Processing of Nanostructured Ferritic Alloys for Advanced Reactor Core Materials
The Fuel Cycle Research and Development Program is investigating methods of burning minor actinides in a transmutation fuel. To achieve this goal, the fast reactor core materials (cladding and duct) must be able to withstand very high doses (>200 dpa design goal) while in contact with the coolant and the fuel. Thus, these materials must withstand radiation effects that promote low temperature embrittlement, high temperature helium embrittlement, swelling, accelerated creep, corrosion with the coolant, and chemical interaction with the fuel (FCCI). One of the most promising materials for this demanding applications are the class of nanostructured ferritic alloys. These materials are ferritic alloys with high chrome (9-14Cr) with a high density (>10{sup 23}/m{sup 3}), fine distribution of nanosized (∼2 nm) oxide particles and a fine grain size (<0.5 micron). This fine microstructure provides an alloy with high strength at high temperatures and excellent radiation tolerance (e.g. reduced void swelling and ductility retention at low temperatures) but also increases the difficulty of producing engineering parts (e.g. thin walled tubes) from these advanced materials. Thus, extensive research is underway to produce tubes using techniques such as high temperature hydrostatic extrusion, intermediate temperature plug drawing and low temperature pilger processing. (authors)