It is desirable that a reactor exhibit a self-regulating effect. If this were not true any disturbance to the reactor would result in a continual increase in the magnitude of the disturbance and the reactor would be unstable. In this investigation the reactor is considered to have two reactivity feed-backs: metal temperature and water temperature reactivity effects. These two variables through a metal temperature coefficient and water temperature coefficient determine not only the reactor stability but also determine many operational characteristics.

A study was made to evaluate the possibility of an explosive reaction occurring in the Hanford Purex Plant concentrators as presently instrumented. Results revealed that the occurrence of an explosive reaction in the Purex Plant concentrators with present instrumentation is very unlikely.