Radiological safety system based on real-time tritium-in-air monitoring indoor and in effluents

In this paper we describe an improved real-time tritium monitoring system designed for Heavy Water Detritiation Pilot Plant of National Institute for Cryogenics and Isotopes Separation, Rm. Valcea, Romania. The system consists of three fixed tritium-in-air monitors which measure continuously tritium-in-air concentration (in both species: vapour and gas) in working areas and gaseous effluents. Portable tritium monitors with ionization chamber, and tritium-in-air collector combined with liquid scintillation counter method are also used to supplement fixed instrument measurements. The main functions of tritium monitoring system are: to measure tritium-in air concentration in working areas and gaseous effluents; to alarm the personnel if tritium concentration thresholds are exceeded; to integrate tritium activity released to the environment during a week and to cut off normal ventilation when the activity threshold is exceeded and start the air cleaning system. Now, several especial functions have been added, so that by using appropriate conversion factors, the tritium monitoring system is able to estimate the effective dose rate before starting an activity into the monitored area, during this activity, or soon as the activity was finished. Another new function has been added by coupling tritium-in-air monitoring system with control access system. This is very useful for quick estimation of tritium doses. For routine dosimetric survey, one the internal dose for individuals by measuring tritium in urine is estimated. With all these features our tritium monitoring system is really a safety system for personnel and for environment. (authors)