Code Manual for CONTAIN 2.0 - Federation of American Scientists

the model is described in the third subsection below. The equations in the third subsection provide
the mass and energy terms that go into the debris and gas mass and energy conservation equations. ~
The final part of the model is the recombination of hydrogen produced by the chemical reactions that
is described in Section 6.4.4.
6.4,1 Gas-Side Transport
The gas-side rate model is based on a heat/mass-transfer analogy, where the transport of oxygen and
steam to the surface of drops in a field is given by a mass transfer coefficient times a density
difference as follows:
()
dm
tio
[1
dm
2
Ko, =
= %,%%,
ND
Sh,02 02
d
= ‘H,oAd ph,o -
(
x ~zo )
K
H20 =
= ‘H20AdPi+zo
N
Sh,H20 ‘HIO
d
P~~ if only Fe is present
otherwise
(6-122)
(6-123) ~
where K, is the mass transfer coefficient for oxidant x; pj is the density of oxidant x in the bulk
atmosphere, corrected to T~~,which is the boundary layer temperature between gas phase and the
drop; N~~Jis the Sherwood number for oxidant x; BXis the gas diffusivity of oxidant x in air; p~~
is the equilibrium density of steam at the drop surface; Ad is the surface area for all drops in the
debris field; d is the diameter of debris in the field; and x stands for either Oz or HZO.
The Sherwood number, analogous to the Nusselt number in heat transfer, is given by the following
correlation
N Sh,x = 2.0 + 0.6 ~~ N&x (6-124)
where NR.,~is the Reynolds number for the gas density and NsC,Xis the Schmidt number for oxidant
x.