Code Manual for CONTAIN 2.0 - Federation of American Scientists

For flow from wetwell to drywell, and assuming overflow does not occur, an equation similar to
Equation (1 1-22) is obtained from Equations (11-14), (11-15), and (11-16),
tq =
[
2F’ [PW- P~ - plg(l + ~)xO] llz
P! g2(l + P)2
1
(11-24)
where F’ is equal to 1-~2+ ~W, ~ equals (F$ - HW,O)/~, and HW,Ois the initial value of ~ at the
beginning of the timestep.
If vent clearing occurs prior to overflow, the vent clearing time ~Cis calculated from Equation
(1 1-24) in a manner similar to that for flow from the drywell to the wetwell. If not, it is first
necessary to calculate a time to overflow tOPAs illustrated in Figure 11-6b, the time to overflow tO~
is computed as tO~= tq - ~, where ~ is the (fictitious) time from overflow to equilibrium when the
gravitational head of the overflow is assumed to be present. The latter is calculated by Equation
(11-24) with XO= HO~- ~.
The second equation set takes into account the fact that the gravitational head of the water above the
overflow point is actually not present. Since H~= HO~during overflow,
g P#-$w= g P~(HOf- HW) for ~~ > HO~ (11-25)
By using Equation (11-16), Equation (11-25) becomes
g p~AH& = g P@Of - HO + px) (11-26)
Note that x is used here as an effective level representing the total inventory on the drywell side.
By substituting Equations (11-17) and (11-26) into Equation(11- 14), dx/dt becomes
—= dx —
2[PW- ‘d - g pe(HOf- HO + ~x)] 1’2
dt
[
F’ pl
1
The integration of Equation (11-27) yields
(11-27)
(11-28)
Rev O 11 16 6/30/97