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.
The Pool/Surface Description allows a static pool to evaporate.
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.
A complete description of the source term and impact algorithms used in the
flat terrain version of the software is
available.
A complete description of the source term and impact algorithms used in the
complex terrain version of the software is
available.