Reliability and redundancy allocation analysis applied to a nuclear protection system

2021 ◽  
Vol 9 (2B) ◽  
Author(s):  
Alexander Lucas Busse ◽  
João Manoel Losada Moreira
Keyword(s):  
Nuclear Power ◽  
Power Plants ◽  
Nuclear Reactor ◽  
Nuclear Reactors ◽  
Block Diagram ◽  
Thermal Power ◽  
Life Time ◽  
Spare Parts ◽  
Protection System ◽  
Under Construction

Brazil is constructing with national technology two small nuclear reactors for propulsion and for radioisotope production with thermal power levels between 20 and 50 MW. These nuclear reactors fit more in the class of small modular reactors (SMR) than in the class of large nuclear power plants. In this article we apply the design approach of SMRs to propose an architecture of reactor protection systems for the small reactor under construction in the country. To do that the probabilistic analysis of the architecture of a nuclear reactor protection system is evaluated to determine the sensitivity of the components through an Reliability Block Diagram modeling. It was evaluated the modification of the architecture and the addition of redundancies when using components with lower life time than the components usually used for this purpose. The results showed that after one year of operation, the reference RPS system presents a failure probability of 0.17 %. The modified system, with components with lower life time, presents a point reliability value only 0.070 % lower than the reference one, but this difference grows exponentially over time, and in 10 years of operation it can reach values above 95%. Using equipment with lower life time characteristics implies a greater number of redundancies and, additionally, a greater number of maintenance procedures and spare parts. Therefore, this technical feasibility analysis should consider a RAM simulation as well.

scholarly journals PRELIMINARY DESIGN OF RDE FEEDWATER PUMP IMPELLER

2018 ◽  
Vol 20 (1) ◽  
pp. 1 ◽  
Author(s):  
Sri Sudadiyo
Keyword(s):  
Nuclear Power ◽  
Power Plants ◽  
Nuclear Reactor ◽  
Thermal Power ◽  
Performance Characteristics ◽  
Preliminary Design ◽  
Triangle Diagram ◽  
Pump Impeller ◽  
Impeller Blade ◽  
Feedwater Pump

Nowadays, pumps are being widely used in the thermal power generation including nuclear power plants. Reaktor Daya Eksperimental (RDE) is a proposed nuclear reactor concept for the type of nuclear power plant in Indonesia. This RDE has thermal power 10 MWth, and uses a feedwater pump within its steam cycle. The performance of feedwater pump depends on size and geometry of impeller model, such as the number of blades and the blade angle. The purpose of this study is to perform a preliminary design on an impeller of feedwater pump for RDE and to simulate its performance characteristics. The Fortran code is used as an aid in data calculation in order to rapidly compute the blade shape of feedwater pump impeller, particularly for a RDE case. The calculations analyses is solved by utilizing empirical correlations, which are related to size and geometry of a pump impeller model, while performance characteristics analysis is done based on velocity triangle diagram. The effect of leakage, pass through the impeller due to the required clearances between the feedwater pump impeller and the volute channel, is also considered. Comparison between the feedwater pump of HTR-10 and of RDE shows similarity in the trend line of curve shape. These characteristics curves will be very useful for the values prediction of performance of a RDE feedwater pump. Preliminary design of feedwater pump provides the size and geometry of impeller blade model with 5-blades, inlet angle 14.5 degrees, exit angle 25 degrees, inside diameter 81.3 mm, exit diameter 275.2 mm, thickness 4.7 mm, and height 14.1 mm. In addition, the optimal values of performance characteristics were obtained when flow capacity was 4.8 kg/s, fluid head was 29.1 m, shaft mechanical power was 2.64 kW, and efficiency was 52 % at rotational speed 1750 rpm.Keywords: Blade, impeller, pump, RDEDESAIN AWAL IMPELER POMPA AIR UMPAN RDE. Saat ini, pompa digunakan secara luas dalam pembangkit tenaga termal termasuk pembangkit listrik tenaga nuklir. Reaktor Daya Eksperimental (RDE) merupakan konsep reaktor nuklir yang diusulkan untuk tipe PLTN di Indonesia. RDE ini memiliki daya termal 10 MWth, dan menggunakan pompa air umpan dalam siklus uapnya. Kinerja pompa air umpan bergantung pada ukuran dan geometri model impeller, seperti jumlah sudu dan sudut sudu. Tujuan dari penelitian ini adalah untuk membuat rancangan awal impeller pompa air umpan untuk RDE dan untuk mensimulasikan karakteristik kinerjanya. Kode Fortran digunakan sebagai bantuan dalam penghitungan data untuk untuk mengkalkulasi secara cepat bentuk sudu impeller pompa air umpan, terutama pada kasus RDE. Analisis perhitungan dipecahkan menggunakan korelasi empiris yang terkait dengan ukuran dan geometri model impeller pompa, sedangkan analisis karakteristik kinerja dilakukan berdasarkan diagram segitiga kecepatan. Pengaruh bocoran, melalui impeler akibat celah yang diperlukan antara impeller pompa air umpan dan saluran volute, juga dipertimbangkan. Perbandingan antara pompa air umpan HTR-10 dan RDE menunjukkan kemiripan dalam garis tren bentuk kurva. Kurva karakteristik ini akan sangat berguna untuk perkiraan nilai kinerja pompa air umpan RDE. Desain awal pompa air umpan memberikan ukuran dan geometri model sudu impeller dengan 5-sudu, sudut masuk 14,5 derajat, sudut keluar 25 derajat, diameter dalam 81,3 mm, diameter luar 275,2 mm, ketebalan 4,7 mm, dan tinggi 14,1 mm. Selain itu, nilai optimal karakteristik kinerja diperoleh ketika kapasitas aliran 4,8 kg/s, head fluida 29,1 m, tenaga mekanik poros 2,64 kW, dan efisiensi 52 % pada kecepatan putaran 1750 rpm.Kata kunci: Sudu, impeler, pompa, RDE

