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X/Q for Releases From Area Sources

X/Q for Releases From Area Sources. 2008 RETS-REMP and NUMUG Workshop Jim Key Key Solutions, Inc. www.keysolutionsinc.com. Industry Tritium Issues Have Revealed Many Unanalyzed Dose Pathways Storm Drains Ground Water Service Water Discharge Basins or Lakes With Little Water Turnover.

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X/Q for Releases From Area Sources

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  1. X/Q for Releases From Area Sources 2008 RETS-REMP and NUMUG Workshop Jim Key Key Solutions, Inc. www.keysolutionsinc.com

  2. Industry Tritium Issues Have Revealed Many Unanalyzed Dose Pathways Storm Drains Ground Water Service Water Discharge Basins or Lakes With Little Water Turnover Concerns

  3. Has Been Mostly Ignored Tritium Concentrations in Bodies of Water Can Continue to Build Up Release from Such Sources are Estimated to be 10 Ci/yr and Higher Evaporation From Area Sources

  4. Simplify Gaussian Model As Follows Ground Level Release Ground Level Receptor Modify From Point Source Geometry to Square Area Geometry Application of Gaussian Model to Release from Area Sources

  5. Standard Gaussian Model

  6. General Gaussian X/Q Downwind Factor Vertical Factor Crosswind Factor

  7. General Gaussian X/Q

  8. yLateral Diffusion Coefficients

  9. zVertical Diffusion Coefficients

  10. Atmospheric Stability Categories

  11. Ground Level Concentration Set z = 0

  12. Crosswind Integrated Concentration

  13. Integral Reduces To:

  14. Crosswind Integrated Concentration

  15. Wind Directions in Each Sector are Distributed Randomly Over Period of Interest Divide Crosswind-Integrated Concentration by Sector Arc Length Sector Averaged Concentration

  16. Ground Level Sector Averaged Concentration

  17. Ground Level Sector Averaged Concentration – Ground Release Set H = 0

  18. Wind Directions in Each Sector are Distributed Randomly Over Period of Interest Calculate X/Q Using Joint Frequency Distribution: f(,S,N)  Direction S Stability Class N Wind Speed Class Time-Averaged Concentration

  19. Ground Level Sector and Time Averaged Concentration – Ground Release

  20. Assume Point Source at Center of Release Very Conservative Does not consider that source is initially distributed over large surface area. Estimation of Release from Area Source

  21. Turner (Workbook of Atmospheric Dispersion Estimates, 1994) Treat area source as having initial horizontal standard deviation - yo - related to area width. Horizontal standard deviation for square source is approximated by L/4.3 (L= Length of a side of the area). Estimation of Release from Area Source

  22. Turner (Workbook of Atmospheric Dispersion Estimates, 1994) Select “Virtual Distance” - xy - based on yo. Calculate X/Q using distance of x + xy. Estimation of Release from Area Source

  23. Calculate X/Q Assuming Ground Level Release Emission Source is One Mile Square Receptor is Due West ½ Mile from Center of Source (i.e. at Boundary) Assume Worst Case Met Conditions Extremely Stabile (Class G) Calm Conditions (0.04 m/s) Least Dispersion Simple Case

  24. Point Source Receptor 1600 meters Geometry for Point Source Distance – 800 m

  25. u = 0.022 m/s x = 800 m zG = 7.5 m Simple X/Q for Point Source

  26. Calculate yo based on 1 mile side 1600 meters/4.3 = 372 m From y table/plot look up distance corresponding to yo for stability class of interest. 20000 m Calculate X/Q for virtual distance:20,000 + 800 = 20,800 m. Simple X/Q for Area Source

  27. Geometry for Area Source Point Source Receptor Virtual Distance – 20,800 m 1600 meters

  28. u = 0.022 m/s x = 20,800 m zG = 7.5 m Simple X/Q for Area Source

  29. XOQDOQ Provides Summary of JFD Data by Stability Class, Sector and Wind Speed Applying JFD Data to X/Q JFD for Receptor in West Sector

  30. Use Average Wind Speed (Not Max Wind Speed) Determine yo for Each Stability Class Determine Virtual Distance (Xv) for Each Stability Class Applying JFD Data to X/Q

  31. Calculate X/Q Using:

  32. X/Q for Stability Class A

  33. Point Source X/Q = 6.4E-06 Area Source X/Q = 5.7E-07 Annual Average X/Q for Receptor

  34. Larger Sources – Expect Greater Difference As Distance to Receptor Increases Difference Slowly Decreases Point Source vs Area SourceX/Q

  35. Point Source vs Area Source

  36. For Nearby Receptors Rule of Thumb Appears to be X/QArea ~ 1/10 X/Qpoint For Distances Out to 10,000 meters X/QArea ~ 1/2 X/Qpoint Point Source vs Area SourceX/Q

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