Numerical modeling of the expansion phase of steam explosions. Part 1, Method and validation

摘要

In the development of the Severe Accident Analysis Program for the Savannah River production reactors, it was recognized that certain accidents have -the potential for causing damaging steam explosions. Steam explosions can occur when metals, such as the aluminum-based fuel used at Savannah River, are melted and come into contact with water. This condition is unstable, and local turbulence can lead to the generation of great quantities of steam within a few milliseconds. This phenomenon has been observed in several reactor incidents and experiments (BORAX, SPERT-1, SL-1, probably Chernobyl) where it caused damage to the reactor and associated structures. The massive SRS reactor buildings are likely to withstand any imaginable steam explosion. However, reactor components and building structures including hatches, ventilation ducts, etc., could be at risk if such an explosion occurred. The goal for this study was to develop a computer code that could be used parametrically to predict the effects of various steam explosions on their surroundings. This would be able to predict whether a steam explosion of a given magnitude would be likely to fail a particular structure. This would require, of course, that the magnitude of the explosion be specified through some combination of judgment and calculation. The requested code, identified as the K-FIX(GT) code, was developed and delivered by the contractor, along with extensive documentation. The several individual reports that constitute the documentation are each being issued as a separate WSRC report. Documentation includes several model calculations, and. representation of these in graphic form. This report incorporates Report GTRSR-006, which gives an overview of the methods used in the development of K-FIX(GT), and the results of a comparison with experiments in the literature. The authors conclude that the results of the comparison calculation are in reasonable agreement with observations.