The Emergency Operating Strategy Study of Containment Spray Based on Radiation Level in LBLOCA Condition

2020 ◽  
Author(s):  
Ke Yi ◽  
Yuanye Li
Keyword(s):  
Nuclear Power ◽  
Power Plants ◽  
Large Space ◽  
Radiation Level ◽  
Term Operation ◽  
Operating Strategy ◽  
Pressure Peak ◽  
Containment Pressure ◽  
Emergency Operating ◽  
Containment Integrity

Abstract Large break LOCA will cause an increase in containment pressure, containment temperature and containment radiation level in nuclear power plants (NPPs). Containment spray is one of the most effective ways to mitigate the consequences of large break LOCA for these following facts, first, with the large space containment design, the containment spray can decrease the pressure peak and keeps containment integrity. Secondly, the containment spray can decrease the aerosol radiation level in containment, iodine in particular, and reduce the risks of radioactive release. Above all, the common strategy of containment spray in NPPs generally includes automatic actuation with high spray flow, in order to achieve good results in relevant accident conditions. Meanwhile, the strategy to shutdown containment spray should be considered as a result of these facts that, a weakened effect in decreasing radiation will occur and negative containment pressure may cause containment integrity damage in post-accident long term operation. For the above considerations, the emergency operating strategy of containment spray based on radiation level in large break LOCA condition and the relevant best estimate work are studied based on one NPP in this paper, in order to achieve reasonable results in containment spray operating strategy, which are able to optimize containment spray and reduce the bad consequences.

scholarly journals Demonstration of Fatigue for LTO License of NPP Borssele

2015 ◽  
Author(s):  
M. H. C. Hannink ◽  
F. J. Blom ◽  
P. W. B. Quist ◽  
A. E. de Jong ◽  
W. Besuijen
Keyword(s):  
Environmental Effects ◽  
Nuclear Power ◽  
Power Plants ◽  
Integrated Approach ◽  
Temperature Measurements ◽  
Fatigue Assessment ◽  
Term Operation ◽  
Load Monitoring ◽  
Number Of Cycles ◽  
Ageing Management

Long Term Operation (LTO) of nuclear power plants (NPPs) requires an ageing management review and a revalidation of Time Limited Ageing Analyses (TLAAs) of structures and components important for nuclear safety. An important ageing effect to manage is fatigue. Generally, the basis for this is formed by the fatigue analyses of the safety relevant components. In this paper, the methodology for the revalidation of fatigue TLAAs is demonstrated for LTO of NPP Borssele in the Netherlands. The LTO demonstration starts with a scoping survey to determine the components and locations having relevant fatigue loadings. The scope was defined by assessment against international practice and guidelines and engineering judgment. Next, a methodical review was performed of all existing fatigue TLAAs. This also includes the latest international developments regarding environmental effects. In order to reduce conservatism, a comparison was made between the number of cycles in the analyses and the number of cycles projected to the end of the intended LTO period. The projected number of cycles is based on transient counting. The loading conditions used in the analyses were assessed by means of temperature measurements by the fatigue monitoring system (FAMOS). As a result of the review, further fatigue assessment or assessment of environmental effects was necessary for certain locations. New analyses were performed using state-of-the-art calculation and assessment methods. The methodology is demonstrated by means of an example of the surge line. The model includes the piping, as well as the nozzles on the pressurizer and the main coolant line. The thermal loadings for the fatigue analysis are based on temperature measurements. Fatigue management of the NPP is ensured by means of the fatigue concept where load monitoring, transient counting and fatigue assessment are coupled through an integrated approach during the entire period of LTO.

Design, calibration, and application of an airborne gamma spectrometer system in Switzerland

Geophysics ◽  
1997 ◽  
Vol 62 (5) ◽  
pp. 1369-1378 ◽  
Author(s):  
Georg F. Schwarz ◽  
Ladislaus Rybach ◽  
Emile E. Klingelé
Keyword(s):  
Power Plant ◽  
Nuclear Power ◽  
Power Plants ◽  
Gamma Ray ◽  
Point Sources ◽  
Swiss Alps ◽  
Artificial Radioactivity ◽  
Radiation Level ◽  
Satellite Navigation System ◽  
Emergency Situations

