Typical Power Plant Research Articles

Evaluation of core-wide fuel pin burst during LOCA in APR1400

Core-wide fuel pin burst fractions in a typical APR1400 nuclear power plant during a loss-of-coolant accident (LOCA) are assessed. For the assessment, fuel pin based power distribution at an initial and an equilibrium core of APR1400 is analyzed. Fuel cladding burst probability curves represented as a local peak power are established up to 70 MWd/kgU fuel burnup. Main uncertainty parameters for pin burst related to the fuel and thermal–hydraulic (TH) performance are identified. Monte Carlo method is used for combining uncertainties. FRAPTRAN and MARS-KS integrated code is employed in this study. In the APR1400 core, power ratio of the fuel pin between a target fuel pin and surrounding ones is ranging 0.899–1.131 within ±2 standard deviation. This power ratio has induced about 1.0–2.1 kW/ft burst power change. In the fuel uncertainties, fuel thermal conductivity, fission gas release (FGR), cladding yield stress shows a relatively strong influence on the burst power change. Groeneveld critical heat flux (CHF) and Chen transition boiling correlation shows a strong influence among TH uncertainty parameters. Established cladding burst probability curves reveal that fresh fuel has a relatively low burst power. But, it increases rather steeply until burnup reaches 5–10 MWd/kgU. Then, the burst power is reduced slowly until the lowest power is attained at the fuel burnup of 70 MWd/kgU. Evaluation of fuel pin burst fraction shows that the most susceptible fuel burnup for the core-wide pin burst is fresh one. Beginning-of-cycle (BOC) at the initial core seems to be the most vulnerable during a reactor life time.

Source profile and health risk assessment of PM2.5 from coal-fired power plants in Fuxin, China.

In order to improve and establish the localized source profile of PM2.5 in Fuxin, the ashes under dust catcher were collected from four typical coal-fired power plants in Fuxin and twenty-eight components were measured. The source profile of PM2.5 in the soot of the four coal-fired power plants was established. SO42- was the most abundant component in the PM2.5 of the soot of the four coal-fired power plants, followed by Ca2+ and organic carbon (OC). The content of element components in PM2.5 smoke ranges from 5.06 to 10.97%, the content of ionic components ranges from 36.53 to 48.59%, and the total carbon content ranges from 9.43 to 11.36%. The divergence coefficient of PM2.5 source profile in Fuxin coal burning smoke is mostly similar to that of Fushun, whereas the divergence coefficient of Colorado reaches 0.65, indicating that Fuxin coal burning power plant smoke has no similarity to Colorado. The order of the geological accumulation index of Ni, Cu, V, Mn, and Cr was Cr (4.58) > Mn (4.42) > V (4.38) > Cu (4.09) > Ni (4.06), showing a heavy pollution level. The health risk assessment model recommended by the USEPA was used to assess the health risk of heavy metals in soot of coal-fired power plants, and the non-carcinogenic risk values of As for children and adults were 45.7 and 4.90, respectively. The carcinogenic risk values of Cr for adults and children were the highest, with values of 3.66 × 10-5 and 2.06 × 10-5, respectively, followed by As.

Assessing the factors affecting the water chemistry parameters in the auxiliary water system of a nuclear power plant

Cooling towers are used as a final heat sink which cools the reactor auxiliary systems and transfers the heat energy to the atmosphere. The reliability endowed upon the cooling tower operation in a nuclear power plant is considerably high when compared to other power plants since the proper functioning of auxiliary systems is crucial for the decay heat removal from the core. Hence, appropriate chemistry control is mandatory in the operation of cooling towers for corrosion control, scale prevention, and control of biological growth. The operating data and water chemistry parameters like conductivity, turbidity, free residual chlorine, pH, cycles of concentration, chlorides, hardness, and alkalinity are analyzed for a typical nuclear power plant. The effect of the individual water quality parameter is correlated by the Pearson matrix to find its influence on the system water chemistry parameter. It is observed that the build-up of chloride ions in the cooling water is the major contributing factor for the cooling tower feed and bleed operations. The aspect of reducing the feed and bleed operation is analyzed, and suitable modifications are suggested to reduce water consumption.

