Flow reversal power limit for the HFBR

The High Flux Beam Reactor (HFBR) is a pressurized heavy water moderated and cooled research reactor that began operation at 40 MW. The reactor was subsequently upgraded to 60 MW and operated at that level for several years. The reactor undergoes a buoyancy-driven reversal of flow in the reactor core following certain postulated accidents. Questions which were raised about the afterheat removal capability during the flow reversal transition led to a reactor shutdown and subsequent resumption of operation at a reduced power of 30 MW. An experimental and analytical program to address these questions is described in this report. The experiments were single channel flow reversal tests under a range of conditions. The analytical phase involved simulations of the tests to benchmark the physical models and development of a criterion for dryout. The criterion is then used in simulations of reactor accidents to determine a safe operating power level. It is concluded that the limit on the HFBR operating power with respect to the issue of flow reversal is in excess of 60 MW. Direct use of the experimental results and an understanding of the governing phenomenology supports this conclusion

Low activity blankets for experimental power reactors

Results of current studies aimed at the development of low activity blankets for Tokamak experimental power reactors are presented. First wall loadings in the range of 0.5 to 1.0 MW(th)/m$sup 2$ have been assumed. Blanket designs are developed for both circular plasma reactors (R = 6.25m, a = 2.1m) and non-circular plasma reactors (R = 4.0m, a = 1.0m, b = 3.0m). For each of these two reactor choices, two blanket options are described. 1) In the first option, the blanket is thick graphite block structure (approximately 50cm thickness) with SAP coolant tubes carrying helium imbedded deep within the graphite to minimize radiation damage. The neutron and gamma energy deposited in the graphite is radiated along internal slots to the coolant tubes where approximately 80 percent of the fusion energy is carried off by He at 380$sup 0$C. The remaining 20 percent of the fusion energy is removed by a separate He stream at a slightly lower temperature. The maximum graphite surface temperature is relatively low (approximately 1700$sup 0$C at 1 MW(th)/m2). 2) In the second blanket option, the blanket is composed of aluminum modules. The aluminum shell (5000 series alloy) is maintained at a low temperature (approximately 200$sup 0$C) by a water coolant stream. Approximately 40 percent of the fusion energy is removed in this circuit. The remaining 60 percent of the fusion energy is deposited in a thermally insulated hot interior (SiC and B$sub 4$C) where it is transferred to a separate He coolant, with exit temperature of 700$sup 0$C. (auth

Design of the CART data system for the US Department of Energy's ARM Program

The Department of Energy (DOE) has initiated a major atmospheric research effort to reduce the uncertainties found in general circulation and other models due to the effects of clouds and radiation. The objective of the Atmospheric Radiation Measurement Program (ARM) is to provide an experimental testbed for the study of important atmospheric effects, particularly cloud and radiative processes, and testing parameterizations of the processes for use in atmospheric models. This experimental testbed, known as the Clouds and Radiation Testbed (CART), will include a complex data system, the CART Data Environment (CDE). The major functions of the CDE will be to: acquire environments from instruments and external data sources; perform quality assessments of the data streams; create data streams of known quality to be used as model input compared to model output; execute the models and capture their predictions; and make data streams associated with model tests available to ARM investigators in near real-time. The CDE will also be expected to capture ancillary information ( meta-data'') associated with the data streams, provide data management facilities for design of ARM experiments, and provide for archival data storage. The first section of this paper presents background information on CART. Next the process for the functional design of the system is described, the functional requirements summarized, and the conceptual architecture of the CDE is presented. Finally, the status of the CDE design activities is summarized, and major technical challenges are discussed

Electrically-induced stresses and deflection in multiple plates

Thermohydraulic tests are being planned at the High Flux Beam Reactor of Brookhaven National Laboratory, in which direct electrical heating of metal plates will simulate decay heating in parallel plate-type fuel elements. The required currents are high if plates are made of metal with a low electrical resistance, such as aluminum. These high currents will induce either attractive or repulsive forces between adjacent current-carrying plates. Such forces, if strong enough, will cause the plates to deflect and so change the geometry of the coolant channel between the plates. Since this is undesirable, an analysis has been made to evaluate the magnitude of the deflection and related stresses. In contrast to earlier publications in which either a concentrated or a uniform load was assumed, in this paper an exact force distribution on the plate is analytically solved and then used for stress and deflection calculations, assuming each plate to be a simply supported beam. Results indicate that due to superposition of the induced forces between plates in a multiple-and-parallel plate array, the maximum deflection and bending stress occur at the midpoint of the outermost plate. The maximum shear stress, which is inversely proportional to plate thickness, occurs at both ends of the outermost plate

Analysis of flow reversal test

A series of tests has been conducted to measure the dryout power associated with a flow transient whereby the coolant in a heated channel undergoes a change in flow direction. An analysis of the test was made with the aid of a system code, RELAP5. A dryout criterion was developed in terms of a time-averaged void fraction calculated by RELAP5 for the heated channel. The dryout criterion was also compared with several CHF correlations developed for the channel geometry

Electrification versus hydrogen for UK road freight: Conclusions from a systems analysis of transport energy transitions

Collectively the UK investment in transport decarbonisation is greater than £27B from government for incentivising zero-emission vehicles as part of an urgent response to decarbonise the transport sector. The investments made must facilitate a transition to a long-term solution. The success relies on coordinating and testing the evolution of both the energy and transport systems, this avoids the risk of unforeseen consequences in both systems and therefore de-risks investment Here, we present a semiquantitative energy and transport system analysis for UK road freight focusing on two primary investment areas for nation-wide decarbonisation, namely electrification and hydrogen propulsion. Our study assembles and assesses the potential roadblocks of these energy systems into a concise record and considers the infrastructure in relation to all other components within the energy system. It highlights that for system-wide success and resilience, a hydrogen system must overcome hydrogen production and distribution barriers, whereas an electric system needs to optimise storage solutions and charging facilities. Without cohesive, co-evolving energy networks, the planning and operational modelling of transport decarbonisation may fall short of meaningful real-world results. A developed understanding of the dependencies between the energy and transport systems is a necessary step in the development of meaningful operational transport models that could de-risk investment in both the energy and transport systems

Triathlon in Alphen a/d Rijn August 1991. Study on health effects and water quality

This report describes an epidemiological study on health effects of participation in a triathlon and their relation to water quality. illness was reported more frequently by participants than by controls. Gastro-instestinal symptoms and head-aches were predominant ; respiratory, skin and mucosal symptoms were also reported. The risk of acquiring highly credible gastro-enteritis was significantly higher for participants (28/439) than for controls (1/217) ; odds ratio 14,7. Prolonged exposure to water of the Zegerplas tended to result in a higher risk of acquiring gastro-enteritis. These findings, together with the absence of an effect of other possible sources, led to the conclusion that the water of the Zegerplas was the most likely source of infection. Electron microscopic examination of faeces showed the presence of viruses in 6/12 participants. Because of the low number of samples and the absence of control samples, no definitive conclusions can be drawn, but viral aetiology of the gastro-intestinal symptoms is likely. Microbiological investigation showed that the faecal pollution of the Zegerplas at the time of the triathlon was considerable (thermotolerant coliforms 750/100mL ; faecal streptococci 20/100mL (geometric mean counts)) ; the source of pollution was the effluent discharge of the waste water treatment plant.GHIGGD Rijnstree