Measurement of Steam Generator or Reactor Vessel Moisture Carryover Using a Non-Radioactive Chemical Tracer

2009 ◽  
Author(s):  
Robert Fournier ◽  
Michael Thibodeau ◽  
Charles T. French
Keyword(s):  
Moisture Content ◽  
Steam Generator ◽  
Power Plants ◽  
Power Level ◽  
Thermal Power ◽  
Reactor Vessel ◽  
Saturated Steam ◽  
Power Calculation ◽  
Pressurized Water ◽  
Chemical Tracer

All nuclear power plants are licensed to operate at a specific thermal power. Verification of this power level is done by measuring the change in the enthalpy of the feedwater times the mass flow of the feedwater through each steam generator for pressurized water reactor or through the reactor vessel for boiling water reactors. When performing this measurement, it is necessary to determine the enthalpy of the steam exiting each steam generator or the reactor vessel. Since the exit enthalpy of most units is saturated steam, the state of the steam must be defined in terms of the enthalpy of dry stream minus the fraction of moisture being carried over with the steam times the heat of vaporization. The quality of the steam can be measured using a throttling calorimeter, but a much more accurate means of measurement is with the use of a chemical tracer salt that is only carried over with the main steam by droplets of water. Thus, the fraction of moisture in the steam can be defined as the ratio of concentration of the tracer in the steam divided by concentration of the tracer in the riser of the generator or reactor vessel. If the moisture content of the steam is not measured, one must assume that it is zero, which is conservative, since it provides an upper limit for the thermal power calculation. However, from an operational standpoint, if moisture carryover is present but is not accounted for, the thermal power of the unit will be below its licensed power level causing a loss in electrical output due both a lower thermal power and a reduction in turbine cycle efficiency. Moreover, if there is significant carryover, there is the potential for additional damage to the turbine blading and housing from the impingement of the water droplets. This paper describes how a chemical tracer can be used to measure the moisture content of the steam, considerations for the injection and sample points, plant alignment recommendations and the support required from a utility, when performing this test. The paper will also discuss the potential for long term degradation, the effects of extended power uprates on carryover and the limitations of chemistry guidelines.

Design Issues and Considerations During Reactor Vessel Head Replacement, Steam Generator Replacement, and Steam Generator Snubber Elimination at Nuclear Power Plants

2004 ◽  
Author(s):  
Dilip Bhavnani ◽  
James Annett
Keyword(s):  
Steam Generator ◽  
Nuclear Power ◽  
Power Plants ◽  
Supply System ◽  
Reactor Vessel ◽  
Original Design ◽  
Pressurized Water ◽  
Class 1 ◽  
Current Design ◽  
Successful Design

One of the key maintenance activities in a nuclear power plant is the replacement of major components in the Nuclear Steam Supply System. In order to achieve significant operational improvements, the replacement components are not an exact replacement of the existing components. The replacement of components in the nuclear steam supply system in many Pressurized Water Reactor plants may include steam generators, replacement of reactor vessel heads with integrated head assemblies, and elimination of steam generator snubbers. The replacement components may not be supplied and/or designed by the original supplier. The changes in the components have to be compared to a plant’s current design and licensing bases and regulatory commitments. The qualification of these components involves non-linear, Nuclear Class 1 analyses, where portions of the configuration and analyses are proprietary, and there is a coupling of the response between the containment structure and the components. Ultimately, the qualification of the reactor coolant system and reactor vessel internals must be demonstrated, not just the qualification of the replacement components. A key element for the successful completion of these component replacements is the method by which the design and licensing bases is maintained and the work of the various groups involved in the design coordinated. This paper outlines how in a typical two unit PWR plant, major component replacements can impact original design bases and issues that should be considered in creating successful design and configuration documents. Design interface issues, configuration combinations, and coordination requirements are identified.

