Contributions to Integral Nuclear Data in ICSBEP and IRPhEP since ND 2019

. The status of the two neutronics international benchmark projects sanctioned by the Organisation for Economic Co-operation and Development Nuclear Energy Agency (OECD NEA), the International Criticality Safety Benchmark Evaluation Project (ICSBEP) and the International Reactor Physics Experiment Evaluation Project (IRPhEP), was last directly discussed with the international nuclear data community at the 14th International Conference on Nuclear Data for Science and Technology (ND2019) in Beijing, China. Since ND2019, the quantity of available integral benchmark experiment data has increased. The primary purpose of the ICSBEP and IRPhEP is to provide extensively peer-reviewed benchmark data to the international nuclear community in support of validation and testing of nuclear data and models. A total of 28 countries have contributed to the past and continued success of these projects as benchmark evaluations, technical reviews, and experimental data using their own time and resources: 26 to the ICSBEP and 25 to the IRPhEP. Key contributions to the handbooks over the past three years can only be highlighted within this paper. Full technical details and benchmark experiment descriptions can be located within the benchmark reports distributed within recent editions of the handbooks.


Introduction
The International Criticality Safety Benchmark Evaluation Project (ICSBEP) [1] and the International Reactor Physics Experiment Evaluation Project (IRPhEP) [2] continue to represent the gold standard for neutronics benchmark data as sanctioned activities of the Organisation for Economic Co-operation and Development Nuclear Energy Agency (OECD NEA). The status of these two international benchmark projects was last provided to the international nuclear data community at the 14 th International Conference on Nuclear Data for Science and Technology (ND2019) in Beijing, China [3] along with a summary of best practices observed during the benchmark evaluation process [4]. These projects enable international success in criticality and reactor physics safety, neutronics code and nuclear data validation, methods development, experiment and reactor design, licensing, training, and education [5]. The contributions towards each of these projects are concatenated within their respective handbooks: the International Handbook of Evaluated Criticality Safety Benchmark Experiments (ICSBEP Handbook) [6] and the International Handbook of Evaluated Reactor Physics Benchmark Experiments (IRPhEP Handbook) [7]. The handbook covers are shown in Fig. 1 and Fig. 2, respectively.
A total of 28 countries have contributed to the past and continued success of these projects: 26 to the This paper only briefly summarizes the latest benchmark contributions over the past three years. The full technical details and benchmark experiment descriptions, including sample calculations, can be found within the benchmark reports on the most recent editions of each of these handbooks. Many evaluations are also periodically updated to correct errors, incorporate additional evaluated data, or clarify further the content based upon handbook-user feedback. Summaries of various revisions incorporated with the annual releases of the handbooks were previously published [8,9,10,11,12]. It should also be noted that some benchmark evaluations are included within both handbooks because of their versatile applicability within both criticality safety and reactor physics applications.

Latest ICSBEP Contributions
The 2021 edition of the ICSBEP Handbook now includes 587 evaluations with benchmark specifications for 5,098 critical, near-critical, or subcritical configurations; 45 criticality-alarm-placement/shielding configurations with multiple dose points apiece (contained within 7 evaluations); and 237 configurations that have been categorized as fundamental physics measurements relevant to criticality safety applications (contained within 10 evaluations). An additional 838 configurations deemed unacceptable to support highquality criticality safety validation needs; however, the experimental data have been evaluated and preserved to prevent duplication of efforts and identify gaps in existing data to be resolved with improved experimental measurements. A summary of the handbook contents is provided in Table 1 with a breakdown of contributions by country shown in Fig. 3.
Access to the ICSBEP Handbook is available to OECD NEA member countries and recent handbook contributors from non-member countries; requests can be made using the following website: https://oe.cd/ICSBEP.
The Database for the International Handbook of Evaluated Criticality Safety Benchmark Experiments (DICE) tool was developed to facilitate use and searching of the extensive ICSBEP database [13]; it can also be accessed online: https://oe.cd/nea-dice.

Latest IRPhEP Contributions
The 2021 edition of the IRPhEP Handbook now contains data for 57 unique nuclear facilities with evaluations containing benchmark specifications for 169 experimental series. Four of the 169 evaluations are draft benchmarks specifications yet to be formally adopted into the handbook. Draft evaluations typically represent incompletely evaluated experiments, where the data has been preserved and made available for public use. A summary of the handbook contents is provided in Table 2 with a breakdown of contributions by country shown in Fig. 4. Access to the IRPhEP Handbook is available to OECD NEA member countries and recent handbook contributors from non-member countries; requests can be made using the following website: https://oe.cd/IRPHE. Similarly, the IRPhEP Database and Analysis Tool (IDAT) was prepared for use with the IRPhEP Handbook [14] and is also available online: https://oe.cd/idat. Since ND2019 there have been a total of 10 new benchmark evaluations contributed to the IRPhEP Handbook.
The new contributions include one pressurized water reactor (PWR), one gas cooled fast reactor (GCFR), two light water moderated reactor (LWR), one molten salt reactor (MSR), on space reactor (SPACE) and four fundamental physic reactor (FUND) benchmarks.

Gas Cooled Fast Reactors (GCFR)
ZPR-GCFR-EXP-001 ZPR-9/29: Gas Cooled Fast Reactor Critical Experiments -Phase II   [15] and the Spent Fuel Composition (SFCOMPO) database [16]. There are no shortages of international opportunities for involvement via the OECD NEA. Contributions include provision of additional experimental data to evaluate, evaluation of experimental data to prepare new benchmark reports, service as technical reviewers, and programmatic or financial support. Additionally, as users of these handbooks have questions or identify possible errors in the benchmark reports, they are encouraged to inform the leadership of these projects so that improvements can be made in future revisions of the handbooks.

Conclusions
Hundreds of contributors from 28 different countries have combined their efforts to enable the continued success of the ICSBEP and IRPhEP. The handbooks from these two projects continue to grow and are utilized worldwide to support research activities in government, industrial, commercial, and educational environments. The high-quality integral benchmark data within these handbooks support nuclear and criticality safety, as well as enable testing of nuclear data for contemporary and future needs.