Airborne radiometric surveys are finding increasingly wider applications in environmental mapping and monitoring. They are the most efficient tool to delimit surface contamination and to locate lost radioactive sources. To secure radiometric capability in survey and emergency situations, a new sensitive airborne system has been built that includes an airborne spectrometer with 256 channels and a sodium iodide detector with a total volume of 16.8 liters. A rack mounted PC with memory cards is used for data acquisition, with a GPS satellite navigation system for positioning. The system was calibrated with point sources using a mathematical correction to take into account the effects of gamma‐ray scattering in the ground and in the atmosphere. The calibration was complemented by high precision ground gamma spectrometry and laboratory measurements on rock samples. In Switzerland, two major research programs make use of the capabilities of airborne radiometric measurements. The first one concerns nuclear power plant monitoring. The five Swiss nuclear installations (four power plants and one research facility) and the surrounding regions of each site are surveyed annually. The project goal is to monitor the dose‐rate distribution and to provide a documented baseline database. The measurements show that all sites (with the exception of the Gösgen power plant) can be identified clearly on the maps. No artificial radioactivity that could not be explained by the Chernobyl release or earlier nuclear weapons tests was detected outside of the fenced sites of the nuclear installations. The second program aims at a better evaluation of the natural radiation level in Switzerland. The survey focused on the crystalline rocks of the Central Massifs of the Swiss Alps because of their relatively high natural radioactivity and lithological variability.

Guided Waves as an Online Monitoring Technology for Long-Term Operation in Nuclear Power Plants: Experimental Results on a Steam Discharge Pipe

2019 ◽  
Vol 5 (1) ◽  
Author(s):  
Mauro Cappelli ◽  
Francesco Cordella ◽  
Francesco Bertoncini ◽  
Marco Raugi
Keyword(s):  
Nuclear Power ◽  
Power Plants ◽  
Nuclear Power Plants ◽  
Guided Waves ◽  
Complex Structure ◽  
Theoretical Background ◽  
Guided Wave ◽  
Experimental Results ◽  
Term Operation

Guided wave (GW) testing is regularly used for finding defect locations through long-range screening using low-frequency waves (from 5 to 250 kHz). By using magnetostrictive sensors, some issues, which usually limit the application to nuclear power plants (NPPs), can be fixed. The authors have already shown the basic theoretical background and simulation results concerning a real steel pipe, used for steam discharge, with a complex structure. On the basis of such theoretical framework, a new campaign has been designed and developed on the same pipe, and the obtained experimental results are now here presented as a useful benchmark for the application of GWs as nondestructive techniques. Experimental measures using a symmetrical probe and a local probe in different configurations (pulse-echo and pitch-catch) indicate that GW testing with magnetostrictive sensors can be reliably applied to long-term monitoring of NPPs components.

scholarly journals Reactor performance, system reliability, instrumentation and control

2020 ◽  
Vol 6 ◽  
pp. 43
Author(s):  
Andreas Schumm ◽  
Madalina Rabung ◽  
Gregory Marque ◽  
Jary Hamalainen
Keyword(s):  
Nuclear Power ◽  
Power Plants ◽  
Nuclear Power Plants ◽  
Lessons Learned ◽  
Software Systems ◽  
Reactor Performance ◽  
Horizon 2020 ◽  
Term Operation ◽  
In The Beginning ◽  
Electrical Cables

We present a cross-cutting review of three on-going Horizon 2020 projects (ADVISE, NOMAD, TEAM CABLES) and one already finished FP7 project (HARMONICS), which address the reliability of safety-relevant components and systems in nuclear power plants, with a scope ranging from the pressure vessel and primary loop to safety-critical software systems and electrical cables. The paper discusses scientific challenges faced in the beginning and achievements made throughout the projects, including the industrial impact and lessons learned. Two particular aspects highlighted concern the way the projects sought contact with end users, and the balance between industrial and academic partners. The paper concludes with an outlook on follow-up issues related to the long term operation of nuclear power plants.

Research Activities in the European Union on Ageing Management for Long Term Operation of Nuclear Power Plants

2010 ◽  
Author(s):  
Oliver Martin ◽  
Antonio Ballesteros ◽  
Christiane Bruynooghe ◽  
Michel Bie`th
Keyword(s):  
Energy Supply ◽  
Nuclear Power ◽  
Power Plants ◽  
Nuclear Power Plants ◽  
Age Distribution ◽  
Term Operation ◽  
Research Activities ◽  
Ageing Management ◽  
The Eu

