scholarly journals Development of Efficient External Multi-Hazard Risk Quantification Methodology for Nuclear Facilities

Energies ◽  
2019 ◽  
Vol 12 (20) ◽  
pp. 3925 ◽  
Author(s):  
Shinyoung Kwag ◽  
Jeong Gon Ha ◽  
Min Kyu Kim ◽  
Jung Han Kim
Keyword(s):  
Probability Distribution ◽  
Nuclear Power ◽  
Power Plants ◽  
Algebraic Approach ◽  
Computational Time ◽  
Nuclear Facilities ◽  
Fukushima Accident ◽  
Current Sampling ◽  
The Impact ◽  
Energy Plants

Probabilistic safety assessment (PSA) of nuclear facilities on external multi-hazards has become a major issue after the Fukushima accident in 2011. However, the existing external hazard PSA methodology is for single hazard events and cannot cover the impact of multi-hazards. Therefore, this study proposes a methodology for quantifying multi-hazard risks for nuclear energy plants. Specifically, we developed an efficient multi-hazard PSA methodology based on the probability distribution-based Boolean algebraic approach and sampling-based method, which are currently single-hazard PSA methodologies. The limitations of the probability distribution-based Boolean algebraic approach not being able to handle partial dependencies between the components are solved through this sampling-based method. In addition, we devised an algorithm that was more efficient than the existing algorithm for improving the limits of the current sampling-based method, as it required a significant computational time. The proposed methodology was applied from simple examples to single- and multi-hazard PSA examples of actual nuclear power plants. The results showed that the proposed methodology was verified in terms of accuracy and efficiency perspectives. Regarding the sampling-based method, it was confirmed that the proposed algorithm yielded fragility and risk results that have similar degrees of accuracy, even though it extracted a smaller number of samples than the existing algorithm.

scholarly journals Use of historical information in extreme-surge frequency estimation: the case of marine flooding on the La Rochelle site in France

2015 ◽  
Vol 15 (7) ◽  
pp. 1515-1531 ◽  
Author(s):  
Y. Hamdi ◽  
L. Bardet ◽  
C.-M. Duluc ◽  
V. Rebour
Keyword(s):  
Nuclear Power ◽  
Power Plants ◽  
Frequency Estimation ◽  
Atlantic Coast ◽  
Historical Period ◽  
Data Sets ◽  
Nuclear Facilities ◽  
Threshold Method ◽  
Historical Information ◽  
The Impact

Abstract. Nuclear power plants located in the French Atlantic coast are designed to be protected against extreme environmental conditions. The French authorities remain cautious by adopting a strict policy of nuclear-plants flood prevention. Although coastal nuclear facilities in France are designed to very low probabilities of failure (e.g., 1000-year surge), exceptional surges (outliers induced by exceptional climatic events) have shown that the extreme sea levels estimated with the current statistical approaches could be underestimated. The estimation of extreme surges then requires the use of a statistical analysis approach having a more solid theoretical motivation. This paper deals with extreme-surge frequency estimation using historical information (HI) about events occurred before the systematic record period. It also contributes to addressing the problem of the presence of outliers in data sets. The frequency models presented in the present paper have been quite successful in the field of hydrometeorology and river flooding but they have not been applied to sea level data sets to prevent marine flooding. In this work, we suggest two methods of incorporating the HI: the peaks-over-threshold method with HI (POTH) and the block maxima method with HI (BMH). Two kinds of historical data can be used in the POTH method: classical historical maxima (HMax) data, and over-a-threshold supplementary (OTS) data. In both cases, the data are structured in historical periods and can be used only as complement to the main systematic data. On the other hand, in the BMH method, the basic hypothesis in statistical modeling of HI is that at least one threshold of perception exists for the whole period (historical and systematic) and that during a giving historical period preceding the period of tide gauging, only information about surges above this threshold have been recorded or archived. The two frequency models were applied to a case study from France, at the La Rochelle site where the storm Xynthia induced an outlier, to illustrate their potentials, to compare their performances and especially to analyze the impact of the use of HI on the extreme-surge frequency estimation.

scholarly journals Uncertainties in the assessment of the radiation impact on biota in the vicinity of nuclear facilities

2021 ◽  
Vol 30 (3) ◽  
pp. 112-123
Author(s):  
S.I. Spiridonov ◽  
◽  
V.E. Nushtaeva ◽  
Keyword(s):  
Radiation Dose ◽  
Dose Rate ◽  
Nuclear Power ◽  
Power Plants ◽  
Nuclear Facilities ◽  
Radiation Dose Rate ◽  
Radiation Background ◽  
Dose Rates ◽  
Radioactive Release ◽  
The Impact

