Patent ID: 9082519
Filing Date: 2015-07-14
Classification: G21C,Y02E

Abstract:
1. A pressurized water nuclear reactor comprising: a pressure vessel; an upper removable head for sealably engaging an upper opening in the pressure vessel; a core having an axial dimension supported within the pressure vessel; a plurality of nuclear fuel assemblies supported within the core; at least some of the fuel assemblies having at least one instrumentation tube extending therethrough; an upper core plate extending over the nuclear fuel assemblies; an upper support plate attached to either the upper removable head or the pressure vessel and extending across the upper opening in the pressure vessel; a plurality of support columns extending at least partially between the upper core plate and the upper support plate, at least some of the support columns having an axially extending opening therethrough with the opening extending a length of the support column and being aligned axially with a corresponding instrumentation tube through an opening in the upper core plate; and an axially slidable sleeve through which a measurement device can travel as the measurement device is moved into or out of one of the instrumentation tubes during reactor outages, the sleeve extending at least partially through and into an upper end in at least some of the support columns that are aligned with the corresponding instrumentation tube, the sleeve having at least a portion thereof captured within the axially extending opening in the support column and, during an outage in which the core is to be accessed, substantially the entire sleeve is configured to be axially moveable within the corresponding support column's axially extending opening and extendable from the corresponding support column through an opening in the upper support plate into an area above the upper support plate in a manner that varies an axial length of the sleeve a distance that withdraws the measurement device completely from the instrument tube without the sleeve leaving the upper end of the support column while continuing to shield a portion of the measurement device that was shielded from a reactor coolant during reactor operation, from the coolant above the upper support plate.