Dr Thomas Davis’ scientific publication on neutron radiation damage of structural steels for advanced nuclear reactors

04 Nov 2020 | Publications

Dr Thomas Davis has published a paper with Materialia entitled, ‘Atom probe characterisation of segregation driven Cu and Mn–Ni–Si co-precipitation in neutron irradiated T91 tempered-martensitic steel’.

The T91 grade and similar 9Cr tempered-martensitic steels (also known as ferritic-martensitic) are leading candidate structural alloys for fast fission nuclear and fusion power reactors. Grade 91 (referred hereafter as T91) steel is a candidate for sodium and lead/lead-bismuth cooled advanced nuclear reactors. Similar reduced activation variants are candidates for structural components in future fusion power reactors. The attractive properties of T91 steels for these applications include: a) excellent void swelling resistance; b) high thermal conductivity and low thermal expansion; c) existing supply chain for steels widely used in boiler tubes, heat exchangers and piping and; d) American Society of Mechanical Engineers (ASME) BPVC Section III Division 5 nuclear code qualification. At low temperatures (300–400 °C) neutron irradiation hardens and embrittles these steels, therefore it is important to investigate the origin of this mode of life limiting property degradation. Neutron irradiation drives microstructural and microchemical evolutions in TMS, like T91, which have detrimental effects on the mechanical properties, thus limiting the lifetime and performance of reactor structural components.

This study has provided an insight into the MNSP compositions, volume fractions and sizes, which may contribute to a better understanding of the embrittlement of T91 steel. Moreover, this study builds upon the extensive understanding of precipitation in RPV steels and corresponding much more limited Fe–Cr alloy systems.

The post neutron irradiation examination was conducted at the Microscopy and Characterization Suite located at the Center for Advanced Energy Studies (CAES) with the support from the Nuclear Science User Facility Department of Energy funding programme. 

Access the paper here.

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