scholarly journals Aerosol dynamics and dispersion of radioactive particles

2021 ◽  
Vol 21 (6) ◽  
pp. 5173-5193
Author(s):  
Pontus von Schoenberg ◽  
Peter Tunved ◽  
Håkan Grahn ◽  
Alfred Wiedensohler ◽  
Radovan Krejci ◽  
...  
Keyword(s):  
Power Plant ◽  
Nuclear Power Plant ◽  
Wet Deposition ◽  
Nuclear Power ◽  
Full Range ◽  
Radioactive Material ◽  
Dynamic Processes ◽  
Ambient Aerosol ◽  
Aerosol Dynamics ◽  
The Impact

Abstract. In the event of a failure of a nuclear power plant with release of radioactive material into the atmosphere, dispersion modelling is used to understand how the released radioactivity is spread. For the dispersion of particles, Lagrangian particle dispersion models (LPDMs) are commonly used, in which model particles, representing the released material, are transported through the atmosphere. These model particles are usually inert and undergo only first-order processes such as dry deposition and simplified wet deposition along the path through the atmosphere. Aerosol dynamic processes including coagulation, condensational growth, chemical interactions, formation of new particles and interaction with new aerosol sources are usually neglected in such models. The objective of this study is to analyse the impact of these advanced aerosol dynamic processes if they were to be included in LPDM simulations for use in radioactive preparedness. In this investigation, a fictitious failure of a nuclear power plant is studied for three geographically and atmospherically different sites. The incident was simulated with a Lagrangian single-trajectory box model with a new simulation for each hour throughout a year to capture seasonal variability of meteorology and variation in the ambient aerosol. (a) We conclude that modelling of wet deposition by incorporating an advanced cloud parameterization is advisable, since it significantly influence simulated levels of airborne and deposited activity including radioactive hotspots, and (b) we show that inclusion of detailed ambient-aerosol dynamics can play a large role in the model result in simulations that adopt a more detailed representation of aerosol–cloud interactions. The results highlight a potential necessity for implementation of more detailed representation of general aerosol dynamic processes into LPDMs in order to cover the full range of possible environmental characteristics that can apply during a release of radionuclides into the atmosphere.

Application of Risk-Informed Methods to Improve Plant Operation at Kozloduy Nuclear Power Plant

2009 ◽  
Author(s):  
Emil Kichev ◽  
Ivan Ivanov ◽  
Kaliopa Mancheva ◽  
Yasen Petrov ◽  
Vesselina Vladimirova ◽  
...  
Keyword(s):  
Power Plant ◽  
Nuclear Power Plant ◽  
Nuclear Power ◽  
Power Level ◽  
Full Range ◽  
Economic Benefits ◽  
Pressurized Water ◽  
Safety Systems ◽  
The Impact ◽  
Service Inspection

Refueling outages at the Kozloduy Nuclear Power Plant (KNPP) Units 5 and 6 are used to perform annual repairs and preventive maintenance activities, piping inspections, and test activities. A refueling outage at KNPP typically requires 60 days and occurs on an annual basis. Testing of safety systems at the KNPP Units 5 and 6 is an extensive exercise that results in multiple actuations of all components during each test and a relatively high number of component actuations each year. This results in equipment wear out issues that can lead to considerable component replacement and/or refurbishment. Numerous piping in-service inspections are conducted in locations where there has been no industry or plant-specific indications or failures, leading to unnecessary personnel exposure. KNPP is interested in using risk-informed (RI) approaches to reduce refueling outage length, piping inspections, testing, and exposure. KNPP is a four-loop Voda-Vodyanoi Energetichesky Reaktor (VVER) with a power level of 1000 MWe. Safety systems consist of three trains. The KNPP at-power probabilistic safety assessment (PSA) model includes internal and external events. It addresses the full range of events leading to core damage frequency (CDF) and includes a simplified level 2 model leading to large early release frequency (LERF). The RI approach, as defined in the U.S. Nuclear Regulatory Commission’s (NRC’s) risk-informed (RI) Regulatory Guides (RGs) 1.174, 1.177, and 1.178, was used in this program. The specific approach used for risk-informed in-service inspection (RI-ISI) is based on the Pressurized Water Reactor Owner’s Group methodology. The overall approach for each of the three applications used a multi-step process which included the following: identification of systems to address; identification of alternatives to current maintenance, inspection, and testing practices; a risk assessment of the proposed alternatives; an assessment of the impact of the changes on deterministic considerations; identification of monitoring requirements; and an assessment of the economic benefits. The RI-ISI program also considered the impact of the changes on personnel exposure. The overall approach made extensive use of data assessments, reliability methods, and risk assessments. The results demonstrated that the proposed changes in maintenance, in-service inspection, and testing programs have a small impact on risk, based on CDF and LERF. In addition, the proposed changes provide significant benefits in terms of reduced outage time, in-service inspections, testing requirements, and personnel exposure. The economic analysis demonstrated that changes to the maintenance program provide the largest benefit followed by the changes to the in-service inspection program and then the changes to the testing program.

