Warm Pre-Stress Effect Measured at Irradiated RPV Weld Material

2005 ◽  
Author(s):  
Elisabeth Keim ◽  
Reinhard Langer ◽  
Hilmar Schnabel ◽  
Reinhard Bartsch
Keyword(s):  
Fracture Toughness ◽  
Power Plants ◽  
Large Scale ◽  
Load Capacity ◽  
Specimen Thickness ◽  
Test Machine ◽  
Stress Effect ◽  
Load Path ◽  
Pressurized Water ◽  
Opening Load

The recently initiated German project CARISMA (Crack Initiation and Arrest of Irradiated Steel Materials) will create a data base on pre-irradiated original materials of the four generations of German nuclear pressurized water reactors, which allows the examination of the consequences if the Master Curve instead of the RTNDT concept is applied. Several original materials of the four generations of German nuclear power plants (typical for KWO, KKS - Biblis A, Biblis B, KKU - KKG, KWG, KKP2, KBR - KKE, KK12, GKN2) will be investigated. They have been irradiated in six large scale irradiation capsules in a German research reactor (the VAK plant) at corresponding plant conditions. The capsules contain regular tensile and Charpy impact specimens as well as Pellini and fracture toughness wedge opening load specimens up to a specimen thickness of 100 mm. The first fracture toughness tests have been performed on a weld metal NiCrMo1 UP(mod.)/LW320, LW340 (1. generation, lower bound of the weld materials)—with a fluence Φ = 2,12E19 cm−2 (E > 1 MeV). This weld has a Cu-content of 0.22 wgt.% and it was therefore supposed to show a large transition temperature shift. Some fracture toughness tests in the irradiated material condition were already available and during this project four 100 mm thick wedge opening load (WOL) specimens were tested. At one of the specimens brittle failure could not be achieved during the test, because the load capacity of the test machine was exceeded. Therefore the specimen was loaded by a load-unload-cool-fracture load path to demonstrate the warm pre-stress effect of this highly irradiated specimen. At the final fracture of the specimen at a lower temperature, the failure load was significantly higher than the original one (factor 3 higher), which clearly indicates that the benefit of warm pre-stressing will not be eroded with irradiation.

The Fracture Toughness Properties of China Manufactured Reactor Pressure Vessel Steels in Transition Temperature Range

2018 ◽  
Author(s):  
Kai Sun ◽  
Xiaoyong Wu ◽  
Guoyun Li ◽  
Bang Wen
Keyword(s):  
Fracture Toughness ◽  
Transition Temperature ◽  
Pressure Vessel ◽  
Power Plants ◽  
Reactor Pressure Vessel ◽  
Pressurized Water ◽  
Integrity Assessment ◽  
Temperature Range ◽  
Pressure Vessel Steels ◽  
Reactor Pressure

Over the past decade, many generation III pressurized water reactor power plants have been under construction in China. Most reactor pressure vessel steels for these plants construction are homemade. Historically, Charpy V-notch specimens are predominantly used to monitor the toughness of RPV steels. However, fracture toughness provides the quantitative predictions of the critical crack size and the allowable stress in structural integrity assessment. This paper evaluates the fracture toughness properties of China manufactured RPV steels directly measured in transition temperature range by using master curve method. Some specimens were irradiated in the High Flux Engineering Test Reactor. The influences of loading rate, test temperature, specimen configuration and neutron irradiation on T0 were also investigated. The experimental results show that China manufactured RPV steels exhibit good fracture toughness properties.

Inherent Margin in the Brittle Failure Assessment for RPV

2008 ◽  
Author(s):  
Dieter Siegele ◽  
Igor Varfolomeyev ◽  
Gerhard Nagel
Keyword(s):  
Fracture Toughness ◽  
Brittle Fracture ◽  
State Of The Art ◽  
Crack Arrest ◽  
Pressure Vessels ◽  
Assessment Procedure ◽  
Load Path ◽  
Pressurized Water ◽  
Load Paths ◽  
Water Reactors

