Nuclear Power Plant Risk Research Articles

Analysis of the Relationship between Risk Perception and Willingness to Pay for Nuclear Power Plant Risk Reduction

With the adoption of new technologies, more risk is introduced into modern society. Important decisions about new technologies tend to be made by specialists, which can lead to a mismatch of risk perception between citizens and specialists, resulting in high social cost. Using contingent valuation methods, this paper analyzes the relationship between willingness to pay (WTP) and the factors expressed through people’s image of nuclear power plants (NPP), their perception of NPP safety, and how these can be affected by their scientific background level. Results indicate that groups with a high scientific background level tend to have low risk perception level, represented through their image and safety levels. Further, the results show that mean WTP is dependent on scientific background and image levels. It is believed that these results could help decision makers address the mismatch of trust between the public and specialists in terms of new policy.

A Fuzzy Gradient Chance-Constrained Evacuation Model for Managing Risks of Nuclear Power Plants under Multiple Uncertainties

Emergency evacuation is one of the most important risk management measures for nuclear accidents. Evacuation management systems contain various complexities, which have posed many challenges for decision makers. In the study, a fuzzy gradient chance-constrained evacuation model (FGCCEM) is proposed to address different uncertainties in evacuation management and planning. The FGCCEM is developed by incorporating fuzzy gradient chance-constrained programming into an inexact optimization framework. It is capable of balancing decision makers’ optimism and pessimism, and can also reflect uncertainties expressed as discrete intervals. The proposed model is applied to a hypothetical case study of emergency evacuation planning for nuclear power plants. The results indicate that the FGCCEM can generate optimized evacuation schemes to maximize the total number of evacuees within limited time. Meanwhile, evacuation schemes with decision makers’ varied preferences can be obtained through post-optimization analysis. The information obtained in this study can provide an insight into the complex relationships in evacuation management systems. It can also provide valuable decision support for effective risk management in response to nuclear emergencies.

Hedonic valuation of the perceived risks of nuclear power plants

We use the 2011 Fukushima accident to evaluate the impact of the perceived risks of nuclear power plants on apartment rents in Switzerland. Using online advertisements over 12 years and a difference-in-differences approach, we find a 2.3% price discount after the accident for apartments near nuclear power plants.

Overview on hydrogen risk research and development activities: Methodology and open issues

During the course of a severe accident in a light water nuclear reactor, large amounts of hydrogen can be generated and released into the containment during reactor core degradation. Additional burnable gases [hydrogen (H2) and carbon monoxide (CO)] may be released into the containment in the corium/concrete interaction. This could subsequently raise a combustion hazard. As the Fukushima accidents revealed, hydrogen combustion can cause high pressure spikes that could challenge the reactor buildings and lead to failure of the surrounding buildings. To prevent the gas explosion hazard, most mitigation strategies adopted by European countries are based on the implementation of passive autocatalytic recombiners (PARs). Studies of representative accident sequences indicate that, despite the installation of PARs, it is difficult to prevent at all times and locations, the formation of a combustible mixture that potentially leads to local flame acceleration. Complementary research and development (R&D) projects were recently launched to understand better the phenomena associated with the combustion hazard and to address the issues highlighted after the Fukushima Daiichi events such as explosion hazard in the venting system and the potential flammable mixture migration into spaces beyond the primary containment. The expected results will be used to improve the modeling tools and methodology for hydrogen risk assessment and severe accident management guidelines. The present paper aims to present the methodology adopted by Institut de Radioprotection et de Sûreté Nucléaire to assess hydrogen risk in nuclear power plants, in particular French nuclear power plants, the open issues, and the ongoing R&D programs related to hydrogen distribution, mitigation, and combustion.

