scholarly journals Fuzzy Based Risk Assessment for Decommissioning Concrete Bioshield Structures in Nuclear Power Plants: Structural Risks and Worker Safety

2020 ◽  
Vol 10 (7) ◽  
pp. 2614
Author(s):  
Byeol Kim ◽  
Joo sung Lee ◽  
Yong han Ahn
Keyword(s):  
Risk Assessment ◽  
Nuclear Power ◽  
Safety Assessment ◽  
Power Plants ◽  
Statistical Data ◽  
Developed Countries ◽  
Assessment Model ◽  
Worker Safety ◽  
Nuclear Facilities ◽  
Safety Issues

Few studies have assessed the safety issues involved in decommissioning nuclear facilities, especially from a structural and job perspective; in most developed countries, the focus is generally on the radiological risks. This study highlights the inadequacy of existing deterministic risk assessment methods, which cannot account for the uncertainty and complexity of hazards that workers are exposed to. We instead propose a fuzzy logic based safety assessment model that can analyze and compare alternatives utilizing a step-by-step risk quantification and multidimensional approach. This enables personnel to assess the various risks involved when decontaminating and decommissioning nuclear power plant structures that cannot be quantitatively assessed owing to a lack of data. Our proposed fuzzy based risk assessment model can also be applied to risk assessment in other engineering fields that depend on the judgment of experts supported by little or no statistical data.

Application of Probabilistic Safety Assessment in the Design of Instrumentation and Control Systems for Nuclear Power Plants

2017 ◽  
Author(s):  
Pengyi Peng ◽  
Weidong Liu ◽  
Zhichao Yang
Keyword(s):  
Risk Assessment ◽  
Optimal Design ◽  
System Design ◽  
Nuclear Power ◽  
Safety Assessment ◽  
Power Plants ◽  
Nuclear Power Plants ◽  
Probabilistic Safety Assessment ◽  
And Control ◽  
Probabilistic Safety

Instrumentation and control (I&C) systems in nuclear power plants (NPPs) have the ability to initiate the safety-related functions necessary to shut down the plants and maintain the plants in a safe shutdown condition. I&C systems of low reliability will bring risks to the safe operation of NPPs. A sufficient level of redundancy and diversity of I&C design to ensure the safety is a major focus when designing a new reactor. Usually multiple signal paths are included in an I&C system design. Meanwhile, besides the protection and safety monitoring system (PMS), other sub-systems of I&C such as the diverse actuation system (DAS) will be included as a diverse backup of PMS to perform the functions of reactor trip and engineered safety features actuation systems (ESFAS). However, the construction costs increase as the level of system redundancy and diversity grows. In fact, from the perspective of deterministic theory, an I&C system of only two chains can meet the single failure criterion. So how to obtain the balance of safety and economy is a challenging problem in I&C system designing. Probabilistic Safety Assessment (PSA) is the most commonly used quantitative risk assessment tool for decision-making in selecting the optimal design among alternative options. In this paper, PSA technique was used to identify whether the I&C system design offers adequate redundancy, diversity, and independence with sufficient defense-in-depth and safety margins in the design of a new reactor. Firstly, detailed risk assessment criteria for I&C design were studied and identified in accordance with nuclear regulations. Secondly, different designs were appropriately modeled, and the risk insights were provided, showing the balance of safety and economy of each design. Furthermore, potential design improvements were evaluated in terms of the current risk assessment criterion. In the end, the optimal design was determined, and uncertainty analyses were performed. The results showed that all four designs analyzed in this paper were met the safety goals in terms of PSA, but each design had a different impact on the balance of risk. As the support systems of the NPP we analyzed were relatively weak, loss of off-site power and loss of service water were two main risk contributors. The common cause failure of reactor trip breakers and the sensors of containment pressure were risk-significant. After identifying the major risk factors, the I&C design team can perform subsequent optimizations in the further design based on the PSA results and achieve an optimal balance between safety and economy.

