The Influence of Intra-Day Non-Uniformity of Operation of Large Hydroelectric Powerplants on the Performance Stability of Water Intakes Located in Their Upper Pools

The creation of reservoirs in water streams leads to significant changes in the hydrological regime of water bodies: it allows smoothing the peaks of maximum water discharge during a flood period and regulating low-water flow. The creation of reservoirs with significant storage capacity makes it possible to solve a wide range of water-management problems, including the use of falling water energy for hydropower purposes, and maintenance of the uninterrupted water supply and navigation. Since constructed dams are usually operated by hydropower companies, the regulatory regime for the discharge of water into the lower pool is often determined by the daily electricity consumption regime. Intra-day variations in the volume of water discharges through hydroelectric power stations generate multidirectional streams in the upper pool, which can affect the operation of other water withdrawal systems. This paper considers the effect of intraday variations in water discharges into the lower pool on the dynamic and physical properties of the water mass in the region of the location of drinking water-intake heads of Perm city and the quality of the withdrawn water.

An In Vitro Nerve Agent Brain Poisoning Transwell Model for Convenient and Accurate Antidote and Nanomedicine Evaluation

Background: Nerve agents (NAs) can irreversibly inhibit acetylcholinesterase (AChE). An effective NA antidote should permeate the blood–brain barrier (BBB) to reactivate the inhibited AChE in brain. There is an urgent requirement for the large-scale evaluation and screening of antidotes. Existing methods for evaluating reactivators in vitro can only examine the reactivation effect of drugs and not brain-target properties. The current Transwell BBB model can only evaluate the drug penetration performance for crossing the barrier, but not the pharmacodynamics. Methods: Highly purified rat brain microvascular endothelial cells (RBMECs) from 2-week-old Sprague Dawley rats were inoculated into the upper chamber of Transwell plates to establish a BBB model. Three key parameters of AChE reactivation were determined by the Ellman method: the minimum detection limit of AChE, the effective dosage of NAs (70% enzyme inhibition rate), and the optimal dosage of reactivators. AChE and NAs were added to the lower pool of Transwell plates to simulate central poisoning, and antidotes of reactivators were added to the upper pool to simulate drug administration. The AChE activity of samples, collected from the lower pool, was measured. A liposomal nanomedicine loaded with the reactivator asoxime chloride (HI-6) was prepared using the extraction method and tested by the model.Results: The obtained RBMECs exhibited a typical monolayer “paving stone” morphology, and tight junctions were expressed among the RBMECs. The concentrations of AChE, sarin, and the reactivator were 0.07 mg/mL, 10–6 v/v, and 0.03 mg/mL, respectively. The reaction rate of the reactivators obtained from the model was significantly lower than that obtained from the non-model group. Furthermore, a nanomedicine loaded with HI-6 was synthesized. The final results and rules obtained from the model were in accordance with those evaluated in vivo. Conclusion: The therapeutic effect of antidotes can be rapidly and accurately evaluated using this model. In addition to small-molecule drugs, nanomedicines can also be evaluated by this method. A liposomal nanomedicine with a high reactivation rate against the nerve agent sarin was discovered.

Hydraulic studies of the throughput of the water intake structure of the Tuyamuyun hydroelectric complex

The article presents the results of experimental studies to determine the throughput of the right-bank water intake structure and bottom galleries, the hydraulic regime in the galleries, and the movement of bottom sediments in them. Based on the results of the studies, a series of curves were obtained for the dependence of the discharge on the water horizon in the upper pool and the value of the opening of the gate of the intake structure. Checking the work of the galleries together with the working water intake holes showed that there is no mutual influence of them on each other. The total consumption of water passed through the water intake and galleries is practically equal to the sum of the consumption of water passed through these structures separately. It was found that the main amount of sediment accumulated in the headwater will fall into the left gallery, while slightly less (about one third) will fall into the right span, and only a small remainder leaves through the weir, while the water flow rate was distributed as follows: Qgal = 1.65Qwater.

Fish passage system in an irrigation dam (Pilcomayo River basin ): when engineering designs do not match ecohydraulic criteria

The Route 28 Dam has the potential to block fish movements from La Estrella marsh to the Pilcomayo River. In addition, the many fish that concentrate immediately downstream of the dam may suffer high mortality when they are stranded during low water periods. The goals of this study are to determine if fish are able to pass the spillway and to assess if the design of the installed ladders (pool and weir type) effectively supports upstream migration of Prochilodus lineatus (sábalo). Results showed that only fish longer than 39 cm should be able to ascend the spillway chute, but when water levels on the spillway crest are over 0.4 m. Fish are also unable to jump from spillway toe to spillway crest because the downstream dissipation pool does not meet the minimum depth criterion for fish to accelerate to sufficient velocity. Fish ladders have insufficient number of pools and some pool dimensions and designs depart from accepted standard designs. Volumetric dissipation power in the upper pool of each fish ladder is too low for fish to rest. Also, attraction flows relative to total spillway discharge at the entrance to each fishway are insufficient. Fish passage failures of both the spillway and pool and weir systems in La Estrella marsh can be traced to the "salmon-centric" concept used by the designers. We conclude that the Route 28 Dam design including its fish passage systems, do not follow criteria to cope with the strong hydrological variability and bioecological characteristics of fish inhabiting pulsatile systems such as La Estrella marsh.

