In Full-d uplex Cognitiv e Radios, the silen t period of the Secondary User (SU) during the Spectrum Sensing can be elimina ted by appl ying the Self -Interf erence Cancella tion (SIC). Due to the channel estima tion error and the hardw are imperf ections (the Phase Noise and the Non-Linear Distortion (NLD)) SIC is not perf ectl y perf ormed and resul ts in the Resid ual Self -Interf erence (RSI) which aects the Spectrum Sensing reliability . In this paper , the eect of RSI on Spectrum Sensing is anal yticall y deriv ed by expressing the detection (pd ) and false alarm (pf a) probabilities under FD in terms of the ones under Half -Duplex (HD) (where SU shoul d remain silen t during the Spectrum Sensing period). In addition, an algorithm is proposed to suppress the NLD and improv es the Spectrum Sensing perf ormance. Hereinafter , the SU throughput under FD is anal ysed comparing to HD by deriving the upper and lower bounds to be respected by pf a and pd respectiv ely in order to make FD beneficia rela tiv e to HD.