| 摘要 |
793,771. Automatic control systems for nuclear reactors. WILSON, V. C., OVERBECK, W. P., SLOTIN, L., and FROMAN, D. K. April 25, 1946 [April 14, 1945], No. 12576/46. Drawings to Specification. Class 38 (4). [Also in Group XL (a)] In a nuclear reactor, the neutron density is automatically controlled by positioning rods of neutron-absorbing material within either a reactor consisting of uranium interspersed geometrically in a lattice structure in a graphite moderating body or a reactor in which deuterium oxide surrounds uranium rods. In both cases a safety rod of neutron-absorbing material is drawn into the reactor, by gravity, upon energization of electromagnetic retaining means. The neutron density measuring device comprises an ionization chamber containing BF 3, Argon, Freon. In the automatic control system, a regulating rod of cadmium or boron is moved horizontally into or out of the pile on rollers by electric motors energized through grid-controlled thyratrons the bias voltage of which varies in correspondence with the pile neutron density as determined by the ionization chamber. A further control signal corresponding to the rate of change of neutron density is developed in a resistance, condenser network in the thyratron grid circuit and the datum level of operation of the control system is manually adjustable. The safety-rod, of cadmium or cadmium steel, is mounted horizontally, on rollers, and is moved into the pile on a track by a weight. Near the limit of the movement of the safety rod into the pile a braking force is applied to the sides of the rod by fixed brake shoes. The rod is moved out of the pile by an electrically-driven chain to which the rod may be engaged. In the event of an electric power failure, both the safety control rods are automatically drawn into the pile. Visual indication is given of the position of the control and safety-rods. |
