Nuclear disarmament treaties are not sufficient in and of themselves to neutralize the existential threat of the nuclear weapons. Technologies are necessary for verifying the authenticity of the ...nuclear warheads undergoing dismantlement before counting them toward a treaty partner's obligation. Here we present a concept that leverages isotope-specific nuclear resonance phenomena to authenticate a warhead's fissile components by comparing them to a previously authenticated template. All information is encrypted in the physical domain in a manner that amounts to a physical zero-knowledge proof system. Using Monte Carlo simulations, the system is shown to reveal no isotopic or geometric information about the weapon, while readily detecting hoaxing attempts. This nuclear technique can dramatically increase the reach and trustworthiness of future nuclear disarmament treaties.
•The ARC conceptual design study has been extended to include a divertor.•Long legged X-point target divertors are implemented with no impact on core plasma.•All superconducting coils are shielded ...and the tritium breeding ratio is ≈1.08.•An ITER-like tungsten swirl-tube cooling channel with molten FLiBe coolant is used.•The ARC reactor divertor design simplifies detachment control and diagnostics.
The ARC pilot plant conceptual design study has been extended beyond its initial scope B. N. Sorbom et al., FED 100 (2015) 378 to explore options for managing ∼525 MW of fusion power generated in a compact, high field (B0 = 9.2 T) tokamak that is approximately the size of JET (R0 = 3.3 m). Taking advantage of ARC’s novel design – demountable high temperature superconductor toroidal field (TF) magnets, poloidal magnetic field coils located inside the TF, and vacuum vessel (VV) immersed in molten salt FLiBe blanket – this follow-on study has identified innovative and potentially robust power exhaust management solutions. The superconducting poloidal field coil set has been reconfigured to produce double-null plasma equilibria with a long-leg X-point target divertor geometry. This design choice is motivated by recent modeling which indicates that such configurations enhance power handling and may attain a passively-stable detachment front that stays in the divertor leg over a wide power exhaust window. A modified VV accommodates the divertor legs while retaining the original core plasma volume and TF magnet size. The molten salt FLiBe blanket adequately shields all superconductors, functions as an efficient tritium breeder, and, with augmented forced flow loops, serves as an effective single-phase, low-pressure coolant for the divertor, VV, and breeding blanket. Advanced neutron transport calculations (MCNP) indicate a tritium breeding ratio of ∼1.08. The neutron damage rate (DPA/year) of the remote divertor targets is ∼3–30 times lower than that of the first wall. The entire VV (including divertor and first wall) can tolerate high damage rates since the demountable TF magnets allow the VV to be replaced every 1–2 years as a single unit, employing a vertical maintenance scheme. A tungsten swirl tube FLiBe coolant channel design, similar in geometry to that used by ITER, is considered for the divertor heat removal and shown capable of exhausting divertor heat flux levels of up to 12 MW/m2. Several novel, neutron tolerant diagnostics are explored for sensing power exhaust and for providing feedback control of divertor conditions over long time scales. These include measurement of Cherenkov radiation emitted in FLiBe to infer DT fusion reaction rate, measurement of divertor detachment front locations in the divertor legs with microwave interferometry, and monitoring “hotspots” on the divertor chamber walls via IR imaging through the FLiBe blanket.
The Polaris-LAMP multi-modal 3-D gamma-ray imager is a radiation mapping and imaging platform which uses a commercial off-the-shelf (COTS) detector integrated with a contextual sensor localization ...and mapping platform. The integration of these systems enables a free-moving radiation imaging capability with proximity mapping, coded-aperture, and Compton imaging modalities, which can create 3-D reconstruction of photon sources from tens of keV to several MeV. Gamma-ray events are recorded using a segmented cadmium zinc telluride (CZT) detector (Polaris-H Quad by H3D Inc., Ann Arbor, MI, USA), while scene data are derived from a contextual sensor and computation package developed by Lawrence Berkeley National Laboratory which includes GPS, laser ranging, and inertial measurement sensors. An onboard computer uses these inputs to create rapidly updating pose (10 Hz) and 3-D scene estimates using a simultaneous localization and mapping (SLAM) algorithm. The precise gamma-ray event location and timing resolution of the Polaris CZT sensor enables Compton imaging above several hundred keV, while photon sources at lower images are localized using coded-aperture imaging techniques. The multi-modal imaging concept enables imaging of diverse radiation sources spanning from the 59-keV emission of 241 Am to the 1.1 and 1.3 MeV lines of 60 Co. This work focuses on the description of the operational principles of the detector system and demonstrating the 3-D imaging performance in a variety of source detection and mapping scenarios. As a proof of concept, we demonstrate mapping complex environments, including both point source and distributed-source environments using proximity, coded-aperture, and Compton imaging modalities. Furthermore, we show the successful use of the system to perform measurements in high-background environments through analysis of arrays of uranium hexafluoride cylinders at the Paducah UF6 project site.
