PLANT OPERATION MANAGEMENT(3)

Radiation Management in Tritium Environment In Fugen, during the works with the possibility of tritium release, such as overhaul of components of the heavy water or heavy water upgraders, a plastic-sheet green house is installed around the work area to prevent tritium leakage to the environment. The green house is ventilated by a tritium removal system.*1 In addition, for working in such tritium environment, workers have to wear airline respirators and anti-tritium protective clothing in order to prevent the intake of tritium depending on the tritium concentration in air.

Example of Setting Green House

The airline respirator protects the workers from breathing in tritium by providing clean air into the respirator through a hose. The anti-tritium protective clothing is a neoprene-diving suit that has perforated plastic tubes to let air in and is slightly pressurized by air flow, keeping out tritium-contaminated air and preventing the absorption of tritium through the skin.

The work environment is monitored by means of a condensation method*2 at proper intervals if necessary in overhaul work, and continuously monitored with portable room monitors (membrane separation type). The precaution measures are taken against an abrupt increase in the tritium concentration. In Fugen, those measures have greatly helped to keep workers' internal exposure due to tritium sufficiently at a quite low level. *1(Tritium removal system): A system that channels the house air through an intake duct to a dehumidifier (molecular sieve) that removes tritium-containing moisture from the air. *2 (Moisture condensation method): A method to measure tritium using liquid scintillator after collecting tritium as condensate.
		Membrane Separation Tritium Monitor