Application of tritium behavior simulation code (TBEHAVIOR) to an actual-scale tritium handling room

It is essential from the viewpoint of fusion safety to confine and remove tritium in a room since tritium handling room is placed as 'final barrier' of fusion plant to prevent the environmental discharge of tritium. At the Tritium Process Laboratory (TPL) of Japan Atomic Energy Agency (JAEA), the application of our original three-dimensional TBEHAVIOR code to the tritium behavior in a room of 3000 m3 was verified. The Renormalization Group Theory (RNG) model was selected as Low-Reynolds model for practical calculation time as well as to reasonable precision in evaluation of velocity from the engineering viewpoint. A series of evaluated results indicated that a flow adjacent to a wall surface plays an important role for tritium transport in a ventilated room. Evaluation of attenuating behavior is further important since the ventilation is normally stopped for the tritium confinement in the case of tritium leakage. We demonstrated that an attenuating behavior can also be evaluated well by the TBEHAVIOR code. Even an attenuating or stagnant flow of less than 10mm/s in a room mixed tritium concentration uniform promptly. The presence of apparatuses in a room did not generally affect tritium behavior. Although the effect of buoyancy was limited to the initial period after the leak, the spread of tritium was promoted by buoyancy. It led to the shortening of elapsed time until the concentration became uniform. (author)