Environmental sustainability of electricity generation: Case study of lignite combustion

AbstractLignite is one of the most used Turkey's energy sources for electricity generation as there are large lignite reserves in the country. Lignite power plants are one of Turkey's main sources of GHG emissions. Therefore, understanding the environmental sustainability of generating electricity from lignite burning is essential for reducing environmental impacts. This research aims to assess the life cycle environmental impacts from a typical Turkish lignite power plant. In this paper, a system of the electricity from the lignite power plant is presented which covers all the life cycle stages—starting from the lignite mining up to the delivery of electricity to the grid. For this work to generate 1 kWh of generated is defined as the functional unit. The principal conclusion, to be drawn from this LCA of lignite power in Turkey, is that the majority of the emissions mostly originate from lignite burning to and lignite mining stages. The global warming potential associated with electricity generation from lignite power is estimated at 1,290 g CO2 eq./kWh. The results obtained from this study provide a baseline for future scenarios to reduce the environmental impacts from the energy sector and to build a sustainable energy policy.

New procedure in solar system dynamic simulation, thermodynamic analysis, and multi-objective optimization of a post-combustion carbon dioxide capture coal-fired power plant

One of the most vital concerns in evaluating power generation systems is the comprehensive review of all useful indexes. In the vast range of researches regarding renewable energy systems, just the thermodynamic performance of a typical power plant is considered without solar system operating time management. Thus, in this paper, a novel approach, simultaneous dynamic simulation, and conventional thermodynamic analysis are used for the evaluation of a solar-assisted post-combustion CO2 capture, integrated into a coal-fired steam power plant as a case study. For the dynamic simulation of linear parabolic solar collector, the non-linear sliding mode control (SMC) approach, and for thermodynamic modeling, the prevalent technique (exergy analysis) is employed. The effects of thermodynamic parameters, on control system performance, are appeared during the investigation of the power generation system. Therefore, the control system characteristic (settling time), as well as exergetic parameters, are affected power generation system. Finally, to achieve an optimal configuration, multi-objective optimization (using PSO Algorithm Tool) is performed to make a power generation system with maximum agility (minimum settling time) and maximum efficiency. The promising two-objective optimization outcomes indicated 14.42 and 0.8% enhancement in settling time and exergetic efficiency, and the three-objective optimization revealed 14.4and 0.74% of improvement in settling time and thermal efficiency, respectively.

Subcritical Thermodynamic Cycles with Organic Medium and Isothermal Expansion

The efficiencies of the Organic Rankine Cycle (ORC) are not very high and only very seldom do they exceed 20%. The increase and optimization of initial parameters and certain modifications of the thermodynamic cycle make it possible to overcome these drawbacks. A new modified cycle has been described and analyzed in detail in the paper. Similarly to the Ericsson cycle for gas turbines, isothermal expansion in the turbine is suggested for the power plant with organic media. The new cycle and the typical ORC power plants have the same block diagram. The only difference is that expansion in the proposed cycle occurs not adiabatically but as an isothermal process. The thermodynamic calculations have been carried out for 11 various fluids and 4 different cycles. The obtained results have clearly shown that cycles with isothermal expansion (isothermal turbines) are characterized by remarkably higher efficiency than typical power plants with adiabatic turbines. The increase in efficiency varies from 6 to 12 percent points for cycles with saturated live vapor and from 4 to 7 percent points for cycles with superheated live vapor. The performed analyses have shown that it is possible to achieve a very high efficiency (over 45%) of organic cycle, which is a very competitive value. In such cases the proposed power plants can achieve an efficiency which is higher than that of modern steam turbine plants with supercritical parameters.