To date, antineutrino experiments built for the purpose of demonstrating a nonproliferation capability have typically employed organic scintillators situated as close to the core as possible ...(typically at a distance of a few meters to tens of meters) and have not exceeded a few tons in size. One problem with this approach is that proximity to the reactor core requires accommodation by the host facility. Water Cherenkov detectors located offsite, at distances of a few kilometers or greater, may facilitate nonintrusive monitoring and verification of reactor activities over a large area. As the standoff distance increases, the detector target mass must scale accordingly. This paper quantifies the degree to which a kiloton-scale gadolinium-doped water Cherenkov detector can exclude the existence of undeclared reactors within a specified distance, and remotely detect the presence of a hidden reactor in the presence of declared reactors, by verifying the operational power and standoff distance using a Feldman-Cousins-based likelihood analysis. A 1-kton scale (fiducial) water Cherenkov detector can exclude gigawatt-scale nuclear reactors up to tens of kilometers within a year. In conclusion, when attempting to identify the specific range and power of a reactor, the detector energy resolution is not sufficient to delineate between the two.
The Polaris-LAMP multi-modal 3D gamma-ray imager is a radiation mapping and imaging platform which uses a commercial-off-the-shelf detector integrated with a contextual sensor localization and ...mapping platform. The integration of these systems enables a free-moving radiation imaging capability with proximity mapping, coded aperture, and Compton imaging modalities, which can create 3D reconstruction of photon sources from tens of keV to several MeV. Gamma-ray events are recorded using a segmented cadmium zinc telluride detector (Polaris-H Quad by H3D inc.), while scene data is derived from a contextual sensor and computation package developed by Lawrence Berkeley National Laboratory which includes GPS, laser ranging and inertial measurement sensors. An onboard computer uses these inputs to create rapidly-updating pose (10 Hz) and 3D scene estimates using a simultaneous localization and mapping algorithm. The precise gamma-ray event location and timing resolution of the Polaris CZT sensor enables Compton imaging above several hundred keV, while photon sources at lower images are localized using coded aperture imaging techniques. The multi-modal imaging concept enables imaging of diverse radiation sources spanning from the 59 keV emission of 241Am to the 1.1 and 1.3 MeV lines of 60Co. This work focuses on the description of the the operational principles of the detector system and demonstrating the 3D imaging performance in a variety of source detection and mapping scenarios. As a proof of concept, we demonstrate mapping complex environments, including both point source and distributed-source environments using proximity, coded aperture, and Compton imaging modalities. Further, we show the successful use of the system to perform measurements in high-background environments through analysis of arrays of uranium hexafluoride cylinders at the Paducah UF6 project site.
Portable radiation detection systems can be equipped with contextual sensors to allow free-moving 3D gamma-ray imaging in a method called scene data fusion (SDF). The scene information provided by ...the contextual sensors can be used to enable 3D imaging and constrain image reconstruction to improve imaging accuracy and computational efficiency and visualization. SDF could be a useful tool in many applications, including radiation mapping for accident assessment and remediation. To demonstrate this concept, Polaris-LAMP, a commercially available detector that has been integrated with contextual sensors, was operated in some areas in and around the Chernobyl Nuclear Power Plant (ChNPP). Here, we present results employing Compton image reconstruction in combination with SDF of data that were collected over series of 20-50 minute dynamic measurements around Pripyat, a nearby town which has been abandoned since the accident in 1986 and in some locations within ChNPP. With the SDF enabled Polaris-LAMP it was possible to create 3D maps of gamma-ray sources and to successfully identify hot spot candidates of Cs-137 on key features of the scenes investigated, demonstrating the usefulness of SDF in the mapping of unknown distributed source environments. In addition, the reconstructed 3D scenes provide important context and visualization of structures and objects.
To date, antineutrino experiments built for the purpose of demonstrating a nonproliferation capability have typically employed organic scintillators, were situated as close to the core as possible ...-typically a few meters to tens of meters distant and have not exceeded a few tons in size. One problem with this approach is that proximity to the reactor core require accommodation by the host facility. Water Cherenkov detectors located offsite, at distances of a few kilometers or greater, may facilitate non-intrusive monitoring and verification of reactor activities over a large area. As the standoff distance increases, the detector target mass must scale accordingly. This article quantifies the degree to which a kiloton-scale gadolinium-doped water-Cherenkov detector can exclude the existence of undeclared reactors within a specified distance, and remotely detect the presence of a hidden reactor in the presence of declared reactors, by verifying the operational power and standoff distance using a Feldman-Cousins based likelihood analysis. A 1-kton scale (fiducial) water Cherenkov detector can exclude gigawatt-scale nuclear reactors up to tens of kilometers within a year. When attempting to identify the specific range and power of a reactor, the detector energy resolution was not sufficient to delineate between the two.
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