Modeling of pool growth

In studies of postaccident fuel behavior in LMFBRs, it is of interest to examine the interaction of the core debris with the reactor cavity environment in the event that the fuel melts through the reactor and guard vessels. The core debris may thereupon come in contact with the structural concrete or the materials of an engineered core retention system, if one is provided. Such materials presently being considered include commercial refractories of high alumina, magnesia, or zirconia content. A relatively simple model of the growth of core debris pools in refractory materials was developed earlier, and was used in the computer program GROWS. Briefly, the model consisted of striking a heat balance over the fuel pool to determine the distribution of the decay heat rejection in the upward, downward, and horizontal directions. Heat rejected in the downward and horizontal directions was then assumed to result in pool growth by melting of the concrete or core retainer material. Improvements to the model are discussed