Shielding plug for LMFBR type reactor

Since a rotary plug loading portion and a rotary plug step portion are in contact with each other over a wide horizontal surface, if the pressure of the contact surface is small, the surface pressure for crushing and removing sodium is small, and there is no substantial room for discharging the crushed sodium. Then, in the present invention the horizontal surface of the rotary plug loading portion of a stationary plug, that is, the area of contact with the rotary plug step portion is decreased so as to obtain a sufficient surface pressure for crushing accumulated sodium, as well as an inner radial side of the horizontal surface is tapered so as to easily discharge the crushed sodium. With such a constitution, since the accumulated and solidified sodium is easily crushed and discharged, abnormality such as the rotary plug is not returned to a normal position or slanted does not occur and the plant can be operated smoothly. (T.M.)