Ultimate load behaviour of internally pressurized "cut-and-cover" type underground nuclear reactor containments

Abstract

The static and dynamic nonlinear response to internal pressurization, due to a loss-of-coolant type accident, is investigated for a "cut-and-cover" prestressed concrete horseshoe-shaped containment in a clay medium with and without a stiffening (concrete - foamed concrete) jacket. The loading conditions considered are: (i) sustained prestress only, and (ii) sustained prestress and static-dynamic internal pressure. The yield condition used is the Drucker-Prager criterion. Axisymmetric finite-element analysis is carried out for various media patterns (concrete - foamed concrete - clay) using the computer code NONSAP. The results indicate considerable increase in structural integrity due to embedment.