ICONE23-2017 BRANCH-AND-BOUND ALGORITHM APPLIED TO DYNAMIC PRA WITH UNCERTAINTY QUANTIFICATION FOR LWR STATION BLACKOUT

Probabilistic Risk Assessment (PRA) is an important tool for evaluating risk in nuclear power plants. Dynamic PRA (DPRA) is an extension of traditional PRA methods that account for dynamic and phenomenological effects associated with time-dependent complex dynamic systems. Here we investigated dynamic event trees and optimization per focus on identifying the highest probability of system failure. Using a Branch-and-Bound (B&B) algorithm that relies on and develops bounding functions to prune or delete branches that will not yield the optimal solution (i.e., clad failure). The approach also used novel LENDIT (length, energy, number, distribution, information, time) metrics and S2R2 (state, systems, resources, response) sets to support an expert-based approach that is linked to constraints per use of the B&B algorithm. Results to date indicate that this approach is effective in reducing simulation time and thus mitigating the state explosion of thermal-hydraulic states. The work demonstrated the ability to evaluate uncertainty such that a risk-informed, quantitative PIRT (phenomena identification ranking table) is generated. Quantitative PIRT (QPIRT) can be used to improve models and identify validation needs with respect to risk. Two case studies using reference PWR and BWR plant configurations under SBO were evaluated. The implementation of the B&B algorithm yielded a significant reduction (>50%) in simulation costs. QPIRT ranking for the PWR showed that lower fidelity models combined with system redundancy produces adequate results with respect to risk. For BWR SBO, the modeling uncertainty does not present a challenge with respect to risk. Recovery of the SBO requires either restoration of the AC power or activation of firewater injection combined with operator action to depressurize the system through the automatic depressurization system. The timing of both automatic and manual safety system actuation is indeed critical to the outcome reactor state. Reactor power and firewater injection capacity provided the highest degree of correlation to model success.

Large LOCA accident analysis for AP1000 under earthquake

Seismic probabilistic safety assessment (PSA) is developed to give the insight of nuclear power plant risk under earthquake and the main contributors to the risk. However, component failure probability including the initial event frequency is the function of peak ground acceleration (PGA), and all the components especially the different kinds of components at same place will share the common ground shaking, which is one of the important factors to influence the result. In this paper, we propose an analysis method based on Monte Carlo (MC) simulation in which the effect of all components sharing the same PGA level can be expressed by explicit pattern. The Large LOCA accident in AP1000 is analyzed as an example, based on the seismic hazard curve used in this paper, the core damage frequency is almost equal to the initial event frequency, moreover the frequency of each accident sequence is close to and even equal to the initial event frequency, while the main contributors are seismic events since multi components and systems failures will happen simultaneously when a high value of PGA is sampled. The component failure probability is determined by uncertainties in PGA and in component seismic capacity, and the former is the crucial element to influence the result.

Hedonic Valuation of the Perceived Risks of Nuclear Power Plants

We use the 2011 Fukushima accident to evaluate the impact of the perceived risks of nuclear power plants on apartment rents in Switzerland. Using online advertisements over 12 years and a difference-in-differences approach, we find a 2.3% price discount after the accident for apartments near nuclear power plants.

Development and application of a living probabilistic safety assessment tool: Multi-objective multi-dimensional optimization of surveillance requirements in NPPs considering their ageing

The benefits of utilizing the probabilistic safety assessment towards improvement of nuclear power plant safety are presented in this paper. Namely, a nuclear power plant risk reduction can be achieved by risk-informed optimization of the deterministically-determined surveillance requirements.A living probabilistic safety assessment tool for time-dependent risk analysis on component, system and plant level is developed. The study herein focuses on the application of this living probabilistic safety assessment tool as a computer platform for multi-objective multi-dimensional optimization of the surveillance requirements of selected safety equipment seen from the aspect of the risk-informed reasoning. The living probabilistic safety assessment tool is based on a newly developed model for calculating time-dependent unavailability of ageing safety equipment within nuclear power plants. By coupling the time-dependent unavailability model with a commercial software used for probabilistic safety assessment modelling on plant level, the frames of the new platform i.e. the living probabilistic safety assessment tool are established. In such way, the time-dependent core damage frequency is obtained and is further on utilized as first objective function within a multi-objective multi-dimensional optimization case study presented within this paper. The test and maintenance costs are designated as the second and the incurred dose due to performing the test and maintenance activities as the third objective function.The obtained results underline, in general, the usefulness and importance of a living probabilistic safety assessment, seen as a dynamic probabilistic safety assessment tool opposing the conventional, time-averaged unavailability-based, probabilistic safety assessment. The results of the optimization, in particular, indicate that test intervals derived as optimal differ from the deterministically-determined ones defined within the existing technical specifications. Substantial risk reduction, supplemented with reduction in costs and dose is implicated if the selected existing surveillance test intervals are replaced with the corresponding optimal ones. By this, the benefits of applying risk-informed decision making are once more emphasized. Also, the importance of the inclusion of safety equipment ageing in the plant long-term probabilistic safety assessment is recognized.

