3. DESCRIPTION OF PROBLEM OR FUNCTION
AIROS-2A solves the space-
independent reactor kinetics equations and provides for the
determination of reactivity by solving in addition the discretized
equations that represent the spatial heat and mass transfer model
for several fuel channels. In addition, variation of the film
coefficient with flow is accounted for along with the provision
for flow decay and afterglow heating. Scrams can be initiated by
delayed signals from instruments that sense any quantity
calculated, e.g., power, inverse period or temperature.
Generalized feedback equations are used to provide flexibility in
the models that represent multichannel heat transfer including
conduction and convection, energy, pressure and other phenomenon
such as fuel melting, coolant boiling and voiding burn-out. The
reactivity equation is also generalized. The reactivity feedback
coefficients can be constant or vary as the square root or
reciprocal of temperature. Furthermore, any feedback variable can
be used to initiate a reactivity scram, each with a unique delay
time. An input generator computes the conduction and convection
coefficients for an n x m nodal, multichannel system using built-
in tables of specific heat, density, conductivity and viscosity
for the common fuel, structure and coolant materials, and performs
an initial temperature calculation. The film coefficients may be
specified or calculated using Lyon's equation or the Dittus-
Boelter equation.
