LESTO - LEad fast reactor Safety design and TOols

ID Call: HORIZON-EURATOM-2023-NRT-01-03 Safety of advanced and innovative nuclear designs

Sapienza's role in the project: Affiliated entity

Scientific supervisor for Sapienza: Fabio Giannetti

Department: Astronautical, Electrical and Energy Engineering

Project start date:  November 1, 2024

Project end date: October 31, 2028

Abstract:

Lead Fast Reactors (LFRs) are a crucial technology for advancing both hydrogen energy and nuclear power solutions, offering a promising and ambitious approach. LESTO project aims to further develop this technology, advancing it along its established roadmap and demonstrating its safety, efficiency, and other key features. To achieve this, the project will leverage the most relevant facilities in Europe and the UK to thoroughly validate, assess, and assist in the continued development of LFR technology.

Shortening the time-to market of the LFR technology is an ambitious, but undeniably important factor to attract additional investments, thanks to the lower initial risk, added flexibility, and faster return of experience. Industries and utilities sharing the vision of a competitive LFR of a small and medium-size with modular features will be attracted by the compressed deployment roadmap, and will play a leverage role at national and European level, strengthening synergies and creating public–private–partnership opportunities. In this context, the European community working on the LFR development and deployment assumed the commitment, among others, to highlight the technical open issues and existing research infrastructures, aiming to support the R&D phase through European, national and in-kind contribution of the involved partners. The aim of the LESTO project is moving on along the depicted roadmap, aiming at further developing the LFR technology, supporting the demonstration that LFRs can be designed, sited, constructed, commissioned and operated in line with the requirements of the actual safety standards, with particular focus on their safety features and passive safety systems. Along the project the most relevant facilities in Europe and UK will be adopted to implement a large and very comprehensive experimental database for code validation, safety assessment and component/system demonstration. Among the others, it is worth to mention the large-scale pool type ATHENA facility, being commissioned in Romania, the CIRCE pool in Italy, as well as MELECOR in UK. These facilities, with the support of research infrastructure in Belgium, Germany and Sweden represent the state of art for the LFR R&D. Large emphasis will be devoted to transient analysis in large pools, allowing the community to cross the death valley from laboratory to industry scale.

In the LESTO project, Sapienza University of Rome participates as an affiliated entity to the National Interuniversity Consortium for Nuclear Technological Research (CIRTEN). It contributes to the development and validation of lead-cooled fast reactor (LFR) technology, particularly by providing scientific support for research on passive safety, modelling, and code validation. Sapienza collaborates in the use of European experimental infrastructures and in the transfer of results to support future industrial deployment of LFR technology.
In WP2 – Passive Safety Systems, Sapienza University of Rome supports experimental activities at the SIRIO facility (SIET, ENEA), studying advanced passive cooling systems such as the DecayHeat Removal system designed for ALFRED. This includes pre-test analyses of natural circulation, condensation, and the presence of non-condensable gases. Sapienza will then be involved in validating these phenomena in RELAP5, comparing them with the experimental data obtained. With the aim of validating the tool primarily for the heating and plumbing of lead swimming pools, thermal stratification, and the transition from forced to natural convection, Sapienza will also be involved in numerical simulations at the ATHENA facility (RATEN) within WP4.
In WP3, Sapienza will develop reduced order modelling approaches with the reactive transport simulation will also be developed by UNIROMA1 (compared with the CFD-GEMS approach for fission product transport in the reactor), useful for routine analyses, parameter studies, and sensitivity testing. ROMs will be validated through direct comparison with detailed GEMS simulations and available experimental data, ensuring their reliability.