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Sandia National Laboratories is investigating advanced Brayton cycles using supercritical working fluids for application to a variety of heat sources, including geothermal, solar, fossil, and nuclear power. This work is centered on the supercritical CO 2 (S-CO 2 ) power conversion cycle, which has the potential for high efficiency in the temperature range of interest for these heat sources and is very compact-a feature likely to reduce capital costs. One promising approach is the use of CO 2 -based supercritical fluid mixtures.

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The Very High Temperature Reactor (VHTR) is the leading candidate for the reactor component of the Next Generation Nuclear Plant (NGNP). This is because the VHTR demonstrates great potential in improving safety characteristics, being economically competitive, providing a high degree of proliferation resistance, and producing high outlet temperatures for efficient electricity generation and/or other high temperature applications, most notably hydrogen production. In addition, different fuel types can be utilized by VHTRs, depending on operational goals. In this case, the recovery and utilization of the valuable energy left in LWR fuel in order to create ultra long life single batch cores by taking advantage of the properties of TRU fuels. This paper documents the initial process in the study of TRU fueled VHTRs, which concentrates on the verification and validation of the developed whole-core 3D VHTR models. Many of the codes used for VHTR analysis were developed without a full appreciation of the importance of randomness in particle distribution. With this in mind, the SCALE code system was chosen as the computational tool for the study. It provides the opportunity of utilizing SCALE versions 5.0 and 5.1, making it possible to compare and analyze different techniques accounting for the double heterogeneity effects associated with VHTRs. Startup physics results for Japan’s High Temperature Test Reactor (HTTR) were used for experiment-to-code benchmarking. MCNP calculations were employed for code-to-code benchmarking. Results and analysis are included in this paper.

Damage to the electric power system was confined to the distribution system, in particular to electric power poles that were downed by the tsunami. The power generation plants and substations were over 1 km inland and escaped damage. The telecommunication system performed well, and the postdisaster response was reasonably efficient, but inundation caused the shutdown of equipment. The major Tamil Nadu port, the Port of Chennai, performed well, and its seawalls reduced the tsunami impact. However, all the fish auction stations were damaged, thus affecting many villagers’ livelihoods. The transportation system in the southern coast suffered heavy damage, and much of the infrastructure along the east coast was damaged. Most municipal water storage tanks remained intact. However, seawater contaminated wells and arable land, and the long-term environmental and ecological effects of this are unknown.