Reliability Analysis and Availability Enhancements for Redundant Systems With Reparable Components

2016 ◽  
Author(s):  
Shuqiao Zhou ◽  
Duo Li ◽  
Chao Guo
Keyword(s):  
Nuclear Power ◽  
Power Plants ◽  
Markov Chain Model ◽  
Life Time ◽  
Theoretical Models ◽  
Chain Model ◽  
Monitoring And Control ◽  
Monitoring Methods ◽  
Under Construction ◽  
Redundant Systems

Redundancy is widely used for enhancing a system’s overall availability. As an HTR demonstrated plant, a high temperature gas-cooled reactor pebble-bed module (HTR-PM) now is under construction in China and the construction will be completed around 2017. In HTR-PM, there are many devices and device groups used in a redundant way to guarantee the high availability of the related functions, especially the functions shared by two reactors during the entire life time. It is very important and necessary to determine their reliabilities as well as how to make a decision about the related maintenance policies to enhance their availabilities. In this paper, typical redundant styles in the HTR-PM are summarized and demonstrated. Accordingly, the theoretical models, which are able to describe the reliabilities of the redundant systems, are proposed based on Markov chain model. Moreover, for a specific redundant structure, the relationship between the availability and the maintenance period is analytically addressed. Based on the model, we address that: as the digital monitoring and control technologies are widely used in nuclear power plants, monitoring methods targeting for decreasing maintenance costs and meanwhile increasing the availabilities for different redundant styles are very beneficial.

An Assessment of Mechanical Properties of A508-3 Steel Used in Chinese Nuclear Reactor Vessels

2014 ◽  
Author(s):  
Meifang Yu ◽  
Zhen Luo ◽  
Y. J. Chao
Keyword(s):  
Mechanical Properties ◽  
Nuclear Power ◽  
Power Plants ◽  
Fossil Fuels ◽  
Nuclear Reactor ◽  
Structural Integrity ◽  
Construction Materials ◽  
Under Construction ◽  
Made In China ◽  
Phase Out

