Mortar Models of Prestressed Concrete Reactor Vessels

The construction and testing of a small-scale mortar model of a prestressed concrete reactor vessel is described at Oak Ridge National Laboratory to determine to what extent small-mortar models and models of elastic materials, such as epoxy, can be used to investigate the stress distributions and the cracking and ultimate failure modes of prestressed concrete reactor vessels. Mortar model design and fabrication techniques are discussed. Test results for the various steps of the prestressing sequence, for a short creep test period, and for a pneumatic pressure test to failure are presented. Vessel failure was gradual; after extensive concrete cracking, the vessel liner failed with an immediate loss of pressure. The elastic and short-term creep behavior are compared to finite-element analysis predictions. Preliminary comparisons are also made with the test results for a second identical mortar model, tested hydraulically, and with the results for a small concrete prototype vessel.