Evaluation of radiation impact on biota inhabiting near nuclear facilities of radioactive release to atmosphere from reactors of different types (WWER-1200, BN-600, BN-800, UVV-2M) is consid-ered in the paper. Radiation dose rates to reference groups of terrestrial biota species (annelids, insects, large and small mammals, grasses and conifers) vary from 0.01 to 0.2 µGy/day. The im-pact of the NPP using up-to-date reactor WWER-1200 is shown to be not exceeding 1% of the to-tal radiation impact. To compare correctly radiation impacts on the biota species from radioactive release and from exposure to established radiation dose rate limits, it is necessary to take into account contribution of all constituents of radiation background. Impacts on biota species from the total exposure to radioactive release or the exposure to established radiation dose rate limits were evaluated. Estimated radiation impact from exposure to the radioactive release did not ex-ceed 0.1; the impact from the established dose rate limits was 0.9. Obtained information allows making the following conclusion: uncertainty of quantitative evaluation of radiation impact on bio-ta in planned radiation situations is mainly caused by uncertainty of established dose rate limits. There is a need to establish dose criteria for emergency, it will allow creating “weighty” radioeco-logic justification of “nuclear power plants with account for potential emergency conditions.

scholarly journals Global Radioxenon Emission Inventory from Nuclear Power Plants for the Calendar Year 2014

2020 ◽  
Author(s):  
Martin B. Kalinowski ◽  
Halit Tatlisu
Keyword(s):  
Nuclear Power ◽  
Power Plants ◽  
Nuclear Power Plants ◽  
Emission Inventory ◽  
Atmospheric Transport ◽  
Noble Gas ◽  
Nuclear Facilities ◽  
Transport Modelling ◽  
Atmospheric Transport Modelling ◽  
The Impact

Abstract For the purpose of monitoring for compliance with the Comprehensive Nuclear-Test-Ban Treaty (CTBT), the International Monitoring System (IMS) is being established that includes 40 sensor systems for atmospheric xenon radioactivity. Its purpose is to monitor the atmosphere for signatures that may indicate a nuclear explosion. Normal operational releases of radioxenon from nuclear facilities can regularly be observed by these very high-sensitive noble gas systems. Existing best estimates of releases for a generic year are unlikely to apply for any specific year at the level of individual facilities because their releases are highly variable and can change by several orders of magnitude from year to year. In this paper, best knowledge of the radioxenon emission inventory from nuclear power plants (NPPs) is collected for the calendar year 2014. The distribution function for each CTBT relevant radioxenon isotope is derived from all releases from NPPs as reported for 2014. The data of this paper can be used for developing and validating methods based on atmospheric transport modelling that are designed to enhance understanding of the impact of known sources on the IMS background observations.

scholarly journals Comparison and Evaluation of Domestic and Foreign Radiation Environmental Standards for Nuclear Power Plants

2021 ◽  
Vol 2083 (2) ◽  
pp. 022020
Author(s):  
Jiahuan Yu ◽  
Xiaofeng Zhang
Keyword(s):  
Power Plant ◽  
Nuclear Power Plant ◽  
Nuclear Power ◽  
Power Plants ◽  
Nuclear Power Plants ◽  
The United States ◽  
Discharge System ◽  
Radioactive Effluent ◽  
Effluent Discharge ◽  
The Impact

Abstract With the development of the nuclear energy industry and the increasing demand for environmental protection, the impact of nuclear power plant radiation on the environment has gradually entered the public view. This article combs the nuclear power plant radiation environmental management systems of several countries, takes the domestic and foreign management of radioactive effluent discharge from nuclear power plants as a starting point, analyses and compares the laws and standards related to radioactive effluents from nuclear power plants in France, the United States, China, and South Korea. In this paper, the management improvement of radioactive effluent discharge system of Chinese nuclear power plants has been discussed.

scholarly journals Radioactivity control strategy for the JUNO detector

2021 ◽  
Vol 2021 (11) ◽  
Author(s):  
◽  
Angel Abusleme ◽  
Thomas Adam ◽  
Shakeel Ahmad ◽  
Rizwan Ahmed ◽  
...  
Keyword(s):  
Natural Radioactivity ◽  
Nuclear Power ◽  
Power Plants ◽  
Liquid Scintillator ◽  
Neutrino Flux ◽  
Neutrino Interaction ◽  
Background Count ◽  
Background Count Rate ◽  
Scientific Goal ◽  
The Impact

Abstract JUNO is a massive liquid scintillator detector with a primary scientific goal of determining the neutrino mass ordering by studying the oscillated anti-neutrino flux coming from two nuclear power plants at 53 km distance. The expected signal anti-neutrino interaction rate is only 60 counts per day (cpd), therefore a careful control of the background sources due to radioactivity is critical. In particular, natural radioactivity present in all materials and in the environment represents a serious issue that could impair the sensitivity of the experiment if appropriate countermeasures were not foreseen. In this paper we discuss the background reduction strategies undertaken by the JUNO collaboration to reduce at minimum the impact of natural radioactivity. We describe our efforts for an optimized experimental design, a careful material screening and accurate detector production handling, and a constant control of the expected results through a meticulous Monte Carlo simulation program. We show that all these actions should allow us to keep the background count rate safely below the target value of 10 Hz (i.e. ∼1 cpd accidental background) in the default fiducial volume, above an energy threshold of 0.7 MeV.