A wet-oxidation procedure of radioactive waste resin and waste concentrated liquid for 3H and 14C analysis

3H and 14C are two of the principal isotopes that should be considered in the characterization of radioactive waste from the nuclear power plant. In this paper, an analytical method of 3H and 14C in radioactive waste resin and waste concentrated liquid with a wet-oxidation process was presented, which allowed us to obtain both samples of 3H and 14C simultaneously. The chemical yields were optimized based on an orthogonal experiment with fresh resin. The analytical precision and the minimum detectable concentration (MDC) were provided. The chemical yield of 14C during the process for resin was about 96.8%. There was no significant difference between the analytical results of 14C with the wet-oxidation method and those with the oxygen-bomb combustion method. The MDCs of activity of 3H and 14C were 41 Bq/gww and 1.3 Bq/gww for waste resin, and 1.3 Bq/gww and 0.02 Bq/gww for waste concentrated liquid. The method was applied to determine the radioactivity concentrations in the waste from a typical nuclear power plant. It was shown that the averaged concentrations of 3H and 14C in the radioactive waste resin were 6134 Bq/gww and 2724 Bq/gww, and the averages in waste concentrated liquid were 104.7 Bq/gww and 27.3 Bq/gww, respectively.

Assessment of erosive wear of Pelton turbine injector: Nozzle and spear combination – A study of Chenani hydro-power plant

This study concerns with erosion of Pelton turbine injector i.e. (nozzle spear tribo pair) by sediment particles for a typical power plant located in Himalayan belt of Jammu and Kashmir in India. Erosion of hydro turbine/runner and its allied parts by the sediment particles suspended in the river water is one of the challenging problems (faced by maintenance personnel of hydro power plants). Injector assembly is subjected to severe erosion which renders it dysfunctional in relatively short span of time compared to other parts of the hydro power plant. A detailed study regarding erosion measurement has been conducted using novel technique of 3D optical scanning to assess material loss and identify type of wear for spear and nozzle combination used at Chenani power plant (5 units each with a 4.66 MW capacity). Hydro-abrasive wear was quantified on the basis of measurement of material removed by process of erosion on spear and nozzle (virgin parts) compared with weight of eroded parts (scanned). The erosion was found to be 3.71% and 5% on spear and nozzle respectively (of virgin volume).

ITER and the prospects for commercial fusion

The article “The challenge and promise of studying burning plasmas” by Richard Hawryluk and Hartmut Zohm (Physics Today, December 2019, page 34) contains a nice description of the physics involved in a burning plasma, which ITER, the international prototype fusion energy reactor, hopefully will produce. But ITER has had a troubled history. It was approved in 2005 for an estimated construction cost of approximately $5 billion, and deuterium–tritium experiments were expected to start in 2027. At present, the estimated cost has mushroomed to at least $25 billion in today’s dollars, and the start date for D–T experiments has slipped to 2035, with their completion expected around 2040.Realistically, though, ITER’s development path is unlikely to produce commercially competitive electricity in this century. According to the ITER website (www.iter.org), the reactor is designed to produce a 10-fold or better return on energy; that is, it should produce 500 MW of fusion power from its 50 MW of input heating power.Let’s assume that ITER achieves that return in about 2040. What would that mean for power production? Electricity is generally produced with an efficiency of around one-third, so as a power plant, ITER would generate approximately 170 MW of electricity (MWe). Yet it requires 50 MW of beams or microwaves to power it. But beams and microwaves are themselves produced at around one-third efficiency, meaning that they would require 150 MW of input power. That would leave virtually nothing for the power grid. A typical commercial power plant, by comparison, will generate about 3 GW of heat or 1 GW of electricity.For an ITER-like tokamak to be economically integrated into the grid, it would need its gain increased by at least a factor of three or four, its power increased by about a factor of six (to be on par with a typical commercial power plant), and both its size and cost reduced. Such a tokamak would deliver at least an order of magnitude more power to the wall and diverter plates. These requirements are not minor details! In all likelihood, reaching them would take decades and tens of billions of dollars, assuming they could be accomplished at all.© ITER ORGANIZATIONPPT|High-resolutionIn addition to these obvious difficulties, tokamaks are limited in pressure and density, as Hawryluk and Zohm point out. They are also limited in current. The limits are not controversial; they have been well established theoretically and confirmed experimentally. Yet the constraints they place on fusion power, which I have called “conservative design rules,”11. W. Manheimer, J. Fusion Energy 33, 199 (2014). https://doi.org/10.1007/s10894-014-9690-9,22. W. Manheimer, IEEE Access 6, 64954 (2018). https://doi.org/10.1109/ACCESS.2018.2877672 have been ignored by the tokamak community. Furthermore, conservative design rules have been in the literature for a decade. I have given many presentations on them at fusion labs and other places, and they have never been challenged, in print or in my seminars.As long as tokamaks remain so constrained, they are unlikely to generate economic power. However, there is an alternative. As a breeder of nuclear fuel, an ITER-like tokamak would work well. Most likely it could economically breed uranium-233 from thorium. It would be a much more prolific fuel producer than a fission breeder of equal power and could become the basis of a worldwide, sustainable, carbon-free, nuclear infrastructure. Furthermore, it might well be able to do so soon after midcentury, assuming ITER is successful.11. W. Manheimer, J. Fusion Energy 33, 199 (2014). https://doi.org/10.1007/s10894-014-9690-9,22. W. Manheimer, IEEE Access 6, 64954 (2018). https://doi.org/10.1109/ACCESS.2018.2877672ReferencesSection:ChooseTop of pageReferences <<CITING ARTICLES1. W. Manheimer, J. Fusion Energy 33, 199 (2014). https://doi.org/10.1007/s10894-014-9690-9, Google ScholarCrossref2. W. Manheimer, IEEE Access 6, 64954 (2018). https://doi.org/10.1109/ACCESS.2018.2877672, Google ScholarCrossref© 2020 American Institute of Physics.

