MATERIAL PROBLEMS IN ACCIDENT ANALYSIS OF PRESTRESSED CONCRETE REACTOR VESSELS.

Prestressed concrete reactor vessles are not presently designed for nuclear accidents. However, in view of the recent public concern about safety of nuclear plants, it may become necessary to design them to sustain certain hypothetical core disruptive accidents of extremely low probability. Analysis of such accidents is particularly needed in case of liquid metal cooled fast breeder reactors. Some of the basic uncertainties in predicting the response of a concrete vessel to a core-disruptive accident may be eliminated with a more complete understanding of concrete behavior including the nonlinear triaxial stress-strain relations, the laws of cracking and damage of reinforced concrete, and the response to high temperature exposure. An extensive program, concerned with these problems, has been in progress at Northwestern University, and the purpose of this paper is to give a summary of some of some of the recent achievements.