Patent Number: 043057861
Section: claims

1. In a system wherein radioactive neutron-emitting elements are placed in succession in a liquid-filled tank and wherein the addition of each successive fuel element will cause a sub-critical multiplication factor, k, to approach a critical value of unity in accordance with the equation: EQU CR.sub.2 /CR.sub.1 =(.alpha..sub.2 /.alpha..sub.1).(1-k.sub.1)/(1-k.sub.2) providing a neutron flux from a source in said tank;  counting the rate of neutron delivery (CR) to a detector location spaced from said source;  storing electrical signals indicative of the quantity CR at said detector location before and after each successive fuel element is added to the tank;  storing a value indicative of .alpha..sub.2 /.alpha..sub.1 for each said fuel element added to the tank based upon a given geometric positioning of fuel elements already in the tank; and  computing k.sub.2 after the insertion of each successive fuel element in the tank from the equation: EQU Cr.sub.2 /CR.sub.1 =(.alpha..sub.2 /.alpha..sub.1).(1-k.sub.1)/(1-k.sub.2)