It had been discovered through overall inspection of HP cylinder in the tenth major repair of turbine no.1 at Dayabay Nuclear Power Station that the shrinkage movement measured during dis-assemblage was less than the designed value of 0.75 mm.After related measurement

inspection

and analysis

combined with variated clearance of the axial flow passage

it is determined to push the HP cylinder backward(to direction of bearing no.2) for 0.5 mm.From situation of start-up and operation after said major repair

it can be seen that the abnormal shrinkage movement problem of HP rotor for turbine no.1 has effectively been solved

ensuring smooth start-up

as well as safe and reliable operation of the unit.