Safety Study of Primary Loop System of Civil Marine Nuclear Power Plant

For evaluate the risk of civil marine nuclear power plant, through the searching related standards for ship, external environmental parameters that the nuclear ship should be suited was found. Based on the characteristics of power plant of civil nuclear-powered ship, the hierarchy system of primary loop system was established and corresponding indicator marking criteria were formulated for the risk assessment. The result shows that the Reactor Safety Injection System (RIS), the Reactor Boron and the Water Supply System (REA), the Control Rods and the Hull of Fuel Canning are the key risk factors in the primary loop system. Finally, the comprehensive evaluation was carried out for collision, stranding and swing of multi-degree of freedom, and put forward relative countermeasures to cope with the possible risks based on the comprehensive evaluation and combined with the literatures.

The perception of risk on human health from nuclear power among educated Swedish young adults: a pilot qualitative study

This paper aims at exploring how young adults in Sweden perceive the risk of nuclear power on human health. Purposive sampling technique was applied to recruit study subjects who were individually interviewed. Manifest and latent content analysis of the interview narratives were applied. All the informants perceive nuclear power as a source of risk but they differed in their assessment of risk from nuclear power. The Swedish nuclear governance authorities need to intensify their efforts in building trust with young adults by providing more credible information and by facilitating as well as initiating open discussions about the risks of Nuclear Power Plants (NPPs). This may reduce the fear from the NPPs and thus the risk of potentially related health problems.

Case studies for evaluating conditional probabilities of external explosions

Abstract In recent years international experience has shown that external hazards can be safety significant contributors to the risk for nuclear power plants because such hazards have the potential to reduce simultaneously the level of redundancy by damaging redundant systems. Therefore, effective protections against external hazards have to be accurately assessed applying deterministic, probabilistic or combined methodologies. With respect to the external hazard “explosion” – two different types of risky situations for the plant under consideration have to be investigated: the explosive material is available as a stationary source in the neighbourhood of the plant or the explosive material is mobile (i. e. by ships, rails or trucks). In the latter case, the situation changes with the varying distances. Moreover, the transport way could be a straight line or a bent which also has to be addressed in the calculations. Methods which can be applied to evaluate the probability of occurrence of an external explosion event are, e. g., fault tree analyses, event tree analyses and Monte Carlo simulations. Two case studies applying Monte Carlo simulations for assessing the probability of occurrence of external explosion events, given an accident with creation of an explosive gas cloud, are presented.

Attenuation of radioactive releases from NPP under accident conditions: An experimental research on risk-dominant scenarios

Accident scenarios in which a nuclear power plant (NPP) containment is by-passed, may become a significant contribution to the NPP risk. The reason is the direct access to the environment that any radioactive material escaping from a degrading core would have. This is the case of steam generator tube rupture (SGTR) severe accident sequences in pressurized water reactors (PWRs), in which tube breaches in the steam generator communicate the primary system of the nuclear reactor and the environment.This paper presents the major results of an experimental investigation aimed to assess and characterize the mitigation of radioactive releases when flowing through the secondary side of a steam generator during SGTR severe accident sequences. A set of experiments performed in a mock-up tube bundle scaled from a real steam generator has demonstrated that particles are significantly retained in the region around the breach, even in the total absence of water. The tests explored the anticipated conditions in the scenario: gas jet injection, micron particles of different nature (dense spheres vs. aggregates) and tube breach types (guillotine vs. fish-mouth). The main variable affecting retention is the particle nature. The collection efficiency reached 75–95% in the case of dense spheres. The influence of natural aerosol mechanisms like inertial impaction, turbulent deposition, resuspension and fragmentation are discussed in the paper.

Economics of Global Early Warning: Monitoring Global Risks on Environment, Development, Peace and Human Rights

