Code Manual for CONTAIN 2.0 - Federation of American Scientists

The heat transfer coefficient between the debris and vessel wall can be written as
where
h,,w=hd,w[fi]
Pwcp,wb’h,r
P = ~h,
d,w
h, d,w = 0.0292 + N~~~08NP,033
D’hr =
[Ah;hAg]
2h’d ~AT,
Pw [Cp,w~mp,w - ‘w) + ‘f,w]
(6-30)
(6-3 1)
(6-32)
(6-33)
The thermal conductivity of the debris, ~, is calculated by the code from the user-supplied
conductivity tables, L is the thickness of the RPV wall specified by THKWAL, and NR.&and NR me
the Reynolds number and Prandtl number, defined as (pdvdL)/ p~ and (~,~%) / ~, respectively. The
debris viscosity p~ is calculated by the code from the user-supplied viscosity tables. A factor of the
ratio of the debris area to hole area has been included in Equation (6-30) to simulate reduced contact
between the debris and vessel walls as the gas exit quality increases.
If the user has decided to specify an entrained fraction of debris or to invoke an entrained fraction
model, the time-dependent RPV hole size is not determined using Equations (6-29) through (6-33)
after the onset of gas blowthrough and two-phase discharge from the RPV. Instead, the hole size
following gas blowthrough is determined using the method described in Section 6.2.10.2.5.
6.2.10 Cavity Models
6.2.10.1 Entrainment Rate Correlations. If the user specifies only an entrainment rate correlation,
without speci~ng a correlation or a value for the entrained fractions, the amount of debris dispersed
will simply equal the integral of the entrainment rate. When this option is selected, the dynamic
feedback between debris entrainment and cavity conditions (e.g., gas densities and flow velocities)
that control entrainment rates is included in the modeling.
Five different correlations are provided as options for calculating the entrainment rate of debris in
the cavity. These include three forms of the Whalley-Hewitt model, the Levy correlation, and the
Tutu correlation. Each of the five entrainment rate correlations includes a cavity constant ~ as a
multiplier to the entrainment rate. This factor, which is CCENR in the CONTAIN input, is specific
to both the cavity being modeled and the correlation being used. It is the user’s responsibility to
select reasonable values for this constant, based on the guidance provided in the references cited for
Rev O 621 6/30/97