Background: The damage equivalence coefficient is the key factor to appraise the difference of radiation damage between different neutron spectra. Purpose: This research is to obtain the equivalence coefficient of radiation damage between two different neutron spectra. Methods: The silicon bipolar transistors (3DG121C) with good similarity of parameters have been employed as the displacement damage monitors based on the liner relationship between the reciprocal of direct current gain and the neutron flux. Results: The radiation damages of two sets of selected 3DG121C transists placed at the two special sites on CFBR-II have been obtained by the in-situ on-line measuring of the change of gain with the accumulation of neutron flux

and the equivalence coefficient were deduced. Conclusion: The results show that the damage constants at different sites on CFBR-II are of great similarity. Abstract