Abstract. The main temperature characteristics of a pressurized water reactor are distinguished, supporting its safety and reliable operation. The special role of the uranium fuel effective temperature is emphasized and the accuracy of the analytical determination of the power effect is increased. The calculation of the temperature distribution along the radius of the fuel rod was carried out taking into account the temperature dependence of the thermal conductivity UO2. The design procedure was corrected for using the Finca-Ronchi dependence for the thermal conductivity of 95% density of the theoretical one.

Abstract. The main temperature characteristics of a pressurized water reactor are distinguished, supporting its safety and reliable operation. The special role of the uranium fuel effective temperature is emphasized and the accuracy of the analytical determination of the power effect is increased. The calculation of the temperature distribution along the radius of the fuel rod was carried out taking into account the temperature dependence of the thermal conductivity UO 2 . The design procedure was corrected for using the Finca-Ronchi dependence for the thermal conductivity of 95% density of the theoretical one. Primary temperature characteristics of reactorThese include the following integral and differential characteristics [1,2].The temperature effect of reactivity (TER), which is defined by the difference of reactivity, caused by the same temperature change from the cold to the hot state of all materials in reactor core (RC). The initial temperature of the cold reactor is set to 20-40 °C. Hot reactor temperature varies with a minimum controlled power level due to external heat sources. Fuel reactivity effect is responsible for forming the neutron spectrum and its leakage.The power reactivity effect (PRE) N U is determined by the mean or effective temperature of uranium fuel eff T and the actual presence an isotope 238 U in it. Due to the Doppler effect, there are resonance levels of the uranium isotope broadening with temperature rise, which increases the neutron absorption probability, thereby reducing reactivity. The higher the fuel temperature and the lower its concentration, the greater the effect. Also, magnitude N U is important for to assess the mode extension fuel campaign using the power effect reactivity. U reactivity coefficients determine self-regulation, self-protection, reliability and safety of the nuclear reactor. Both coefficients to provide these nuclear reactor properties must be negative: the first is near the operative point, the second is on the entire range of power transient.The fuel effective absolute temperature is determined by the exact integral formula