China has very ambitious goals of expanding its commercial nuclear power by 30 Giga-Watts within the decade and wishes to phase out fossil fuels emissions by 40–45% by 2020 (from 2005 levels). With over 50 new nuclear power plants under construction or planned and a design life of 60 years, any discussions on structural integrity become very timely. Although China adopted its nuclear technology from France or US at present time, e.g. AP1000 of Westinghouse, the construction materials are primarily “Made in China”. Among all issues, both the accumulation of the knowledge base of the materials and structures used for the power plant and the technical capability of engineering personnel are imminent. This paper attempts to compile and assess the mechanical properties, Charpy V-notch impact energy, and fracture toughness of A508-3 steel used in Chinese nuclear reactor vessels. All data are collected from open literature and by no means complete. However, it provides a glimpse into how this domestically produced steel compares with western reactor vessel steels such as US A533B and Euro 20MnMoNi55.

scholarly journals Nuclear Restart Politics: How the ‘Nuclear Village’ Lost Policy Implementation Power

2020 ◽  
Author(s):  
Florentine KOPPENBORG
Keyword(s):  
Decision Making ◽  
Policy Implementation ◽  
Goal Setting ◽  
Nuclear Power ◽  
Power Plants ◽  
Nuclear Power Plants ◽  
Nuclear Reactor ◽  
Nuclear Reactors ◽  
Nuclear Industry ◽  
Nuclear Policy

Abstract The March 2011 nuclear accident (3.11) shook Japan’s nuclear energy policy to its core. In 2012, the Liberal Democratic Party (LDP) returned to government with a pro-nuclear policy and the intention to swiftly restart nuclear power plants. In 2020, however, only six nuclear reactors were in operation. Why has the progress of nuclear restarts been so slow despite apparent political support? This article investigates the process of restarting nuclear power plants. The key finding is that the ‘nuclear village’, centered on the LDP, Ministry of Economy Trade and Industry, and the nuclear industry, which previously controlled both nuclear policy goal-setting and implementation, remained in charge of policy decision making, i.e. goal-setting, but lost policy implementation power to an extended conflict over nuclear reactor restarts. The main factors that changed the politics of nuclear reactor restarts are Japan’s new nuclear safety agency, the Nuclear Regulation Authority (NRA), and a substantial increase in the number of citizens’ class-action lawsuits against nuclear reactors. These findings highlight the importance of assessing both decision making and implementation in assessments of policy change.

scholarly journals Anthropogenic Radiocarbon: Past, Present, and Future

Radiocarbon ◽  
1986 ◽  
Vol 28 (2A) ◽  
pp. 668-672 ◽  
Author(s):  
Pavel Povinec ◽  
Martin Chudý ◽  
Alexander Šivo
Keyword(s):  
Nuclear Power ◽  
Power Plants ◽  
Nuclear Reactor ◽  
Nuclear Reactors ◽  
Pressurized Water Reactors ◽  
Anthropogenic Radionuclides ◽  
Pressurized Water ◽  
Heavy Water Reactor ◽  
Weapon Testing ◽  
Water Reactors

14C is one of the most important anthropogenic radionuclides released to the environment by human activities. Weapon testing raised the 14C concentration in the atmosphere and biosphere to +100% above the natural level. This excess of atmospheric C at present decreases with a half-life of ca 7 years. Recently, a new source of artificially produced 14C in nuclear reactors has become important. Since 1967, the Bratislava 14C laboratory has been measuring 14C in atmospheric 14CO2 and in a variety of biospheric samples in densely populated areas and in areas close to nuclear power plants. We have been able to identify a heavy-water reactor and the pressurized water reactors as sources of anthropogenic 14C. 14C concentrations show typical seasonal variations. These data are supported by measurements of 3H and 85Kr in the same locations. Results of calculations of future levels of anthropogenic 14C in the environment due to increasing nuclear reactor installations are presented.

scholarly journals Analysis of Possible Application of High-Temperature Nuclear Reactors to Contemporary Large-Output Steam Power Plants on Ships

2016 ◽  
Vol 23 (2) ◽  
pp. 32-41 ◽  
Author(s):  
T. Kowalczyk ◽  
J. Głuch ◽  
P. Ziółkowski
Keyword(s):  
High Temperature ◽  
Nuclear Power ◽  
Power Plants ◽  
Nuclear Reactor ◽  
Nuclear Reactors ◽  
Operational Parameters ◽  
Steam Power ◽  
Operational Conditions ◽  
Steam Power Plants ◽  
Large Output

Abstract This paper is aimed at analysis of possible application of helium to cooling high-temperature nuclear reactor to be used for generating steam in contemporary ship steam-turbine power plants of a large output with taking into account in particular variable operational parameters. In the first part of the paper types of contemporary ship power plants are presented. Features of today applied PWR reactors and proposed HTR reactors are discussed. Next, issues of load variability of the ship nuclear power plants, features of the proposed thermal cycles and results of their thermodynamic calculations in variable operational conditions, are presented.