Validation and sensitivity study of Micro-SWIFT SPRAY against wind tunnel experiments for air dispersion modeling with both heterogeneous topography and complex building layouts

Micro-SWIFT SPRAY (MSS) is a 3D Lagrangian particle dispersion model that maintains a good balance between accuracy and computational cost. However, its capabilities for air dispersion modeling in the presence of both complex topography and high building densities have not been investigated for nuclear emergency response. In this study, MSS is systematically evaluated against two wind tunnel experiments that simulate a typical Chinese nuclear power plant with the above two features. The MSS predictions are compared with both 2D horizontal and vertical measurements. Sensitivity studies are performed with respect to the particle number, the lower bound of the turbulence intensity, and the horizontal and vertical grid size. The results demonstrate that ground-level predictions of both wind and radionuclide concentrations are in satisfactory agreement with the measurements under optimized parameter values. The vertical predictions exhibit site-dependent accuracy, but generally consistent tendencies. The default lower bound of the turbulence intensity in MSS may be insufficient for reproducing the correct plume width observed in the wind tunnel experiments. An increased lower bound is suggested to solve this problem. In addition, artificially high concentrations may arise near steep slopes if large horizontal/vertical grid sizes are used. Suitable parameters for preventing this problem are also provided.

Measurement of Radon Concentration and Estimation of Its Emission of Coal-Fired Power Plants

In the experiment, RAD7 multi-functional electronic radon meter was used to measure the radon (222Rn) concentration at key points in the production process of three typical coal-fired power plants in Hunan, Hubei and Jiangxi provinces along the Yangtze river in China. The results show that after the combustion of raw coal, the radon was released, which caused radon concentration after the boiler’s gas system to be significantly higher than the air intake. Combined with the measurement and survey data, two different estimation methods of radon emission were established. First, based on radon concentration measured on site and the air volume at each inlet and outlet, the normalized radon emission of three coal fired power plants are calculated to be 102 GBq/GWa order of magnitude. The second one is using activity concentration of 226Ra in combination with actual coal use to calculate the emission, in this way, that typical value of normalize radon emission 151.3 GBq/GWa is obtained. This study provides data support for the construction of nuclear power plants in inland China.