The Role of Local Governments in the Japanese Nuclear Governance: Case Analysis of “Safety Agreements” in Siting Areas

2009 ◽  
Author(s):  
Shin-etsu Sugawara ◽  
Hiroshi Kimura
Keyword(s):  
Local Governments ◽  
Nuclear Power ◽  
Power Plants ◽  
Nuclear Safety ◽  
Regulation System ◽  
Public Confidence ◽  
Nuclear Facilities ◽  
National Regulation ◽  
Safety Issues

Non-institutional measures often play an important role in the governance between technology and institutional system which have legal basis. In this study, we analyze the role of the “safety agreements” in Japan’s current regulation system of nuclear power plants (NPPs). In Japan, the national government regulates exclusively the safety of nuclear facilities based on the regulaions. But local governments also involve in the nuclear safety regulation de facto, to protect the publics’ safety and welfare. All the local governments in the siting areas concluded “safety agreements”, a gentleman-like agreement between local governments and power companies on safety issues. These Agreements contain various provisions, such as, the immediate notification procedures of accidents in NPPs, the access and inspection of NPPs after accidents, etc... However, these provisions don’t have a legal-binding of the power companies but, the local governors and local governments sometimes strongly assert the control for the restart operation of NPPs after the accidents utilizing the “safety agreements” as the pretext. This situation has sometimes been criticized by some experts who argue that the “safety agreements” have become an obstacle for stable NPPs operation and electricity supply. Since there are no studies which analyze the actual situations of local governments’ control on nuclear safety based on the “safety agreements,” we analyzed the situation by performing a qualitative survey and conducting a series of interview with personnel of the power companies and local governments. We found from our analysis that the “safety agreements” were utilized positively. For example, the inspection of NPPs by local government functions as an endorsement for the national regulation and assures public confidence. In this case the “safety agreements” promote and provide public acceptance on nuclear governance. However, the measures in these “safety agreements” could be over-extended in the political contexts because of the ambiguity and flexibility in the interpretation. In our paper, we would illustrate the merits and demerits of the role of local governments based on these “safety agreements” and suggest to improve the nuclear safety governance within the local governments’ capacity.

scholarly journals Safety Assessment of Low-Contaminated Equipment Dismantling at Nuclear Power Plants

2015 ◽  
Vol 2015 ◽  
pp. 1-11 ◽  
Author(s):  
Egidijus Babilas ◽  
Eugenijus Ušpuras ◽  
Sigitas Rimkevičius ◽  
Gintautas Dundulis ◽  
Mindaugas Vaišnoras
Keyword(s):  
Power Plant ◽  
Nuclear Power Plant ◽  
Nuclear Power ◽  
Safety Assessment ◽  
Power Plants ◽  
Structural Integrity ◽  
Building Structures ◽  
Nuclear Facilities ◽  
Energy Agency ◽  
Force Calculation

The decommissioning of nuclear facilities requires adequate planning and demonstration that dismantling and decontamination activities can be conducted safely. Existing safety standards require that an appropriate safety assessment be performed to support the decommissioning plan for each facility (International Atomic Energy Agency, 2006). This paper presents safety assessment approach used in Lithuania during the development of the first dismantling and decontamination project for Ignalina NPP. The paper will mainly focus on the identification and assessment of the hazards raised due to dismantling and decontamination activities at Ignalina Nuclear Power Plant and on the assessment of the nonradiological and radiological consequences of the indicated most dangerous initiating event. The drop of heavy item was indicated as one of most dangerous initiating events for the discussed Ignalina Nuclear Power Plant dismantling and decontamination project. For the analysis of the nonradiological impact the finite element model for the load drop force calculation was developed. The radiological impact was evaluated in those accident cases which would lead to the worst radiological consequences. The assessments results show that structural integrity of the building and supporting columns of building structures will be maintained and radiological consequences are lower than the annual regulatory operator dose limit.

Study on the Technical Method of Level 2 Probabilistic Safety Assessment in Multiple External Hazards Compound Situations

2017 ◽  
Author(s):  
Liu Wei-dong ◽  
Dai Hong-wei ◽  
Peng Peng-yi ◽  
Zhang Ze-feng ◽  
Wang En-qi
Keyword(s):  
Nuclear Power ◽  
Safety Assessment ◽  
Power Plants ◽  
Nuclear Power Plants ◽  
Assessment Model ◽  
Risk Indicators ◽  
Frequency Of Occurrence ◽  
Probabilistic Safety Assessment ◽  
Level 2 ◽  
Probabilistic Safety

The article introduces the method of level 2 probabilistic safety assessment in multiple external hazards compound situations, and the application of probabilistic safety assessment technology in building a Level 2 probabilistic safety assessment model for a domestic nuclear power plant under such circumstances. This model can be used to quantitatively evaluate important risk indicators like the frequency of a large release of radionuclides, frequency of occurrence of each release category, in order to identify weaknesses of nuclear power plants in responding to risks. Corresponding risk insights are provided to enhance the safety of nuclear power plants.

