METHOD OF REMOVING FISSION PRODUCTS FROM A NUCLEAR REACTOR COOLANT

摘要

1404282 Nuclear reactors WESTINGHOUSE ELECTRIC CORP 20 Sept 1973 [28 Sept 1972] 44065/73 Heading G6C Fission products are removed from the coolant of a nuclear reactor by passing the coolant in a flow loop connected to the reactor primary circuit 12, the coolant being conducted through a first vessel 22 at a relatively high temperature, where it picks up precipitation-facilitating reactants, and then through a second vessel 24 at a relatively low temperature, where reactants and fission products are precipitated, and, when the reactants in the first vessel are substantially exhausted, the flow direction is reversed so that coolant passes first through the second vessel 24 at a relatively high temperature, where reactants and fission products become re-dissolved in the coolant, and then through the first vessel 22 at a relatively low temperature, where reactants and fission products are precipitated. The direction of flow is determined by the settings of various valves 18-20 which are switched automatically by means of a monitor 25 which senses the radio-active impurity concentration in the loop between the two vessels 22, 24 and hence assesses when the reactant contents of the appropriate vessel 22 or 24 has fallen to a level requiring flow reversal. Automatic switching is also effected by the monitor 25 to change the mode of operation of the appropriate vessel 22 or 24 from hot to cold and vice versa. Wire mesh within the vessels, and on which the deposits collect, are replaced as necessary when indicated by a monitor 26 on the output side of the loop. Where the reactor is a fast breeder employing liquid sodium as coolant, the reactants comprise NaH, Na 2 O, and NaI for removal of tritium, Ba-140, Cs-134, Cs-137; Cs-141, Zr-95, I-125 and I-131.