The first generation GEWS ( global early waning system) designed by Akira Onishi in 1985-86 is known as global early warning system for forced migration. The next generation FGMS ( Futures of Global Iinterdependence Modeling system) has been designed by the author in 1987-2011 as global early warning system for monitoring global risks on environment, economic development, peace and human rights as economics model as a major core. It is worth noting that East Japan great disaster coinsides of earthqwake and tsunami, subsequent meltdown of reacors, occured on March 11 in 2011 has brought attention on importance of early warning for monitoring natural sisasters and profound potencial risks of nuclear power plants near bay sides. At the same time, recent financial risks initiated from Greek and Euro zone might quickly induce global financial risks, if immediate proper actions could not be performed. The US economy also faces new economic risks starting from increasing gap between the 1 percent rich and 99percent poor strata of the population together with increasing mass unemployment rates. In the developing countries, new demonstration against the Egypt and Siria government have provoked new waves of political unrests not only in Africa but Middle East as awhole. Iran started from developing nucler weapons has paramount risk to incuce new oil crisis and potencial military conflicts. hina also faces economic dilenma setting lower growth target on the way of sustainable development of in the global economy. strengthen missile powers of North Korea also may induce increasing fears and potencial conflicts in the Asia-Pacific area, while movement toward Asain community and econoic ties will be strengthen in the futures. Again Japan should take initiative towards innovative technology for sustainable development of global interdependent econmy. Japan faces the most aging society among the global community and should introduce new strategy for green revilution. In order to improve QOL ( Quality of life) beyond HOB happiness of Bhutan, Japan should try to cutback standard labor days and hours, raising labor productivity by introducing humanoid robotics. The UN organizations will be hoped to take preventive meadures against global risks and preparation of new guidlines for solidarity and harmony by introducing cosmic mind to overcome differences between race, culture and religion on the planet Earth.

Preferences, Knowledge, and Citizen Probability Assessments of the Terrorism Risk of Nuclear Power

AbstractHow does the American public assess risk when it comes to national security issues? This paper addresses this question by analyzing variation in citizen probability assessments of the terrorism risk of nuclear power plants. Drawing on the literature on how motivated reasoning, selective information processing, and domain‐specific knowledge influence public opinion, we argue that heterogeneous issue preferences and knowledge of nuclear energy and homeland security have important explanatory power. Using original data from a unique 2009 national survey in the United States, we show that Americans are divided in their probability assessments of the terrorism risk of nuclear power plants. Consistent with our theoretical expectations, individuals who support using nuclear power to meet rising energy demands, who are generally less concerned with terrorism, or who are more knowledgeable about terrorism and nuclear security tend to provide lower assessments of the likelihood that nuclear power plants increase terrorist attacks, and vice versa. The findings have implications for the literature on public opinion, risk assessment, energy policy and planning, and homeland security.

The Effect on the Voltage Sag of Safety Related Bus and the Operating Characteristics of Motor due to Electrical Transients in Nuclear Power Plants

When electric faults take place in onsite power system of nuclear power plants, the voltage of safety related bus can be affected, as a form of voltage sag, by electrical transients. The safety related buses in nuclear power plants have a role of power supplying to essential loads for safety shutdown of reactor. If voltage sag of the safety related bus would be occurred and impact on the operating characteristics of motor would be existed, the risk of nuclear power plants will be increased. Therefore, it is important to analyze the effect on voltage sag of safety related bus and operating characteristics of motor due to electrical transients in nuclear power plants. This study performed that the phenomenon of voltage sag and the effect on motor operation by various electrical transients are simulated and analyzed.

Low Cholesterol is Associated with Mortality from Cardiovascular Diseases: A Dynamic Cohort Study in Korean Adults

This study was conducted to evaluate the association of single serum total cholesterol (TC) measurement with cardiovascular diseases (CVD) deaths in Korean adults. The study subjects were taken from the multi-site collaborative dynamic prospective cohort for epidemiologic investigation on cancer risk in residents nearby nuclear power plants in Korea. A total of 12,740 adults aged 40 to 69 yr who underwent a mass screening examination were followed up from 1993 to 2008. Occurring CVD deaths were confirmed by the death certificates in the National Statistical Office, Korea. Groups with the lowest group having TC < 160 mg/dL as well as the highest group having >= 240 mg/dL were associated with higher CVD mortality in Cox proportional hazards analysis adjusting for age, sex, smoking and drinking status, body mass index, level of blood pressure, triglyceride and high density lipoprotein cholesterol. The distribution of adjusted hazard ratios showed the U-shaped curve. Based on the results of this study, caution should be taken in prescribing statins for primary prevention among people at low cardiovascular risk in Korean adults.

