scholarly journals An emergency response model for evaluating the formation and dispersion of plumes originating from major fires (BUOYANT v4.20)

2021 ◽  
Author(s):  
Jaakko Kukkonen ◽  
Juha Nikmo ◽  
Kari Riikonen ◽  
Ilmo Westerholm ◽  
Pekko Ilvessalo ◽  
...  
Keyword(s):  
Source Term ◽  
Atmospheric Dispersion ◽  
Plume Rise ◽  
Pool Fires ◽  
Operational Model ◽  
Buoyant Plumes ◽  
Emergency Personnel ◽  
Fire Plumes ◽  
Research Experiment ◽  
Source Term Model

Abstract. A mathematical model called BUOYANT has previously been developed for the evaluation of the dispersion of positively buoyant plumes originating from major warehouse fires. The model addresses the variations of the cross-plume integrated properties of a rising plume in a vertically varying atmosphere and the atmospheric dispersion after the plume rise regime. We have described in this article an extension of the BUOYANT model to include a detailed treatment of the early evolution of the fire plumes, before the plume rise and atmospheric dispersion regimes. The model input and output consist of selected characteristics of forest or pool fires, and the properties of a source term for the plume rise module, respectively. The main model structure of this source term model is based on the differential equations for low-momentum releases of buoyant material, which govern the evolution of the plume radius, velocity and density differences. The model is also partially based on various experimental results on fire plumes. We have evaluated the refined BUOYANT model by comparing the model predictions against the experimental field-scale data of the Prescribed Fire Combustion and Atmospheric Dynamics Research Experiment, RxCADRE. The predicted concentrations of CO2 agreed fairly well with the aircraft measurements conducted in the RxCADRE campaign. We have also compiled an operational version of the model. The operational model can be used for emergency contingency planning and for the training of emergency personnel, in case of major forest and pool fires.

scholarly journals Applicability of an integrated plume rise model for the dispersion from wild-land fires

2014 ◽  
Vol 7 (1) ◽  
pp. 483-527 ◽  
Author(s):  
J. Kukkonen ◽  
J. Nikmo ◽  
M. Sofiev ◽  
K. Riikonen ◽  
T. Petäjä ◽  
...  
Keyword(s):  
Field Experiments ◽  
Prescribed Burning ◽  
Inversion Layer ◽  
Atmospheric Dispersion ◽  
Heat Fluxes ◽  
Airborne Lidar ◽  
Plume Rise ◽  
Buoyant Plume ◽  
Buoyant Plumes ◽  
Model Predictions

Abstract. We have presented an overview of a mathematical model, BUOYANT, that was originally designed for the evaluation of the dispersion of buoyant plumes originated from major warehouse fires. The model addresses the variations of the cross-plume integrated properties of a buoyant plume in the presence of a vertically varying atmosphere. The model also includes a treatment for a rising buoyant plume interacting with an inversion layer. We have compared the model predictions with the data of two prescribed wild-land fire experiments. For the SCAR-C experiment in Quinault (US) in 1994, the predicted vertical extents of the plume at maximum plume rise were between 500–800 m and 200–700 m, using two alternative meteorological datasets. The corresponding observed injection heights of the aerosol particles measured using an airborne LIDAR (LIght Detection And Ranging) ranged from 250 and 600 m. For the prescribed burning experiment in Hyytiälä (Finland) in 2009, the model predictions were compared with plume elevations and diameters, determined based on particulate matter number concentration measurements on board an aeroplane. The agreement of modelled and measured results was good, provided that one assumes the measured maximum convective heat fluxes as input data for the model. The results demonstrate that in field experiments on wild-land fires, there are substantial uncertainties in estimating both (i) the source terms for the atmospheric dispersion computations, and (ii) the relevant vertical meteorological profiles. The results provide more confidence that cross-plume integrated mathematical models, such as the BUOYANT model, can be used to fairly good accuracy for evaluating the dispersion from major wild-land fires.

Operational Model for the Spent Nuclear Fuel Radionuclides Source Term in Presence of Water

2001 ◽  
Author(s):  
Christophe Poinssot ◽  
Christophe Jegou ◽  
Pierre Toulhoat ◽  
Jean-Marie Gras
Keyword(s):  
Nuclear Fuel ◽  
Closed System ◽  
Source Term ◽  
Spent Nuclear Fuel ◽  
Driving Forces ◽  
Spent Fuel ◽  
Microscopic Description ◽  
Operational Model ◽  
Geological Disposal ◽  
Source Term Model

Abstract Under the geological disposal conditions, spent fuel (SF) is expected to evolve during the 10,000 years while being maintained isolated from the biosphere before water comes in. Under those circumstances, several driving forces would lead to the progressive intrinsic transformations within the rod which would modify the subsequent release of radionuclides: the production of a significant volume of He, the accumulation of irradiation defects, the slow migration of radionuclides (RN) within the pellet. However, the current RN source terms for SF never accounted for these evolutions and was based on the existing knowledge on the fresh SF. Two major mechanisms were considered, the leaching of the readily available fraction (one which was supposed to be instantly accessible to water), and the release of RN through alteration of the UO2 grains. We are now proposing a new RN source term model based on a microscopic description of the system in order to also account for the early evolution of the closed system, the amplitude of which increases with the burnup and is greater for MOX fuels.

