Joseph R. Wermer

Development of membranes for hydrogen separation: Pd coated V–10Pd

Abstract Numerous group IVB and VB alloys were prepared and tested as potential membrane materials, but most of these materials were brittle or exhibited cracking during hydrogen exposure. One of the more ductile alloys, V–10Pd (at.-%), was fabricated into a thin foil (107 μm thick) composite membrane coated with 100 nm of Pd on each side. The material was tested for hydrogen permeability, resistance to hydrogen embrittlement, and long term hydrogen flux stability. The hydrogen permeability ϕ of the V–10Pd membrane was 3·86×10–8 mol m–1 s–1 Pa–0·5 (average of three different samples) at 400°C, which is slightly higher than the permeability of Pd–23Ag at that temperature. A 1400 h hydrogen flux test at 400°C demonstrated that the rate of metallic interdiffusion was slow between the V–10Pd foil and the 100 nm thick Pd coating on the surface. However, at the end of testing, the membrane cracked at 118°C because of hydrogen embrittlement.

Anomalous yield reduction in direct-drive deuterium/tritium implosions due to H3e additiona)

Glass capsules were imploded in direct drive on the OMEGA laser [Boehly et al., Opt. Commun. 133, 495 (1997)] to look for anomalous degradation in deuterium/tritium (DT) yield and changes in reaction history with H3e addition. Such anomalies have previously been reported for D/H3e plasmas but had not yet been investigated for DT/H3e. Anomalies such as these provide fertile ground for furthering our physics understanding of inertial confinement fusion implosions and capsule performance. Anomalous degradation in the compression component of yield was observed, consistent with the “factor of 2” degradation previously reported by Massachusetts Institute of Technology (MIT) at a 50% H3e atom fraction in D2 using plastic capsules [Rygg, Phys. Plasmas 13, 052702 (2006)]. However, clean calculations (i.e., no fuel-shell mixing) predict the shock component of yield quite well, contrary to the result reported by MIT but consistent with Los Alamos National Laboratory results in D2/H3e [Wilson et al., J. Phys.: Conf....

Nitriding reactions with a Zr–Mn–Fe metal getter

Abstract The metal getter Zr–Mn–Fe (SAES ST909) is an important component of a metal hydride-based tritium clean-up system at Los Alamos National Laboratory (LANL). The system is normally used to clean a glovebox with a helium/nitrogen atmosphere. During start-up operations, it was found that the Zr–Mn–Fe alloy exhibited an anomaly during activation, namely an exotherm upon initial exposure to nitrogen. The purpose of this work is to better understand this nitriding reaction. Nitrogen absorption studies, temperature profile experiments, and powder X-ray diffraction (XRD) were used to study the nitriding reaction. An exothermic reaction between nitrogen and ST909 was observed at ∼450°C only when the getter was heated for the first time. ST909 that had been previously heated without nitrogen did not produce an exotherm when heated a second time with nitrogen. Based on the XRD evidence, it was speculated that nitrogen reacts exothermically with the zirconium in the ST909 material. After heating above ∼660°C, the aluminum binder in the ST909 melts and may alloy with the zirconium. The resulting alloy appears to be less reactive with nitrogen and does not produce an exotherm.

MEASUREMENT OF THE 3HE PERMEABILITY OF DT-FILLED FUSED SILICA INERTIAL CONFINEMENT FUSION (ICF) TARGETS TO STUDY THE EFFECTS OF 3HE ON NEUTRON EMISSION DURING IMPLOSION

Abstract A set of laser implosion experiments were conducted at the OMEGA laser at the University of Rochester, Laboratory for Laser Energetics (LLE) to study the effect of 3He concentration in DT-filled target shells on fusion yield in ICF implosions.. Eleven laser fusion shells consisting of 1100-μm diameter, hollow, fused silica spheres with 4.6 to 4.7-μm-thick walls were loaded with 520 kPa of deuterium-tritium (DT) and then with 3He (101.3 or 520 kPa). The 3He permeabilities of the shells were determined by measuring the pressure rate of rise into a system with known volume. A mathematical method was developed that relied on the experimental fill pressure and time, and the rate of rise data to solve differential equations using MathCAD to simultaneously calculate 3He permeability and initial 3He partial pressure inside the shell. Because of the high permeation rate for 3He out of the shells compared to that for DT gas, shells had to be recharged with 3He immediately before being laser imploded or “shot” at LLE. The 3He partial pressure in each individual shell at shot time was calculated from the measured 3He permeability. Two different partial pressures of 3He inside the shell were shown to reduce neutron and gamma yields during implosion.

Thermal Cycling Absorption Process (TCAP): Instrument and Simulation Development Status at Los Alamos National Laboratory

The Thermal Cycling Absorption Process (TCAP) Project at Los Alamos National Laboratory has been a collaborative effort with Savannah River Site to demonstrate the Tube-in-Tube (TnT) column design and to improve TCAP science. TnT TCAP is an alternative design which uses a liquid to thermally cycle the metal hydride packed column. Inert gas displacement tests and deuterium pulse tests have been performed on the TnT TCAP column. The inert gas displacement tests are designed to measure plug flow in the column while the deuterium pulse tests determine the separation ability of the column. A residual gas analyzer measures the gases in the exit stream and the experimental results are compared with pulse test model results.

