The Study On The Ultimate Bearing Capability Of Nuclear Power Plant's Containment With Temperature Effect

Containment is the final shield of nuclear power plant to protect the environmental safety.In the design of pressurized water nuclear power station with Generation III feature,the containment should keep its integrality after the severe accident and has the capability to prevent the diffusion of fission products.The domestic and oversea institutes have made lots of experiments and studies on the ultimate bearing capability of containment under internal pressure,however few of study is about it under the combined temperature effect and pressure in severe accident condition.Thus,the research on this area is valuable and meaningful to self-design of “Nuclear power station with Generation III feature”.This paper has established the 3D finite element model with same design size,including concrete,steel liner,pre-stressed steel cable and normal steel bar of certain NPP project based on large commercial finite software Abaqus.The study has used the methods combined by theory derivation,numerical approach and Computer programming to simulate the effect of adding pre-stressing force;During the calculation and analysis,it has simulated the temperature effect to structure in severe accident condition,the tensile failure of containment concrete,the nonlinear evolution process of yield of steel liner;in the calculation,the nonlinear non-convergence problem has been properly handled to get the accurate ultimate bearing capability result.After the severe accident,the pressure is below 1.43 times of design value,the containment keeps its integrality and is in plastic phase,then the containment concrete starts to quit working and the hoop stress on concrete starts to transfers to normal steel bar,steel lining and pre-stressing steel cable.When the inner pressure went up to 2.38 times of design value,the containment concrete will crack on the whole section and quit working,the hoop stress on concrete has transferred to normal steel bar,steel linier and pre-stressing steel cable while these three materials are still on plastic phase and has not been yielded and has certain load capability;When the inner pressure increased to 2.9 times of design value,the stress of steel liner near the equipment hatch has yielded and the strain is over 0.15%,thus the steel liner may have part laceration and containment has lost its integrality.To sum up,under this condition,most concrete has quit working and the steel liner near the equipment hatch has yielded so that we can consider that 2.9 times of design pressure value(1.23 MPa)is ultimate bearing capability of internal containment of the nuclear power plant when the temperature effect has been taken into account.At last,the paper made the analysis and statement of the conservation of containment ultimate bearing capability calculation results.