Kyle Bunch

Advances in computational power over the last few decades have dramatically opened up the modeling capability of the typical researcher. Although laborious analysis and approximations of physical systems were quite the norm some decades ago, today complex problems can be simulated extensively before being built or committed to design. Today, the pursuit of computational experimentation has displaced, to a large extent, either laboratory experimentation or extensive theoretical analysis… Show more

Advances in computational power over the last few decades have dramatically opened up the modeling capability of the typical researcher. Although laborious analysis and approximations of physical systems were quite the norm some decades ago, today complex problems can be simulated extensively before being built or committed to design. Today, the pursuit of computational experimentation has displaced, to a large extent, either laboratory experimentation or extensive theoretical analysis, especially in systems in which the governing equations are well developed. Indeed, in the field of electromagnetics (EM), where only select canonical problems are amenable to analytical solutions, computer simulations have allowed for great flexibility in searching for new applications to Maxwell’s equations. In light of this flexibility, however, one should not abandon completely either the approaches or models researchers have developed over the years. Show less

We describe a means to use homomorphic encryption to implement an information barrier for use in the verification of nuclear assets. This encryption method allows data to remain encrypted while its content is queried from an encrypted measurement data set. Data exchange and processing are performed without the decryption of potentially classified design information allowing for the verification of nuclear assets with multiple parties of interest participating. Further, rather than using a… Show more

We describe a means to use homomorphic encryption to implement an information barrier for use in the verification of nuclear assets. This encryption method allows data to remain encrypted while its content is queried from an encrypted measurement data set. Data exchange and processing are performed without the decryption of potentially classified design information allowing for the verification of nuclear assets with multiple parties of interest participating. Further, rather than using a conventional computing platform with a complex operating system involved, we propose to use a system based on Field-Programmable Gate Arrays in which an open-hardware architecture design is available to all verifying parties and in which the hardware wiring scheme is programmable. The process is shown to have the dual advantages of a transparent architecture combined with a means to protect any sensitive or potentially classified data. Show less

Research at the Pacific Northwest National Laboratory (PNNL) demonstrated that the low frequency electromagnetic (EM) response of a sealed metallic container interrogated with an encircling coil is a strong function of its contents and can be used to form a distinct signature confirming the presence of specific components without revealing hidden geometry or classified design information. Finite element simulations further investigated this response for a variety of configurations of an… Show more

Research at the Pacific Northwest National Laboratory (PNNL) demonstrated that the low frequency electromagnetic (EM) response of a sealed metallic container interrogated with an encircling coil is a strong function of its contents and can be used to form a distinct signature confirming the presence of specific components without revealing hidden geometry or classified design information. Finite element simulations further investigated this response for a variety of configurations of an encircling coil and a typical nuclear material storage container. Excellent agreement was obtained between simulated and measured impedance signatures for electrically conducting spheres placed inside an AT-400Rnuclear material container. Simulations determined the effects ofexcitation frequency and of the geometry of the encircling coil,nuclear material container, and internal contents. It is possibleto use electromagnetic models to evaluate the application of theEM signature technique to proposed versions of nuclear weaponscontainers which can accommodate restrictions imposed by internationalarms control and treaty verification legislation. Show less

The 2010 ratification of the New START Treaty has been widely regarded as a noteworthy national security achievement for both the Obama administration and the Medvedev-Putin regime, but deeper cuts are envisioned under future arms control regimes. Future verification needs will include monitoring the storage of warhead components and fissile materials and verifying dismantlement of warheads, pits, secondaries, and other materials. From both the diplomatic and technical perspectives… Show more

The 2010 ratification of the New START Treaty has been widely regarded as a noteworthy national security achievement for both the Obama administration and the Medvedev-Putin regime, but deeper cuts are envisioned under future arms control regimes. Future verification needs will include monitoring the storage of warhead components and fissile materials and verifying dismantlement of warheads, pits, secondaries, and other materials. From both the diplomatic and technical perspectives, verification under future arms control regimes will pose new challenges. Since acceptable verification technology must protect sensitive design information and attributes, non-nuclear non-sensitive signatures may provide a significant verification tool without the use of additional information barriers. The use of electromagnetic signatures to monitor nuclear material storage containers is a promising technology with the potential to fulfill these challenging requirements. Research performed at Pacific Northwest National Laboratory (PNNL) has demonstrated that low frequency electromagnetic signatures of sealed metallic containers can be used to confirm the presence of specific components on a “yes/no” basis without revealing classified information. Arms control inspectors might use this technique to verify the presence or absence of monitored items, including both nuclear and non-nuclear materials. Although additional research is needed to study signature aspects such as uniqueness and investigate container-specific scenarios, the technique potentially offers a rapid and cost-effective tool to verify reduction and dismantlement of U.S. and Russian nuclear weapons. Show less

At Pacific Northwest National Laboratory, wideband antenna arrays have been successfully used to reconstruct three-dimensional images at microwave and millimeter-wave frequencies. Applications of this technology have included portal monitoring, through-wall imaging, and weapons detection. Fractal antennas have been shown to have wideband characteristics due to their self-similar nature (that is, their geometry is replicated at different scales). They further have advantages in providing good… Show more