50MW급 프란시스 수차발전기 운영시 발생되는 진동 특성에 관한 연구

Vibration characteristics of the rotating machinery has been usually managed to facilitate the deterioration of the equipment and to prevent accident in advance. In a hydropower turbine, pressure pulsation characteristics to induce vibration is investigated during the model testing with a small scale model turbine for various operating conditions, and a prototype turbine is constructed to operate stably on the site. However, the model test has limitation that can’t be considered together with the vibration characteristics of a generator itself and of civil engineering structures for the building that support a turbine and a generator. Therefore, field tests of vibration for a hydroelectric power plant are carried out periodically, thereby maintaining reliability for safe operation of power generation facilities. In the study, the vibration of a Francis type hydroelectric power plant operated over 30 years and overhauled a year and a half ago was measured and its characteristics has been investigated. Displacement and velocity sensors were installed at appropriate positions to measure the vibration of the rotating shaft and bearing support of a turbine and a generator, and the vibration characteristics of a typical hydroelectric power plant have confirmed by analyzing the measurement results. The vibration characteristics of rotating shaft and non-rotating parts of the hydroelectric turbine have been analyzed to confirm the degree of aging of the plant. Vibration in the power plant building depending on the operating conditions was also measured to be large enough to sense, and its frequency characteristics were analyzed.

Characteristics of condensable particulate matter before and after wet flue gas desulfurization and wet electrostatic precipitator from ultra-low emission coal-fired power plants in China

Total particulate matters emitted from coal-fired power plants generally include condensable particulate matter (CPM) and filterable particulate matter (FPM). Based on the on-site sampling of CPM, this study investigated four typical coal-fired power plants equipped with ultra-low emission facilities in north China. In order to clarify the characteristics of CPM before and after wet flue gas desulfurization (WFGD) and wet electrostatic precipitator (WESP), the mass concentrations, organic and inorganic compositions of the CPM were analyzed. Among the four test power plants, the emission concentrations of CPM were 2.20–7.33 mg/Nm3, accounting for 57.74–91.79% of PM2.5. The organic component accounted for 59.64% of the total mass concentration of CPM on average. Alkanes, esters and amides were the major organic components. And the water-soluble ions contributed significantly to the inorganic component of CPM. The proportion of SO42− was the highest, followed by Cl− and NO3−. In addition, this study found that the concentration of SO42− increased significantly while SO3 decreased from WESP inlet to outlet. It was indicated that ultrafine particles and soluble SO2 in flue gas could contribute to the formation of SO42− in CPM besides SO3. As an important part of CPM, further studies should be conducted on the factors affecting SO42−.

Development and application of MOQUICO code to study molten corium-concrete interaction

After the Fukushima nuclear accident, great attention is being paid to the late-phase behavior of the severe accident in the reactor, especially the molten corium-concrete interaction (MCCI). The MCCI process is very complex, involving physical and chemical reactions, heat and mass transfer processes. Many factors will affect the final result, with a high degree of uncertainty and there are still many unknowns based on current knowledge. In this paper, aimed at the MCCI phenomena in the containment cavity during a hypothetical accident in the nuclear power plant, an MCCI analysis code MOQUICO was developed by coupling the models of molten corium-concrete heat transfer, the concrete pyrolysis, and the corium cooling characteristics. The code MOQUICO was validated using the CCI-2, CCI-3 and SURC-2 tests with limestone-common sand concrete (LCS), siliceous concrete (SIL), and basaltic concrete (BAS), respectively. The simulant axial and radial ablation depths, upward heat flux and melt temperature agreed well with the experimental measurements. Afterwards, the code was used to simulate the typical PWR and BWR nuclear power plants. The ablation depth and gas production were analyzed for both simulations. Furthermore, the corium cooling was studied with eight different water injection moments for PWR and sensitivity analysis for decay heat and concrete type was conducted for BWR. The analysis proved that the developed code is capable of simulating MCCI and related phenomena of Light Water Reactor (LWR).

Non-Negligible Stack Emissions of Noncriteria Air Pollutants from Coal-Fired Power Plants in China: Condensable Particulate Matter and Sulfur Trioxide.

