UT-Battelle

Experimentally measured nuclear fragment-production cross-sections are needed for the development of cross-section models implemented in the radiation transport codes used for several endpoints, including radiation protection and health risk assessment in space. Elemental and isotopic fragment-production cross-section data have been collected from literature in a publicly available database through a combined GSI-ESA-NASA effort. The collected data for systems of interest for space exploration are discussed, and the literature gaps are indicated. The data are also compared with the nuclear fragmentation models implemented in the NASA radiation transport code HZETRN2020, namely NUCFRG3 and RAADFRG. The results show that NUCFRG3 does not take into account nuclear-structure effects, while RAADFRG does. Therefore, RAADFRG can estimate more precisely the production of certain projectile fragments, in particular helium. Nevertheless, for some systems and high energies, RAADFRG overestimates the oscillations due to odd-even effects.

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The distribution and transmission grids are observing an increased penetration of power electronics in loads and generations. For example, there is increasing interest in integrating in extreme fast charging (XFC) systems for fast charging of electrical vehicles. As these systems are integrated, developing high-fidelity electromagnetic transient model of XFC systems in distribution grids and evaluating their interactions with the power grid would be of significant interest. This model will be utilized for design of XFC systems, to identify upgrades in distribution and/or transmission grids, for planning purposes by transmission planners or operators or owners, among others. It can also be utilized in operations for improved reliable performance of the grid and/or XFC station. The challenge with simulating these models is the high computational complexity introduced by the large number of states present in the system and the time-step needed to simulate the system. In this paper, advanced simulations algorithms are applied to reduce the computational complexity of simulating large-scale XFC systems. The algorithms include numerical stiffness-based segregation, time constant-based segregation, clustering and aggregation on differential algebraic equations (DAEs), and multi-order integration approaches. While the first three algorithms split the matrix that needs to be inverted from a large matrix to much smaller matrices, the final algorithm reduces the computational burden of applying higher-order integration approaches in the complete system. The comparison made in the previous sentence is with respect to use of homogeneous integration approaches used in conventional electromagnetic transient simulators like power systems computer aided design (PSCAD). The approaches mentioned here have resulted in speed-up of 36x in the simulation of a single distribution system with 15 XFCs.

Inhalation and ingestion dose coefficients for the embryo and fetus from intakes of radionuclides by the mother are provided in the International Commission on Radiological Protection (ICRP) Publication 88 for intake of each of 74 radionuclides. To address the many other possible radionuclides to which workers may be exposed, effective dose coefficients were developed for the embryo/fetus for all additional radionuclides addressed in ICRP Publication 107 with half-life of 10min or more. The general approach was to use the estimated dose to the mother's uterus during pregnancy as a scalable proxy for the dose to the embryo/fetus. The set of scaling factors used in the study was derived from analyses of the relationships of the dose to the mother's uterus and the effective dose to the embryo/fetus for the ~400 cases (considering two intake modes and multiple forms of many of the radionuclides) addressed in Publication 88.

The helium coolant in high-temperature reactors inevitably contains low levels of impurities during steady-state operation, primarily consisting of small amounts of H{sub 2}, H{sub 2}O, CH{sub 4}, CO, CO{sub 2}, and N{sub 2} from a variety of sources in the reactor circuit. These impurities are problematic because they can cause significant long-term corrosion in the structural alloys used in the heat exchangers at elevated temperatures. Currently, the primary candidate materials for intermediate heat exchangers are Alloy 617, Haynes 230, Alloy 800H, and Hastelloy X. This project will evaluate the role of impurities in helium coolant on the stress-assisted grain boundary oxidation and creep crack growth in candidate alloys at elevated temperatures. The project team will: • Evaluate stress-assisted grain boundary oxidation and creep crack initiation and crack growth in the temperature range of 500-850°C in a prototypical helium environment. • Evaluate the effects of oxygen partial pressure on stress-assisted grain boundary oxidation and creep crack growth in impure helium at 500°C, 700°C, and 850°C respectively. • Characterize the microstructure of candidate alloys after long-term exposure to an impure helium environment in order to understand the correlation between stress-assisted grain boundary oxidation, creep crack growth, material composition, and impurities in the helium coolant. • Evaluate grain boundary engineering as a method to mitigate stress-assisted grain boundary oxidation and creep crack growth of candidate alloys in impure helium. The maximum primary helium coolant temperature in the high-temperature reactor is expected to be 850-1,000°C.Corrosion may involve oxidation, carburization, or decarburization mechanisms depending on the temperature, oxygen partial pressure, carbon activity, and alloy composition. These corrosion reactions can substantially affect long-term mechanical properties such as crack- growth rate and fracture toughness, creep rupture, and fatigue. Although there are some studies on the effects of impurities in helium coolant on creep rupture and fatigue strength, very little is known about their effects on creep crack initiation and crack growth rate at elevated temperatures.

