Phase Transformation in Uranium

Butcher, B.R.; Rowe, Albert H.

doi:10.1038/172817a0

Cited by 7 publications

(4 citation statements)

References 5 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Where ρ fm = fuel meat density (g•cm -3 ) N A = 6.022•10 23 = Avogadro's constant (atoms•mol -1 ) w U = weight fraction of uranium in the fuel meat (0.3 for MARVEL fuel) 91.22 = atomic weight of zirconium (g•mol -1 ) 91. 22 1…”

Section: Fuel Meat Composition and Microstructurementioning

confidence: 99%

“…As shown in the phase diagram of elemental uranium in Figure 8, uranium crystallizes at room temperature in the α (orthorhombic) phase [21]. Assuming low pressure conditions, a phase transition from α to β (body-centered tetragonal (BCT)) occurs at about 665 °C, then again from β to γ (body-centered cubic (BCC)) at 776 °C, associated with relative volume changes of +1.0% and +0.6%, respectively [19,22,23]. Since U-ZrH x fuel with 30 wt% uranium content is about 11.2 vol% uranium (see Table 2), such a phase transition (i.e., exceeding a temperature of 660 °C within the fuel for an extended period) is expected to result in a volumetric change of about +0.1% due to the α→β phase transition alone (i.e., not including subsequent thermal expansion, fission gas pressure, etc.).…”

Section: Fuel Meat Composition and Microstructurementioning

confidence: 99%

“…oxy = H/Zr ratio once all oxygen impurity atoms have formed FP-oxide compounds x 0 = nominal H/Zr ratio of the fresh fuel = 1.6 for MARVEL fuel n oxy = uranium fissions per Zr atom in the fuel required to bind all oxygen atoms to FPs Y Zr = fission yield of zirconium (0.3 for thermal fission of 235 U[10]) z = O/Zr ratio due to 1400 ppm-wt O contamination in the fresh fuel meat ≈ 0.0114 for MARVEL fuel N Zr = zirconium atomic density (atoms•cm -3 ), about 3.3⸱1022 (see Equation3…”

mentioning

confidence: 99%

See 2 more Smart Citations

MARVEL Reactor Fuel Performance Report

Evans

Keiser

Sweet

2023

View full text Add to dashboard Cite

The Microreactor Applications Research Validation and EvaLuation (MARVEL) project is producing a high temperature liquid metal-cooled nuclear test bed at the Idaho National Laboratory (INL) to ultimately improve integration of microreactors to end-user applications. This ambitious effort seeks to design, authorize, construct, test, and operate the reactor within five years. In order to construct and operate the MARVEL reactor in a timely manner, the system will utilize materials and component designs which have already been used, qualified, or licensed from previous reactors. The MARVEL reactor will be located at the INL Transient Reactor Test (TREAT) facility in the north high-bay equipment pit and will use the existing 304 stainless steel-clad U-ZrH 1.6 pin-type fuel system developed by General Atomics and purchased from TRIGA International. This fuel has been previously qualified under the United States Department of Energy's Reduced Enrichment for Research and Test Reactors (RERTR) Program.Even though the regulator of the MARVEL reactor is the United States Department of Energy, the standards and approach recommended by the Nuclear Regulatory Commission is well-defined and utilized here. Following NUREG-1537 regulatory guidance, this report documents the authorization case for the MARVEL fuel system's application to MARVEL and establishes stable and predictable fuel performance during the most thermophysically unfavorable conditions achievable in the MARVEL reactor. To that end, this report provides a comprehensive survey of the known thermophysical properties, performance, and quantitative relationships associated with the MARVEL reactor fuel element and uses this information to determine its mechanical integrity and risk of reaching unacceptable conditions during the most extreme accident scenarios predicted for the reactor using the most conservative assumptions available. The information contained herein is compiled from a combination of historical reports and peer reviewed scientific publication manuscripts. Known mechanisms under which the fuel is susceptible to failure are highlighted and compared to conditions that could exist in the MARVEL reactor during an unanticipated transient or accident scenario.The two scenarios considered for analysis in this report are (1) an unprotected loss of flow accident and (2) a hypothetical unprotected loss of coolant accident during the loss of flow accident. Preliminary 2D steady-state analyses herein indicate that both fuel-cladding chemical interactions and fuel-cladding mechanical interactions are negligible throughout the fuel's operational cycle under both normal and high temperature accident scenario conditions. Although higher fidelity 3D time-dependent modeling and simulations are planned, the following may be concluded presently. The MARVEL fuel element maintains its geometric stability and structural integrity during the most extreme accident scenarios predicted for the MARVEL reactor. The hoop stress during the unprotected loss of flow accident reaches a...

show abstract

Section: Fuel Meat Composition and Microstructurementioning

confidence: 99%

Section: Fuel Meat Composition and Microstructurementioning

confidence: 99%

mentioning

confidence: 99%

See 1 more Smart Citation

MARVEL Reactor Fuel Performance Report

Evans

Keiser

Sweet

2023

View full text Add to dashboard Cite

show abstract

“…Thus, control of the microstructures by different heat treatment processes allows determining the mechanical properties. Various investigators [3][4][5][6][7][8] showed that addition of small amounts of certain solutes (less than 1-2 at.%), of which Cr was mostly studied, retains the b ? a phase transformation at lower temperature followed by an isothermal transformation.…”

Section: Introductionmentioning

confidence: 99%

Precipitates Morphology in Iron-Diluted U–Fe Alloys

Aizenshtein¹,

Hamawi²

2014

Metallogr. Microstruct. Anal.

View full text Add to dashboard Cite

The morphology of U 6 Fe precipitates were investigated in the different allotropic states of uranium matrix. The morphology of c-U is equiaxed and the characteristic size is *65 lm. The excess dissolved iron in b-U precipitates discontinuously through a eutectoid reaction during cooling at the grain boundaries, while a-phase precipitates have a ''needle-like'' morphology (in many cases, aspect ratio )10) with a well-defined direction in the uranium matrix. This morphology may compensate for the large density differences of *9 % between a-U and U 6 Fe (*19 and *17.4 g/cm 3 , respectively) and the fact that precipitation takes place at relatively low temperatures. It was shown that U 6 Fe precipitates do not introduce new nucleation sites in b and a phases of uranium.

show abstract

Transformation Kinetics in Uranium-Chromium Alloys

White

1955

JOM

View full text Add to dashboard Cite

Phase Transformation in Uranium

Cited by 7 publications

References 5 publications

MARVEL Reactor Fuel Performance Report

MARVEL Reactor Fuel Performance Report

Precipitates Morphology in Iron-Diluted U–Fe Alloys

Transformation Kinetics in Uranium-Chromium Alloys

Contact Info

Product

Resources

About