b'Development of Advance High-Cr Ferritic/MartensiticSteel for Reactor ApplicationsPrincipal Investigator: K.D. ClarkeTeam Members/ Collaborators: C.J. Rietema, M.A. Walker, S.K. Ullrich, M.M. Hassan, M.R. Chancey, C.B. Finfrock, T.R. Jacobs, G.R. Bourne, D.V. Marshall, B.P. Eftink, O. Anderoglu, Y.Q. Wang, T.A. Saleh, S.A. Maloy, and A.J. ClarkeFigure 1. A schematic of theT he fuel cladding in sodium- mize irradiation hardening after low-general microstructure of 12Cr- cooled fast reactor designs calltemperature irradiation, while main-1MoWV steel at three differentfor irradiation resistant mate- taining excellent high-temperature length scales after conventionalrials able to withstand a wide range ofirradiated properties, will improve heat treatment. (a) shows the prior austenite grain structuretemperatures and pressures, all withinreactor efficiency and help generation with laths of tempered martensitea corrosive environment. The high CrIV reactor technology progress. The having developed during heat(12 wt%) ferritic/martensitic (FM)work performed here to optimize HT9 treatment. (b) shows a magnifiedsteel HT9 is a candidate material, butmicrostructures to enhance ductility region within (a) revealing the presence of M23C6 and V(C,N)irradiation at low temperatures (300during low-temperature irradiation decorating the lath boundaries.C) can sharply reduce ductility. Thus,by fundamental understanding of (c) shows a magnified regionimproving ductility of the fuel clad- nitrogen (N) alloying effects is a within (b), illustrating the differentding at lower temperatures is criticalcollaborative effort between Colorado morphologies and volume fractions of intralath V(C,N) found across theto ensure safe and efficient reactorSchool of Mines (CSM), Los Alamos low, mid, and high N alloys. operation. Alloys designed to mini- National Laboratory (LANL) and the University of New Mexico (UNM).108 2021|AFC ACCOMPLISHMENTS'