While inhalation dose coefficients are provided for about 800 radionuclides in International Commission on Radiological Protection (ICRP) Publication 68, many radionuclides of practical dosimetric interest for facilities such as high-energy proton accelerators are not specifically addressed, nor are organ-specific dose coefficients tabulated. The ICRP Publication 68 dosimetry concepts are used, along with updated radiological decay data and metabolic data, to calculate committed equivalent dose coefficients [h(T)(50)] and committed effective dose coefficients [e(50)] for radionuclides produced at the Oak Ridge National Laboratory's Spallation Neutron Source.

Deposition of particles in sampling lines may occur due to various physical forces. Particles in the nanoscale are not highly susceptible to inertial or sedimentary deposition, and electrical losses are reportedly controlled by using conductive tubing. Particle losses from diffusion affect size distribution and number concentration. Selectively removing the smallest particles has the effect of increasing the statistical measure of particle size-the geometric mean-while decreasing number concentration and geometric standard deviation. Quantification of losses is necessary to interpret or correct the data. Sample loss from a rigid graphitic or flexible Tygon tube attached to a scanning mobility particle sizer inlet was investigated during sampling at the Center for Nanophase Materials Sciences. Mean concentrations and particle size parameters determined from samples collected with and without sample inlet extensions were compared. Number concentration decreased and mean particle size increased for both tubing types at lengths of approximately 0.7 m.

In the fall of 2008, a low-altitude airborne geophysical survey was carried out at a military installation in Australia, the primary goal of which was detection and mapping of infrastructure, buried wastes, and other buried and surface metallic objects within a 1738 hectare area. The primary survey system was the Battelle VG-16 vertical magnetic gradient system. Because the base is active, the time frame for conducting the survey was limited to a few weeks. The short time frame and the added expense of an additional system were factors against adding on an electromagnetic survey. However, the Australian Department of Defence suggested that there might be non-ferrous targets of significance that the magnetic system would not detect. Moreover, the base was located some tens of kilometers from a field of extinct volcanoes, presenting the possibility of magnetic geology in the form of mafic igneous units. Therefore, it was determined that an airborne transient electromagnetic system should be included in the project. The added electromagnetic system proved valuable, but not in the way that was expected. Concentrations of strong anomalies appeared in the magnetic data, the sources of which could be either buried debris or geological. The TEM-8 system was flown over some of the more dense concentrations of magnetic anomalies. In some of these areas the TEM data showed very few anomalies, indicating that either the VG-16 anomalies are associated with magnetic rock types, or that the metallic sources detected by the VG-16 system are too deeply buried to be detected with the TEM-8 system. A few carefully located excavations indicated that the sources of the magnetic anomaly concentrations without associated electromagnetic anomalies were localized concentrations of very magnetic iron-bearing rock.

In 2008, design and construction was completed on a new boom‐mounted airborne time‐domain electromagnetic system, the Battelle TEM‐8 system. Review of survey results led to secondary hardware and software modifications throughout following year. The system was designed primarily for widearea assessment of sites contaminated with unexploded ordnance (UXO), but has already found broader application. To date it has seen use in five deployments: 1) Battelle's UXO airborne technology test grid in Ohio, 2) an Australian air base where infrastructure mapping was needed in advance of new construction, 3) Twentynine Palms, a Marine base in California, 4) Camp LeJeune, a Marine base in North Carolina, and 5) a pair of proximal sites in New Mexico which were used for bomber training. Results of these surveys are compiled to provide insight into the capabilities of airborne metaldetecting systems in general, and the TEM‐8 system in particular. Sensitivity is assessed as a function of the ability to detect ordnance of different sizes. Positional accuracy is also derived from the UXO surveys. Comparison of airborne magnetometer and TEM‐8 results provide a basis for assessing the strengths of each. Likewise, the advantages of joint analysis of magnetometer and electromagnetic data sets can be assessed at sites where both were acquired. Finally, the benefits of TEM data for mapping infrastructure and distinguishing spurious geologic response from metallic waste can be demonstrated.