TECHNICAL BACKGROUND DOCUMENT FOR OFFSITE CONSEQUENCE ANALYSIS FOR ANHYDROUS AQUEOUS AMMONIA, CHLORINE, AND SULFUR DIOXIDE Chemical Emergency Preparedness and Prevention Office U.S. Environmental Protection Agency Prepared by: Geoffrey D. Kaiser, Joseph D. Price, and José Urdaneta Science Applications International Corporation 11251 Roger Bacon Drive Reston, Virginia 20190 Background Document for Offsite Consequence Analysis, April 1999 TABLE OF CONTENTS Page CHAPTER 1: INTRODUCTION ................................................................................................................... 1-1 1.1 BACKGROUND ................................................................................................................................. 1-1 1.2 PURPOSE ........................................................................................................................................... 1-1 1.3 GENERAL APPROACH ..................................................................................................................... 1-1 1.4 ASSUMPTIONS ................................................................................................................................. 1-2 CHAPTER 2: UNCERTAINTIES AND MODELS USED ............................................................................ 2-1 2.1 ANHYDROUS AMMONIA ................................................................................................................ 2-1 2.1.1 SAIC Proprietary Model ............................................................................................................ 2-1 2.1.2 USEPA RMP Offsite Consequence Analysis Guidance (OCAG) ................................................. 2-3 2.1.3 TFI ............................................................................................................................................ 2-3 2.1.4 DNV-UDM-Technica ................................................................................................................. 2-5 2.1.5 AWWARF Approach .................................................................................................................. 2-6 2.1.6 Additional ALOHA Run ............................................................................................................. 2-6 2.1.7 Comparison with Available Data ............................................................................................... 2-6 2.1.7.1 Data from Accidents ............................................................................................................................. 2-6 2.1.7.2 Experimental Data--Desert Tortoise ...................................................................................................... 2-9 2.1.7.3 Data from Modeling ........................................................................................................................... 2-10 2.1.7.4 Interpretation of Figures 2-2 and 2-3 ................................................................................................... 2-10 2.1.7.5 Choice of a Single Curve for AR and WWTP Guidance ....................................................................... 2-11 2.1.7.6 10-Minute vs. 60-Minute Releases ...................................................................................................... 2-11 2.1.8 Anhydrous Ammonia--Urban Site, Worst-Case ......................................................................... 2-13 2.1.9 Anhydrous Ammonia--Alternative Scenarios ............................................................................ 2-13 2.2 AQUEOUS AMMONIA .................................................................................................................... 2-17 2.3 CHLORINE ...................................................................................................................................... 2-17 2.3.1 Worst-Case Scenarios .............................................................................................................. 2-17 2.3.2 Alternative Scenario ................................................................................................................ 2-23 2.4 SULFUR DIOXIDE ........................................................................................................................... 2-23 2.5 BACKGROUND DESCRIPTION OF SENSITIVITY STUDIES ....................................................... 2-24 2.5.1 Dry Deposition ........................................................................................................................ 2-24 2.5.2 Puff Releases ........................................................................................................................... 2-25 2.5.3 Qualitative Uncertainties and Conservatisms .......................................................................... 2-25 2.5.3.1 Duration of Worst-Case Weather Conditions ....................................................................................... 2-25 2.5.3.2 Pooling ............................................................................................................................................... 2-25 2.5.3.3 Time Varying Toxic Endpoints ........................................................................................................... 2-25 2.5.4 Conclusion–Sensitivity Studies ................................................................................................. 2-26 CHAPTER 3: GASES LIQUEFIED UNDER PRESSURE ............................................................................ 3-1 CHAPTER 4: ADJUSTMENT OF MEAN CONCENTRATION FOR AVERAGING TIME ..................... 4-1 CHAPTER 5: AMMONIA/MOIST-AIR THERMODYNAMICS ................................................................ 5-1 5.1 CALCULATION OF THERMODYNAMIC PROPERTIES OF MIXTURES OF AMMONIA AND AIR ........................................................................................................................ 5-1 5.1.1 Methods ..................................................................................................................................... 5-1 5.1.1.1 Physical Property Data .......................................................................................................................... 5-2 5.1.1.2 Algorithm for Determination of Final Cloud Conditions ........................................................................ 5-5 5.1.2 RESULTS ................................................................................................................................ 5-10 5.2 EFFECT ON PREDICTION OF DISTANCES TO TOXIC ENDPOINT ............................................ 5-12 5.3 POTENTIAL FOR LIFT-OFF ........................................................................................................... 5-13 ii Background Document for Offsite Consequence Analysis, April 1999 CHAPTER 6: EFFECT OF AMMONIA RELEASES ON STRUCTURES .................................................. 6-1 6.1 PROLONGED RELEASES ................................................................................................................. 6-1 6.1.1 Building Structural Response ..................................................................................................... 6-2 6.1.2 Building Attenuation of Release ................................................................................................. 6-2 6.2 SUMMARY OF CONCLUSIONS ....................................................................................................... 6-3 REFERENCES ..................................................................................................................................................... iii Background Document for Offsite Consequence Analysis, April 1999 LIST OF FIGURES Page Figure 2-1. Sensitivity Studies for Worst-Case Anhydrous Ammonia Scenarios - Predicted Distances to Toxic Endpoint, Rural Site, Atmospheric Stability F, Windspeed 1.5 m/s ...................................................................................................... 2-4 Figure 2-2. Ammonia Dispersion Data Accidents and Desert Tortoise Experiments ........ 2-8 Figure 2-3. Ammonia Dispersion Data (Enlarged) ....................................................... 2-12 Figure 2-4. Sensitivity Studies For Worst-Case Anhydrous Ammonia Scenarios Predicted Distances To Toxic Endpoint, Urban Site, Atmospheric Stability F, Windspeed 1.5 m/s .................................................................................. 2-14 Figure 2-5. Sensitivity Studies for Alternative Anhydrous Ammonia Scenarios Predicted Distances to Toxic Endpoint, Rural Site, Atmospheric Stability Category D, Windspeed 3 m/s ..................................................................................... 2-15 Figure 2-6. Sensitivity Studies for Alternative Anhydrous Ammonia Scenarios Predicted Distances To Toxic Endpoint, Urban Site, Atmospheric Stability Category D, Windspeed 3 m/s ..................................................................................... 2-16 Figure 2-7. Sensitivity Studies for Worst-Case Aqueous Ammonia Scenarios Predicted Distances to Toxic Endpoint, Rural Site, Atmospheric Stability F, Windspeed 1.5 m/s .................................................................................................... 2-18 Figure 2-8. Sensitivity Studies For Worst-Case Aqueous Ammonia Scenarios Predicted Distances to Toxic Endpoint, Urban Site, Atmospheric Stability F, Windspeed 1.5 m/s ...................................................................................................