Amorphous Alloy Membranes Prepared by Melt-Spin methods for Long-Term use in Hydrogen Separation Applications

Amorphous Ni-based alloy membranes show great promise as inexpensive, hydrogenselective membrane materials. In this study, we developed membranes based on nonprecious Ni-Nb-Zr alloys by adjusting the alloying content and using additives. Several studies on crystallization of the amorphous ribbons, in-situ x-ray diffraction, SEM and TEM, hydrogen permeation, hydrogen solubility, hydrogen deuterium exchange, and electrochemical studies were conducted. An important part of the study was to completely eliminate Palladium coatings of the NiNbZr alloys by hydrogen heattreatment. The amorphous alloy (Ni0.6Nb0.4)80Zr20 membrane appears to be the best with high hydrogen permeability and good thermal stability.

Cameco UO3 Materials Analysis

Uranium trioxide (UO{sub 3}) was characterized using a variety of techniques to better understand its physical properties. Scanning electron microscope (SEM) images were collected to examine particle morphology, which consisted of semi-spherical particles that tended to agglomerate before sonication. Particle size analysis revealed a singular mode distribution with a mean particle size of 43.0 {micro}m. After sonication a bimodal distribution was produced with peak particle sizes at 0.226 {micro}m and 9.43 {micro}m. The O/U ratio was measured to be 3.09 by Cameco in 2009, by gravimetric analysis. X-ray diffraction (XRD) showed that the sample was mostly {gamma}-UO{sub 3} (87.1%) with a small amount of UO{sub 3} {center_dot} 0.80 H{sub 2}O (12.9%). Bulk and tap densities were determined to be 3.678 {+-} 0.2 and 4.81 {+-} 0.2 g/cm{sup 3}, respectively (crystalline density is 7.3 g/cm{sup 3}). The stoichiometry was measured to be 2.99 in 2012.

A TECHNIQUE FOR SYNTHESIZING METAL TRITIDE STANDARDS

Abstract Before surplus plutonium pits can be decommissioned and converted into metal oxides to be used as reactor fuels, residual tritium must be reduced to an acceptable level. We have developed two analytical methods involving melting and acid dissolution, combined with liquid scintillation counting as a quantitative and sensitive technique for measuring residual tritium in Pu metal. The detection limit, linearity, and reproducibility of these analytical methods must be validated with a series of metal tritide standards. Since there are no commercially available metal tritide standards, we have developed a technique for their synthesis. The synthesis of these low-level metal tritide standards is accomplished by charging cerium powder with a known amount of tritium to form a master cerium tritide alloy and then by aliquoting from this master alloy and diluting with pure cerium powder to form a series of standards with different tritium concentrations. The major difficulty in synthesizing these standards is that the samples contain extremely low levels of tritium, which span over three decades of concentrations. The synthesis technique and initial data obtained for cerium hydride samples will be presented.

Design, fabrication, and testing of a getter-based atmosphere purification and waste treatment system for a nitrogen-hydrogen-helium glovebox

Abstract A system containing a combination of getters (Zr-Mn-Fe, SAES St909; and Zr2Fe, SAES St198) was used to process the nitrogen-hydrogen-helium atmosphere in a glovebox used for handling metal tritide samples. During routine operations, the glovebox atmosphere is recirculated and hydrogenous impurities (i.e. CQ4, Q2O, and NQ3, where Q [is equivalent to] H, D, T) are decomposed (cracked) and removed by Zr-Mn-Fe without absorbing elemental hydrogen isotopes. If the tritium content of the glovebox atmosphere becomes unacceptably high, the getter system can rapidly strip the glovebox atmosphere of all hydrogen isotopes by absorption on the Zr2Fe, thus lessening the burden on the facility waste gas treatment system. The getter system was designed for high flowrate (> 100 l/min), which is achieved by using a honeycomb support for the getter pellets and 1.27-cm diameter tubing throughout the system for reduced pressure drop. The novel getter bed design also includes an integral preheater and copper liner to accommodate swelling of the getter pellets, which occurs during loading with oxygen and carbon impurities. Non-tritium functional tests were conducted to determine the gettering efficiencies at different getter bed temperatures and flowrates by recirculating gas through the system from a 6-m3 glovebox containing known concentrations of impurities.

Tritium production by fast neutrons on oxygen : an integral experiment /

This report describes an integral experiment of tritium production in water by neutrons from the LANSCE/WNR spallation neutron source. Neutron energies covered the range from 1 MeV to about 300 MeV. The neutron fluence was determined with a 238U fission chamber. After irradiation, the water samples were analyzed for tritium. The results are compared with calculations and agreement is found to within a factor of 2.