Root Cause of Thermal Sleeve Loosening in a Korean Standard Nuclear Power Plant

2006 ◽  
Author(s):  
Sang-Nyung Kim ◽  
Sang-Gyu Lim
Keyword(s):  
Power Plant ◽  
Nuclear Power Plant ◽  
Nuclear Power ◽  
Power Plants ◽  
Measurement Data ◽  
Significant Loss ◽  
Design Modification ◽  
Root Cause ◽  
Explosive Expansion ◽  
The Impact

The safety injection (SI) nozzle of a 1000MWe-class Korean standard nuclear power plant (KSNP) is fitted with thermal sleeves (T/S) to alleviate thermal fatigue. Thermal sleeves in KSNP #3 & #4 in Yeonggwang (YG) & Ulchin (UC) are manufactured out of In-600 and fitted solidly without any problem, whereas KSNP #5 & #6 in the same nuclear power plants, also fitted with thermal sleeves made of In-690 for increased corrosion resistance, experienced a loosening of thermal sleeves in all reactors except KSNP YG #5-1A, resulting in significant loss of generation availability. An investigation into the cause of the loosening of the thermal sleeves only found out that the thermal sleeves were subject to severe vibration and rotation, failing to uncover the root cause and mechanism of the loosening. In an effort to identify the root cause of T/S loosening, three suspected causes were analyzed: (1) the impact force of flow on the T/S when the safety SI nozzle was in operation, (2) the differences between In-600 and In-690 in terms of physical and chemical properties (notably the thermal expansion coefficient), and (3) the positioning error after explosive expansion of the T/S as well as the asymmetric expansion of T/S. It was confirmed that none of the three suspected causes could be considered as the root cause. However, after reviewing design changes applied to the Palo Verde nuclear plant predating KSNP YG #3 & #4 to KSNP #5 & #6, it was realized that the second design modification (in terms of groove depth & material) had required an additional explosive energy by 150% in aggregate, but the amount of gunpowder and the explosive expansion method were the same as before, resulting in insufficient explosive force that led to poor thermal sleeve expansion. T/S measurement data and rubbing copies also support this conclusion. In addition, it is our judgment that the acceptance criteria applicable to T/S fitting was not strict enough, failing to single out thermal sleeves that were not expanded sufficiently. Furthermore, the T/S loosening was also attributable to lenient quality control before and after fitting the T/S that resulted in significant uncertainty. Lastly, in a flow-induced vibration test planned to account for the flow mechanism that had a direct impact upon the loosening of the thermal sleeves that were not fitted completely, it was discovered that the T/S loosening was attributable to RCS main flow. In addition, it was proven theoretically that the rotation of the T/S was induced by vibration.

Nuclear power generation, renewable resources and endogenous growth

2012 ◽  
pp. 65-93
Author(s):  
Riccardo Costantini
Keyword(s):  
Radioactive Waste ◽  
Endogenous Growth ◽  
Nuclear Power ◽  
Power Plants ◽  
Preference Relation ◽  
Learning By Doing ◽  
Environmental Literature ◽  
Long Run ◽  
Simplifying Assumptions ◽  
The Impact

The author develops an endogenous growth framework in which energy production is based on a learning by doing technology exploiting renewable reproducible capital and nuclear power plants. Consumption activities generates radioactive waste according to an exogenous factor reflecting the economy energy mix, while an abatement technology, reducing the impact of solid waste accumulation on welfare, is explicitly taken into account. Differently from traditional growth and environmental literature, the author includes an explicit preference for the technology mix by postulating a non separable utility in consumption, radioactive waste and stock of renewable capital. Within this framework the author derives conditions on preferences under which sustained growth is attainable without imposing, ex ante, neither compensation nor a distaste effect characterizing utility. Finally, introducing simplifying assumptions on the preference relation, an investigation of the dynamic property of the equilibrium is provided. The results obtained suggest a high complementarity of renewable capital and nuclear technology exploitation in determining potential long run growth.

Cyber Security Assessment of NPP I&C Systems

2020 ◽  
pp. 221-238
Author(s):  
Oleksandr Klevtsov ◽  
Artem Symonov ◽  
Serhii Trubchaninov
Keyword(s):  
Control Systems ◽  
Cyber Security ◽  
Nuclear Power ◽  
Power Plants ◽  
Cyber Attacks ◽  
Security Assessment ◽  
Nuclear Facilities ◽  
Security Risks ◽  
Cyber Threats ◽  
And Control

The chapter is devoted to the issues of cyber security assessment of instrumentation and control systems (I&C systems) of nuclear power plants (NPP). The authors examined the main types of potential cyber threats at the stages of development and operation of NPP I&C systems. Examples of real incidents at various nuclear facilities caused by intentional cyber-attacks or unintentional computer errors during the maintenance of the software of NPP I&C systems are given. The approaches to vulnerabilities assessment of NPP I&C systems are described. The scope and content of the assessment and periodic reassessment of cyber security of NPP I&C systems are considered. An approach of assessment to cyber security risks is described.

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