scholarly journals A pre-test analysis of ATLAS SBO with RCP seal leakage using MARS code

2021 ◽  
Vol 7 (4) ◽  
pp. 26-33
Author(s):  
Quang Huy Pham ◽  
Sang Yong Lee ◽  
Seung Jong Oh
Keyword(s):  
Coping Strategies ◽  
Nuclear Power ◽  
Power Plants ◽  
Nuclear Power Plants ◽  
Cooling System ◽  
Water Injection ◽  
Cooling Water ◽  
Feed Water ◽  
Test Loop ◽  
Station Blackout

The accident in Fukushima Daiichi nuclear power plants shows the important of developing coping strategies for extended station blackout (SBO) scenarios of the nuclear power plants (NPPs). Many NPPs in United State of America are applying FLEX approach as main coping strategies for extended station blackout (SBO) scenarios. In FLEX strategies, outside water injection to reactor cooling system (RCS) and steam generators (SGs) is considered as an effective method to remove residual heat and maintain the inventory of the systems during the accident. This study presents a pretest calculation using MARS code for the Advanced Thermal-hydraulic Test Loop for Accident Simulation (ATLAS) SBO experiment with RCP seal leakage scenario. In the calculation, the turbinedriven auxiliary feed water pumps (TDAFPs) are firstly used after SBO initiation. Then, the outside cooling water injection method is used for long term cooling. In order to minimize operator actions and satisfy requirements of APR1400 emergency operation procedure (EOP), the SGs Atmospheric Dump Valve (ADV) opening ratio, auxiliary feed water (AFW) and outside cooling water injection flow rates were investigated to have suitable values. The analysis results would be useful for performing the experiment to verify the APR 1400 extended SBO optimum mitigation strategy using outside cooling water injection.

Treatment of Wastewater to Meet the Requirements for Cooling Water Systems in Jordan’s Nuclear Plants

2013 ◽  
Vol 34 (2) ◽  
pp. 253-267 ◽  
Author(s):  
Aiman Eid Al-Rawajfeh ◽  
Kamal Araj
Keyword(s):  
Nuclear Power ◽  
Power Plants ◽  
Municipal Wastewater ◽  
Cooling System ◽  
Wastewater Reuse ◽  
Cooling Water ◽  
Hard Water ◽  
Chemical Cleaning ◽  
Makeup Water ◽  
Promising Alternative

Scaling and corrosion associated with the use of natural hard water in cooling towers during recirculation pose great problems from both economical and technical points of view, such as decreased system efficiency and increased frequency of chemical cleaning. Treated municipal wastewater (MWW) is a promising alternative to freshwater as power plant cooling system makeup water, especially in arid regions. In this work, hybrid systems of salt precipitation (SP), nanofiltration (NF) and reverse osmosis (RO) were investigated, as potential pretreatment processes for wastewater reuse as cooling water in the planned Jordan nuclear power plants. The As-Samra wastewater was used to calculate the potential of carbonate and sulfate scale formation. The results were compared to scale potentials from Palo Verde wastewater. Four cases were investigated; SP, NF, SP-RO and NF-RO. The SP pretreatment cases showed the highest monovalent to divalent ratio because of a high removal of Ca and Mg and addition of Na from the chemicals of the SP step. The NF pretreatment cases, showed the lowest calcium sulfate scale potential and this potential decreases with the % pretreatment. The scale amount increases very slightly with concentration times when the SP and NF product is desalinated by RO step.

scholarly journals Extended Station Blackout Coping Capabilities of APR1400

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
Sang-Won Lee ◽  
Tae Hyub Hong ◽  
Mi-Ro Seo ◽  
Young-Seung Lee ◽  
Hyeong-Taek Kim
Keyword(s):  
Nuclear Power ◽  
Power Plants ◽  
Water Injection ◽  
Severe Accident ◽  
Injection Strategy ◽  
Safety Improvement ◽  
External Injection ◽  
Station Blackout ◽  
The Government ◽  
External Water

The Fukushima Dai-ichi nuclear power plant accident shows that an extreme natural disaster can prevent the proper restoration of electric power for several days, so-called extended SBO. In Korea, the government and industry performed comprehensive special safety inspections on all domestic nuclear power plants against beyond design bases external events. One of the safety improvement action items related to the extended SBO is installation of external water injection provision and equipment to RCS and SG. In this paper, the extended SBO coping capability of APR1400 is examined using MAAP4 to assess the effectiveness of the external water injection strategy. Results show that an external injection into SG is applicable to mitigate an extended SBO scenario. However, an external injection into RCS is only effective when RCS depressurization capacity is sufficiently provided in case of high pressure scenarios. Based on the above results, the technical basis of external injection strategy will be reflected on development of revised severe accident management guideline.

