[en] This study aimed to determine the effect of dose absorbed by two types of transistors(JFET and BJT) after irradiation by neutrons into reactor and by exposition to Gamma rays source . In order to know the neutrons energy spectrum and Gamma photons flux accompanying fission, a mode for the reactor was done. Also modeling the transistors structure for the absorbed dose calculation was done. Modeling and calculation are carried out using the MCNP code. The dose of Gamma source has been measured experimentally. Results showed a decrease overall amplification coefficients as a function of dose for a given radiation. They show also that the JFET transistors are more hardness than BJTs. For a mixed sources, as the irradiation within reactor(Gamma and neutrons), the decrease depends also on the radiation kind, or in other words, the mechanism of interaction of radiation with the electronic component material. The effect of neutrons is greater than the effect of Gamma rays on the two transistors types. It results not only the dose but also the kind of radiation that is playing an important role in damage influencing the semiconductor components (author).