Research reactor with a moderator in the form of a flue speed signal

摘要

1,074,089. Reactors. AMERICAN MACHINE & FOUNDRY CO. Sept. 10, 1964 [Sept. 25, 1963], No. 37041/64. Heading G6C. In a swimming pool reactor, pulsed increases of power, e.g. of about 1000 fold, are produced and automatic shutdown following each pulse is effected, by Doppler broadening of the resonance peaks in the capture cross-section of U238 in the low enrichment fuel. Pulsing is obtained by rapid withdrawal of a control rod. Forced or natural convection cooling of the core is provided. Uranium dioxide pin type fuel elements are mounted inside zirconium or aluminium tubes filled with helium to form the core. The dioxide is in the form of pellets which are dished to reduce thermal displacement. Control members are movable between the fuel tubes and are provided with shock absorbers. Each control rod is of cadmium and moves within a guide and thus does not require a hold-down mechanism. A graphite column positioned at one side of the core provides a beam of thermal neutrons for experimental purposes, further horizontal tubes leading from the core provide fast neutron experimental beams. Specimens to be irradiated may be passed into the core pneumatically.