GB783094A - Improvements in or relating to support devices for use in nuclear reactors - Google Patents

Abstract

783,094. Nuclear reactors. UNITED KING- DOM ATOMIC ENERGY AUTHORITY. July 27, 1955 [July 28, 1954], No. 22017/54. Class 39(4). A support device for use in a nuclear reactor having a vertical orientation comprises means for supporting and axially locating a column of moderator material and providing a coolant fluid entry to a vertical fuel element channel defined by and passing through the column of moderator material; means permitting free movement of the supporting and locating means over a base member ; a boss joined with and coaxial to the supporting and locating means ; a guide member carried freely in the boss; a fuel element support member penetrating into the guide and latched therein by a device releasable when the load in the fuel element support member exceeds a predetermined figure ; blade means carried by the fuel element support member ; and a member, also carried freely in the boss, exposing a surface to be cut by the blade means when the latch device is released. Referring to Fig. 1, a load support strut 210 is located in a guide 211 by a shear pin 212 and is provided at its end with four blades 213 which can move over the inner wall of a member 215. The member 215 has a flange which rests on aboss 217 supported by three webs 219 which are part of a locating sleeve 220 resting on a top steel plate 221 mounted on a ball race on a bottom steel plate 223. The plate 223 is located by a ring 224 which at its upper end limits the movement of the ball race and at its lower end is located in a main support plate 227. The top plate 221 supports a graphite column, of which the lowest brick 232 is surmounted by two tiles 233, 234, Fig. 2, devised to allow for Wigner growth and by the lowest brick 235 of the moderator structure proper. The brick 232 has a step 236, the part below the step being free from Wigner growth, and these lower parts below the step butt together on adjacent bricks to keep the moderator structure rigid. The strut 210 is made of low neutron absorbing material (such as magnesium) and it supports a graphite pillar 237 encased in a magnesium can 238 and has a centre tie rod 239 screwed into a boss 240 at the top of strut 210. A boss 241 is provided at the other end of the rod 239 and this carries a conical member 242 having three locating legs 243. A fuel element 244 having a cone 247 locating in the member 242 is partly shown. The guide 211 has a flange 245 and webs 246, the diameter of the flange being such as to provide an appropriate rate of gas flow through the channel so that the temperature rise in passing through the core is approximately the same as that in other channels. The shear pin 212 is arranged to pass through both the guide 211 and the member 215 so that on withdrawing the assembly from the reactor by lifting on the locating legs 243, the base of the blades 213 lift on the guide 211 which transmits a lift to the member 215 by way of the remaining broken part of the pin 212.