Probabilistic Safety Assessment Technology for Commercial Nuclear Power Plant Security Evaluation

2004 ◽  
Author(s):  
James K. Liming ◽  
David H. Johnson ◽  
Andrew A. Dykes
Keyword(s):  
Risk Assessment ◽  
Power Plant ◽  
Nuclear Power Plant ◽  
Nuclear Power ◽  
Safety Assessment ◽  
Power Plants ◽  
Nuclear Power Plants ◽  
Security Management ◽  
Probabilistic Safety Assessment ◽  
Tools And Techniques

Commercial nuclear power plant physical security has received much more intensive treatment and regulatory attention since September 11, 2001. In light of advancements made by the nuclear power industry in the field of probabilistic safety assessment (PSA) for its power plants over that last 30 years, and given the many examples of successful applications of risk-informed regulation at U. S. nuclear power plants during recent years, it may well be advisable to apply a “risk-informed” approach to security management at nuclear power plants from now into the future. In fact, plant PSAs developed in response to NRC Generic Letter 88-20 and related requirements are used to help define target sets of critical plant safety equipment in our current security exercises for the industry. With reasonable refinements, plant PSAs can be used to identify, analyze, and evaluate reasonable and prudent approaches to address security issues and associated defensive strategies at nuclear power plants. PSA is the ultimate scenario-based approach to risk assessment, and thus provides a most powerful tool in identifying and evaluating potential risk management decisions. This paper provides a summary of observations of factors that are influencing or could influence cost-effective or “cost-reasonable” security management decision-making in the current political environment, and provides recommendations for the application of PSA tools and techniques to the nuclear power plant operational safety response exercise (OSRE) process. The paper presents a proposed framework for nuclear power plant probabilistic terrorist risk assessment (PTRA) that applies these tools and techniques.

scholarly journals New trends in Multihazards Probabilistic Safety Assessment for nuclear installations: the H2020-NARSIS Project

2020 ◽  
Author(s):  
Evelyne Foerster ◽  
Behrooz Bazargan-Sabet ◽  
James Daniell ◽  
Pierre Gehl ◽  
Philip J. Vardon ◽  
...  
Keyword(s):  
Nuclear Power ◽  
Safety Assessment ◽  
Power Plants ◽  
Severe Accident ◽  
Management Decision ◽  
Nuclear Facilities ◽  
Probabilistic Safety Assessment ◽  
Human Aspects ◽  
Support Organizations ◽  
Probabilistic Safety

<p>The methodology for Probabilistic Safety Assessment (PSA) of Nuclear Power Plants (NPPs) has been used for decades by practitioners to better understand the most probable initiators of nuclear accidents by identifying potential accident scenarios, their consequences, and their probabilities. However, despite the remarkable reliability of the methodology, the Fukushima Dai-ichi nuclear accident in Japan, which occurred in March 2011, highlighted a number of challenging issues (e.g. cascading event - cliff edge - scenarios) with respect to the application of PSA questioning the relevance of PSA practice, for such low-probability but high-consequences external events. Following the Fukushima Dai-ichi accident, several initiatives at the international level, have been launched in order to review current practices and identify shortcomings in scientific and technical approaches for the characterization of external natural extreme events and the evaluation of their consequences on the safety of nuclear facilities.</p><p>The H2020 project “New Approach to Reactor Safety ImprovementS” (NARSIS, 2017-2021) aims at proposing some improvements to be integrated in existing PSA procedures for NPPs, considering single, cascade and combined external natural hazards (earthquakes, flooding, extreme weather, tsunamis). It coordinates the research efforts of eighteen partners encompassing leading universities, research institutes, technical support organizations (TSO), nuclear power producers and suppliers, reactor designers and operators from ten countries.</p><p>The project will lead to the release of various tools together with recommendations and guidelines for use in nuclear safety assessment, including a Bayesian-based multi-risk framework able to account for causes and consequences of technical, social/organizational and human aspects and as well as a supporting Severe Accident Management decision-making tool for demonstration purposes.</p><p>The NARSIS project has now been running for two years and a half, and the first set of deliverables and tools have been produced as part of the effort of the consortium. Datasets have been collected, methodologies tested, states of the art have been produced, and various criteria and plans developed. First results have started to emerge and will be presented here.</p>

