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The U.S. has transitioned from being the 20th-century global leader in civilian nuclear power to a nation searching for ways to revive its once-dominant nuclear enterprise. The future of U.S. civilian nuclear power transcends that of a science and technology issue and, fundamentally, is a policy issue. This is a policy paper that uses a nuclear power policy framework to analyze current and historical U.S. civilian nuclear power policy and to identify weaknesses and deficiencies that need to be overcome in order for the U.S. to (1) leverage advanced nuclear reactors as a domestic technology to meet energy security and reliability objectives under carbon constraints, (2) operationalize national security as a priority objective and (3) restore the U.S. as a major global exporter of nuclear technology. The results of this analysis indicate that the national security implications of U.S. nuclear power have been marginalized in general due to the domestic market challenges of competing with less expensive and oftentimes more socially acceptable technologies, as well as the international challenges of competing with state-owned nuclear enterprises. The results are then discussed and used for making three following policy recommendations: (1) conduct a U.S. nuclear industrial base review; (2) create a demand signal using U.S. military installations; and (3) shift away from a sell-side nuclear vendor model for global exports to a buy-side model brokered by a third-party integrator that can work with multiple U.S. nuclear partners.

The science and engineering of materials have always been fundamental to the success of nuclear power to date. They are also the key to the successful deployment and operation of a new generation of nuclear reactor systems and their associated fuel cycles. This article reflects on some of the historical issues, the challenges still prevalent today and the requirement for significant ongoing materials R&D and discusses the potential role of small modular reactors.

Following the Fukushima accident, the safety features of Nuclear Power Plants (NPP) are being re-examined worldwide including India to demonstrate capabilities to cope with severe accidents. In order to restore public confidence and support for nuclear power, it is felt necessary to design future NPPs with near zero impact outside the plant boundary and thus enabling elimination of emergency planning in public domain. Authors have identified a set of safety features which are needed to be incorporated in advanced reactors to achieve this goal. These features enabling prevention, termination, mitigation and containment of radioactivity for beyond design basis accidents arising from extreme natural events are essential for achieving the goal of elimination of emergency planning in public domain. Inherent safety characteristics, passive and engineered safety features to achieve these functions are discussed in this paper. Present trends and future developments in this direction are also described briefly.

As part of the pyrometallurgical treatment of used Experimental Breeder Reactor-II fuel, a metal waste stream is generated consisting primarily of cladding hulls laden with fission products noble to the electrorefining process. Consolidation by melting at high temperature [1873 K (1600 °C)] has been developed to sequester the noble metal fission products (Zr, Mo, Tc, Ru, Rh, Te, and Pd) which remain in the iron-based cladding hulls. Zirconium from the uranium fuel alloy (U-10Zr) is also deposited on the hulls and forms Fe-Zr intermetallics which incorporate the noble metals as well as residual actinides during processing. Hence, Zr has been chosen as the primary indicator for consistency of the metal waste. Recently, the first production-scale metal waste ingot was generated and sampled to monitor Zr content for Fe-Zr intermetallic phase formation and validation of processing conditions. Chemical assay of the metal waste ingot revealed a homogeneous distribution of the noble metal fission products as well as the primary fuel constituents U and Zr. Microstructural characterization of the ingot confirmed the immobilization of the noble metals in the Fe-Zr intermetallic phase.

A modification of the “rate theory” approach to point defect balance modeling is considered in which the production term is written to explicitly capture the discrete occurrence of distinct displacement damage cascades. The constant production rate density is replaced with a pulsed source that operates for very short periods at randomly selected points in time and space to produce new defects. In addition, dislocation sinks are modeled as discrete regions with perfect crystal in between instead of being uniformly distributed in space. Simulations reveal that under conditions of high sink strength, fast diffusion, and lower production rate (cascade frequency) defect populations liberated in any given cascade can be completely eliminated by absorption and recombination well before any new defects are introduced into the same region of space. Populations from distinct cascades may not have the opportunity to intermingle and overlap with each other to approach the bulk average values predicted by standard theory driven by a constant, average production term. Due to the large difference between vacancy and interstitial diffusivities, absorption of defects at microstructural sinks can occur in rapid pulses of interstitials followed by a much delayed influx of vacancies over a longer period. This is in stark contrast to the typical picture of a reasonably constant, perhaps slightly biased flow of one species of defect over the other. Expansion of the model to two spatial dimensions allowed for more explicit treatment of dislocation microstructure through informed dislocation arrangement and the use of proper boundary conditions at the edge of the dislocation core.

A very high-temperature reactor (VHTR) has been studied among generation IV nuclear power plants owing to its many advantages such as high-electric efficiency and massive hydrogen production. The material used for the heat exchanger should sustain structural integrity for its life even though the material is exposed to a harsh environment at 1223 K (950 °C) in an impure helium coolant. Therefore, an enhancement of the material performance at high temperature gives a margin in determining the operating temperature and life time. This work is an effort to find an optimum combination of alloying elements and processing parameters to improve the material performance. The tensile property and microstructure for nickel-based alloys fabricated in a laboratory were evaluated as a function of the heat treatment, cold working, and grain boundary strengthener using a tension test at 1223 K (950 °C), scanning electron microscopy, and transmission electron microscopy. Elongation to rupture was increased by additional heat treatment and cold working, followed by additional heat treatment in the temperature range from 1293 K to 1383 K (1020 °C to 1110 °C) implying that the intergranular carbide contributes to grain boundary strengthening. The temperature at which the grain boundary is improved by carbide decoration was higher for a cold-worked specimen, which was described by the difference in carbide stability and carbide formation kinetics between no cold-worked and cold-worked specimens. Zr and Hf played a scavenging effect of harmful elements causing an increase in ductility.