Gauge plate for use in customizing a replacement upper core plate in a

Abstract

A gauge plate for use in customizing replacement upper core plate inserts of a nuclear reactor which comprises: a circular metal plate of a known diameter corresponding to that of the upper core plate of the nuclear reactor to be gauged; a plurality of U-shaped gauging slots of known size formed in the peripheral surface of the gauge plate at locations corresponding to the locations of the guide pins for the lower internals of the reactor; an arrangement for positioning the gauge plate within the core barrel at the normal elevation of the upper core plate inserts and the guide pins; and devices, disposed on the gauge plate, for positioning the gauge plate relative to the reactor baffle plate arrangement; and, for determining the actual position of the gauge plate relative to the baffle plate arrangement. The gauge plate is positioned in a core barrel containing a baffle plate arrangement but no upper internals so that the gauge plate rests on the upper end of the baffle plates with the guide pins extending into the gauging slots and with the gauge plate properly positioned relative to the baffle plates; the clearances between the gauge plate and the inner surface of the core barrel, and between the three sides of a gauging slot and the adjacent sides of the associated guide pin are measured at each gauging slot; and, the actual position of the gauge plate relative to the baffle plates is determined by gauging devices.