A Review on Specific Features of Small and Medium Sized Nuclear Power Plants

2010 ◽  
Author(s):  
Salah Ud-din Khan ◽  
Minjun Peng ◽  
Muhammad Zubair ◽  
Shaowu Wang
Keyword(s):  
Nuclear Power ◽  
Power Plants ◽  
Nuclear Reactor ◽  
Nuclear Reactors ◽  
Fixed Bed ◽  
Nuclear Industry ◽  
Energy Agency ◽  
Pressurized Water ◽  
Water Reactor ◽  
Energy Supply System

Due to global warming and high oil prices nuclear power is the most feasible solution for generating electricity. For the fledging nuclear power industry small and medium sized nuclear reactors (SMR’s) are instrumental for the development and demonstration of nuclear reactor technology. Due to the enhanced and outstanding safety features, these reactors have been considered globally. In this paper, first we have summarized the reactor design by considering some of the large nuclear reactor including advanced and theoretical nuclear reactor. Secondly, comparison between large nuclear reactors and SMR’s have been discussed under the criteria led by International Atomic Energy Agency (IAEA). Thirdly, a brief review about the design and safety aspects of some of SMR’s have been carried out. We have considered the specifications and parametric analysis of the reactors like: ABV which is the floating type integral Pressurized water reactor; Long life, Safe, Simple Small Portable Proliferation Resistance Reactor (LSPR) concept; Multi-Application Small Light Water Reactor (MASLWR) concept; Fixed Bed Nuclear Reactor (FBNR); Marine Reactor (MR-X) & Deep Sea Reactor (DR-X); Space Reactor (SP-100); Passive Safe Small Reactor for Distributed energy supply system (PSRD); System integrated Modular Advanced Reactor (SMART); Super, Safe, Small and Simple Reactor (4S); International Reactor Innovative and Secure (IRIS); Nu-Scale Reactor; Next generation nuclear power plant (NGNP); Small, Secure Transportable Autonomous Reactor (SSTAR); Power Reactor Inherently Safe Module (PRISM) and Hyperion Reactor concept. Finally we have point out some challenges that must be resolved in order to play an effective role in Nuclear industry.

scholarly journals The Best Estimate Plus Uncertainty approach in nuclear reactor safety and licensing: Brief history and the elements after licensing

2019 ◽  
Vol 34 (3) ◽  
pp. 299-312
Author(s):  
Francesco D’Auria ◽  
Giorgio Galassi
Keyword(s):  
Nuclear Power ◽  
Power Plants ◽  
Nuclear Reactor ◽  
Nuclear Reactors ◽  
Thermal Hydraulics ◽  
Reactor Safety ◽  
Two Phase ◽  
Best Estimate ◽  
Nuclear Reactor Safety ◽  
The Impact

The best estimate plus uncertainty is, at the same time, an approach, a procedure and a frame- work in nuclear thermal-hydraulics and nuclear reactor safety and licensing. The motivation at the basis of the best estimate plus uncertainty is the lack of knowledge in the areas of single and, mainly, two-phase transient thermal-hydraulics. In other terms and introducing some simplifications, the insufficient knowledge of turbulence imposes the design of roadmaps for the application of imperfect (thermal-hydraulic) models to the evaluation of design features and of safety for complex technological installations or systems like the nuclear power plants and, more specifically, the water cooled nuclear reactors. Furthermore, the legal counterpart of nuclear reactor safety, or the licensing, is concerned: therefore the best estimate plus uncertainty must account for rules and regulations derived from the fundamental radioprotection principle which imposes the minimization of the impact of radiations upon humans and the environment under any circumstance. In the present paper, the key elements of the approach are identified and characterized. These shall be seen as the support for a consistent application of thermal-hydraulics to the design and safety of water-cooled nuclear reactors.

