[en] The NEA Expert Group on Multi-physics Experimental Data, Benchmarks and Validation (EGMPEBV) brings together experts on multiphysics experiments and simulation to review the state of the art in multi-physics validation, and provide guidance on best practices. The expert group has started collecting experimental data for validation purposes with the aim of underlining the value of the significant investments that NEA member countries have made in code development. As part of the next phase of the EGMPEBV activities, first-of- a-kind multi-physics benchmarks are being developed to test the novel modelling and simulation systems that are the subject of multiple code development projects in member countries. Following an agreement with the Russian State Nuclear Energy Corporation, Rosatom, a unique benchmark using data from the Rostov Unit 2 VVER-1000 reactor has been specified and will now be distributed to expert benchmark participants as the first power plant multi-physics benchmark exercise of the expert group. This benchmark will be run in parallel to two others using data from the Studsvik R2 research reactor in Sweden and the Tennessee Valley Authority (TVA) Watts Bar 1 reactor in the United States, which was established as part of the Consortium for Advanced Simulation of Light Water Reactors (CASL) project

[en] In 2013, the NEA launched a project with all the nuclear data evaluation projects from around the world to review the requirements for an international replacement for the ENDF-6 format. Over a three-year process, representatives from all member countries developed an extensive set of requirements that cover not only the necessary nuclear physics, but also rules for data interpolation, the storage of cross-correlations between data, mechanisms to build-in documentation as part of Quality Assurance procedures, and much more. Experts convened by the NEA proposed a new format specification for a Generalised Nuclear Data Structure (GNDS) in 2016 that has been further developed over another three-year process and subjected to rigorous international review. The Generalised Nuclear Database Structure 1.9, published in May 2020, is the outcome of this work. The international community of nuclear data centres has responded to the GNDS project by adopting GNDS into their work-flows and releases. A large body of computer codes have been developed that rely on ENDF-6 formatted data and the re-factoring of these to accommodate a wholly new structure from scratch would be a challenging task. This issue can be significantly simplified with the implementation of an application programming interface (API), which serves as an intermediary between the data files and the software that requires the data within those files. GNDS is technically a structure, in that it can be realised in multiple file formats that are commonly used. GNDS has been engineered as a replacement and extension of the ENDF-6 format. As such, it maintains a strict one-to-one translation capability with the legacy file format and files that are compliant with the ENDF format rules

[en] The FISPACT-II inventory simulation platform is a modern computational tool with advanced and unique capabilities. It is sufficiently flexible and efficient to make it an ideal basis around which to perform extensive simulation studies to scope a variety of responses of many materials (elements) to several different neutron irradiation scenarios. This paper briefly presents the typical outputs from these scoping studies, which have been used to compile a suite of nuclear physics materials handbooks, providing a useful and vital resource for material selection and design studies. Several different global responses are extracted from these reports, allowing for comparisons between materials and between different irradiation conditions. A new graphical output format has been developed for the FISPACT-II platform to display these “global summaries”; results for different elements are shown in a periodic table layout, allowing side-by-side comparisons. Several examples of such plots are presented and discussed

[en] The Consultants’ Meeting on the Fusion Evaluated Nuclear Data Library (FENDL) was held at the IAEA Headquarters in Vienna from 1 to 4 August 2016. A summary of the presentations, discussions, actions and strategies for the future library versions and distributions are provided in this report. (author)

[en] This report summarizes the IAEA Technical Meeting on the International Network of Nuclear Reaction Data Centres held at the IAEA Headquarters in Vienna, Austria from 9 to 12 April 2019. The meeting was attended by 16 participants representing 12 cooperative Centres from eight Member States (China, Hungary, India, Japan, Korea, Russia, Ukraine and USA) and two International Organisations (NEA, IAEA) as well as a participant from Kazakhstan. A summary of the meeting is given in this report along with the conclusions and actions. (author)

[en] A Consultants Meeting on the Resonance Parameters of Fissile Actinides of the International Nuclear Data Evaluation Network (INDEN) was held at the IAEA headquarters in Vienna from 21 to 24 October 2019. The meeting was a follow-up of the working group on evaluations in the resonance region of actinide nuclei. Special focus was on issues in the evaluation in the unresolved resonance region (URR). On-going evaluation work was discussed, and new experimental and evaluation projects targeted at improving the evaluations reviewed. (author)

[en] To address the needs of activation-transmutation simulation in incident-particle fields with energies above a few hundred MeV, the FISPACT-II code has been extended to splice TENDL standard ENDF-6 nuclear data with extended nuclear data forms. The JENDL-2007/HE and HEAD-2009 libraries were processed for FISPACT-II and used to demonstrate the capabilities of the new code version. Tests of the libraries and comparisons against both experimental yield data and the most recent intra-nuclear cascade model results demonstrate that there is need for improved nuclear data libraries up to and above 1 GeV. Simulations on lead targets show that important radionuclides, such as ¹⁴⁸Gd, can vary by more than an order of magnitude where more advanced models find agreement within the experimental uncertainties. (paper)

[en] The Consultancy Meeting on the Fission Product Yield Experimental Database was held at Tokyo Institute of Technology, Tokyo, Japan, from 27th to 30th of May 2019, which aims to grasp the current status of experimental activities on the fission product yields (FPY), development of FPY fission modeling and data evaluation methods, and the EXFOR database compilation. The meeting brought opportunities for the participants from six different countries to discuss on our common topics of interests, such as a novel technique to measure fission-related observables, data evaluation methods by applying theoretical and/or empirical models, a consistent treatment of FPY data together with uncertainties (covariances), possible extension of the EXFOR data format to accommodate various fission-related observables, and improvement of user interface in the EXFOR web retrieving system maintained by IAEA. (author)

[en] This study utilises self-shielding factors as a means to optimise energy group structures for fusion activation calculations. Informed by an analysis of important fusion resonances and a survey of relevant incident particle spectra, we develop and test two new group structures designed to more accurately represent the physics of nuclear reactions. They are compared to group structures commonly used in fusion research & analysis. When used in a JET activation foil scenario, the optimised group structures outperform reference group structures, such as CCFE-709, while requiring fewer bins.

[en] The OECD Nuclear Energy Agency (NEA) Nuclear Science Committee (NSC) established the Expert Group on Multi-physics Experimental Data, Benchmarks and Validation (EGMPEBV) in 2014 to bridge the gap between advanced, multi-physics simulation capabilities and the relatively low availability of dedicated, high-fidelity experimental data and benchmarks specifically for multi-physics modelling and simulation tools. The EGMPEBV was mandated to establish mechanisms for the certification of experimental data and benchmark models and to establish the processes and procedures for the validation of multi-physics modelling and simulation tools. The EGMPEBV oversees three task forces, covering (1) experimental data qualification and benchmark evaluation, (2) validation guidelines and needs and (3) example application of validation experiments. These have generated numerous reports surveying the state-of-the-art in multi-physics validation, challenge areas and recommendations for the evaluation of multi-physics benchmarks, while in parallel developing the specifications for multi-physics benchmarks. Three benchmark specifications are in active development, including a reactivity compensation scenario in the Rostov Unit 2 VVER-1000, multi-cycle depletion of the TVA Watts Bar Unit 1 and study of pellet cladding mechanical interaction within ramp tests performed at the Studsvik R2 reactor. We provide an overview of the recent progress in these areas and a summary of the future activities of the EGMPEBV in establishing international multi-physics benchmarks.