scholarly journals Wood Chip Drying through the Using of a Mobile Rotary Dryer

Energies ◽  
2019 ◽  
Vol 12 (9) ◽  
pp. 1590 ◽  
Author(s):  
Angelo Del Giudice ◽  
Andrea Acampora ◽  
Enrico Santangelo ◽  
Luigi Pari ◽  
Simone Bergonzoli ◽  
...  
Keyword(s):  
Moisture Content ◽  
Power Plants ◽  
Black Locust ◽  
Thermal Power ◽  
Initial Moisture Content ◽  
Wood Chip ◽  
Wood Chips ◽  
Cocurrent Flow ◽  
Drying Process ◽  
Rotary Dryer

Drying is a critical point for the exploitation of biomass for energy production. High moisture content negatively affects the efficiency of power generation in combustion and gasification systems. Different types of dryers are available however; it is known that rotary dryers have low cost of maintenance and consume 15% and 30% less in terms of specific energy. The study analyzed the drying process of woody residues using a new prototype of mobile rotary dryer cocurrent flow. Woodchip of poplar (Populus spp.), black locust (Robinia pseudoacacia L.), and grapevine (Vitis vinifera L.) pruning were dried in a rotary drier. The drying cycle lasted 8 h for poplar, 6 h for black locust, and 6 h for pruning of grapevine. The initial biomass had a moisture content of around 50% for the poplar and around 30% for grapevine and black locust. The study showed that some characteristics of the biomass (e.g., initial moisture content, particle size distribution, bulk density) influence the technical parameters (i.e., airflow temperature, rate, and speed) of the drying process and, hence, the energy demand. At the end of the drying process, 17% of water was removed for poplar wood chips and 31% for grapevine and black locust wood chips. To achieve this, result the three-biomass required 1.61 (poplar), 0.86 (grapevine), and 1.12 MJ kgdry solids−1 (black locust), with an efficiency of thermal drying (η) respectively of 37%, 12%, and 27%. In the future, the results obtained suggest an increase in the efficiency of the thermal insulation of the mobile dryer, and the application of the mobile dryer in a small farm, for the recovery of exhaust gases from thermal power plants.

scholarly journals Reactor Vessel Internals Segmentation Experience using Mechanical Cutting Tools

2013 ◽  
Vol 10 (2) ◽  
pp. 6-10 ◽  
Author(s):  
Petr Pospíšil
Keyword(s):  
Nuclear Power ◽  
Power Plants ◽  
Cutting Tools ◽  
Reactor Vessel ◽  
Boiling Water Reactors ◽  
Abrasive Waterjet ◽  
Pressurized Water ◽  
Water Reactors ◽  
Mechanical Cutting ◽  
Reactor Internals

Abstract Some commercial nuclear power plants have been permanently shut down to date and decommissioned using dismantling methods. Other operating plants have decided to undergo an upgrade process that includes replacement of reactor internals. In both cases, there is a need to perform a segmentation of the reactor vessel internals with proven methods for long term waste disposal. Westinghouse has developed several concepts to dismantle reactor internals based on safe and reliable techniques, including plasma arc cutting (PAC), abrasive waterjet cutting (AWJC), metal disintegration machining (MDM), or mechanical cutting. Mechanical cutting has been used by Westinghouse since 1999 for both Pressurized Water Reactors (PWR’s) and Boiling Water Reactors (BWR’s) and its process has been continuously improved over the years. The complexity of the work requires well designed and reliable tools. Different band saws, disc saws, tube cutters and shearing tools have been developed to cut the reactor internals. All of those equipments are hydraulically driven which is very suitable for submerged applications. Westinghouse experience in mechanical cutting has demonstrated that it is an excellent technique for segmentation of internals. In summary, the purpose of this paper will be to provide an overview of the Westinghouse mechanical segmentation process, based on actual experience from the work that has been completed to date.

