Taking the half speed saturated steam turbine in a 1 000 MW nuclear power unit as the research object

modeling calculation for eight support bearings was carried out by using the rotor dynamic analysis software ARMD

to get the static and dynamic performance parameters.Then

four shafts of the unit were modelled considering the effect of spring foundation

and the foundation-bearing-rotor dynamics model was established.Through the comparison of dynamics calculation and measured critical speed of the shafting

the accuracy of the calculation model was verified.On this basis

the HP/IP rotor vibration response was calculated with a balance weight or first mode shape bending

then compared with the same capacity of thermal power units.The results show that

the response sensitivity of the nuclear power units was only1/6of that of the 1 000 MW thermal power units with the same capacity.For nuclear units

the HP/IP rotor with less than 0.06 mm bending in barycenter can make the unit meet the requirements of operation by dynamic balance screw in HP/IP rotor dynamic balance channels.But the HP/IP rotor with more than0.06 mm bending in barycenter must carry out exposed cylinder inspection to add dynamic balance screw in rotor central hub or choice factory maintenance

which will cause extending time limit to a project.Therefore

to prevent the rotor shaft bending accident

the operation in daily running and start/stop process of the nuclear power units should obey more strict standards.