[ADORA for RMP]
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ADORA Advantage for RMP

ADORA is the only software that couples air dispersion with chemical reactions and heat release.  This coupling is critical to realistic modeling of potential hazards. Such predictions often result in reduced hazard distances compared to the other models which introduce unnecessary conservatism by not accounting for the physics accurately. ADORA:

  • Lowers the cost of risk management
  • Facilitates the approval of site permitting

In comparison, other codes are unable to predict the natural rise of the toxic cloud and its rapid dispersion after a chemical release.  This results in their excessively conservative prediction of a greater hazard distance and impacted area.

Cloud Lift-off Due to Chemical Reactions with Moisture

 Halogenated inorganic chemicals such as boron trichloride and titanium tetrachloride have a strong tendency to react with moisture. Other models neglect such reactions and therefore predict unrealistic hazard distances.  ADORA, on the other hand, accounts for such chemical reactions with the entrained moisture during atmospheric dispersion.

Boron trichloride is initially heavier than air at ambient temperatures.  In the absence of chemical reactions with ambient moisture, the BCl3 cloud hugs the ground over large distances.  Chemical reactions with moisture result in the formation of hydrogen chloride (HCl) and the heat released due to chemical reactions lifts the cloud off the ground reducing the ground level hazard.

(a) No reaction: Contour of Reactant BCl3

(b) With reaction: Contour of Reactant HCl

Concentration contours (mg/m3) for BCl3 releases

The following table shows the effect of accounting for chemical reactions with ambient moisture for four chemicals.

Chemical Released

With no reaction

With reaction

TLV (mg/m3)

Hazard Distance

(km)

TLV (mg/ m3)

Hazard Distance

(km)

BCl3

10

5.4

30

0#

COCl2 

40.61

2.4

30

0#

TiCl4

16

4.2

30

3.3

UF6

111

5.1

2.5

6.4

    1. Reactant equivalent TLV calculated based on the product TLV.
    2. Downwind hazard distances are computed at ground-level.
    # Cloud lifts off

In summary, ADORA solves for the exothermic reactions between the released chemical and ambient moisture for the release of moisture-reactive chemicals. If the heat release from the reaction is significant enough, it predicts the lift-off of the initially dense ground-hovering clouds.   

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