In tritium process systems, vacuum pumps are typically used to evacuate volumes and piping, as well as transfer gas to other parts of the process. This was done using the combination of an all-metal scroll pump with a metal bellows backing pump. The all-metal scroll pump, manufactured by Normetex, has been unavailable since 2012, and efforts continue to find a suitable replacement. The main obstacle is finding a pump that has no oils or polymer components, which degrade when exposed to tritium and introduce corrosive and/or hazardous impurities into the process.Since turbomolecular pumps are used in tritium processing, it is thought that pumps similar to the turbomolecular pumps would be of interest. The pumps would need to operate at lower rotational speeds to handle higher pressures and flow rates, which is best suited for Molecular Drag Pumps (MDP). To determine this, the vacuum pump characteristics must be determined for the MDP. This report details pump characteristics using an MDP backed by a Metal Bellows (Met-Bel) pump under static and flow conditions for various gases.

Deuterium (D), which is found in natural water at ~ 150 ppm, seems to play an important role in biology; however, research in this field has likely been stalled by the limited availability of D2O with varying D concentrations needed to accurately study the deuterium effects in biological systems. SRNL can currently manufacture D2O in varying concentrations, and we have assembled an interdisciplinary research group to study cell cycle in human normal and cancer cells as a function of D concentration over time in order to address several fundamental science questions.

We would like to acknowledge the following SRNL staff members for their technical input, their hands on work, and support: Dean Thompson and Annamarie MacMurray for conducting all the braze trials, for valuable input into processing, and for suggestions to improve the product and process; Patrick Kuzbary for preparing all the samples, taking pictures of samples, imaging the microstructures, measurements and developing a routine to obtain the data; and Tony Curtis for preparing all the metallographic samples. We would also like to acknowledge Melissa Golyski as the Diffuser Engineer as we work towards developing a reliable and robust process to make diffuser tubes. Finally, we would like to thank the PDRD committee for funding this project.

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The Tritium Facility process for stripping tritium from the glovebox atmosphere currently relies on the use of hot magnesium beds (mag beds) to "crack" tritiated water, releasing hydrogen isotopes as a gas. This is a safe and effective process for recovering hydrogen isotopes from water for further processing. However, due to the thermodynamic properties of magnesium, mag beds are single use -once the magnesium metal is converted to magnesium oxide the bed must be replaced. Replacing mag beds is a labor-intensive and operationally complex task. In order to streamline operations and reduce costs, it is desirable to develop a reusable system that recovers hydrogen isotopes from water, while safely sequestering oxygen in a stable form.The following document reviews the results from the Plant Directed Research, Development, and Demonstration (PDRD) project "Durable Water Splitting using Thermochemical Cycles of Nanostructured Metal Oxides" (SR16009), which had the specific goal of developing a process for stripping tritium from the glovebox atmosphere that eliminates magnesium beds. The research focused on using the reductionoxidation cycles of metals to create a reusable system that behaved similarly to the current process. The concept is straightforward; a tritium-contaminated steam passes over a hot metal bed, converting the metal to a metal oxide and liberating hydrogen. The bed is regenerated by converting the metal oxide back to a bare metal using protium gas, creating a clean water stream. Free oxygen is not produced during the cyclical process, making it safe for use in a hydrogen processing facility. The only by-product is detritiated water, which could simplify disposal over the current mag bed process. An experimental down-selection of materials was conducted, and porous zero valent iron (p-ZVI) was identified as an ideal candidate base material due to its low cost, large hydrogen generation capacity, and moderate operational temperatures. Further investigations of p-ZVI were conducted to better understand how a bed composed of such material would behave in the facility. In particular, the thermal and physical properties were assessed, along with long term cycling and isotope effects. The results indicate that p-ZVI beds could serve as low cost, reusable replacements for mag beds in the Tritium Facility. Revision vi