Comparison of Nuclear Power Plant Risk using Dose-based Risk Measure

In the current risk-informed framework, core damage frequency (CDF) and large early release frequency (LERF) are being widely used as two representative alternative measures to a plant risk. As both measures are focused on frequency itself rather than the plant risk, a simplified and more risk-relevant measure (SiRD) based on both the frequency and the individual dose is proposed as a surrogate for CDF and/or LERF. The whole-body dose and thyroid dose at the exclusion area boundary are introduced to define the surrogate plant risk measure. The site atmospheric dispersion factor, the dose conversion factor for the semi-infinite cloud model for fission products, the breathing rate, and the total activity of the fission product are considered for the dose calculations. The SiRD indices have been calculated for the source term release categories that have been defined at UCN 3&4 (PWR) and WS 1 (PHWR) probabilistic safety assessments (PSAs) in Korea and they were used to compare the nuclear power plant risk as a relative risk measure. The results show that the individual risk at WS 1 is less than that at UCN 3&4, due to the lower release fraction of fission products and the lower frequency of the initiating events.

Managing construction risks of AP1000 nuclear power plants in China

Large and complex construction projects face risk from various sources and the successful completion of such projects depends on effective risk management. This study investigates the risk faced by Chinese firms participating in constructing AP1000 nuclear power plants in China. AP1000 nuclear reactors are new, Generation III+ reactors designed by Westinghouse and to be built first in China. The semi-structured interview approach is used to elicit information from experts involved in the AP1000 projects in China. Based on the interviews, various sources of risk are identified. In addition to general risks that megaprojects normally face, there are unique risks that arise from various sources such as technological, political, organizational, and individual personnel risks. Risk management strategies are proposed to manage general and unique risks identified in the study. The findings of this study would be helpful for Chinese companies involved in the construction of AP1000 nuclear power plants to mitigate the risks associated with the projects.

ICONE19-43305 Development of Level 1 Seismic PSA Method for Multi-Unit Site

Internal events as well as external events as initiators that may entail potential consequence have to be considered when we discuss the comprehensive risk of Nuclear Power Plant (NPP). Two or more NPPs that are located at a multi-unit site or close to each other could fail simultaneously at seismic event as one of external events, depending on the degree of seismic ground motion and its impact to units of the site. The seismometers at the Kashiwazaki-Kariwa NPPs recorded different time-histories of ground motion due mainly to the folding structure beneath the free field rock surface and to the installation condition of the embedded buildings, when the Niigata-ken Chuetsu-oki earthquake in July, 2007, impacted on the Site significantly. This suggested the different input ground motions on all plants at the site. Then the method is being enhanced to be applicable even if different input ground motions to respective plants at the site may happen to be generated. The interface of seismic hazard evaluation method, structure, system and component (SSC) fragility evaluation method, and accident sequence evaluation method were carefully and systematically considered. The enhanced method was preliminary applied to a hypothetical site where a highly-aseismatic and a lesser-aseismatic designed plant were located, and the applicability of the developed method to LWRs was discussed, applying typical correlation factor to the analysis model. Some insights on accident sequences for both plants failure and for either plant failure ("plant failure" is defined as "serious damage to the reactor core" in this paper.) were obtained from the analysis results. The developed method is robust to delineate the risk profile of multiple NPPs close to each other, being impacted by a strong seismic motion.

Determinants and Mapping of Collective Perceptions of Technological Risk: The Case of the Second Nuclear Power Plant in Taiwan

Nuclear power is a highly controversial and salient example of environmental risk. The siting or operating of a nuclear power plant often faces widespread public opposition. Although studies of public perceptions of nuclear power date back to 1970s, little research attempts to explain the spatial heterogeneity of risk attitude toward nuclear power among individuals or communities. This article intends to improve the knowledge about the major factors contributing to nuclear power plant risk perceptions by mapping the geographical patterns of local risk perception and examining the determinants in forming the nature and distribution of the perceived risk among potentially affected population. The analysis was conducted by a case study of the Second Nuclear Power Plant (SNPP) in Taiwan by using a novel methodology that incorporates a comprehensive risk perception (CRP) model into an ethnographic approach called risk perception mapping (RPM). First, we examined the determinants of local nuclear power risk perceptions through the CRP model and multivariate regression analysis. Second, the results were integrated with the RPM approach to map and explain the spatial pattern of risk perceptions. The findings demonstrate that the respondents regard the nuclear power plant as an extremely high-risk facility, causing them to oppose the SNPP and reject the compensation payment to accept its continuing operation. Results also indicate that perceptions of nuclear power risk were mainly influenced by social trust, psychological and socioeconomic attributes, proximity, and the perceived effects of the SNPP on the quality of everyday life.