-3 library which is maintained by the Nuclear Energy Agency of the OECD. The evaluated files will be implemented in the next release of the JEFF-3 library which is maintained by the Nuclear Energy Agency of the OECD.JRC.D.4-Standards for Nuclear Safety, Security and Safeguard

New resonance parameters for the stable tungsten isotopes from thermal to 1 keV

Neutron resonance parameters of the 182,183,184,186W isotopes were obtained by a resonance shape analysis of experimental data measured at the time-of-flight facility GELINA using the REFIT code. In this document the analysis procedures of capture and transmission data are described. The deduced resonance parameters have been adopted in the new release of the Joint Evaluated Fusion and Fission file, i.e. JEFF-3.2, maintained by the Nuclear Energy Agency of the OECD.JRC.D.4-Standards for Nuclear Safety, Security and Safeguard

Results of time-of-flight transmission measurements for 197Au at a 50 m station of GELINA

Transmission measurements have been performed at the time-of-flight facility GELINA to determine the total cross section for neutron induced reactions in 197Au. The measurements have been carried out at a 50 m transmission station of GELINA with the accelerator operating at 800 Hz. This report provides the experimental details required to deliver the data to the EXFOR data library which is maintained by the Nuclear Data Section of the IAEA and the Nuclear Energy Agency of the OECD. The experimental conditions and data reduction procedures are described. In addition, the full covariance information based on the AGS concept is given such that nuclear reaction model parameters together with their covariances can be derived in a least squares adjustment to the data.JRC.D.4-Standards for Nuclear Safety, Security and Safeguard

Characterisation of plastic scintillators used as an active background shield for neutron detection

This work is part of a JRC Exploratory Research project to develop an active shield that is used to reduce the background due to cosmic radiation in a low-level nuclear waste detection system. The shield consists of an array of plastic scintillators surrounding the detection system. Commercially available plastic scintillation detectors with different thicknesses were characterized for their response to gamma rays, neutrons and muons. Response functions to gamma rays were determined by measurements with radionuclide sources in the energy range from 0.6 MeV to 6.0 MeV. Neutron response functions were measured at mono-energetic neutron beams produced at the Van de Graaff accelerator of the JRC Geel (B) and were derived from results of time-of-flight measurements at the Van de Graaff accelerator of the INFN Legnaro (I). From the response functions for gamma rays and neutrons, light output and resolution functions for protons and electrons were derived. Experimental response functions for muons were determined with the detectors positioned at different orientations. The muon peak is more pronounced in horizontally oriented detectors. Using a scintillator with a minimum thickness of 20 mm a signal caused by the detection of a muon can be separated from events due to natural gamma ray background. For detectors that are stacked, signals caused by the detection of muons can be identified based on a coincidence pattern. Hence, requirements on such a coincidence pattern together with requirements on the light production are effective as parameters for the veto system to be designed.JRC.D.4-Standards for Nuclear Safety, Security and Safeguard