6 research outputs found
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Behavior of low-burnup metallic fuels for the integral fast reactor at elevated temperatures in ex-reactor tests
A series of ex-reactor heating tests on low burnup U-26wt.%Pu-10wt.%Zr metallic fuel for the PRISM reactor was conducted to evaluate fuel/cladding metallurgical interaction and its effect on cladding integrity at elevated temperatures. The reaction between the fuel and cladding caused liquid-phase formation and dissolution of the inner surface of the cladding. The rate of cladding penetration was below the existing design correlation, which provides a conservative margin to cladding failure. In a test which enveloped a wide range of postulated reactor transient events, a substantial temporal cladding integrity margin was demonstrated for an intact, whole fuel pin. The cause of the eventual pin breach was reaction-induced cladding thinning combined with fission-gas pressure loading. The behavior of the breached pin was benign. 7 refs., 7 figs., 1 tab
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Strain-Rate Effects on Microstructural Deformation in Irradiated 316 SS
A series of studies have been performed to investigate the post-irradiation deformation and failure behavior of 12% cold-worked 316 stainless steel following irradiation to variety of doses and temperatures in the outer rows of the experimental breeder reactor II (EBR-II). In the current phase of these studies, three sets of samples with different radiation induced microstructures have been characterized with transmission electron microscopy (TEM) following tensile testing to failure at a ‘fast’ strain-rate (1 x 10-3 s-1) and a ‘slow’ strain-rate (1 x 10-7 s-1). The samples were irradiated to doses between 9 and 41 dpa at temperatures between 383 and 443 degrees C. Tensile tests were conducted at a temperature of 430 degrees C and only regions outside of the necked region were examined. Over the parameters tested, strain-rate had a negligible effect on the deformation microstructure. In addition, there was no clear evidence of localized deformation behavior and the deformation appeared relatively homogeneous, characterized by unfaulting and incorporation of faulted dislocation loops into the general dislocation network structure. The influence of the defect microstructures and strain-rate on deformation behavior is discussed
Mechanical property testing of irradiated Zircaloy cladding under reactor transient conditions, Small specimen test techniques: Fourth volume
ABSTRACT: Specimen geometries have been developed to determine the mechanical properties of irradiated Zircaloy cladding subjected to the mechanical conditions and temperatures associated with reactivity-initiated accidents (RIA) and loss-of-coolant accidents (LOCA). Miniature ring-stretch specimens were designed to induce both uniaxial and plane-strain states of stress in the transverse (hoop) direction of the cladding. Also, longitudinal tube specimens were also designed to determine the constitutive properties in the axial direction. Finite-element analysis (FEA) and experimental parameters and results were closely coupled to optimize an accurate determination of the stress-strain response and to induce fracture behavior representative of accident conditions. To determine the constitutive properties, a procedure was utilized to transform measured values of load and displacement to a stress-strain response under complex loading states. Additionally, methods have been developed to measure true plastic strains in the gauge section and the initiation of failure using real-time data analysis software. Strain rates and heating conditions have been selected based on their relevance to the mechanical response and temperatures of the cladding during the accidents
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A versatile apparatus for studying irradiated fuel behavior
A computer-controlled furnace system in the Alpha-Gamma Hot Cell Facility (ACHCF) at the Argonne National Laboratory in Illinois is being used to investigate the behavior of irradiated fuel materials under a variety of thermal conditions. The Fuel Behavior Test Apparatus (FBTA) is capable of accurate specimen temperature control over extended periods at temperatures up to {approximately}1000{degree}C, with short-term capability up to 1600{degree}C. The principal current use of the FBTA is to study the compatibility between irradiated metal fuels and stainless steel claddings at elevated temperatures to support the fuel development for the Integral Fast Reactor. Other types of experiments, such as investigating fission-gas release characteristics, fuel dimensional stability, and fuel motion, are also possible with this apparatus. The system performance has been excellent and over seventy tests have been conducted over a two-year period
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Fuel/cladding compatibility in irradiated metallic fuel pins at elevated temperatures
Over fifty fuel/cladding compatibility tests on irradiated metallic fuel specimens have been conducted in an in-cell facility at elevated temperatures. At temperatures below 700--725{degree}C, no fuel/cladding interaction was noted in tests up to 7 h. Liquid-phase cladding penetration occurred in some of the tests at temperatures greater than 725--750{degree}C. The effective rates of liquid- phase cladding penetration of six different fuel/cladding combinations during 1-h testing are reported. After the initial liquefaction at the fuel/cladding interface, which may be affected by the solid-state diffusional interaction during the steady-state irradiation, the rate of further cladding penetration stays constant or decreases with time. There was no runaway cladding penetration in the latter part of a heating cycle
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Reliability of fast reactor mixed-oxide fuel during operational transients
Results are presented from the cooperative DOE and PNC Phase 1 and 2 operational transient testing programs conducted in the EBR-2 reactor. The program includes second (D9 and PNC 316 cladding) and third (FSM, AST and ODS cladding) generation mixed-oxide fuel pins. The irradiation tests include duty cycle operation and extended overpower tests. the results demonstrate the capability of second generation fuel pins to survive a wide range of duty cycle and extended overpower events. 15 refs., 9 figs., 4 tabs