Thermodynamic Considerations for a Single-Reheat Cycle SCWR

2009 ◽  
Author(s):  
M. C. Naidin ◽  
R. Monichan ◽  
U. Zirn ◽  
K. Gabriel ◽  
I. Pioro
Keyword(s):  
Thermal Efficiency ◽  
Nuclear Power ◽  
Power Plants ◽  
Nuclear Reactor ◽  
Thermal Power ◽  
Electrical Energy ◽  
Performance Simulation ◽  
Development Costs ◽  
And Performance ◽  
Steam Cycle

Currently, there are a number of Generation IV SuperCritical Water-cooled nuclear Reactor (SCWR) concepts under development worldwide. The main objectives for developing and utilizing SCWRs are: 1) Increase gross thermal efficiency of current Nuclear Power Plants (NPPs) from 30 – 35% to approximately 45 – 50%, and 2) Decrease capital and operational costs and, in doing so, decrease electrical-energy costs. SCW NPPs will have much higher operating parameters compared to current NPPs (i.e., steam pressures of about 25 MPa and steam outlet temperatures up to 625°C). Additionally, SCWRs will have a simplified flow circuit in which steam generators, steam dryers, steam separators, etc. will be eliminated. Furthermore, SCWRs operating at higher temperatures can facilitate an economical co-generation of hydrogen through thermo-chemical cycles (particularly, the copper-chlorine cycle) or direct high-temperature electrolysis. To decrease significantly the development costs of a SCW NPP, to increase its reliability, and to achieve similar high thermal efficiencies as the advanced fossil steam cycles it should be determined whether SCW NPPs can be designed with a steam-cycle arrangement that closely matches that of mature SuperCritical (SC) fossil-fired thermal power plants (including their SC-turbine technology). The state-of-the-art SC-steam cycles at fossil-fired power plants are designed with a single-steam reheat and regenerative feedwater heating. Due to that, they reach thermal steam-cycle efficiencies up to 54% (i.e., net plant efficiencies of up to 43% on a Higher Heating Value (HHV) Basis). This paper analyzes main parameters and performance in terms of thermal efficiency of a SCW NPP concept based on a direct regenerative steam cycle. To increase the thermal efficiency and to match current SC-turbine parameters, the cycle also includes a single steam-reheat stage. The cycle is comprised of: an SCWR, a SC turbine, which consists of one High-Pressure (HP) cylinder, one Intermediate-Pressure (IP) cylinder and two Low-Pressure (LP) cylinders, one deaerator, ten feedwater heaters, and pumps. Since this option includes a “nuclear” steam-reheat stage, the SCWR is based on a pressure-tube design. A thermal-performance simulation reveals that the overall thermal efficiency is approximately 50%.

Study on Thermal Efficiency of SuperCritical Water NPPs

2016 ◽  
Author(s):  
Cristina Mazza ◽  
Paul Ponomaryov ◽  
Yifeng Zhou ◽  
Igor Pioro
Keyword(s):  
Supercritical Water ◽  
Thermal Efficiency ◽  
Nuclear Power ◽  
Power Plants ◽  
Nuclear Reactors ◽  
Thermal Power ◽  
Vital Role ◽  
Energy Market ◽  
Power Cycle ◽  
Cost Efficient

As the demand for emission-free energy increases, the continued improvement of Nuclear Power Plants (NPPs) and their thermal efficiencies is crucial to fulfilling that demand. Current NPPs, especially, with water-cooled reactors, have significantly lower thermal efficiencies (32–36%) compared to those of modern advanced thermal power plants (55–62%). Even Generation-III+ water-cooled NPPs will have thermal efficiencies not higher than 37–38%. Therefore, to be competitive on the energy market, new nuclear reactors and NPPs, so-called, Generation-IV concepts, should be designed and commissioned. The paper discusses the vital role that thermal efficiency plays with respect to how far nuclear reactors can be more cost efficient and competitive. An evaluation of thermal efficiencies has been carried out for SuperCritical Water (SCW) NPPs with Rankine “steam”-turbine power cycle using the IAEA DEsalination Thermodynamic Optimization Program (DE-TOP). Various options for improving thermal efficiencies of SCW NPPs have been studied. This study was performed in support of possible designs of the first experimental SCW reactors.

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