Innovative Robot Technologies for Nuclear Power Plants Inspection and Maintenance

2014 ◽  
Author(s):  
Seungho Kim ◽  
Kyung Min Jung ◽  
Sung Uk Lee ◽  
Hocheol Shin ◽  
Chang Hoi Kim ◽  
...  
Keyword(s):  
Nuclear Power ◽  
Power Plants ◽  
Nuclear Power Plants ◽  
High Dose ◽  
Nuclear Facilities ◽  
Human Errors ◽  
Safety Issues ◽  
Safety And Reliability ◽  
Inspection And Maintenance ◽  
Remote Inspection

Nuclear energy has become the main energy source in Korea, but the safety issues are being debated since the Fukusima accident. In order to guarantee the safety and reliability of nuclear power plants, the uncertainty of human errors are being minimized by utilizing innovative technologies for inspection and maintenance. KAERI has developed robotic systems to upgrade and ensure the safety of nuclear facilities, to detect unusual conditions of facilities through remote inspection and to prevent human workers from high dose radiation with efficient plant maintenance.

scholarly journals Radiation risk and level 3 probability safety assessment of nuclear facilities

2021 ◽  
Vol 30 (4) ◽  
pp. 117-130
Author(s):  
V.A. Panteleev ◽  
◽  
M.D. Segal ◽  
A.E. Pimenov ◽  
◽  
...  
Keyword(s):  
Nuclear Power ◽  
Safety Assessment ◽  
Power Plants ◽  
Radiation Risk ◽  
Risk Level ◽  
Nuclear Facilities ◽  
Social Risks ◽  
Initial Stage ◽  
Wide Range ◽  
Level 3

The paper considers the current state in the field of level 3 probabilistic safety assessment (PSA Level 3) of nuclear facilities. The issues on rationing individual and social risks in various indus-tries and practice of legislative control in some countries are examined. Some attention is paid to the identification of acceptable risk level and features of radiation risk perception. The paper ad-dresses possibilities of use of PSA Level 3 methodology for radiation risk assessment. We pro-pose a practical approach to quantify specific features that may affect individual, collective and social radiation-associated cancer risks at the initial stage of severe radiation accidents at nuclear power plants. PSA Level 3 capacities are demonstrated on the example of individual and social radiation risks assessment at the initial stage of a severe accident at a model nuclear power plant. When performing numerical simulations of the consequences of the accident of such type with the program developed at the Nuclear Safety Institute of the Russian Academy of Sciences, the nuclide composition of the emission is similar to one of the emissions during the Fukushima accident, and the distribution of population density and weather conditions correspond to real values in Fukushima Prefecture. We evaluated the effectiveness of various options for protective countermeasures based on the results of risk assessments. We have shown that the PSA Level 3 methodology allows us to obtain information about the risks associated with accidents at nuclear facilities in the form of standard risk-informative safety management methods. This will strength-en scientific and technical support for the processes of interaction with experts, decision-makers, the media and the public in making a wide range of decisions in the event of a threat, occurrence and elimination of the consequences of an emergency with a radiation factor.

scholarly journals Basic Risk Assessment of Nuclear Power Plants

2021 ◽  
Vol 31 (1) ◽  
pp. 95-108
Author(s):  
Zoltán Antal
Keyword(s):  
Risk Factors ◽  
Risk Assessment ◽  
Power Plant ◽  
Nuclear Power ◽  
Power Plants ◽  
Nuclear Power Plants ◽  
Nuclear Safety ◽  
Critical Systems ◽  
Nuclear Facility ◽  
Nuclear Facilities

Nuclear power plants are classified as highly important and dangerous facilities. Therefore, in addition to the directives  for dangerous establishments, they also have to adhere to  further special criteria. This article investigates those  essential security factors which are designed to ensure  nuclear safety. It is very important that the operation of a  nuclear power plant is covered from every professional aspect for the sake of nuclear safety. To demonstrate this,  various risk factors will be paired with the operational  status of the facility. This relates to the fact that the  operation of the Hungarian nuclear facility is primarily  governed by the Nuclear Safety Manual. Current legislation  contains all those important safety precautions which are in  accordance with all the highly critical systems of the  nuclear facilities that are in operation today. It also includes international recommendations and their relevant points.

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