Safety of GFR through innovative materials, technologies and processes

Project Information

SafeG

Grant agreement ID: 945041

DOI

10.3030/945041

Project closed

EC signature date 19 May 2020

Start date 1 October 2020

End date 30 September 2024

Funded under

• Euratom

Total cost

€ 4 495 010,00

EU contribution

€ 3 799 914,75

Coordinated by

VUJE AS
Slovakia

Periodic Reporting for period 3 - SafeG (Safety of GFR through innovative materials, technologies and processes)

Reporting period: 2023-10-01 to 2024-09-30

Summary of the context and overall objectives of the project

Nuclear energy is recognized by many of the EU countries as a low-carbon energy source to be included in the energy mix. Advanced nuclear systems should become the backbone of the European nuclear power generation plants in the mid and long-term. Making efficient use of uranium natural resources and minimising waste production become major concerns.
Gas-cooled fast reactor (GFR) is considered as one of the six most promising advanced nuclear reactor technologies. This concept is designed to provide highly efficient and sustainable energy solution, with the potential to meet both electricity and industrial heat demands. One of the key advantages of GFR technology is its ability to operate at very high core outlet temperatures, which significantly improves thermal efficiency. Furthermore, GFR supports a closed fuel cycle, enabling the recycling of nuclear fuel and contributing to long-term sustainability and resource efficiency in nuclear energy production.
The global objective of the SafeG project was to further develop the GFR technology and strengthen its safety by reaching specific objectives:
• To strengthen safety of the GFR demonstrator ALLEGRO using innovative technologies, materials, and systems.
• To review the GFR reference options in materials and technologies
• To adapt GFR safety to changing needs in electricity production worldwide
• To bring in students and young professionals, boosting interest in GFR research
• To deepen the collaboration with international non-EU research teams, and relevant European and international bodies.

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

During the project implementation we made a significant step towards improvements in various fields of ALLEGRO demonstrator design:

GFR Core and Fuel Design
• Refractory core optimization– methodology of control and shutdown system, optimization processes and results,
• Reflector optimization - requirements of reflector materials, excess reactivity and peaking factors at BOC, assembly-wise power distribution, neutron spectrum of fuel assemblies, pin-wise power distribution,
• Shielding optimization - examination of potential shielding materials, examination of coolant channel arrangements.

GFR material R&D
• Material research - details on selected materials for HTGR systems, innovative cladding materials development & testing, ODS material development and compatibility of materials with media in GFR conditions,
• Advanced manufacturing process - advanced manufacturing processes development of safety critical GFR components for ALLEGRO, implementation of materials with better performance and processes with enhanced capabilities,
• Needs for material standardization specific for GFRs - standardization and codes in the nuclear industry, especially in relation to GFR, adding new materials and processes into the code, ensuring validity of the data in the codes, uncertainty and limitations of using the codified data.

Safety-related R&D
• S-Allegro experiments - detailed background, its layout with emphasis on loop design parameters, heating power and ability to simulate LOCA/LOFA and heavy gas injection,
• ALLEGRO core CFD simulations - details of ALLEGRO Core CFD Simulations with focus on models of individual sub-assemblies, CFD Simulation of Core Cooling LOFAs,
• Nitrogen injection simulations – related to selection of initiating event, phenomena identification and selection of relevant inputs, TH simulations and design change proposal and comparison with reference solution,
• Assessment of technology readiness level of GFR and R&D needs - various aspects of TRL on a level of benefits and limitations, assessment method, TRL of GFR and remaining challenges and R&D needs.

Education and Training
• Education and On-job Training Activities of the SafeG - realization of the SafeG GFR summer school, SafeG Workshop on advance modelling techniques, as well as thermal-hydraulics benchmark focused on PhD. students and young professionals, successful result in area of exchange students between universities involved in the SafeG and diploma theses connected to the project,
• Results of the SafeG benchmarking activities - results of the thermal hydraulic benchmark on S-Allegro ITF and CFD benchmark on PIROUETTE facility, TH model development and validation, steady state TH calculations, on-transient TH calculations, flow Straightener CFD analyses and Rod Bundle CFD analyses.

The most significant results achieved in project were summarized in public deliverables and published in journals and conferences listed at web page https://www.safeg.eu/documents.

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

The main ambition of the SafeG project was to bring cutting-edge technological innovations to the concept of GFR and to implement them to its demonstrator ALLEGRO. The SafeG project has brought solutions that far exceed the state of the art of the GFR technology. In some special cases, specifically the high-temperature material testing and fuel qualification options, the outcomes of the project represent a breakthrough in the level of knowledge in these areas Fuel qualification assessment of innovative advanced fuel provided unique insight into this problematic that can serve as a basis for a general methodology of advanced fuels qualification for advanced nuclear reactors in Europe in future.

The SafeG project aims at bringing the design and safety of ALLEGRO reactor a considerable step further, mainly in the following areas:
• Core safety – significant progress beyond the state of the art of GFR core safety - start up core as well as refractory core with spacer grid has been designed and optimized - investigation of reactivity feedback coefficients and irradiation capabilities of the ALLEGRO core.
• Automatic shutdown system – current design of the reactor shut-down system has been updated, using state-of-the art reactivity control system with the assemblies enabling smooth reactivity control.
• Instrumentation – Instrumentation of GFRs have been assessed with unprecedented depth of the involved analyses with possible use of advanced measuring technologies and techniques for high temperatures and high flow rates of gas coolant.
• Main heat exchanger design has been updated. Actual design of main heat exchanger is a helium/helium helical shell-and-tube type with compact design and coaxial duct on both sides.
• Main loop isolation valves have been redesigned from active to fully passive design, which is the main feature of the GEN IV reactor systems.
• DHR system – innovative DHR solution has been developed based on cutting-edge technology represented by the tanks, which enable additional injection of the Helium and Nitrogen to the core.
• Significant progress beyond the state of the art has already been made on DHR system. A brand new – fully passive DHR system, which is based on natural circulation was designed.
• Experiments carried out within material research brought first-of-a-kind results of structural materials behaviour in He-N2 mixtures at very high temperatures. Application of these results far exceeds applications in GFR and nuclear in general.

Promotion of the SafeG - social media