TENDL-2017 Library Research Articles

Modern Nuclear Data Evaluation with the TALYS Code System

This paper presents a general overview of nuclear data evaluation and its applications as developed at NRG, Petten. Based on concepts such as robustness, reproducibility and automation, modern calculation tools are exploited to produce original nuclear data libraries that meet the current demands on quality and completeness. This requires a system which comprises differential measurements, theory development, nuclear model codes, resonance analysis, evaluation, ENDF formatting, data processing and integral validation in one integrated approach. Software, built around the TALYS code, will be presented in which all these essential nuclear data components are seamlessly integrated. Besides the quality of the basic data and its extensive format testing, a second goal lies in the diversity of processing for different type of users. The implications of this scheme are unprecedented. The most important are:1. Complete ENDF-6 nuclear data files, in the form of the TENDL library, including covariance matrices, for many isotopes, particles, energies, reaction channels and derived quantities. All isotopic data files are mutually consistent and are supposed to rival those of the major world libraries.2. More exact uncertainty propagation from basic nuclear physics to applied (reactor) calculations based on a Monte Carlo approach: “Total” Monte Carlo (TMC), using random nuclear data libraries.3. Automatic optimization in the form of systematic feedback from integral measurements back to the basic data. This method of work also opens a new way of approaching the analysis of nuclear applications, with consequences in both applied nuclear physics and safety of nuclear installations, and several examples are given here. This applied experience and feedback is integrated in a final step to improve the quality of the nuclear data, to change the users vision and finally to orchestrate their integration into simulation codes.

From average parameters to statistical resolved resonances

This paper presents a novel approach using average parameters from statistical models in the continuum to produce statistical resolved resonances in the resonance range. Based on unresolved resonance parameters and the random ladder method, average parameters such as the scattering radius, level spacing, reduced neutron width and the radiative width are used to create resolved resonances from thermal energy up to the first excited level. Using the TALYS reaction code and the CALENDF processing code, the method is tested on ≃2400 isotopes and will be used to produce resolved resonance ranges in the TENDL libraries for reactions missing experimental resolved and unresolved parameters. Additionally, the R-matrix code AVEFIT is used to approximate the resonance structure effects above the first excited level of selected isotopes.

Analysis of integral experiment on erbia-loaded thermal spectrum cores using Kyoto University Critical Assembly by MCNP code with various cross section libraries

Under the project on high burnup nuclear fuel development using erbium as a burnable poison, a series of experiments were performed at the Kyoto University Critical Assembly. The experimental results have formed the basis for this study which aims to analyze the suitability of various evaluated nuclear data libraries for using them in neutronic calculations under the project. The MCNP code was used for the analysis. Calculation model geometry was fully detailed, and ENDF, JENDL, JEFF, and TENDL libraries were used during calculation. For the cross sections of erbium nuclides, the analysis revealed that calculated results upon all the libraries corresponded with experimental data within the errors. However, in some libraries, significant differences were found in case of carbon and uranium nuclides under certain conditions.

TENDL - Library of Evaluated Neutron Data for Transmutation Problem Solving

At present nuclear power plants provide more than 15 per cent of world’s energy production. But some problems arise from this technology, and among the others problems is the nuclear waste products utilization. As a result of nuclear energy production process, both the new fissionable material is produced and accumulated in fuel material and fuel is enriched with highly active fission products. That fact poses a several environmental threat. One of known ways to neutralize highly active isotopes contained in nuclear spent fuel is a transmutation-based technology. The TENDL library presented is to provide recommended neutron-nuclei interaction characteristics for isotope set of interest in numerical transmutation computations. 103 isotopes including 6 effective fission fragments from the world libraries of evaluated constants are involved into the current version of TENDL library. The methods and criteria of data selection, the content of TENDL library are described in this report.

Resonance fluorescence with nuclei: Hg 109

The TENDL library is now established as one of the major nuclear data libraries in the world, striving for completeness and quality of nuclear data files for all isotopes, evaluation methods, processing and applied performance. To reach this status, some basic principles have been applied which sets it apart from other libraries: reproducible dedicated evaluations when differential data are available, through determination of nuclear models implemented in TALYS and their parameters, completeness (with or without experimental data), format and processing standardization, automation of production and reproducibility. In this paper, we will outline how such an approach has become a reality, and recall some of the past successes since the first TENDL release in 2008. Next, we will demonstrate the performance of the latest TENDL releases for different application fields, as well as new approaches for uncertainty quantification based on Bayesian inference methods and possible differential and integral adjustments. Also, current limitations of the library performances due to modelling and needs for new and more precise experimental data will be outlined.