In this study, we investigated the emission characteristics of condensable particulate matter (CPM) and sulfur trioxide (SO3) simultaneously through ammonia-based/limestone-based wet flue gas desulfurization (WFGD) from four typical coal-fired power plants (CFPPs) by conducting field measurements. Stack emissions of filterable particulate matter (FPM) all meet the Chinese ultralow emission (ULE) standards, whereas CPM concentrations are prominent (even exceed 10 mg/Nm3 from two CFPPs). We find that NH4+ and Cl- increase markedly through the ammonia-based WFGD, and SO42- is generally the main ionic component, both in CPM and FPM. Notably, the occurrence of elemental Se in FPM and CPM is significantly affected by WFGD. Furthermore, the established chemical profiles in FPM and CPM show a distinct discrepancy. In CPM, the elemental S mainly exists as a sulfate, and the metallic elements of Na, K, Mg, and Ca mainly exist as ionic species. Our results may indicate that not all SO3 are included in CPM and they co-exist in stack plume. With the substantial reduction of sulfur dioxide (SO2), S distributed in SO3, CPM, and FPM becomes non-negligible. Finally, the emission factors of CPM and SO3 under typical ULE technical routes fall in the ranges of 74.33-167.83 and 48.76-86.30 g/(t of coal) accordingly.

Hollow fiber-based rapid temperature swing adsorption process for carbon capture from coal-fired power plants

Post-combustion carbon capture is one of the feasible methods to reduce emission of carbon dioxide (CO2) from coal-fired power plants. The biggest challenge in this technology is reduction of energy consumption. This work proposes a hollow fiber based rapid temperature swing adsorption (RTSA) method for capturing CO2 from typical coal-fired power plants. The proposed RTSA approach can shorten the operating time and using low-grade energy for regeneration of adsorption elements. In this study, the tank-in-series model is used to simulate the RTSA process including adsorption and desorption periods. A dual-column operating procedure is then used to treat the flue gas continuously from the coal-fired power plants. Main operating variables including inlet gas volume flow rate (0.1–0.2 m3/s), abandon time (0–10 s), desorption temperature (80–120 °C) on key performance factors such as discharge gas purity, capture ratio of CO2, and energy consumption per unit CO2, etc. are investigated for reducing the energy consumption. This study found that the inlet gas volume flow rate will significantly affect the capture ratio, where smaller gas volume flow rate would be beneficial to increase capture ratio. The abandon time obviously affects the purity of the captured CO2, where the longer abandon time leads to higher purity. Desorption temperature affects both the capture ratio and purity of captured CO2. The higher the desorption temperature, the greater the purity and capture ratio. For one typical basic unit with dual-column hollow fiber-based RTSA, the study found that when the inlet gas volume flow rate is 0.12 m3/s, the desorption waiting time is 7 s, and the desorption temperature is 120 °C, both the CO2 purity and capture ratio can exceed 90%. With considering the possibility of using steam in a low-pressure turbine as a source of heat required for Dual column vacuum RTSA (DC-vRTSA), the impact on the efficiency and stream data of typical coal-fired power plants are calculated. DC-vRTSA at 120 °C, 100 °C and 80 °C will reduce the efficiency of coal-fired power plants by 8.2%, 6%, and 3.4%, respectively.

A novel approach in exergy optimization of a WWER1000 nuclear power plant using whale optimization algorithm

Nowadays, the scarcity of energy resources and the intensive demand of energy leads the researchers and scientists to find the efficient ways to save the energy and decrease the exergy loss. In this study, a new exergy optimization framework for a typical WWER1000 nuclear power plant (Bushehr NPP) is suggested. It is aimed to optimize the total efficiency of the power plant by decrease the exergy destruction using the first and second laws of thermodynamics. First, the main parameters of Bushehr NPP (BNPP) stream lines and exergy destruction of components are determined and the accuracy of the model is assessed. According to the analysis result, the reactor pressure vessel is the most inefficient equipment in the NPP and the steam generators are the next. Then, the exergy optimization of the steam cycle is evaluated using WOA (Whale Optimization Algorithm). To investigate the performance of the WOA, four general fitness functions are determined and compared with GA and PSO and in next exergy optimization is compared. The total exergy destruction for Bushehr power plant is decreased from 1968.9MWth to 1914.7MWth and the overall thermal efficiency of the BNPP increases from 33.66% to 36.42% using WOA. The results demonstrate that the new algorithm WOA has a proper efficiency to implement in this optimization problem.

