Load Effects Inside NPP VVER-1000 Containment Wall Cross Section

In connection with the use of the SPZO-M modernized system for prestressing the NPP containment, it became necessary to determine the effect of loads inside the containment wall on the stress-strain state of the containment. Because of the particularities of the technology used to install the reinforcing elements, where the ducts are filled with grout under pressure up to 1 MPa, there is a possibility of cracking at the construction stage of the structure. Calculations established that on simultaneous injection of the middle and outer or inner channels the maximum principal stresses in the thinnest zones between the crossing channels reach the tensile strength of concrete 2 MPa. For this reason, it is recommended that simultaneous injection of these channels should be excluded. On prestressing and long-term operation, tensile stresses act in the radial reinforcement that can cause cracks to appear in the containment wall. On using the SPZO-M system, the radial stresses in the rod reinforcement increased by 19.4% compared to SPN-1000. Measures are proposed to limit cracking in the containment body.