The brittle fracture assessment of the reactor pressure vessels (RPV) of the EON Kernkraft (EKK) pressurized water reactors has been updated to the state of the art. The reference temperatures of the RPV for the design fluence of 5E18 n/cm2 are at or below 0°C. The weld joint between vessel flange and cylinder as well as the hot and the cold leg nozzle corners proved to be the prominent and covering situations for the RPV. The fracture mechanics results for these configurations for operational and loss of coolant transients (LOCA) were produced rerunning the assessment procedure established for the licensing of the RPV and additionally with the application of state of the art procedure. Big margin inherent to the older procedure was disclosed with the more realistic but still conservative input. Most of the margin resulted from the application of the fracture toughness based reference temperature RTTo in place of RTNDT, from the constraint representative fracture toughness applied in the nozzle corner situation and from taking into account the results of the non destructive evaluation (NDE) during the manufacture and the in-service inspection (ISI) with defect postulates of allowable size. The results show the load paths with large distance to the fracture toughness curve, in the upper shelf temperature region of fracture toughness and/or with negligible values far below the lower shelf, both demonstrating an excessive inherent safety of the older procedure. In addition, for the LOCA, a multi barrier concept is applied. Besides the flawless state of the vessel and the preclusion of initiation from postulated flaws, with the arrest of postulated crack initiation and break preclusion for crack extension from postulated rising load after crack arrest two additional barriers against failure were proven. For all load cases the relevant load path temperatures proved to be in the upper shelf regime of fracture toughness, where ductile fracture is the failure mechanism and brittle fracture is precluded.

Integrity Assessment of a German PWR RPV Considering Loss of Constraint

2010 ◽  
Author(s):  
Dieter Siegele ◽  
Igor Varfolomeev ◽  
Jo¨rg Hohe ◽  
Volker Hardenacke ◽  
Gerhard Nagel
Keyword(s):  
Fracture Toughness ◽  
Brittle Failure ◽  
Power Plants ◽  
Pressure Vessels ◽  
Significant Loss ◽  
Flange Joint ◽  
Local Approach ◽  
Pressurized Water ◽  
Integrity Assessment ◽  
Failure Assessment

The brittle failure assessment for five pressurized water reactor pressure vessels (RPV) of German nuclear power plants (NPP) has been revisited according to an advanced state of the art. Besides of recent innovation in fracture toughness curves and reference temperatures being already in the codes, also the effect of loss of constraint had to be considered when fracture toughness values determined from deep cracks in fracture toughness specimen with high multi-axial state of stress were transferred to crack configurations in the component. Thus, the available concepts were compared for their fitness for purpose, i.e. for their ability to give a fracture toughness representative to the crack configuration or flaw postulate in the component. The results of the investigation reveal a significant lower constraint in the component resulting in increased fracture toughness and showing that the brittle failure assessment based on the high constraint fracture toughness from the standard specimens can be very conservative. For consideration of the constraint conditions in the component besides the deterministic T-stress parameter also probabilistic local approach concepts based on the Weibull model were used which have the advantage of considering both the local stress strain field and the material volume under high loading. The loss of constraint was determined for several flaw postulates in the leading situations on the RPV being the coolant inlet nozzle corner and the flange joint. A considerable loss of constraint was demonstrated for flaw postulates with broken clad in the ferritic nozzle corner. Also in the flange joint the loss of constraint is evident for small flaws. In addition, for flaw postulates under the intact cladding the loss of constraint is remarkably higher than with broken postulated cladding. In summary, with the measured material toughness and the significant loss of constraint a considerable inherent margin against brittle failure can be demonstrated for the investigated load cases.

scholarly journals Capital Cost Estimation for Advanced Nuclear Power Plants

2021 ◽  
Author(s):  
William Robb Stewart ◽  
Koroush Shirvan
Keyword(s):  
Cost Estimation ◽  
Nuclear Power ◽  
Power Plants ◽  
Large Scale ◽  
Capital Cost ◽  
Reactor Power ◽  
Passive Safety ◽  
Cost Overrun ◽  
Plant Design ◽  
Pressurized Water

The first-of-a-kind (FOAK) nuclear plants built in the last 20 years are on average 2X over budget and schedule. One of the nuclear industry’s proposed remedies is the small modular reactor (SMR). SMR designs leverage five factors to be more economically competitive than large size reactors: 1) multiple units at a site; 2) increased factory production and learning; 3) reduced construction schedules; 4) plant design simplification and 5) unit timing. There are currently no studies that quantitatively account for these factors and compare different SMR architectures with Gen III+ large plants. This work presents a nuclear plant cost estimating methodology using a detailed bottoms-up approach for over 200 structures, systems, and components. The results compare relative cost for two large pressurized water reactors, one with active safety and one with passive safety, to two SMR designs, one with multiple reactor power modules and one with a single reactor module. Passive safety systems showed noticeable savings at both the large scale and small modular scale reactors. The power uprating of a SMR by 20% resulted in ~15% savings in the overnight capital cost. Overall, if built by an inexperience vendor and work force, the two SMRs’ overnight cost were higher than large reactors since significant on-site labor still remains while losing economy of scale. However, the single-unit SMR had significantly less total person-hours of onsite labor, and if built by an experienced vendor and workforce, its overnight construction cost showed potential to be competitive and avoid cost-overrun risks associated with megaprojects.

