Temperature is a key parameter for most irradiation experiments; Major Difficulties are associated with high-temperature measurements for long-term irradiations. As Type K and Type N thermocouples fail frequently under irradiation above 1000°C (the commonly accepted limit for Type K is about 1080°C), in-pile temperature measurements in this range have typically employed Tungsten-Rhenium thermocouples (W・5％Re- W・26％Re alloys) at the same time YAMARI recommends not to use this thermocouple in air or other oxidizing atmospheres because of its strong affinity to oxygen.