Steam Generator Replacement Project at TVA’s Sequoyah Unit 1 Nuclear Power Plant

2004 ◽  
Author(s):  
Myron R. Anderson
Keyword(s):  
Steam Generator ◽  
Nuclear Power ◽  
Power Plants ◽  
Reactor Power ◽  
Original Design ◽  
Pressurized Water ◽  
Repair Work ◽  
Building Roof ◽  
Tennessee Valley ◽  
Generator Replacement

Pressurized Water Reactor Power Plants have at times required that large components be replaced (steam generators weighing 750,000 lbs) which have necessitated performing first time modifications to the plant that were unintended during the original design. The steam generator replacement project at Tennessee Valley Authority (TVA’s) Sequoyah Nuclear Power Station necessitated (1) two large temporary openings (21’×45’) in the plant’s Shield Building roof (2’ thick concrete) by hydro-blasting to allow the removal of the old generators and installation of the new, (2) removal and repair of the concrete steam generator enclosure roofs (20’ diameter, 3’ thick) which were removed by wire saw cutting and (3) the seismic qualification of; the design and construction of an extensive ring foundation for; the use of one of the world largest cranes to remove these components through the roof. This removal and replacement process had to be performed in an expeditious manner to minimize the amount of time the plant is shutdown so the plant could return to providing power to the grid. This paper will address some of the many technical and construction considerations required to perform this demolition and repair work safely, efficiently and in a short as possible duration.

Parametric Study on Determining Optimal Eddy Current Testing Method for Inspection of Steam Generator Tubes in SMART Plant

2010 ◽  
Author(s):  
Dae-Kwang Kim ◽  
Sung-Jin Han ◽  
Hak-Joon Kim ◽  
Sung-Jin Song ◽  
Yun-hang Choung
Keyword(s):  
Steam Generator ◽  
Eddy Current ◽  
Nuclear Power ◽  
Power Plants ◽  
Eddy Current Testing ◽  
Pressurized Water Reactor ◽  
Pressurized Water ◽  
Current Testing ◽  
Current Test ◽  
Testing Condition

The SMART (System-integrated Modular Advanced ReacTor) is small sized integral type pressurized water reactor designed by KAERI (Korea Atomic Energy Research Institute), Korea. But, shape of steam generator (SG) in SMART plant differs from those in operated nuclear power plants (NPPs). Especially, SG tubes in SAMRT plant is helical type with around 600 mm of innermost diameter and thickness of 2.5 mm which is thicker than general NPPs one. For providing integrity of SG tube in SMART plant, new types of ECT method are needed because eddy current testing (ECT) is one of widely adopted method for inspection of SG tubes in NPPs. Therefore, in this study, we investigate optimal conditions or parameters for detecting and evaluating of flaws in the SG tubes in SMART plant by simulation of ECT signals with various testing condition or parameter such as frequency, coil gap and etc. From the simulated ECT signals optimal eddy current test condition or parameters are proposed.

scholarly journals THERMOACOUSTIC ENGINE AS A LOW-POWER COGENERATION ENERGY SOURCE FOR AUTONOMOUS CONSUMER POWER SUPPLY

2021 ◽  
Vol 18 (2) ◽  
pp. 60-66
Author(s):  
A.D. Mekhtiyev ◽  
Keyword(s):  
Power Plant ◽  
Low Power ◽  
Power Supply ◽  
Thermal Power Plant ◽  
Power Plants ◽  
Thermal Power ◽  
Saturated Steam ◽  
Working Fluid ◽  
Thermoacoustic Engine ◽  
Basic Principles

The article deals with the issue of using a thermoacoustic engine as a low-power cogeneration source of energy for autonomous consumer power supply capable of operating on various types of fuel and wastes subject to combustion. The analysis of the world achievements in this field of energy has been carried out. A number of advantages make it very promising for developing energy sources capable of complex production of electrical and thermal energy with a greater efficiency than that of present day thermal power plants. The proposed scheme of a thermal power plant is based on the principle of a Stirling engine, but it uses the most efficient and promising thermoacoustic converter of heat into mechanical vibrations, which are then converted into electric current. The article contains a mathematical apparatus that explains the basic principles of the developed thermoacoustic engine. To determine the main parameters of the thermoacoustic engine, the methods of computer modeling in the DeltaEC environment have been used. A layout diagram of the laboratory sample of a thermal power plant has been proposed and the description of its design has been given. It has been proposed to use dry saturated steam as the working fluid, which makes it possible to increase the generated power of the thermoacoustic engine.

