Interface requirements to couple thermal-hydraulic codes to severe accident codes: ATHLET-CD

Conference · Tue Jul 01 04:00:00 EDT 1997

OSTI ID:544397

Trambauer, K ^[1]

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1. GRS, Garching (Germany)

The system code ATHLET-CD is being developed by GRS in cooperation with IKE and IPSN. Its field of application comprises the whole spectrum of leaks and large breaks, as well as operational and abnormal transients for LWRs and VVERs. At present the analyses cover the in-vessel thermal-hydraulics, the early phases of core degradation, as well as fission products and aerosol release from the core and their transport in the Reactor Coolant System. The aim of the code development is to extend the simulation of core degradation up to failure of the reactor pressure vessel and to cover all physically reasonable accident sequences for western and eastern LWRs including RMBKs. The ATHLET-CD structure is highly modular in order to include a manifold spectrum of models and to offer an optimum basis for further development. The code consists of four general modules to describe the reactor coolant system thermal-hydraulics, the core degradation, the fission product core release, and fission product and aerosol transport. Each general module consists of some basic modules which correspond to the process to be simulated or to its specific purpose. Besides the code structure based on the physical modelling, the code follows four strictly separated steps during the course of a calculation: (1) input of structure, geometrical data, initial and boundary condition, (2) initialization of derived quantities, (3) steady state calculation or input of restart data, and (4) transient calculation. In this paper, the transient solution method is briefly presented and the coupling methods are discussed. Three aspects have to be considered for the coupling of different modules in one code system. First is the conservation of masses and energy in the different subsystems as there are fluid, structures, and fission products and aerosols. Second is the convergence of the numerical solution and stability of the calculation. The third aspect is related to the code performance, and running time.

• Research Organization: Nuclear Regulatory Commission, Washington, DC (United States). Div. of Systems Technology; Nuclear Energy Agency, 75 - Paris (France); SCIENTECH, Inc., Boise, ID (United States)
• OSTI ID: 544397
• Report Number(s): NUREG/CP--0159; NEA/CSNI/R--(97)4; CONF-961192--; ON: TI97008508
• Country of Publication: United States
• Language: English

Related Subjects

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS
22 GENERAL STUDIES OF NUCLEAR REACTORS
99 GENERAL AND MISCELLANEOUS
A CODES
COMPUTERIZED SIMULATION
EQUIPMENT INTERFACES
FAILURES
FISSION PRODUCT RELEASE
HYDRAULICS
LEAKS
MODIFICATIONS
PRESSURE VESSELS
REACTOR ACCIDENTS
REACTOR CORE DISRUPTION
TRANSIENTS
WATER COOLED REACTORS