1. Air Dispersion Modeling: Planning for Airborne Terrorism Release
National Science Foundation, The University of Texas at Arlington
Joel Hernandez
Crosswinds High School
Teacher Assistant
Tiffany LeBlanc
Baton Rouge Community College
Environmental Engineering
Gerald Gruber
St. Mary’s University
Engineering Science
Dr. Melanie Sattler
University of Texas Arlington
Faculty, Civil Engineering
Dr. Yvette Weatherton
University of Texas Arlington
Faculty, Civil Engineering
Ketwalee Kositkanawuth
University of Texas Arlington
Graduate Student
Outcomes and Impact
Worst Case Scenario:
-This plot shows a graph of the plume and important measurements. The Inner Contour line affected the population the most due to the highest concentration of deadly radiation. (Figure 7)
-If you look at the picture closely, you see that the plume covers a large amount of area. This is more damaging because the wind speed was slow and the stability was class F. Both of these factors caused the concentration to be high. (Figure 8)
-Here is a picture of the plume that we put onto Google Earth. As you can see, the plume travelled far due to the wind speed. The pollutant was slowly dispersed into the atmosphere because the air was moderately stable. (Figure 9)
Best Case Scenario:
-We wanted to show you this model so we can compare and contrast the results with our worst case. As you can see, the area of the plume is significantly smaller. (Figure 6)
-The concentration is spread out quickly over a long land range due to high wind speed. Though the stability class is F, moderately stable, the area of impact that is fatal is significantly smaller. This is because of two variables that are different. The wind speed is higher and the amount of explosive is significantly larger. (Figure 5)
Abstract
Since 911, the government of the United States has been concerned about another terrorist attack and radiological threats. In this study, potential scenarios were examined using HotSpot. We created a scenario of an airborne terrorist attack outside the 2012 Super Bowl using Plutonium-238. The scenario was created based on wind speed, air stability, and the amount of explosives.
Methods
With our scenario, we input information into HotSpot. We ran several tests with different variables to obtain our results.
Steps for our Methods:
1. We chose the type of model we needed.
2. We selected type of explosive, amount of explosive, and the MAR (Material at Risk).
3. We then input the different meteorological affects.
4. We saved the TEDE Contour File and viewed the Contour plot on Google Earth.
After running the tests, we were able to determine the worse case scenario.
Worst Case Scenario: Backpack Stability Class F with a wind speed of 2 m/s
Figure 7: Table Output
Introduction
REU is the abbreviation for Research Experience for Undergraduates. The project on Hazard Mitigation is funded by the National Science Foundation. Our research was conducted at the University of Texas-Arlington with the help of professors and graduate students.
Results
Figure 4: Modeling Results
* Rem is a measurement of radiation exposure
> 1.0E+03
Fatal
200 to 1,000
Causes serious illness and could be fatal
50 to 200
Can cause illness
< 50
Rarely causes illness or harmful to the human tissue
Objective
The objective of this project was to investigate a scenario portraying a nuclear terrorist attack using the software HotSpot.
-This is a table comparing all of our results with the variables of each test run. It has the area of the isopleths with 1000 rem. This is the area of the plume concentration that is fatal. (Figure 4)
Figure 8: TEDE Contour Plot
Background Information
Wind
-Affects plume rise, the concentration, and the travel time of the pollutant.
-Wind is inversely proportional to concentration.
Air Stability
-Tells us the amount of vertical motion in the air.
-Two categories: Stable and Unstable Atmosphere.
Gaussian Dispersion Equation
-Used to calculate concentration.
-Basis for air dispersion programs.
-Uses a three dimensional axis system.
HotSpot
-Program provides approximation of the radiation effects.
-Models short term accidents.
-Evaluates and models how a pollutant disperses into the atmosphere.
50 rem
Best Case Scenario: Car Stability Class F with a wind speed of 12 m/s
200 rem
Conclusions
By examining the variables, we were able to model the most devastating scenario. The variables that caused the most destruction were wind speed at 2 m/s in a stable environment and a lower amount of explosives. This evidence agrees with all of the background information we learned about air dispersion before we modeled our scenarios.
1,000 rem
Figure 5: Table Output
Figure 9: TEDE Contour Plot
Works Cited
Cooper, C. David., and F. C. Alley. "Chapter 20 Atmospheric Dispersion Modeling." Air Pollution Control: aADesign Approach. Third ed. Prospect Heights, IL: Waveland, Print.
Homann, Steven G. HotSpot. Computer software. National Atmospheric Release Advisory Center (NARAC). Vers Mar Web. <
Figure 6: TEDE Contour Plot
Figure 1: Air Stability Chart
Figure 2: Gaussian Dispersion Equation
50 rem
Figure 3:
Gaussian Model
200 rem
1,000 rem