A Research Reactor Source Term and Dose Results in the Event of a LOCA

2014 ◽  
Author(s):  
Charalampos Pappas ◽  
Andreas Ikonomopoulos ◽  
Athanasios Sfetsos ◽  
Spyros Andronopoulos ◽  
Melpomeni Varvayanni ◽  
...  
Keyword(s):  
Research Reactor ◽  
Source Term ◽  
Dispersion Model ◽  
Ventilation System ◽  
Atmospheric Dispersion ◽  
Reactor Core ◽  
Forecast Model ◽  
Scale Model ◽  
Continuous Reactor ◽  
Reactor Building

The present study discusses the source term derivation and dose result calculation for a hypothetical accident sequence in the Greek Research Reactor – 1 (GRR-1). A loss-of-coolant accident (LOCA) has been selected as a credible accident sequence. The source term derivation has been based on the GRR-1 confinement performance where the inventory has been computed assuming continuous reactor operation. A core damage fraction of 30% has been considered for the calculations while conservative core release fractions have been employed. The radionuclides released from the reactor core to the confinement atmosphere have been subjected to natural decay, deposition on and resuspension from various internal surfaces before being led to the release pathway. It has been assumed that an emergency shutdown is initiated immediately after the beginning of the accident sequence and the emergency ventilation system is also activated. Subsequently, the source term has been derived comprising of noble gases, iodine and aerosol. The JRODOS computational software for off-site nuclear emergency management has been utilized to estimate the dose results from the LOCA-initiated source term that is released in its entirety from the reactor stack at ambient temperature. The Local Scale Model Chain in conjunction with the DIPCOT atmospheric dispersion model that is embedded in JRODOS have been used with proper parameterization of the calculation settings. Five weather scenarios have been selected as representative of typical meteorological conditions at the reactor site. The scenarios have been assessed with the use of the Weather Research and Forecast model. Total effective, skin, thyroid, lung and inhalation doses downwind of the reactor building and up to a distance of 10 km have been calculated for each weather scenario and are presented. The total effective gamma dose rate at a fixed distance from the reactor building has been assessed. The radiological consequences of the dose results are discussed.

Buoyant plumes of large-scale pool fires

1982 ◽  
Vol 19 (1) ◽  
pp. 905-912 ◽  
Author(s):  
Hsiang-Cheng Kung ◽  
Paraskevas Stavrianidis
Keyword(s):  
Large Scale ◽  
Pool Fires ◽  
Buoyant Plumes

Using plume rise schemes to model highly buoyant plumes from large fires

2011 ◽  
Vol 44 (1/2/3/4) ◽  
pp. 226
Author(s):  
H.N. Webster ◽  
B.J. Devenish ◽  
J.M. Haywood ◽  
A.P. Lock ◽  
D.J. Thomson
Keyword(s):  
Plume Rise ◽  
Buoyant Plumes ◽  
Large Fires

scholarly journals Detailed source term estimation of the atmospheric release for the Fukushima Daiichi Nuclear Power Station accident by coupling simulations of an atmospheric dispersion model with an improved deposition scheme and oceanic dispersion model

2015 ◽  
Vol 15 (2) ◽  
pp. 1029-1070 ◽  
Author(s):  
G. Katata ◽  
M. Chino ◽  
T. Kobayashi ◽  
H. Terada ◽  
M. Ota ◽  
...  
Keyword(s):  
Dose Rate ◽  
Nuclear Power ◽  
Source Term ◽  
Dispersion Model ◽  
Atmospheric Dispersion ◽  
Air Concentration ◽  
Power Station ◽  
Release Rates ◽  
Surface Deposition ◽  
Fukushima Daiichi

Abstract. Temporal variations in the amount of radionuclides released into the atmosphere during the Fukushima Daiichi Nuclear Power Station (FNPS1) accident and their atmospheric and marine dispersion are essential to evaluate the environmental impacts and resultant radiological doses to the public. In this paper, we estimate the detailed atmospheric releases during the accident using a reverse estimation method which calculates the release rates of radionuclides by comparing measurements of air concentration of a radionuclide or its dose rate in the environment with the ones calculated by atmospheric and oceanic transport, dispersion and deposition models. The atmospheric and oceanic models used are WSPEEDI-II (Worldwide version of System for Prediction of Environmental Emergency Dose Information) and SEA-GEARN-FDM (Finite difference oceanic dispersion model), both developed by the authors. A sophisticated deposition scheme, which deals with dry and fog-water depositions, cloud condensation nuclei (CCN) activation, and subsequent wet scavenging due to mixed-phase cloud microphysics (in-cloud scavenging) for radioactive iodine gas (I2 and CH3I) and other particles (CsI, Cs, and Te), was incorporated into WSPEEDI-II to improve the surface deposition calculations. The results revealed that the major releases of radionuclides due to the FNPS1 accident occurred in the following periods during March 2011: the afternoon of 12 March due to the wet venting and hydrogen explosion at Unit 1, midnight of 14 March when the SRV (safety relief valve) was opened three times at Unit 2, the morning and night of 15 March, and the morning of 16 March. According to the simulation results, the highest radioactive contamination areas around FNPS1 were created from 15 to 16 March by complicated interactions among rainfall, plume movements, and the temporal variation of release rates. The simulation by WSPEEDI-II using the new source term reproduced the local and regional patterns of cumulative surface deposition of total 131I and 137Cs and air dose rate obtained by airborne surveys. The new source term was also tested using three atmospheric dispersion models (Modèle Lagrangien de Dispersion de Particules d'ordre zéro: MLDP0, Hybrid Single Particle Lagrangian Integrated Trajectory Model: HYSPLIT, and Met Office's Numerical Atmospheric-dispersion Modelling Environment: NAME) for regional and global calculations, and the calculated results showed good agreement with observed air concentration and surface deposition of 137Cs in eastern Japan.

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