Reactimeter

A reactimeter is a diagnostic device used in nuclear power plants (and other nuclear applications) for measuring the reactivity of the nuclear chain reaction (in inhours) of fissile materials as they approach criticality.[1]

References

1. G., Chauvet; R., Gariod; E., Tournier (1966). "Réactimètre" [Reactimeter]. Nuclear Electronics Conference Proceedings (in French) (1966). Vienna: International Atomic Energy Agency: 365–378 – via International Nuclear Information System.