In measuring the temperature, with thermocouples, in the zone of action of the intense radiation of a reactor, the allowance for the influence of radiation effects, which can distort the thermocouple readings, acquires importance. Despite the considerable number of published reports on this question, there is no single o~inion concerning the existence of an instantaneous effect of the action of the radiation field on the thermo-emf. For example, some authors have not observed instantaneous deflections in the reading of Chromel--Alumel (CA) thermocouples during a sharp drop in reactor power, with the initial flux density of fast neutrons reaching ~i0 ~ neutrons/(cm=~ In other cases instantaneous deflections in the readings of CA thermocouples reaching --5.6 and --10~ were observed during the shutdown of a reactor with a flux density of fast neutrons of ~i013 and ~6.5.1012 neutrons/(cm2.sec), respectively [i]. For the SM-2 reactor with a flux density of fast neutrons of ~4,10 ~4 neutrons/(cm2osec) the instantaneous deflection for CA thermocouples reached +26~ [2]. Such disagreement of the experimental results casts doubt on the reliability of thermometry using thermocouples under the conditions of the active zones of reactors.