scholarly journals Investigation of the saturated steam sampling method influence on the sample representativeness in chemical control systems at thermal power plants

2021 ◽  
Vol 2088 (1) ◽  
pp. 012052
Author(s):  
O V Yegoshina ◽  
S K Zvonareva
Keyword(s):  
High Pressure ◽  
Chemical Control ◽  
Power Plants ◽  
Thermal Power ◽  
Steam Line ◽  
Saturated Steam ◽  
Thermal Power Plants ◽  
Sample Representativeness ◽  
Main Steam Line ◽  
Main Steam

Abstract The most important requirement for sampling is the sample representativeness, which is achieved by the design and location choice of sample nozzle, as well as the speed mode and the presence of sharp pressure drops in the saturated steam flow. The Ansys CFX software package simulates the sampling processes saturated steam in power units with low, medium and high pressure boilers which are used on operating thermal power plants. The saturated steam was sampled from low-pressure boiler by a single-strip probe with a Venturi nozzle, from the medium-pressure boiler was sampled by tapping a pipe at 90 to the main steam line, and the steam of the high – pressure boiler was sampled by a wellhead probe. In three sampling cases it is found that of saturated steam, the flow in the sample nozzle loses speed and decreases to values unacceptable for the selection of a representative sample-below tear rate of the moisture film from the surface. It is confirmed that in the industrial sampling conditions, the condition of speeds equality in the main steam line and in the sample nozzle is not met, which leads to a violation of the sample representativeness. The paper studies the change in the composition of the sampled saturated vapor sample after the film formation on the sample’s nozzle wall in relation to power units with ammonia dosing. It was found that the sample received by the chemical control analyzers is depleted due to the formation of a film and the ferrum and ammonia concentration in moisture droplets on the inner surface of the sampling line.

scholarly journals Exergy efficiency analysis of lignite-fired steam generator

2018 ◽  
Vol 22 (5) ◽  
pp. 2087-2101
Author(s):  
Drenusha Krasniqi-Alidema ◽  
Risto Filkoski ◽  
Marigona Krasniqi
Keyword(s):  
Steam Generator ◽  
Flue Gas ◽  
Power Plants ◽  
Thermal Power ◽  
Calorific Value ◽  
Feed Water ◽  
Low Grade ◽  
Gas Temperature ◽  
Steam Generators ◽  
Energy And Exergy

The operation of steam generators and thermal power plants is commonly evaluated on a basis of energy analysis. However, the real useful energy loss cannot be completely justified only by the First law of thermodynamics, since it does not differentiate between the quality and amount of energy. The present work aims to give a contribution towards identification of the sources and magnitude of thermodynamic inefficiencies in utility steam generators. The work deals with a parallel analysis of the energy and exergy balances of a coal-fired steam generator that belongs to a 315 MWe power generation unit. The steam generator is de-signed for operation on low grade coal - lignite with net calorific value 6280 to 9211 kJ/kg, in a cycle at 545?C/177.4 bar, with feed water temperature 251?C, combustion air preheated to 272?C and outlet flue gas temperature 160?C. Since the largest exergy dissipation in the thermal power plant cycle occurs in the steam generator, energy, and exergy balances of the furnace and heat exchanging surfaces are established in order to identify the main sources of inefficiency. On a basis of the analysis, optimization of the combustion and heat transfer processes can be achieved through a set of measures, including retrofitting option of lignite pre-drying with flue gas and air preheating with dryer exhaust gases.

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