Waste minimization program in Shuaiba Industrial Area

1999 ◽  
Vol 39 (10-11) ◽  
pp. 289-295
Author(s):  
Saleh Al-Muzaini
Keyword(s):  
Solid Waste ◽  
Power Plants ◽  
Large Scale ◽  
Industrial Area ◽  
Waste Minimization ◽  
Regulatory Body ◽  
Eastern Sector ◽  
Western Sector ◽  
Petroleum Companies ◽  
The Cost

The Shuaiba Industrial Area (SIA) is located about 50 km south of Kuwait City. It accommodates most of the large-scale industries in Kuwait. The total area of the SIA (both eastern and western sectors) is about 22.98 million m2. Fifteen plants are located in the eastern sector and 23 in the western sector, including two petrochemical companies, three refineries, two power plants, a melamine company, an industrial gas corporation, a paper products company and, two steam electricity generating stations, in addition to several other industries. Therefore, only 30 percent of the land in the SIA's eastern sector and 70 percent of land in the SIA's western sector is available for future expansion. Presently, industries in the SIA generate approximately 204,000 t of solid waste. With future development in the industries in the SIA, the estimated quantities will reach 240,000 t. The Shuaiba Area Authority (SAA), a governmental regulatory body responsible for planning and development in the SIA, has recognized the problem of solid waste and has developed an industrial waste minimization program. This program would help to reduce the quantity of waste generated within the SIA and thereby reduce the cost of waste management. This paper presents a description of the waste minimization program and how it is to be implemented by major petroleum companies. The protocols employed in the waste minimization program are detailed.

Efficient Schedule of Energy-Constrained UAV Using Crowdsourced Buses in Last-Mile Parcel Delivery

2021 ◽  
Vol 5 (1) ◽  
pp. 1-23
Author(s):  
Yan Pan ◽  
Shining Li ◽  
Qianwu Chen ◽  
Nan Zhang ◽  
Tao Cheng ◽  
...  
Keyword(s):  
Traffic Congestion ◽  
Large Scale ◽  
Load Capacity ◽  
Scheduling Algorithm ◽  
Cost Effective ◽  
Promising Alternative ◽  
Logistics Industry ◽  
Last Mile ◽  
Delivery Scheduling ◽  
Schedule Approach

Stimulated by the dramatical service demand in the logistics industry, logistics trucks employed in last-mile parcel delivery bring critical public concerns, such as heavy cost burden, traffic congestion and air pollution. Unmanned Aerial Vehicles (UAVs) are a promising alternative tool in last-mile delivery, which is however limited by insufficient flight range and load capacity. This paper presents an innovative energy-limited logistics UAV schedule approach using crowdsourced buses. Specifically, when one UAV delivers a parcel, it first lands on a crowdsourced social bus to parcel destination, gets recharged by the wireless recharger deployed on the bus, and then flies from the bus to the parcel destination. This novel approach not only increases the delivery range and load capacity of battery-limited UAVs, but is also much more cost-effective and environment-friendly than traditional methods. New challenges therefore emerge as the buses with spatiotemporal mobility become the bottleneck during delivery. By landing on buses, an Energy-Neutral Flight Principle and a delivery scheduling algorithm are proposed for the UAVs. Using the Energy-Neutral Flight Principle, each UAV can plan a flying path without depleting energy given buses with uncertain velocities. Besides, the delivery scheduling algorithm optimizes the delivery time and number of delivered parcels given warehouse location, logistics UAVs, parcel locations and buses. Comprehensive evaluations using a large-scale bus dataset demonstrate the superiority of the innovative logistics UAV schedule approach.

scholarly journals Estimating CO2 Emissions from Large Scale Coal-Fired Power Plants Using OCO-2 Observations and Emission Inventories

Atmosphere ◽  
2021 ◽  
Vol 12 (7) ◽  
pp. 811
Author(s):  
Yaqin Hu ◽  
Yusheng Shi
Keyword(s):  
Power Plant ◽  
Co2 Emissions ◽  
Atmospheric Carbon Dioxide ◽  
Power Plants ◽  
Large Scale ◽  
Global Climate ◽  
Gaussian Model ◽  
Point Sources ◽  
Emission Inventories ◽  
Bottom Up

