Experimental Investigation on Dependence of Decontamination Factor on Aerosol Number Concentration in Pool Scrubbing Under Normal Temperature and Pressure

2018 ◽  
Author(s):  
HaoMin Sun ◽  
Shinichi Machida ◽  
Yasuteru Sibamoto ◽  
Yuria Okagaki ◽  
Taisuke Yonomoto
Keyword(s):  
High Performance ◽  
Nuclear Reactor ◽  
Experimental System ◽  
Decontamination Factor ◽  
Number Concentration ◽  
Severe Accident ◽  
Measurement Instruments ◽  
Aerosol Number Concentration ◽  
Real Phenomenon ◽  
Validation Tests

During a severe accident of a nuclear reactor, radioactive aerosols may be released from degraded nuclear fuels. Pool scrubbing is one of the efficient filters with a high aerosol removal efficiency, in other words a high decontamination factor (DF). Because of its high performance, many pool scrubbing experiments have been performed and several pool scrubbing models have been proposed. In the existing pool scrubbing experiments, an experimental condition of aerosol number concentration was seldom taken into account. It is probably because DF is assumed to be independent of aerosol number concentration, at least, in the concentration where aerosol coagulation is limited. The existing pool scrubbing models also follow this assumption. In order to verify this assumption, we performed a pool scrubbing experiment with different aerosol number concentrations under the same boundary conditions. The test section is a transparent polycarbonate pipe with an inner diameter of 0.2 m. 0.5 μm SiO2 particles were used as aerosols. As a result, DF was increasing as decreasing the aerosol number concentration. In order to ensure a reliability of this result, three validation tests were performed with meticulous care. According to the results of these validation tests, it was indicated that DF dependence on the aerosol concentration was not because of our experimental system error including measurement instruments but a real phenomenon of the pool scrubbing.

scholarly journals Experimental Investigation of Decontamination Factor Dependence on Aerosol Concentration in Pool Scrubbing

2019 ◽  
Vol 2019 ◽  
pp. 1-15
Author(s):  
Haomin Sun ◽  
Yasuteru Sibamoto ◽  
Yuria Okagaki ◽  
Taisuke Yonomoto
Keyword(s):  
Particle Number ◽  
Nuclear Reactor ◽  
Gradual Increase ◽  
Decontamination Factor ◽  
Number Concentration ◽  
Aerosol Concentration ◽  
Severe Accident ◽  
Particle Number Concentration ◽  
Aerosol Number Concentration ◽  
Validation Experiments

Because a pool scrubbing is important for reducing radioactive aerosols to the environment for a nuclear reactor in a severe accident situation, many researches have been performed. However, decontamination factor (DF) dependence on aerosol concentration was seldom considered in an aerosol number concentration with limited aerosol coagulation. To investigate an existence of DF dependence on the concentration, DF in a pool scrubbing with 2.4 m water submergence was derived from aerosol measurements by light scattering aerosol spectrometers. It was observed that DF increased monotonically with decreasing particle number concentration in a constant thermohydraulic condition: a gradual increase from 10 to 32 in the range of 1.3×1011 - 8.0×1011/m3 at the inlet and a significant increase from 32 to 77 in the range of 3.6×1010 - 1.3×1011/m3. Two validation experiments were conducted in the range with the gradual DF increase to confirm whether the DF dependence is a real pool scrubbing phenomenon. In addition, characteristics of the DF dependence in different water submergences were investigated experimentally. It was found that the DF dependence became more significant in higher water submergence. Significant DF dependence was observed in the condition of the water submergence higher than 1.6 m and the inlet particle number concentration less than around 1×1011 /m3. It is recommended to perform further analysis for the DF dependence mainly in such condition since it could make a difference to both experiment and model of the pool scrubbing.

scholarly journals Potential source regions of biogenic aerosol number concentration apportioning at King George Island, Antarctic Peninsula

2010 ◽  
Vol 22 (5) ◽  
pp. 580-588 ◽  
Author(s):  
Alexandre S. Alencar ◽  
Heitor Evangelista ◽  
Elaine A. Dos Santos ◽  
Sergio M. Correa ◽  
Myriam Khodri ◽  
...  
Keyword(s):  
Meteorological Data ◽  
Number Concentration ◽  
Weddell Sea ◽  
South Shetland Islands ◽  
Wide Field ◽  
King George Island ◽  
Amundsen Sea ◽  
Atlantic Sector ◽  
Aerosol Number Concentration ◽  
Argentinean Shelf

AbstractNowadays it is well accepted that background aerosols in the boundary layer over remote oceans are of marine origin and not aged continental. Particularly in the Atlantic sector of the Southern Ocean at least four main important regions exhibit significant ocean primary productivity. They are the Bellingshausen–Amundsen Sea, the Weddell Sea, the southern Argentinean shelf and the southern Chilean coast. In this work, we have combined ground-based continuous atmospheric sampling of aerosol number concentration (ANC), over-sea dimethyl sulphide (DMS) measurements, chlorophyll a (chl a) concentration provided by Sea-viewing Wide Field-of-view Sensor (SeaWiFS) satellite images, in situ meteorological data and monthly regional NCEP-NCAR re-analysis wind fields in order to investigate the relative contribution of each of the above regions to the apportionment of the ANC at King George Island (KGI), South Shetland Islands. Our results suggest that, at least during the period from September 1998–December 1999, the southern Argentinean shelf acted as the main contributor to the ANC measured in KGI.

scholarly journals Droplet Clustering in Shallow Cumuli: The Effects of In–Cloud Location and Aerosol Number Concentration

