FUMO INTEGRATED CODE

DCMN started the TH integrated approach by upgrading the FUMO code, developed to analyse containment transients, with the introduction of a simplified PS module and validating the new code

CONTAINMENT MODEL DESCRIPTION

Containment loads evaluation in various accident conditions:
DBA, long term SA pressurisation & hydrogen distribution

	hydrogen combustion
	corium-water interaction
	BWR specific features (i.e., suppression pool & SRV discharge)
	internal/external spray and other ESFs (i.e., Fan coolers, HX, etc.)

Transients due to releases in a multi-compartment containment

	Heat transfer: correlations or heat & mass transfer analogy
	Two regions model: 6 non-condensable gases + steam & a liquid pool
	Gas production: input tables except hydrogen during corium-water interaction, directly calculated

Junctions can be submerged or having a time / pressure dependent area

	Bernoulli equation for water flow
	Buoyancy driven flows by "electrical network" analogy
	Gas stratification inside large compartments

PS MODEL DESCRIPTION

	Homogeneous equilibrium balance equations consider contributions of:
	junctions connecting volumes
	junctions used to simulate injection devices (as ESFs, level control systems, etc.)
	connections with the containment system
	Time discretization on the basis of implicit coupling between pressures & junction flow rates
	Semi-implicit scheme adopted for time advancement

For Passive injection devices involving a water tank discharge:
   model for the tank discharge flow-rate with a
tank pressure trend calculated by the containment module