At nuclear facilities, workers wear impermeable protective clothing to prevent radioactive contamination during inspection and maintenance activities. The heat stroke risk of the workers wearing protective clothing gradually increases, because of retaining heat and humidity inside of protective clothing. Normally, the rectal temperature is used to manage the heat stroke risk. But the rectal temperature measurement is very difficult at the working place. We have already reported that the measurement of infrared tympanic temperature is more realistic than that of rectal temperature to manage the heat stroke risk. But tympanic temperature indicates high temperature compared to rectal temperature. So, the use of the tympanic temperature overestimates core temperature and decreases the work efficiency. Therefore, we attempted to make formulas to predict rectal temperature from measured tympanic temperature, and to use calculated rectal temperature for safer and more efficient management. The rectal temperature predicted with the formulas agreed with the actual measurement within the range of measurement error (±0.1°C). Combination of tympanic temperature measurement and heart rate evaluation enabled the safer management of the heat stroke risk with wearing protective clothing.
Diameter of aerosols dispersed during the plasma cutting of plutonium-contaminated metal components of MOX fuel fabrication equipment was measured. The plasma cutting is performed by workers equipped with air fed suits within the glove box dismantling facility. The aerosols are introduced into multi-stage cascade impactors, enclosed in a small glove box to prevent cross-contamination. The size distribution and the median diameter of the dispersed aerosols were obtained. The activity median aerosol diameter was found to be around 6 micrometers, with a geometric standard deviation of 2.0. Also, the trapping performance of the HEPA filter on this particulate was confirmed by conducting radiological measurements on the outer surface of HEPA filter.