The energy supply of the future in the EU will be a mix of renewable, fossil and nuclear. There are 145 nuclear power reactors in operation in 15 out of the 27 EU countries, with installed power ∼132 GWe. The age distribution of current nuclear power plants in EU is such that in 2010 most of them will have passed 20-years and approximately 25% of them 30 years of age. The decrease of energy supply from nuclear generated electricity can not always be compensated in a reliable and economical way within a short time span. For this situation utilities may be keen to upgrade the reactor output and /or to ask their regulatory bodies for longer term operation. Under the research financed in the Euratom part of the Research Directorate (RTD) of the European Commission several projects explicitly address the safe long term operation of nuclear power plants (NULIFE, LONGLIFE) and the topics proposed in the 2010 call explicitly address issues concerning component ageing, in particular non metallic components, i.e. instrumentation and cables (I&C) and concrete ageing. This paper presents an overview of the plans for long term operation (LTO) of nuclear power plants in the EU. Special emphasis is given on research activities on component ageing management and long term operation issues related to safety.

Long-Term Operation of BWR RPV and its Internals

2018 ◽  
Author(s):  
Otso Cronvall
Keyword(s):  
Nuclear Power ◽  
Power Plants ◽  
Pilot Project ◽  
Computational Time ◽  
Degradation Mechanisms ◽  
Irradiation Embrittlement ◽  
Screening Process ◽  
Term Operation ◽  
Operational Lifetime

This study concerns the long-term operation (LTO) of a boiling water reactor (BWR) reactor pressure vessel (RPV) and its internals. The main parts of this study are: survey on susceptibility to degradation mechanisms, and computational time limited ageing analyses (TLAAs). The ageing of nuclear power plants (NPPs) emphasises the need to anticipate the possible degradation mechanisms. The BWR survey on susceptibility to these uses the OL1/OL2 RPVs and significant internals as a pilot project. It is not necessary to carry out the TLAAs for all components. Some components were excluded from the TLAAs with a screening process. To do this, it was necessary to determine the component specific load induced stresses, strains and temperature distributions as well as cumulative usage factor (CUF) values. For the screened-in components, the TLAAs covered all significant time dependent degradation mechanisms. These include (but are not limited to): • irradiation embrittlement, • fatigue, • stress corrosion cracking (SCC), and • irradiation accelerated SCC (IASCC). For the components that were screened-in, the potential to brittle, ductile or other degradation was determined. Only some of the most significant cases and results are presented. According to the analysis results, the operational lifetime of the OL1/OL2 RPVs and internals can safely be extended from 40 to 60 years.

Fracture Toughness Predictive Models Within the SOTERIA EU Project

2018 ◽  
Author(s):  
P. M. James ◽  
M. Berveiller
Keyword(s):  
Cleavage Fracture ◽  
Nuclear Power ◽  
Power Plants ◽  
Radiation Effects ◽  
Austenitic Stainless Steels ◽  
Irradiation Damage ◽  
Tensile Behaviour ◽  
Horizon 2020 ◽  
Term Operation

SOTERIA is focused on the ‘safe long term operation of light water reactors’. This will be achieved through an improved understanding of radiation effects in nuclear structural materials. This project has received funding from the European Union’s Horizon 2020 research and innovation programme under agreement No 661913. The overall aim of the SOTERIA project is to improve the understanding of the ageing phenomena occurring in ferritic reactor pressure vessel steels and in the austenitic internals in order to provide crucial information to regulators and operators to ensure safe long-term operation (LTO) of existing European nuclear power plants (NPPs). SOTERIA has set up a collaborative research consortium which gathers the main European research centers and industrial partners who will combine advanced modelling tools with the exploitation of experimental data to focus on two major objectives: i) to identify ageing mechanisms when materials face environmental degradation (such as e.g. irradiation and corrosion) and ii) to provide a single platform containing data and tools for reassessment of structural components during NPPs lifetime. This paper provides an overview of the ongoing activities within the SOTERIA Project that are contained within the analytical work-package (WP5.3). These fracture aspects are focused on the estimates of fracture in both ferritic steels and irradiation assisted stress corrosion cracking (IASCC) in austenitic stainless steels, under irradiated conditions. This analytical development is supported by analytical estimates of irradiation damage and the resulting changes in tensile behaviour of the steels elsewhere in SOTERIA, as well as a wider number of experimental programmes. Cleavage fracture estimates are being considered by a range of modelling estimates including the Beremin, Microstructurally Informed Brittle Fracture Model (MIBF), JFJ and Bordet Models with efforts being made to understand the influence of heterogeneity on the predicted toughness’s. Efforts are also being considered to better understand ductile void evolution and the effect of plasticity on the cleavage fracture predictions. IASCC is being modelled through the INITEAC code previously developed within the predecessor project Perform 60 which is being updated to incorporate recent developments from within SOTERIA and elsewhere.

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