Abstract: Through the inspection on physical start-up of reactor, it is identified thatthe.data of critical extrapolation and transition and the implementation of safetylimit are correct. The results of inspection show that the physical start-up for 5MW NDHR is successful. The steady doubling time after critical transition is 237seconds, it is within the acceptance criteria 30--300 seconds. The nuclear instru-mentation systems which are.used for normal operation have response to the neu-tron.flux at this power level. The reactor power is below protection set-point.