CHARM Source Term
With the CHARM source term, you can specify the design, control, and mitigation measures applicable to the source. If the initial model results indicate an unacceptably high consequence, you can use CHARM software to hypothesize what the impacts might be with other designs and mitigation measures. This can allow you to better estimate the impact reduction that an investment in risk reduction might achieve.
CHARM software has three selections for source terms
- Container/Surface Description
- Pool/Surface Description
- User Specified
The Container/Surface Description allows for liquid/vapor to escape from a container. The liquid which releases can flash, form droplets, or form a pool. The pool can grow over time to a given maximum size or to a size where the evaporation rate is equal to the mass addition rate. You can specify the time that it takes for material to get out of containment (e.g., 10 minutes) and CHARM software calculates a required hole size. In the complex terrain version of the model the liquid flow can be affected by the terrain.
Container / Surface Release
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Liquid Release (1)
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Pressure Head Release
(First Depressurization) (2)
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Boil Off (3)
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Second Depressurization (4)
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The Pool/Surface Description allows a static pool to evaporate.
Liquid Pool / Lagoon Release
In Container/Surface and Pool/Surface Description CHARM software calculates all parameters of the release: emission rate, temperature, phases, etc. The User Specified mode lets the user enter these values directly. Normally, the User Specified entries are variations on the CHARM software results from the Container/Surface or Pool/Surface Description calculation.
A mitigation time can be entered for the release from containment and pool evaporation. The release is assumed to stop after the mitigation time is reached. In the User Specified mode a release duration is input.
The results from the source calculation are available in tabular and graphical form.