About

Lance Snead is a Research Professor in the College of Engineering and Applied Sciences at Stony Brook University, specializing in the theory and experimental conduct of radiation materials science studies in support of fusion and fission power systems. His research includes fundamental studies of radiation effects in ceramics, ceramic fuels, graphite, composite materials, and metallic alloy systems. Early in his career, he focused on developing materials with inherently low induced radioactivity for nuclear power applications, particularly silicon carbide and other ceramic composite systems. More recently, his work has emphasized the development of accident tolerant fuel forms and their application to current and next-generation fission power plants.

Research topics

• Metallurgy
• Materials science
• Composite material
• Nuclear engineering
• Physics
• Nuclear chemistry
• Chemistry
• Radiochemistry
• Nuclear physics

Selected publications

• Perspectives and challenges of ultra-high temperature ceramics for fusion plasma-facing applications

  Current Opinion in Solid State and Materials Science · 2025-04-28 · 7 citations

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  PublisherDOI

• Interface instabilities in hafnium hydride entrained iron metal matrix composites

  Journal of Applied Physics · 2025-01-02 · 3 citations

  articleOpen access

  The chemical interactions in Fe–HfH2 metal matrix composites (MMCs) are studied across multiple length scales to elucidate the decomposition of the parent phases and corresponding reaction zone physics during direct current sintering. Fe–HfH2 composites were synthesized with increasing as-mixed hydride contents of Fe–25% HfH2, Fe–40% HfH2, Fe–55% HfH2, and Fe–70% HfH2 (all in vol. %) to demonstrate the ability to achieve sintered MMCs with target hydride contents. Samples were probed across multiple length scales through a multi-modal workflow employing x-ray diffraction, scanning electron microscopy and segmentation analysis, and synchrotron techniques including hard x-ray fluorescence mapping and nanoprobe x-ray absorption near-edge structure measurements. Under the selected sintering temperature and pressure conditions, hydrogen evolution is seen to evolve through parallel paths: thermal decomposition from during the transformation of HfH2 to HfHx<2 and through subsequent reaction with the Fe matrix leading to intermetallic phase formation. Specifically, HfFe and HfFe2 intermetallic formation accelerates the release of hydrogen with a subsequent HfO2 phase forming at grain boundaries. For this MMC, the consumption or loss of hydrogen can be considerable in compacts with initial hydride loading of 25%–40% HfH2 approaching 83% hydrogen loss for the lower volume fraction composites. Increasing the volume fraction of HfH2 to 70% enhanced the retained hydrogen content to 53% and attributed to the reduced interfacial area intrinsic to the increased HfH2 loading in this MMC.

  PublisherDOI

• The Effect of Stress on Laves Phase Precipitation in Creep Ruptured Grade 92 Ferritic Martensitic Steel Determined by an Accessible Volume Fraction and Number Density Quantification Method

  SSRN Electronic Journal · 2025-01-01

  preprintOpen access
  PublisherDOI

• Enhancing low-temperature sintering in the MgO-LiF system: Mechanistic insights

  Journal of the European Ceramic Society · 2025-11-26 · 1 citations

  articleOpen accessSenior author

  In the present article, we provide compelling evidence that minor (1 wt%) additions of micron and nanometre-sized LiF particles in MgO decompose leading to free Li diffusing into MgO surfaces enhancing vacancy production during direct current sintering. The addition of nanometre-sized LiF particles leads to a > 500 °C reduction in the sintering temperature and over 99 % theoretical density of final consolidated compacts. Correlating differential scanning calorimetry with in-situ x-ray diffraction, together with Schottky calculations, post sintering electron microscopy and laser induced breakdown spectroscopy, we uncover critical insights into this impressive reduction in sintering temperature. Our quantitative analysis reveals that MgO and LiF interact at low temperatures with the diffusion of Li into the surface of MgO particles due to the intrinsic structural disorder of the LiF and MgO crystallites. Nanometre-sized LiF particles were found to react the most at low temperatures due to their increased structural disorder. Our multimodal characterization points to a Li-promoted densification and sintering mechanism. This impressive reduction in sintering temperature can be harnessed to promote low-temperature fabrication of MgO-based composites for technological applications.

  PublisherDOI

• Effect of stress on Laves phase precipitation in creep ruptured Grade 92 ferritic martensitic steel characterized by a novel accessible method

  Acta Materialia · 2025-09-18 · 2 citations

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• Bonding of vanadium- and Iron-based alloys as interlayers for plasma-facing and structural materials in fusion systems

  Materials & Design · 2025-09-22

  articleOpen access

  • L2 1 intermetallic phase found at FeCrAl–VCrAl interface. • Interface hardening directly linked to L2 1 phase. • Additively manufactured builds showed B2 phase, unlike sintered samples. • Cr buffer layer proposed to avoid intermetallic formation. • No σ-phase detected in any tested sample across the interface. Vanadium alloys and FeCrAl were investigated as interlayers between tungsten and reduced activation ferritic martensitic steel for fusion system components to avoid formation of intermetallic phase at operating temperatures between 550 and 1100 °C, while maintaining a body centered cubic phase throughout the interface. Physical and mechanical properties need to be graded between tungsten and steel, but recent results showed a significant hardness increase at the FeCrAl to vanadium alloy interface. Here, a sintered sample of these alloys was annealed for extended time, and the microstructure was investigated to provide a better understanding of the phenomena. A comparison with an additively manufactured interface of the same material is provided. An unexpected L2 1 intermetallic phase formation has been revealed using microscopy and synchrotron techniques and will inform future additive manufacturing approaches of the interface. A Cr layer interface as a preliminary solution was proposed between the Vanadium alloy and FeCrAl alloy interface.

