Proposal for computer investigation of LMFBR core meltdown accidents

Abstract

The environmental consequences of an LMFBR accident involving breach of containment are so severe that such accidents must not be allowed to happen. Present methods for analyzing hypothetical core disruptive accidents like a loss of flow with failure to scram cannot show conclusively that such accidents do not lead to a rupture of the pressure vessel. A major deficiency of present methods is their inability to follow large motions of a molten LMFBR core. Such motions may lead to a secondary supercritical configuration with a subsequent energy release that is sufficient to rupture the pressure vessel. The Los Alamos Scientific Laboratory proposes to develop a computer program for describing the dynamics of hypothetical accidents. This computer program will utilize implicit EulerSan fluid dynamics methods coupled with a time-dependent transport theory description of the neutronic behavior. This program will be capeble of following core motions until a stable coolable configuration is reached. Survey calculations of reactor accidents with a variety of initiating events will be performed for reactors under current design to assess the safety of such reactors.

AFDM: An Advanced Fluid-Dynamics Model

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“…In 1974, a project was set up at Los Alamos National Laboratory for the computer analysis of severe liquid-metal fast-breeder reactor (LMFBR) accidents. 1 The project team developed the SIMMER computer code for modeling the coup Ied-neutronics/fIuid-dynamics behavior of a disrupted nuclear reactor core. Two versions of the SIMMER code were produced: SIMMER-I 2 and SIMMER-II.…”