The concentration of atmospheric carbon dioxide (CO2) has increased rapidly worldwide, aggravating the global greenhouse effect, and coal-fired power plants are one of the biggest contributors of greenhouse gas emissions in China. However, efficient methods that can quantify CO2 emissions from individual coal-fired power plants with high accuracy are needed. In this study, we estimated the CO2 emissions of large-scale coal-fired power plants using Orbiting Carbon Observatory-2 (OCO-2) satellite data based on remote sensing inversions and bottom-up methods. First, we mapped the distribution of coal-fired power plants, displaying the total installed capacity, and identified two appropriate targets, the Waigaoqiao and Qinbei power plants in Shanghai and Henan, respectively. Then, an improved Gaussian plume model method was applied for CO2 emission estimations, with input parameters including the geographic coordinates of point sources, wind vectors from the atmospheric reanalysis of the global climate, and OCO-2 observations. The application of the Gaussian model was improved by using wind data with higher temporal and spatial resolutions, employing the physically based unit conversion method, and interpolating OCO-2 observations into different resolutions. Consequently, CO2 emissions were estimated to be 23.06 ± 2.82 (95% CI) Mt/yr using the Gaussian model and 16.28 Mt/yr using the bottom-up method for the Waigaoqiao Power Plant, and 14.58 ± 3.37 (95% CI) and 14.08 Mt/yr for the Qinbei Power Plant, respectively. These estimates were compared with three standard databases for validation: the Carbon Monitoring for Action database, the China coal-fired Power Plant Emissions Database, and the Carbon Brief database. The comparison found that previous emission inventories spanning different time frames might have overestimated the CO2 emissions of one of two Chinese power plants on the two days that the measurements were made. Our study contributes to quantifying CO2 emissions from point sources and helps in advancing satellite-based monitoring techniques of emission sources in the future; this helps in reducing errors due to human intervention in bottom-up statistical methods.

scholarly journals On the Root Causes of the Fukushima Daiichi Disaster from the Perspective of High Complexity and Tight Coupling in Large-Scale Systems

Symmetry ◽  
2021 ◽  
Vol 13 (3) ◽  
pp. 414
Author(s):  
Atsuo Murata ◽  
Waldemar Karwowski
Keyword(s):  
Nuclear Power ◽  
Power Plants ◽  
Large Scale ◽  
High Complexity ◽  
Tight Coupling ◽  
Large Scale Systems ◽  
Safety Issues ◽  
Loss Of Coolant ◽  
Station Blackout ◽  
Fukushima Daiichi

This study explores the root causes of the Fukushima Daiichi disaster and discusses how the complexity and tight coupling in large-scale systems should be reduced under emergencies such as station blackout (SBO) to prevent future disasters. First, on the basis of a summary of the published literature on the Fukushima Daiichi disaster, we found that the direct causes (i.e., malfunctions and problems) included overlooking the loss of coolant and the nuclear reactor’s failure to cool down. Second, we verified that two characteristics proposed in “normal accident” theory—high complexity and tight coupling—underlay each of the direct causes. These two characteristics were found to have made emergency management more challenging. We discuss how such disasters in large-scale systems with high complexity and tight coupling could be prevented through an organizational and managerial approach that can remove asymmetry of authority and information and foster a climate of openly discussing critical safety issues in nuclear power plants.

scholarly journals A Combined Approach for Model-Based PV Power Plant Failure Detection and Diagnostic

Energies ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1261
Author(s):  
Christopher Gradwohl ◽  
Vesna Dimitrievska ◽  
Federico Pittino ◽  
Wolfgang Muehleisen ◽  
András Montvay ◽  
...  
Keyword(s):  
Power Plants ◽  
Large Scale ◽  
Failure Detection ◽  
Energy Yield ◽  
Combined Approach ◽  
Levelized Cost Of Electricity ◽  
Term Operation ◽  
Model Based

Photovoltaic (PV) technology allows large-scale investments in a renewable power-generating system at a competitive levelized cost of electricity (LCOE) and with a low environmental impact. Large-scale PV installations operate in a highly competitive market environment where even small performance losses have a high impact on profit margins. Therefore, operation at maximum performance is the key for long-term profitability. This can be achieved by advanced performance monitoring and instant or gradual failure detection methodologies. We present in this paper a combined approach on model-based fault detection by means of physical and statistical models and failure diagnosis based on physics of failure. Both approaches contribute to optimized PV plant operation and maintenance based on typically available supervisory control and data acquisition (SCADA) data. The failure detection and diagnosis capabilities were demonstrated in a case study based on six years of SCADA data from a PV plant in Slovenia. In this case study, underperforming values of the inverters of the PV plant were reliably detected and possible root causes were identified. Our work has led us to conclude that the combined approach can contribute to an efficient and long-term operation of photovoltaic power plants with a maximum energy yield and can be applied to the monitoring of photovoltaic plants.

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