RESEARCHES ON AIR INGRESS ACCIDENTS OF THE HTTR

This Paper deals with experimental and analytical studies which have b een performed to understand air ingress processes during primary-pipe and stand-pipe rupture accidents of the HTTR. Air ingress processes ar e summarized in the following. During the first stage of the primary-p ipe rupture accident, air enters the reactor by molecular diffusion, a very small natural convection of gas mixture and local natural convec tions with high velocity. On the other hand, air enters the reactor by natural circulation of gas mixture in the second stage. During the st and-pipe rupture accident, air enters the reactor by He/air exchange f low in the first stage, and by natural convection of gas mixture in th e second stage.