Edward D. Blandford

Tritium Control and Capture in Salt-Cooled Fission and Fusion Reactors: Status, Challenges, and Path Forward

Three advanced nuclear power systems use liquid salt coolants that generate tritium and thus face the common challenges of containing and capturing tritium to prevent its release to the environment. The fluoride salt–cooled high-temperature reactor (FHR) uses clean fluoride salt coolants and the same graphite-matrix coated-particle fuel as high-temperature gas-cooled reactors. Molten salt reactors (MSRs) dissolve the fuel in a fluoride or chloride salt with release of fission product tritium into the salt. In most FHR and MSR systems, the baseline salts contain lithium where isotopically separated 7Li is proposed to minimize tritium production from neutron interactions with the salt. The Chinese Academy of Sciences plans to start operation of a 2-MW(thermal) molten salt test reactor by 2020. For high-magnetic-field fusion machines, the use of lithium enriched in 6Li is proposed to maximize tritium generation—the fuel for a fusion machine. Advances in superconductors that enable higher power densities may require the use of molten lithium salts for fusion blankets and as coolants. Recent technical advances in these three reactor classes have resulted in increased government and private interest and the beginning of a coordinated effort to address the tritium control challenges in 700°C liquid salt systems. We describe characteristics of salt-cooled fission and fusion machines, the basis for growing interest in these technologies, tritium generation in molten salts, the environment for tritium capture, models for high-temperature tritium transport in salt systems, alternative strategies for tritium control, and ongoing experimental work. Several methods to control tritium appear viable. Limited experimental data are the primary constraint for designing efficient cost-effective methods of tritium control.

Survey of advanced nuclear technologies for potential applications of sonoprocessing

Ultrasonics has been used in many industrial applications for both sensing at low power and processing at higher power. Generally, the high power applications fall within the categories of liquid stream degassing, impurity separation, and sonochemical enhancement of chemical processes. Examples of such industrial applications include metal production, food processing, chemical production, and pharmaceutical production. There are many nuclear process streams that have similar physical and chemical processes to those applications listed above. These nuclear processes could potentially benefit from the use of high-power ultrasonics. There are also potential benefits to applying these techniques in advanced nuclear fuel cycle processes, and these benefits have not been fully investigated. Currently the dominant use of ultrasonic technology in the nuclear industry has been using low power ultrasonics for non-destructive testing/evaluation (NDT/NDE), where it is primarily used for inspections and for characterizing material degradation. Because there has been very little consideration given to how sonoprocessing can potentially improve efficiency and add value to important process streams throughout the nuclear fuel cycle, there are numerous opportunities for improvement in current and future nuclear technologies. In this paper, the relevant fundamental theory underlying sonoprocessing is highlighted, and some potential applications to advanced nuclear technologies throughout the nuclear fuel cycle are discussed.

Demonstration of Signature-Based Safeguards for Pyroprocessing as Applied to Electrorefining and the Ingot Casting Process

Signature-based safeguards (SBS) is currently being investigated to assist traditional nuclear material accountancy in tracking special nuclear material (SNM) within a fuel cycle facility. SBS involves the identification and detection of signatures from process monitoring data for off-normal operation scenarios that involve the loss or improper movement of SNM. To determine possible realistic signatures, the electrorefiner (ER) process is modeled using the code Enhanced REFIN with Anodic Deposition (ERAD), and the JCC-31 Neutron Coincidence Counter, a nondestructive assay detector, is simulated using MCNPx-POLIMI. The ERAD model is used to determine the elemental composition of the ER cathode deposit, while the MCNPx model is developed to determine the single and double count rates expected for this deposition using ft8 tallies. For the determination of signatures, changes were made in the ER model for current density and diffusion layer thickness. The signatures in terms of both modeled ER and detector output demonstrate distinct signatures to be expected for off-normal operations. The detector response in particular shows significant changes registered in count rates when plutonium is deposited at the cathode, due to the changes in the simulated ER operating conditions.