  PublisherDOI

• Historic and modern nuclear graphite impurities: Pathways to improved waste strategies

  Current Opinion in Solid State and Materials Science · 2025-12-01 · 2 citations

  articleOpen access1st authorCorresponding

  • Survey of impurity content, including 14 C-producting nitrogen, in graphite from original CP-1 AGOT through currently used nuclear grades. • Sources and distribution of nitrogen in artificial graphite identified. • Recommendation made for obtainable nitrogen levels made to reduce cost of irradiated graphite waste disposal. Graphite has been used in large volumes as a structural material and neutron moderator since the earliest days of nuclear fission. However, no international consensus exists on the disposal of irradiated graphite, leaving much of the historic radioactive graphite inventory in interim vault or silo storage. With several new graphite-moderated reactors planned or under construction, the issue of graphite waste management is becoming increasingly urgent. This paper reviews and quantifies impurities in both historic and modern nuclear graphite, with emphasis on nitrogen—responsible for much of the 14 C inventory—and chlorine, which plays a critical role in repository performance and design. Modern graphites, benefitting from stringent quality-control measures developed for non-nuclear industries, meet or exceed the ASTM Ultra-High Purity nuclear standards, even without halide purification. Both chlorine and nitrogen concentrations have declined over time. For chlorine, identified as a key impurity influencing U.S. waste repository design, we propose a target of 0.1 appm in as-fabricated billets as a reasonable benchmark. Nitrogen sources are traced throughout the graphite production process, with surface and bulk concentrations characterized for all materials studied. Modern graphites commonly exhibit nitrogen levels below 5 appm, with values approaching 1 appm achievable. Using such reduced-nitrogen grades is critical to keeping graphite-induced radioactivity below the greater-than-Class-C waste threshold, thereby avoiding disposal cost penalties of nearly an order of magnitude.

  PublisherDOI

• Low temperature neutron irradiation stability of Zirconium hydride and Yttrium hydride

  Journal of Nuclear Materials · 2025-03-18 · 8 citations

  articleOpen accessSenior author

  Metal hydrides, including ZrH x and YH x , are of particular interest for advanced thermal fission reactors as they have high neutron moderating power and can be used at relatively high temperatures. They have direct applications as core components including as a moderating addition in nuclear fuel, and as neutron reflectors or moderators. Understanding their thermal and irradiation-induced property changes are important to their engineering application. Specifically, evolving metal hydrogen ratios are of critical importance. In this work we discuss the post-irradiation examination of neutron irradiated ZrH 2-x and YH 2-x specimens. We employ multiple characterization techniques including X-ray diffraction, scanning electron microscopy and thermophysical (thermal diffusivity) to determine the irradiation-induced macro- and microstructural evolution as a function of irradiation temperature. We readily quantify degradations in the thermal diffusivity, changes in lattice parameters, and an increase in metallic Zr indicative of hydrogen release in ZrH 2-x specimens. Interestingly, minimal-to-nil change in the metallic Y fraction was quantifiable in the YH 2-x specimens and modest changes in the thermal diffusivity occur for the temperature and dose studied. The loss of hydrogen in the ZrH 2-x samples is related to an apparent irradiation-accelerated desorption of hydrogen by the high ionizing radiation components (gamma, epithermal and fast neutron fluxes) from the in-core neutron irradiation. The most apparent feature from the microstructural analysis for both metal hydrides was a temperature-dependent decrease in the X-ray diffraction peak broadening, attributable to changes in the number and makeup of the two-dimensional defects. These results and trends improve both the fundamental understanding of neutron-solid interactions, and the development of such an important class of core materials.

  PublisherDOI

• Microstructure and Mechanical Behavior of a Tic Nanoprecipitate Strengthened V Alloy

  SSRN Electronic Journal · 2025-01-01

  preprintOpen access
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• Thermophysical Properties of Refractory Carbides as NTP Surrogate Fuel

  2025-01-01

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Frequent coauthors

• Yutai Katoh

  Oak Ridge National Laboratory

  51 shared

• S.J. Zinkle

  University of Tennessee at Knoxville

  46 shared

• Kurt A. Terrani

  25 shared

• David Sprouster

  21 shared

• Jason R. Trelewicz

  Stony Brook University

  18 shared

• Thak Sang Byun

  Oak Ridge National Laboratory

  17 shared

• Brian D. Wirth

  Oak Ridge National Laboratory

  17 shared

• B.V. Cockeram

  United States Naval Research Laboratory

  14 shared

Education

• PhD, Department of Nuclear Engineering

  Rensselaer Polytech Institute School of Engineering

  1992

• BS, Nuclear Engineering

  Rensselaer Polytechnic Institute

  1985

• BS, Physics

  SUNY Oneonta

  1984