Utilization of the fish ladder at the Engenheiro Sergio Motta Dam, Brazil, by long distance migrating potamodromous species

Utilization of the fish ladder installed at the Engenheiro Sergio Motta Dam (also known as Porto Primavera) on the Paraná River, Southern Brazil, by long-distance migrating potamodromous species (sampling Protocol I), and ascending and descending movements (Protocol II) were evaluated. Three pools along the fish ladder (designated as lower, middle, and upper) were sampled monthly between December, 2004 and March, 2005 to determine the abundance of species in the ladder. The ascending and descending movements of the species in the ladder were also analyzed in the same period. In the samples for both protocols, 37 species representing 17 families and 5 orders (Characiformes, Siluriformes, Perciformes, Gymnotiformes, and Myliobatiformes) were recorded. Characiformes were represented by 21 species. Long- distance migratory species (11 species) predominated in the ladder (60% of the total number of individuals), with high abundance of Rhinelepis aspera (5645 individuals). For protocol I, mean abundance varied greatly among the months and pools, with lowest values in December and March for all pools, and highest in January for the lower pool due to high capture of R. aspera. Fish abundance declined from the lower to the upper pool, especially for R. aspera and Rhaphiodon vulpinus. For Protocol II, 17 species were recorded ascending the ladder, where Astyanax altiparanae and Leporinus friderici were the most abundant species (684 and 111 individuals, respectively). However, 18 species showed descending movements, with high captures of Metynnis maculatus and A. altiparanae (339 and 319 individuals, respectively). Twelve species (52%) moved in both directions, and among the seven migratory species sampled, four were recorded ascending and descending, and three species only ascending the ladder. The fish ladder appears to selectively favor species with high swimming capabilities. A discussion is presented on the requirements for future research on attraction to the fish ladder entrance, downstream movements, fish utilization of the ladder, and impacts on spawning and rearing habitat both upstream and downstream of the dam.

Investigation of the Fission Product Release From Molten Pools Under Oxidizing Conditions With the Code RELOS

With the purpose of modeling and calculating the core behavior during severe accidents in nuclear power plants system codes are under development worldwide. Modeling of radionuclide release and transport in the case of beyond design basis accidents is an integrated feature of the deterministic safety analysis of nuclear power plants. Following a hypothetical, uncontrolled temperature escalation in the core of light water reactors, significant parts of the core structures may degrade and melt down under formation of molten pools, leading to an accumulation of large amounts of radioactive materials. The possible release of radionuclides from the molten pool provides a potential contribution to the aerosol source term in the late phase of core degradation accidents. The relevance of the amount of transferred oxygen from the gas atmosphere into the molten pool on the specification of a radionuclide and its release depends strongly on the initial oxygen inventory. Particularly for a low oxygen potential in the melt as it is the case for stratification when a metallic phase forms the upper layer and, respectively, when the oxidation has proceeded so far so that zirconium was completely oxidized, a significant influence of atmospheric oxygen on the specification and the release of some radionuclides has to be anticipated. The code RELOS (Release of Low Volatile Fission Products from Molten Surfaces) is under development at the Department of Energy Systems and Energy Economics (formerly Department of Nuclear and New Energy Systems) of the Ruhr-University Bochum. It is based on a mechanistic model to describe the diffusive and convective transport of fission products from the surface of a molten pool into a cooler gas atmosphere. This paper presents the code RELOS, i. e. the features and abilities of the latest code version V2.3 and the new model improvements of V2.4 and the calculated results evaluating the implemented models which deal with the oxygen transfer from the liquid side of the phase boundary to the bulk of the melt by diffusion or by taking into account natural convection. Both models help to estimate the amount of oxygen entering into the liquid upper pool volume and being available for the oxidation reaction. For both models the metallic, the oxidic and a mixture phase can be taken into account when defining the composition of the upper pool volume. The influence of crust formation, i. e. the decrease of the liquid pool surface area is taken care of because it yields the relevant amount of fission products released into the atmosphere. The difference of the partial density between the gas side of the phase boundary and the bulk of the gas phase is the driving force of mass transport.