GAS TURBINE DIRECT EXHAUST GAS INTEGRATION IN PROCESS INDUSTRY – REVIEW OF APPLICATIONS AND OPPORTUNITIES FOR POLISH MARKET

The typical combined heat and power plants requires the introduction of additional heating medium. The alternative solution is the direct integration of the exhaust gases from heat engine. The high temperature, surplus oxygen and low water content of the GTs exhaust gases enabled the successful integration at industrial scale as: preheated combustion air for industrial furnaces, heat source for drying and for absorption chillers. The article comprises the reference list for direct exhaust gas integration of GTs produced by GE, the processes overview, GTs selection criteria, as well as the review of documented GTs applications in process industry focusing on technical and economic considerations. The described solutions allowed to reduce the specific energy consumption in the range from 7 to 20% or the costs of energy consumption by 15-30%. The overall efficiency of cogeneration plant above 90% was achieved. The preliminary assessment of potential applications for GTs produced by GE with TEG integration in Polish process industry is done.

2D PIV study of flow accelerated corrosion downstream a typical industrial gate valve

A critical degradation mechanism of piping systems in either nuclear power plant is Flow Accelerated Corrosion (FAC), which causes wall thinning of pipes and component shells from inside. The valves which are frequently used in power plant piping systems are mostly subjected to FAC. A Gate vale in the feed water piping system of a typical nuclear power plant that it’s downstream had been damaged due to the FAC was considered as a reference. In this study the effect of the mean flow velocity and the opening percentage of gate valve on the flow field downstream the valve was investigated by using 2D PIV. The locus where flow turbulences happen downstream the gate valve was determined by 2D PIV. It is found that there is a very good coincidence between the locus in which the maximum wall thinning measured by Ultrasonic Technique (UT) and that the flow turbulences happen downstream the gate valve determined by 2D PIV.It is observed that the locus of flow turbulences and intense velocity gradients is in the upper part of the pipe and over the domain of 0.2 <L/D < 2.4 along the pipe downstream the gate valves where the minimum wall thickness was measured by using UT. Flow turbulences and velocity gradients near the upper pipe wall result in higher wall shear stress and maximize the mass transfer from the pipe inner wall in turn result in wall thinning. The results of this paper can be useful for optimizing inspection plans in identifying and predicting the vulnerable FAC locations downstream the gate valves.

Thermodynamic Analysis of Advanced Gas Turbine Combined Cycle Integration with a High-Temperature Nuclear Reactor and Cogeneration Unit

The EU has implemented targets to achieve a 20% share of energy from renewable sources by 2020, and 32% by 2030. Additionally, in the EU countries by 2050, more than 80% of electrical energy should be generated using non-greenhouse gases emission technology. At the same time, energy cost remains a crucial economic issue. From a practical point of view, the most effective technology for energy conversion is based on a gas turbine combined cycle. This technology uses natural gas, crude oil or coal gasification product but in any case, generates a significant amount of toxic gases to the atmosphere. In this study, the environmentally friendly power generation system composed of a high-temperature nuclear reactor HTR integrated with gas turbine combined cycle technology and cogeneration unit is thermodynamically analysed. The proposed solution is one of the most efficient ways for energy conversion, and what is also important it can be easily integrated with HTR. The results of analysis show that it is possible to obtain for analysed cycles thermal efficiency higher than 50% which is not only much more than could be proposed by typical lignite or hard coal power plant but is also more than can be offered by nuclear technology.