2018 ◽  
Author(s):  
Dillon S. Dodson ◽  
Jennifer D. Small Griswold
Keyword(s):  
Pair Correlation ◽  
Cloud Droplet ◽  
Number Concentration ◽  
Atmospheric Composition ◽  
Cloud Base ◽  
Arrival Times ◽  
Remotely Piloted Aircraft ◽  
Aerosol Number Concentration ◽  
Aerosol Cloud Interactions ◽  
Lifetime Effects

Abstract. Aerosol–cloud interactions are complex, including albedo and lifetime effects that cause modifications to cloud characteristics. With most cloud–aerosol interactions focused on the previously stated phenomena, there has been no in–situ studies that focus explicitly on how aerosols can affect droplet clustering within clouds. This research therefore aims to gain a better understanding of how droplet clustering within cumulus clouds can be influenced by in–cloud droplet location (cloud edge vs. center) and aerosol number concentration. The pair–correlation function (PCF) is used to identify the magnitude of droplet clustering from data collected onboard the Center for interdisciplinary Remotely–Piloted Aircraft Studies (CIRPAS) Twin Otter aircraft, flown during the 2006 Gulf of Mexico Atmospheric Composition and Climate Study (GoMACCS). Time stamps (at 10−4 m spatial resolution) of cloud droplet arrival times were measured by the Artium Flight Phase–Doppler Interferometer (PDI). Using four complete days of data with 81 non–precipitating cloud penetrations organized into two flights of low (L1, L2) and high (H1, H2) pollution data shows more clustering near cloud edge as compared to cloud center for all four cases. Low pollution clouds are shown to have enhanced overall clustering, with flight L2 being solely responsible for this enhanced clustering. Analysis suggests cloud age plays a larger role in the clustering amount experienced than the aerosol number concentration, with dissipating clouds showing increased clustering as compared to growing or mature clouds. Results using a single, vertically developed cumulus cloud demonstrate more clustering near cloud top as compared to cloud base.

scholarly journals Perspectives on a Severe Accident Consequences—10 Years after the Fukushima Accident

2021 ◽  
Vol 2 (4) ◽  
pp. 398-411
Author(s):  
Jinho Song
Keyword(s):  
Nuclear Reactor ◽  
Severe Accident ◽  
Accident Analysis ◽  
Fukushima Accident ◽  
The Public ◽  
Analysis Methodology ◽  
International Attention ◽  
Nuclear Reactor Safety ◽  
Term Monitoring

Scientific issues that draw international attention from the public and experts during the last 10 years after the Fukushima accident are discussed. An assessment of current severe accident analysis methodology, impact on the views of nuclear reactor safety, dispute on the safety of fishery products, discharge of radioactive water to the ocean, status of decommissioning, and needs for long-term monitoring of the environment are discussed.

State of the Art of Nuclear Reactor Instrument Automation

1974 ◽  
Vol 96 (4) ◽  
pp. 394-398
Author(s):  
M. Taeschner ◽  
R. Gariod
Keyword(s):  
High Performance ◽  
Nuclear Reactor ◽  
Research Reactor ◽  
State Of The Art ◽  
Nuclear Research ◽  
Automation System ◽  
Nuclear Research Reactor ◽  
High Investment

Due to its complexity, nuclear reactor instrument automation is a challenge to engineers. High investment and running costs of a nuclear research reactor imply the use of advanced equipment and concepts for instrument automation when striving for high performance, reliability, and operational convenience under budgetary pressure. The article describes a successfully operating instrument automation system stressing the important underlying concepts trying to avoid too much details on specific hardware which is dependent on the time when one must order things.

Marine Technology Nuclear Propulsion in High-Performance Cargo Vessels

2002 ◽  
Vol 39 (01) ◽  
pp. 1-11
Author(s):  
Julio A. Vergara ◽  
Chris B. McKesson
Keyword(s):  
Gas Turbine ◽  
High Speed ◽  
Nuclear Power ◽  
High Performance ◽  
Nuclear Reactor ◽  
Maritime Transportation ◽  
Stable Operation ◽  
Fuel Price ◽  
Nuclear Propulsion ◽  
Recent Developments

It has been about 40 years since nuclear-powered merchant ships were seriously discussed in the naval architecture community. But recent developments in commercial shipping include bigger, faster, and more powerful ships, where nuclear propulsion may be an option worth considering. The development of advanced ship designs opens an opportunity for high-speed maritime transportation that could create new markets and recover a fraction of the high value goods currently shipped only by air. One of the vessels being considered is FastShip, a large monohull ship that would require 250 MW in 5 gas turbine-waterjet units. An estimate of the operation cost of FastShip reveals that its success relies heavily, among other things, on the fuel price, a single factor that comprises more than one third of the total operating costs. The alternative, a nuclear FastShip, would save, per trip, almost 5000 tons of exposure to fuel price fluctuation, and about half of this savings would further be available for additional cargo and revenues. Nuclear power results in a more stable operation due to the relatively constant low price of nuclear fuel. The nuclear power option is suitable for high-power demand and long-haul applications and a reactor pack could be available within the decade. A candidate design would be the helium-cooled reactor, which has been revisited by several nuclear reactor design teams worldwide. For the FastShip a suggested plant would consist of two modular helium reactors, each one with two 50 MW helium turbines and compressors geared to waterjet pumps, plus a single 50 MW gas turbine. This vessel becomes more expensive to build but saves in fuel, and still provides margin for cost, weight and size optimization. This paper discusses general characteristics of a FastShip with such a nuclear power plant and also highlights the benefits, drawbacks, pending issues and further opportunities for nuclear-powered high-speed cargo ships.

Sign in / Sign up

Export Citation Format

Share Document