Previous Work

1
(No Transcript)
2
Previous Work

• Prediction of flow instabilities in the negative
  slope of natural circulation mass flow rate
  versus power curve ( Chatoorgoon, 2001)

3
STABILITY CODE
(t 0)
GEOMETRY
INITIAL/INLET
(t t?t)
Until (?Ptot/ ?ult?)

• Inputs Geometric Parameters for all components
• Length, Dia, Interfaces
• Heating Condition
• (1, 0, -1 for heat addition,adiabatic and
  heat removal)
• Direction of flow
• (1, 0, -1 for upflow, horizontal flow and
  downflow)

• Sets
• Inlet Conditions (i.e. at t0, sets the
  enthalpy and pressure at the first node)
• Initial Conditions (i.e. at all nodes)
• Guess density and inlet velocity

UPDATE
Update the old properties with the current ones
For I1, No. of com. J 2, interface (I)

• Performs Energy Balance to Calculate the
  Enthalpy at New Node Using
• Guess density values
• Velocity and Pressure at new node as calculated
  using continuity and momentum equation
• Old time step known parameters (i.e. density
  and velocity, Pressure and enthalpy)

• Calculates the Volumetric Heat Generation or
  Removal for
• Heater or Cooler (given constant heat flux or
  wall temperature ). Heat transfer correlations
  used
• - Dittus-Bolter
• - Jackson

• Performs Momentum Balance to Calculate the
  Pressure Using
• Guess density values
• Velocity at new node as calculated using
  continuity equation
• Old time step known parameters (i.e. density
  and velocity, Pressure)

UNTIL (??lt?)
?? (?new-?old)
THERMPROP
DIMLESS
CONTINUTIY

• Solves Continuity Equation to Calculate Velocity
  Using
• Guess values of density for all the nodes at new
  time step
• Old time step known parameters (i.e. density
  and velocity)

• Calculates the Dimensionless Parameters
• Reynolds number
• Prandtl number
• Friction factor

• State Equation
• Calculates improved density as a function of new
  pressure and enthalpy values.

BOUNDARY
ENTHALPY
MOMENTUM

• Assigns the node properties of the first node of
  new component

Update velocity guess based on the pressure drop
?? 10
If (I?last comp.) NEWNODEPROP
?P(Plast node Pfirst node)
END
4
Steady State predictions for UW loop
5

• Future Work
• Stability predictions for the UW and ANL loop.
• Neutronics coupling of the heat source ( using
  point kinetics model)
• Study of instabilities associated with the change
  in moderation due to neutronics feedback.