scholarly journals Ensembles of climate change models for risk assessment of nuclear power plants

2017 ◽  
Vol 232 (2) ◽  
pp. 185-200
Author(s):  
Matteo Vagnoli ◽  
Francesco Di Maio ◽  
Enrico Zio
Keyword(s):  
Climate Change ◽  
Risk Assessment ◽  
Nuclear Power ◽  
Power Plants ◽  
Nuclear Power Plants ◽  
Climate Models ◽  
Cooling System ◽  
Future Projections ◽  
Change Models ◽  
Temperature And Pressure

Climate change affects technical systems, structures and infrastructures, changing the environmental context for which systems, structures and infrastructure were originally designed. In order to prevent any risk growth beyond acceptable levels, the climate change effects must be accounted for into risk assessment models. Climate models can provide future climate data, such as air temperature and pressure. However, the reliability of climate models is a major concern due to the uncertainty in the temperature and pressure future projections. In this work, we consider five climate change models (individually unable to accurately provide historical recorded temperatures and, thus, also future projections) and ensemble their projections for integration in a probabilistic safety assessment, conditional on climate projections. As case study, we consider the passive containment cooling system of two AP1000 nuclear power plants. Results provided by the different ensembles are compared. Finally, a risk-based classification approach is performed to identify critical future temperatures, which may lead to passive containment cooling system risks beyond acceptable levels.

scholarly journals The Problem of Biological Obstacles in the Operation of Nuclear Power Plants (Illustrated by the Operation of Zaporizhzhya NPP Techno-Ecosystem)

2019 ◽  
pp. 54-60
Author(s):  
O. Fedonenko ◽  
O. Marenkov ◽  
O. Petrovsky
Keyword(s):  
Nuclear Power ◽  
Power Plants ◽  
Nuclear Power Plants ◽  
Cooling Water ◽  
Water Reservoir ◽  
Trophic Levels ◽  
Hydraulic Structures ◽  
Cooling Pond ◽  
Biological Barriers ◽  
Mass Development

The article shows the research results on biological obstacles of the Zaporizhzhya NPP cooling pond, which may be harmful for the technological cycles of the plant or even cause emergency in the NPP. This problem is particular importance for cooling water reservoir of energy objects, since the increased temperature regime in such reservoirs creates favorable conditions for the mass development of certain types of hydrobionts, which hinder the operation of hydraulic structures. It was established that for the studied cooling water reservoir of Zaporizhzhya NPP all types of biological barriers that are found in technical reservoirs of nuclear power plants of Ukraine are characteristic. It has been established that all types of biological obstacles found in technical reservoirs of nuclear power plants of Ukraine are common for the researched reservoir. The most common are biological obstacles of bacterial, plant and animal origin. Plant biological obstacles are represented by the excessive growth of blue-green algae, which in the summer cause the "water blooming" of the cooling pond, and the filamentous algae that form thickets on the surfaces of concrete slabs and hydraulic structures. Animal biomarkers include the rapid spread of the mollusks of the Thiaridae family, which were accidentally inhabited into the water reservoir and caused massive fouling of the water development facilities of the NPP. One of the areas of biological control of biological barriers in a Zaporizhzhya NPP cooling water reservoir is ichthyomelioration – biomeliorative release the fish into the reservoir As fish occupy higher trophic levels in aquatic ecosystems, they accumulate organic matter from other trophic units and can inhibit the massive development of hydrobionts. The presented scientific results formed the basis of "Technological substantiation of the biological method of reducing the amount of phytoplankton and mollusks in the hydraulic engineering system of the ZNPP and conducting biomeliorative works using biomeliorative fish for the period2018-2022", the observance of which allows partial resolution of the problems of biological barriers caused by the mass development of certain species.

scholarly journals A Framework for Monitoring and Fault Diagnosis in Nuclear Power Plants Based on Signed Directed Graph Methods

2021 ◽  
Vol 9 ◽  
Author(s):  
Wu Guohua ◽  
Yuan Diping ◽  
Yin Jiyao ◽  
Xiao Yiqing ◽  
Ji Dongxu
Keyword(s):  
Directed Graph ◽  
Process Monitoring ◽  
Nuclear Power ◽  
Power Plants ◽  
Nuclear Power Plants ◽  
High Standard ◽  
Fault Detection And Diagnosis ◽  
Radioactive Material ◽  
Feed Water ◽  
Signed Directed Graph

