Molecular Dynamic Simulation of Sodium in 7-Pin LMFBR Bundle Under Hypothetical Accident Conditions

Conference · Sat Jul 01 00:00:00 EDT 2006

OSTI ID:20995479

Bottoni, Maurizio ^[1]; Bottoni, Claudio; Scanu, John ^[2]

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1. University of Ferrara, Physics Department, Via Paradiso 12, I-44100 Ferrara (Italy)
2. University of Pisa, Lungarno Pacinotti, 43 - 56126 Pisa (Italy)

In the frame of safety analysis of liquid metal fast breeder reactors (LMFBRs) under hypothetical Unprotected Loss of Flow (ULOF) conditions two-phase flow of sodium is simulated in a 7-pin bundle, with hexagonal lattice. Molecular dynamics, with the application of the Direct Simulation Monte Carlo (DSMC) method, and a macroscopic model describing rewetting sequences due to the flow of a sodium liquid film along the pin surfaces, are applied to simulate the coolant in the bundle. The pin surfaces and the inner surface of the hexagonal canning are treated in the Monte Carlo simulation as diffusively reflecting surfaces. Collisions of sodium molecules are computed with the 'hard-sphere' model. With respect to previous work the following improvements of the computational code were made: i) The full bundle is simulated, thus allowing for asymmetries, like a skewed power distribution, to be accounted for; ii) A pin model calculates detailed temperature distributions in the pins, so that temperature boundary conditions are computed and not imposed; iii) Post processing visualisation of computed results was developed. An out of pile sodium boiling experiment run at the Nuclear Research Center of Karlsruhe, Germany, is simulated and conclusions are drawn about the applicability of the methodology in computer codes dedicated to breeder reactors safety analysis. (authors)

• Research Organization: The ASME Foundation, Inc., Three Park Avenue, New York, NY 10016-5990 (United States)
• OSTI ID: 20995479
• Resource Relation: Conference: 14. international conference on nuclear engineering (ICONE 14), Miami, FL (United States), 17-20 Jul 2006; Other Information: Country of input: France
• Country of Publication: United States
• Language: English

Related Subjects

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS
BOILING
CANNING
COMPUTER CODES
COMPUTERIZED SIMULATION
COOLANTS
HARD-SPHERE MODEL
HEXAGONAL LATTICES
HYPOTHETICAL ACCIDENTS
LMFBR TYPE REACTORS
LOSS OF FLOW
MOLECULAR DYNAMICS METHOD
MONTE CARLO METHOD
POWER DISTRIBUTION
SAFETY ANALYSIS
SODIUM
SURFACES
TEMPERATURE DISTRIBUTION
TWO-PHASE FLOW