The thermocouple column assembly and support structure designed by AREVA is a new structure that has not been used in other nuclear power plants in the world.Structural integrity of the assembly and support is an important factor to the long-term safe operation of the plant.In this work

static analysis under dead weight

FIV influence analysis

modal analysis

seismic analysis

and LOCA analysis were performed.The results indicate that the bolts of initial design cannot bear the load of Service Level D with LOCA.Reasonable improvement measures and its reasons were proposed and assessed.The improved structure was installed in the reactor vessel closure head in the period of NPP shut-down and refueling.