This topic seeks to address the challenges in harnessing fusion power, and developing the fusion fuel cycle technology through an advanced breeding blanket, which is designed to breed, extract, and process the nuclear fuel and heat energy necessary for a self-sufficient, electricity-generating reactor. The blanket is a complex, multi-function, multi-material engineered system (structure, breeder, multiplier, coolant, insulator, tritium processing), with many scientific and technological issues in need of resolution. Proposals are requested that address the following issues that include but are not limited to:

• Innovative solid fusion breeder fuel materials development and simulation tools;

• Innovative liquid fusion breeder and/or coolant materials development and simulation tools; Questions – Contact: Daniel Clark, daniel.clark@science.doe.gov

• Advanced materials and tools for simulation and analysis of breeder blanket material and component behavior in the fusion nuclear environment including thermofluid, MHD, and thermomechanical simulation of coolant flows and structural responses;

• Innovative materials and tools for simulation and analysis of materials and systems for tritium processes including creation, extraction, separation, purification, management and containment;

• Diagnostic sensors for blanket systems that are compatible with the fusion environment;

• Neutronic simulation and analysis tools that go beyond the current state of the art.

 More detail on the topics of interest follow:

Solid breeder material concepts that advance as many as possible of the following criteria: (1) high breeder material densities (up to~80%); (2) high thermal conductivities (as opposed to point contacts between pebbles); (3) better thermal contact, such as reliable joined contact, with cooling structures (instead of point contacts between pebbles and wall); (4) the absence of major geometry changes between beginning-of-life and end-of life (such as sintering in pebble beds) in the presence of high neutron fluence; (5) structural integrity in freestanding and self-supporting structures with significant thermo-mechanical flexibility; (6) high breeding ratios that benefit from increased breeder and multiplier material densities (typically lithium and beryllium) and preferably leverage existing R&D in nano and micro engineered materials, such as those developed for advanced lithium ion batteries; and tools for simulation and analysis of materials and systems for solid breeders that leverage advanced computational techniques.

New liquid breeder material concepts that advance as many as possible of the following criteria: (1) new liquid breeder materials that have a high breeding capacity; (2) that are not influenced by the magnetohydrodynamic (MHD) effect; (3) can operate at high temperatures (400-700 deg C); (4) are not corrosive to the materials used in planned fusion systems (RAFM steels, ODS steels, NFAs, SiC); (5) are conducive to tritium extraction, and tools for simulation and analysis of materials and systems for liquid breeders that leverage advanced computational techniques.

Insulating the flowing liquid metal breeder/coolant against MHD and thermal effects with Flow Channel Inserts (FCI), which support liquid metal breeders. These materials have a low electrical conductivity (1 to 50 Ω-1m-1). FCI structural loading is low, but they must be able to withstand radiation damage and thermal stresses from through-surface temperature differences in the range of 150-300K, over a thickness of 3 to 15 mm depending on designs.

Materials, simulations and tools needed for managing tritium used in the fusion fuel cycle in a safer and more efficient manner are needed. Early experiments can be performed using hydrogen as a surrogate, but more advanced technology development will likely need to be partnered with a national laboratory with the ability to handle tritium. Current solid breeders operate with a He purge gas at approximately 8 MPa, and liquid metal breeders at a partial pressure of approximately 0.3 Pa. Tritium extraction technologies including permeator materials and extraction methods need to distinguish between the different species for more efficient trapping and desorption from the He purge gas that operate at better than 40% efficiency on the first pass. An advanced purification system to remove impurities at better than 90% efficiency on the first pass is needed along with tritium barrier and management materials. An integrated multi-physics simulation tool to model tritium chemistry, tritium transport through materials, permeation rates, tritium concentration and flux in materials and systems, at different irradiation levels which goes beyond the current state of the art available domestically and internationally.

Diagnostics for the blanket system are needed, including liquid metal flow sensors that are able to accurately measure the velocity profile across the whole cross-section, and tritium concentration sensors.

Neutronic and safety simulation and analysis tools for determining radiation-induced material damage, tritium breeding efficiency, and worker radiation exposure conditions under a fusion environment with a peak 14 MeV neutron source are needed. The fusion neutronic environment is different, and harsher than the fission environment. Simulation and analysis tools that advance the state of the art to enable effective prediction of the fusion Tritium Breeding Ratio (TBR), material damage effects, such as swelling and creep, and prediction of the effectiveness of fusion radiation shields and barriers designed to limit worker and remote handling equipment exposure to the radiation environment, are critical to the safe adoption of fusion power. Ideally these tools are plug-ins, or compatible modules within existing commercial design software codes for structural, thermal, fatigue, or fluid flow, or safety analyses, such as Ansys®, Fluent®, Nastran®, LS-DYNA®, to enhance the integration, validation, and adoption of the tools.

Questions – Contact: Albert Opdenaker, albert.opdenaker@science.doe.gov

Reference

1. U.S. Department of Energy Office of Fusion Energy Sciences. (2009). Research Needs for Magnetic Fusion Energy Sciences. Report of the Research Needs Workshop (ReNeW). Bethesda, http://science.energy.gov/~/media/fes/pdf/workshop-reports/Res_needs_mag_fusion_report_june_2009.pdf

2. U.S. Department of Energy Office of Science: Fusion Energy Sciences Advisory Committee. (2012). Opportunities for Fusion Materials Science and Technology Research now and During the ITER Era. http://science.energy.gov/~/media/fes/pdf/workshop-reports/20120309/FESAC-Materials-Science-final-report.pdf

3. C. E. Kessel, et al. (2012). Fusion Nuclear Science Pathways Assessment (FNS-PA). Princeton Plasma Physics Laboratory. Available at http://link.springer.com/article/10.1007%2Fs10762-010-9706-0