scholarly journals Aerosol dynamics and dispersion of radioactive particles

2020 ◽  
Author(s):  
Pontus von Schoenberg ◽  
Peter Tunved ◽  
Håkan Grahn ◽  
Alfred Wiedensohler ◽  
Radovan Krejci ◽  
...  
Keyword(s):  
Hot Spots ◽  
Wet Deposition ◽  
Nuclear Power ◽  
Particle Dispersion ◽  
Radioactive Material ◽  
Dynamic Processes ◽  
Aerosol Dynamics ◽  
Aerosol Sources ◽  
Condensational Growth ◽  
Airborne Radioactivity

Abstract. In an event of a nuclear power plant failure with release of radioactive material into the atmosphere, dispersion modelling is used to understand, how the released radioactivity is spread. For the dispersion of particles, Lagrangian Particle Dispersion Models, LPDMs are commonly used in which model particles, representing the released material, are transported through the atmosphere. These model particles are usually inert and undergo only first order processes such as dry deposition and simplified wet deposition along the path through the atmosphere. Aerosol dynamic processes including coagulation, condensational growth, chemical interactions, formation of new particles and interaction with new aerosol sources are usually neglected in such models. The objective for this study is to analyse the importance of including more advanced aerosol dynamic processes in LPDM simulations for the use in radioactive preparedness. In this investigation, a fictitious NPP failure, commencing with hourly separation for a full year, is studied for three geographically and atmospherically different sites. We conclude that: a) modelling of wet deposition by incorporating an advanced cloud parameterisation is advisable since, it significantly influence simulated levels of airborne activity as well as the formation of hotspots, and b) with advanced cloud parametrisation in the model, the inclusion of full aerosol dynamics can make a difference in single events, especially for formation of hot spots e.g. in 5 % of the simulated cases the decrease of airborne radioactivity concentration differed with more than 60 %-points compared to a simplified version of the model.

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.

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.

scholarly journals Blowout Accident Impact Analysis Method for the Siting of Offshore Floating Nuclear Power Plant in Offshore Oil Fields

2019 ◽  
Vol 2019 ◽  
pp. 1-7
Author(s):  
Zhigang Lan
Keyword(s):  
Power Plant ◽  
Nuclear Power Plant ◽  
Nuclear Power ◽  
Power Plants ◽  
Impact Analysis ◽  
Oil Spills ◽  
Oil Field ◽  
Oil Fields ◽  
Offshore Oil ◽  
The Impact

Focused on the utilization of nuclear energy in offshore oil fields, the correspondence between various hazards caused by blowout accidents (including associated, secondary, and derivative hazards) and the initiating events that may lead to accidents of offshore floating nuclear power plant (OFNPP) is established. The risk source, risk characteristics, risk evolution, and risk action mode of blowout accidents in offshore oil fields are summarized and analyzed. The impacts of blowout accident in offshore oil field on OFNPP are comprehensively analyzed, including injection combustion and spilled oil combustion induced by well blowout, drifting and explosion of deflagration vapor clouds formed by well blowouts, seawater pollution caused by blowout oil spills, the toxic gas cloud caused by well blowout, and the impact of mobile fire source formed by a burning oil spill on OFNPP at sea. The preliminary analysis methods and corresponding procedures are established for the impact of blowout accidents on offshore floating nuclear power plants in offshore oil fields, and a calculation example is given in order to further illustrate the methods.

On the Feasibility of Nuclear Versus Combustion Gas Turbine Propulsion for High-Speed Cargo Ships

2004 ◽  
Author(s):  
H. Boonstra ◽  
A. C. Groot ◽  
C. A. Prins
Keyword(s):  
Power Plant ◽  
Nuclear Power Plant ◽  
Gas Turbine ◽  
High Speed ◽  
Nuclear Power ◽  
Parametric Design ◽  
Pebble Bed ◽  
Pressurized Water ◽  
Combustion Gas ◽  
The Impact

This paper presents the outcome of a study on the feasibility of a nuclear powered High-Speed Pentamaran, initiated by Nigel Gee and Associates and the Delft University of Technology. It explores the competitiveness of a nuclear power plant for the critical characteristics of a marine propulsion plant. Three nuclear reactor types are selected: the Pressurized Water Reactor (PWR), the Pebble-bed and Prismatic-block HTGR. Their characteristics are estimated for a power range from 100 MWth to 1000 MWth in a parametric design, providing a level base for comparison with conventional gas turbine technology. The reactor scaling is based on reference reactors with an emphasis on marine application. This implies that preference is given to passive safety and simplicity, as they are key-factors for a marine power plant. A case study for a 60-knot Pentamaran shows the impact of a nuclear power plant on a ship designed with combustion gas turbine propulsion. The Prismatic-block HTGR is chosen as most suitable because of its low weight compared to the PWR, in spite of the proven technology of a PWR. The Pebble-bed HTGR is considered too voluminous for High-Speed craft. Conservative data and priority to simple systems and high safety leads to an unfavorable high weight of the nuclear plant in competition with the original gas turbine driven Pentamaran. The nuclear powered ship has some clear advantages at high sailing ranges.

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