At Pacific Northwest National Laboratory, wideband antenna arrays have been successfully used to reconstruct three-dimensional images at microwave and millimeter-wave frequencies. Applications of this technology have included portal monitoring, through-wall imaging, and weapons detection. Fractal antennas have been shown to have wideband characteristics due to their self-similar nature (that is, their geometry is replicated at different scales). They further have advantages in providing good characteristics in a compact configuration. We discuss the application of fractal antennas for holographic imaging. Simulation results will be presented. Rectennas are a specific class of antennas in which a received signal drives a nonlinear junction and is retransmitted at either a harmonic frequency or a demodulated frequency. Applications include tagging and tracking objects with a uniquely-responding antenna. It is of interest to consider fractal rectenna because the self-similarity of fractal antennas tends to make them have similar resonance behavior at multiples of the primary resonance. Thus, fractal antennas can be suited for applications in which a signal is reradiated at a harmonic frequency. Simulations will be discussed with this application in mind. Show less

The Global Nuclear Energy Partnership (GNEP) has been proposed as a viable system in which to close the fuel cycle in a manner consistent with markedly expanding the global role of nuclear power while significantly reducing proliferation risks. A key part of this system relies on the development of actinide transmutation, which can only be effectively accomplished in a fast-spectrum reactor. The fundamental physics for fast reactors is well established. However, to achieve higher standards of… Show more

The Global Nuclear Energy Partnership (GNEP) has been proposed as a viable system in which to close the fuel cycle in a manner consistent with markedly expanding the global role of nuclear power while significantly reducing proliferation risks. A key part of this system relies on the development of actinide transmutation, which can only be effectively accomplished in a fast-spectrum reactor. The fundamental physics for fast reactors is well established. However, to achieve higher standards of safety and reliability, operate with longer intervals between outages, and achieve high operating capacity factors, new instrumentation and on-line monitoring capabilities will be required--during both fabrication and operation. Since the Fast Flux Test Facility (FFTF) and Experimental Breeder Reactor – II (EBR-II) reactors were operational in the USA, there have been major advances in instrumentation, not the least being the move to digital systems. Some specific capabilities have been developed outside the USA, but new or at least re-established capabilities will be required. In many cases the only available information is in reports and papers. New and improved sensors and instrumentation will be required. Advanced instrumentation has been developed for high-temperature/high-flux conditions in some cases, but most of the original researchers and manufacturers are retired or no longer in business. Show less

Tri-isotropic (TRISO) particle fuels, being considered for use in various advanced nuclear power reactors, consist of sub-millimeter diameter uranium oxide spheres uniformly coated to prevent the release of fission products into the reactor. About 15 billion of these spheres are needed to fuel a single reactor. Current quality control (QC) methods are manual, can destroy test specimens, and are not economically feasible. Replacing these methods with nondestructive evaluation (NDE) techniques… Show more

Tri-isotropic (TRISO) particle fuels, being considered for use in various advanced nuclear power reactors, consist of sub-millimeter diameter uranium oxide spheres uniformly coated to prevent the release of fission products into the reactor. About 15 billion of these spheres are needed to fuel a single reactor. Current quality control (QC) methods are manual, can destroy test specimens, and are not economically feasible. Replacing these methods with nondestructive evaluation (NDE) techniques, automated for higher speed, will make fuel production and reactor operation economically feasible, considering the requirement for extremely large fuel particle throughput rates. This paper reports a project to develop and demonstrate nondestructive examination methods to detect and reject defective particles, and in particular progress made in the final year of a Nuclear Energy Research Initiative (NERI) project . The work explored adapting, developing, and demonstrating innovative nondestructive test methods to cost-effectively assure the quality of large percentages of the fuel particles. Show less

This paper theoretically investigates a novel application of high-temperature superconductors where the superconductor serves as the active component in a microwave or millimeter traveling-wave amplifier. A guided electromagnetic wave interacts with a dc superconducting electron current to set up charge-density gradients within the superconducting electron "plasma." The electromagnetic wave gradually extracts energy from the superconducting electrons by traveling in phase synchronism with these… Show more

This paper theoretically investigates a novel application of high-temperature superconductors where the superconductor serves as the active component in a microwave or millimeter traveling-wave amplifier. A guided electromagnetic wave interacts with a dc superconducting electron current to set up charge-density gradients within the superconducting electron "plasma." The electromagnetic wave gradually extracts energy from the superconducting electrons by traveling in phase synchronism with these charge gradients. The interaction mechanism is similar to that of a conventional traveling-wave tube amplifier or oscillator.
We have modeled the wave behavior of superconducting electrons using the London equations and a two-fluid approach. Our model includes dissipation within the superconductor, and it shows that traveling-wave devices may be possible using high-quality thin-film superconductors in which dissipation is kept low. Show less

There are several advantages of inverse imaging over present standard imaging
methods such as improved spatial resolution , freedom from multiple scattering and
reverberation artifacts, and true quantitative imaging. We verify these advantages and
illuminate t he progression from theory to simulation, to laboratory experiments, and
finally to planned field experiments. We show examples of inverse sca tering in radar,
sonar , and low-frequency electromagnetic (EM) radiation in a… Show more

There are several advantages of inverse imaging over present standard imaging
methods such as improved spatial resolution , freedom from multiple scattering and
reverberation artifacts, and true quantitative imaging. We verify these advantages and
illuminate t he progression from theory to simulation, to laboratory experiments, and
finally to planned field experiments. We show examples of inverse sca tering in radar,
sonar , and low-frequency electromagnetic (EM) radiation in a geophysical context ,
and compare these images with conventional methods. We discuss the importance
of calibration in order to implement inverse scattering procedures, and explain how
such calibration is effected . We summarize the requirements for proper implementation
of inverse scattering imaging and point out where such met hods will yield real benefits
over standard imaging techniques. The paper also enumerates the factors required for
the development of practical field inverse scattering imaging devices. Show less

Methods to compute the minimum and maximum eigenvalues of an infinite-dimensional matrix using extrapolation techniques are presented. These methods are suited for, though not limited to, matrices used in nonorthogonal function fitting.