High Burnup Fuel Cladding Materials R&D for Advanced Nuclear Systems

TLDR

Cladding materials development is essential for achieving highly efficient, high‑burnup operation (>100 GWd/t) in Generation IV reactors such as SCWR and LFR; ODS ferritic/martensitic steels with 9–12 %Cr resist neutron irradiation embrittlement and retain high strength at elevated temperatures, yet their corrosion resistance in supercritical water and lead at high temperatures is insufficient, and anisotropy in tensile properties poses an additional challenge. The study aims to improve corrosion resistance of ODS steels in SCW and lead by developing high‑Cr ODS steels at Kyoto University and conducting surveillance tests of their performance. High‑Cr ODS steels were fabricated at Kyoto University and evaluated through surveillance tests of new processing technologies to assess their corrosion and mechanical behavior. Increasing Cr content drastically improved corrosion resistance in SC.

Abstract

Cladding materials development is crucial to realize highly efficient and high-burnup operation over 100GWd/t of so called Generation IV nuclear energy systems, such as supercritical-water-cooled reactor (SCWR) and lead-cooled fast reactor (LFR). Oxide dispersion strengthening (ODS) ferritic/martensitic steels, which contain 9–12%Cr, show rather high resistance to neutron irradiation embrittlement and high strength at elevated temperatures. However, their corrosion resistance is not good enough in SCW and in lead at high temperatures. In order to improve corrosion resistance of the ODS steels in such environment, high-Cr ODS steels have been developed at Kyoto University. An increase in Cr content resulted in a drastic improvement of corrosion resistance in SCW and in lead, while it was expected to cause an enhancement of aging embrittlement as well as irradiation embrittlement. Anisotropy in tensile properties is another issue. In order to overwhelm these issues, surveillance tests of the material performance have been performed for high Cr-ODS steels produced by new processing technologies. It is demonstrated that high-Cr ODS steels have a high potential as fuel cladding materials for SCWR and LFR with high efficiency and high burnup.