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Title: Interdiffusion and reactions between U–Mo and Zr at 650°C as a function of time

Development of monolithic U-Mo alloy fuel (typically U-10wt.%Mo) for the Reduced Enrichment for Research and Test Reactors (RERTR) program requires a use of Zr diffusion barrier to eliminate the diffusional interaction between the fuel alloy and Al-alloy cladding. The application of Zr barrier to the U-Mo fuel requires co-rolling process that utilizes a soaking temperature of 650°C, which represents the highest temperature the fuel system is exposed to during both fuel manufacturing and reactor application. Therefore, in this study, development of phase constituents, microstructure and diffusion kinetics of U-10wt.%Mo and Zr was examined using solid-to-solid diffusion couples annealed at 650°C for 240, 480 and 720 hours. Diffusional interactions were analyzed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Within the diffusion zone, a single-phase layer of ß-Zr was observed along with a discontinuous layer of Mo2Zr at the interface between the terminal γ-U(Mo) alloy and ß-Zr. In the vicinity of Mo2Zr phase, islands of ß-U and a-Zr phases were also found. In addition, accicular a-Zr phases were observed within the γ-U(Mo). Growth rate of this diffuaional interaction layer was determined to be 8.76 x 10-15 m2/sec, however with an assumption of certain incubation period. Consistency in these observationmore » along with concentration profiles and diffusion paths are presented and discussed with respect to the diffusion couple that was furnace-cooled, annealed at 700°C in our previous study, and isothermal ternary phase diagram at 700°C.« less
Authors:
 [1] ;  [2] ;  [1]
  1. Univ. of Central Florida, Orlando, FL (United States). Advanced Materials Processing and Analysis Center
  2. Idaho National Lab. (INL), Idaho Falls, ID (United States). Nuclear Fuels and Materials Div.
Publication Date:
OSTI Identifier:
1177653
Report Number(s):
INL/JOU--13-30286
Journal ID: ISSN 0022-3115; TRN: US1500186
DOE Contract Number:
AC07-05ID14517
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Nuclear Materials; Journal Volume: 456; Journal Issue: C
Publisher:
Elsevier
Research Org:
Idaho National Laboratory (INL), Idaho Falls, ID (United States)
Sponsoring Org:
USDOE National Nuclear Security Administration (NNSA)
Country of Publication:
United States
Language:
English
Subject:
11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS; SCANNING ELECTRON MICROSCOPY; TRANSMISSION ELECTRON MICROSCOPY; URANIUM BASE ALLOYS; MOLYBDENUM ALLOYS; BINARY ALLOY SYSTEMS; NUCLEAR FUELS; ANNEALING; PHASE DIAGRAMS; RESEARCH AND TEST REACTORS; TEMPERATURE RANGE 0400-1000 K; ROLLING; TIME DEPENDENCE; LAYERS; INTERFACES; KINETICS; DIFFUSION; MICROSTRUCTURE; ZIRCONIUM diffusion; nuclear fuel; uranium molybdenum alloy