When nuclear power plants (NPPs) are in a state of failure, they may release radioactive material into the environment. The safety of NPPs must thus be maintained at a high standard. Online monitoring and fault detection and diagnosis (FDD) are important in helping NPP operators understand the state of the system and provide online guidance in a timely manner. Here, to mitigate the shortcomings of process monitoring in NPPs, five-level threshold, qualitative trend analysis (QTA), and signed directed graph (SDG) inference are combined to improve the veracity and sensitivity of process monitoring and FDD. First, a three-level threshold is used for process monitoring to ensure the accuracy of an alarm signal, and candidate faults are determined based on SDG backward inference from the alarm parameters. According to the candidate faults, SDG forward inference is applied to obtain candidate parameters. Second, a five-level threshold and QTA are combined to determine the qualitative trend of candidate parameters to be utilized for FDD. Finally, real faults are identified by SDG forward inference on the basis of alarm parameters and the qualitative trend of candidate parameters. To verify the validity of the method, we have conducted simulation experiments, which comprise loss of coolant accident, steam generator tube rupture, loss of feed water, main steam line break, and station black-out. This case study shows that the proposed method is superior to the conventional SDG method and can diagnose faults more quickly and accurately.

Analysis on Critical Factors of Marine Organism Impacts on Water Intake Safety at Nuclear Power Plants

2020 ◽  
Vol 6 (4) ◽  
Author(s):  
Xiaocheng Fu ◽  
Fenglei Du ◽  
Xiang Pu ◽  
Xuan Wang ◽  
Fengze Han
Keyword(s):  
Water Intake ◽  
Nuclear Power ◽  
Power Plants ◽  
Nuclear Power Plants ◽  
Marine Organism ◽  
Cooling Water ◽  
Marine Organisms ◽  
Reproductive Capacity ◽  
Driving Mechanism ◽  
Hydrodynamic Conditions

Abstract The safety of cooling water intake in nuclear power plants (NPPs) has gradually become an important factor affecting the safety of NPPs. Marine flora and fauna outbreaks are one of the main types affecting the safety of cooling water intake in NPPs, and the driving mechanism is more complicated and difficult to predict. This paper mainly analyzes the main types and typical cases of marine organisms that cause cooling water intake blockage in NPPs, and analyzes the key factors such as hydrodynamic conditions, timing of organism's outbreak, characteristics of species, and design of the screen systems. The results show that strong hydrodynamic conditions or strong tides caused by special meteorological conditions are important factors. Considering the time of organism's outbreak, spring and summer (May–August, may change slightly according to different latitude) is key period because of the reproduction and growth of most marine organisms, according to the growth law of marine organisms. In terms of biological characteristics, it is sensible to focus on those species with fast growth, strong reproductive capacity, short life cycle, weak swimming ability, and cluster distribution. As to the design of screen systems, the blockage mainly occurs in revolving filter screens. The grid spacing of normal mechanical grille is too large to block the small marine organisms. It is necessary to add trash interception nets according to the type and size of the marine species. Finally, a case is used to confirm the factors needed to pay more attention.

Thermal Effects of Nuclear Power Stations

1974 ◽  
Vol 9 (1) ◽  
pp. 188-195
Author(s):  
G. Bethlendy
Keyword(s):  
Thermal Effects ◽  
Nuclear Power ◽  
Power Plants ◽  
Nuclear Power Plants ◽  
Sea Water ◽  
Waste Heat ◽  
Thermal Power ◽  
Cooling Water ◽  
District Heating ◽  
Before And After

Abstract Even with the latest technology, more than 60% of the heat produced by any thermal engine - whether the fuel is coal, oil, gas or uranium - must be taken back into the environment by cooling water or exhaust gas. For economical reasons, the usual means of disposing of the “waste” heat from a thermal-power plant is to pump river, lake or sea water through the parts of the plant concerned. Nuclear power plants use their heat as efficiently as older thermal plants, 30–33%. Modern thermal plants, however work with as high as 40% efficiency, and release about 10–13% of their total fuel-heat into the air through the stack. As a result of the combination of all these factors, nuclear power plants release about 68–70% of total input heat into the cooling water. In practice this means that the plant must be able to draw upon a source of cooling water which is large enough, which flows quickly or is cold enough not to be seriously effected by the return of warmed-up water from the power station. Where this is not possible, it may be necessary to build relatively expensive cooling ponds and/or towers so that the heat is also released to the air rather than only to a local body of water. The thermal effects could be detrimental or beneficial depending on the utilization of the water body. At the present time the utilities are aware of these problems and very extensive aquatic studies are being made before and after the construction of the plants. Some beneficial uses of waste heat are being sought via research and demonstration projects (e.g. in agriculture, aquaculture, district heating, etc.).

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