SUNRISE mid-term report, 2023-03-31
The SUNRISE centre aims to prepare for the construction and operation of a Swedish lead-cooled research reactor with a target start date in 2030. The work in SUNRISE will not be sufficient to lead to licensing and construction of a reactor and thus it is part of a greater research and development programme with a high profile and significant commercial impact potential. The centre gathers three universities (KTH, Uppsala and Luleå) and a wide range of industrial and societal stakeholders in five work packages that together stake out the path towards advancing lead-cooled fast reactor technology in Sweden. The centre started its operations on January 1 2021 and has since then rather closely followed the plan set out in the application to SSF.
The research advances have so far resulted in four peer reviewed publications and have several results in the pipeline for further dissemination. 45 people have so far joined the centre in different capacities; 19 seniors and 26 juniors, with a mix of MSc students, PhD students and postdocs among the juniors and a mix of professors, associate professors, researchers and industry affiliates among the seniors.
The centre partners have already succeeded in securing funding for the second stage of the greater programme through the Solstice project application which was funded by the Energy Agency by 99 MSEK in 2022. The centre has also secured the planned three year programme access to neutron beam facilities at ANSTO in Australia in late 2022. Additional funding has been secured for the building of local research infrastructure by cash and materials contributions from Blykalla/LeadCold and Alleima. KTH has provided central co-financing to the centre and Luleå University of Technology has provided co-financing for one PhD project. The centre is thus operating with a significantly higher budget than what was awarded by SSF initially.
The centre and the centre staff have had a truly significant impact in media and society. SUNRISE has been discussed in a very large number of invited popular scientific appearances, some of which are recorded and available: television and radio interviews, news articles, podcasts, a Museum exhibition, panel discussions and debates, and not the least a highly successful Youtube channel operated by one of the SUNRISE PhD students, with millions of views and nearly 40.000 subscribers to date. In short, SUNRISE is very visible in society.
2022-01-24 Article publication
An analytic approach to the design of passively safe lead-cooled reactors, Annals of Nuclear Energy 169 (2022) 108971, Fredrik Dehlin, Janne Wallenius, Sara Bortot
A methodology to assist the design of liquid metal reactors, passively cooled by natural circulation during off-normal conditions, is derived from first principle physics. Based on this methodology, a preliminary design of a small LFR is accomplished and presented with accompanying neutronic and reactor dynamic characterizations. The benefit of using this methodology for reactor design compared to other available methods is discussed.
2022-01-31 Article publication
An improved correlation for gas release from nitride fuels, Journal of Nuclear Materials 558 (2022) 153402, Janne Wallenius
An improved correlation for gas release from nitride fuels is elaborated. Introducing empirical activation energies for migration of fission gases in presence of solid fission products and oxide impurities, it becomes possible to better reproduce existing experimental data sets for gas release in sodium and helium bonded rods. The suggested approach may assist in resolving the previously poorly understood dispersion in measured gas release for identical irradiation conditions.
2022-09-25 Article publication
Potential accident tolerant fuel candidate: Investigation of physical properties of the ternary phase U2CrN3, Journal of Nuclear Materials 568 (2022) 153851, Yulia Mishchenko, Sobhan Patnaik, Elina Charatsidou, Janne Wallenius, Denise Adorno Lopes
In the present study, physical properties of the ternary phase U2CrN3 are evaluated experimentally and by modeling methods. High density pellets containing the ternary phase were prepared by spark plasma sintering (SPS). The microstructural and crystallographic analyses of the composite pellets were performed using scanning electron microscopy (SEM), standardised energy dispersive spectroscopy (EDS) and electron backscatter diffraction (EBSD). Evaluation of the mechanical properties was performed by nanoindentation test. The impact of temperature on lattice properties was evaluated using high temperature X-ray diffraction (XRD) coupled with modeling. Progressive change in the lattice parameters was obtained from room temperature (RT) to 673 K, and the result was used to calculate average linear thermal expansion coefficients, as well as an input for the density functional theory (DFT) modeling to reassess the degradation of the mechanical properties. The ab-initio calculation provides an initial assessment of electronic configuration of this ternary phase in a direct comparison with one of UN phase. For this goal, modeling was also employed to evaluate point defect formation energies and electronic charge distribution in the ternary phase. Results indicate that the U2CrN3 phase has similar mechanical properties to UN (Young's, bulk, shear moduli, hardness). No preferential crystallographic orientation was observed in the composite pellet. However, charge electron density distribution highlights the significant directionality of chemical bonds, which is in agreement with the anisotropy and non-linear behaviour of the obtained thermal expansion ((aa) = 9.12×10⁻⁶/K, (ab) = 5.81×10⁻⁶/K and (ac) = 6.08×10⁻⁶/K). As a consequence, uranium was found to be more strongly bound in the ternary structure which may delay diffusion and vacancy formation, promising an acceptable performance as nuclear fuel.
2023-03-20 Article publication
Slow strain rate testing of Fe-10Cr-4Al ferritic steel in liquid lead and lead-bismuth eutectic, Nuclear Materials and Energy 34 (2023) 101403, Christopher Petersson, Peter Szakalos, Daniel Stein
The susceptibility of Fe-10Cr-4Al steel to liquid metal embrittlement (LME) in low oxygen liquid lead and lead–bismuth eutectic (LBE) environments has been investigated using a newly developed slow strain rate testing (SSRT) technique that can be employed at elevated temperatures. This study showed that the Fe-10Cr-4Al steel suffered embrittlement when exposed to LBE over a wide temperature range. The embrittlement, here measured as a reduction in fracture strain, was observed at the melting temperature of LBE and reached a maximum at approximately 375 °C. At temperatures above 425 °C, the material's ductility regained its original levels. The exposures in liquid lead showed no indications of embrittlement, but a ductile behavior over the entire temperature range studied (340–480 °C).