Patent Number: 053234286
Section: description

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIGS. 2 to 5 show details of a preferred embodiment of the present invention. This embodiment features a basic combination of a modified Grayloc hub 100, a seal carrier 102, a retaining nut 104, a belleville washer 106, a loading ring 108 and a column assembly 110. The modified Grayloc hub 100 forms a pressure boundary at the top of the nozzle. It has a clearance fit with the column assembly 110 and includes a stepped bore the upper larger diameter portion of which is threaded to react the loading of the retaining nut 104. It should be noted that with the present invention disassembly of the Grayloc flange is not required for removal of the reactor head. In this arrangement the column assembly serves 110 to allow the penetration of a plurality of ICI (In-Core-Instruments) into the interior of the reactor core. The instant embodiment is such as to support 6 ICI and provides guidance for the guide tube cluster which is associated with the ICI. The ICI column assembly 110 includes six 1/2" Swageloc fittings 112 and bolts to the guide tube cluster. The Swageloc are not loosened unless the ICI are to be discarded and replaced with new units. The seal carrier 102 supports grafoil seals 102a and protects the same from damage during installation. A special T-handle tool is used to engage J-slots (see FIG. 4) Which are formed in a vertical web of the seal carrier 102 during installation and removal. A shown, the seal carrier 102 is disposed in the lower portion of a stepped bore formed in the modified Grayloc hub 100. The retaining nut 104, which is threadedly received in the upper portion of the stepped bore of the Grayloc hub 100, is such as to react against the uplift of the column 110 and compress the grafoil seals 102a. The retaining nut 104 is formed with spanner holes in the upper surface thereof and does not require the application of large amounts of torque in order to thread the same into and out of place. The belleville washer 106 is provided to ensure that a load is maintained on the grafoil seals 102a under all thermal conditions and further prevents loosening of the load ring 108. As will be appreciated, load ring 108 is provided to apply a load to the grafoil seals 102a. In this embodiment it threads onto a threaded portion of the column assembly and is provided with six 5/8" bolts 108a which can be screwed down onto the upper surface of the belleville washer 106 in order to apply the required compressive force to the grafoil seals 102a. In this instance the ICI connectors 116 are staggered at three different elevations and are mounted on an integral bullet nose locking rod 118. During routine disassembly of the flange, there is no need to remove the connectors. FIG. 7 shows the nozzle covered with a bullet nose 120 such as during refueling when the reactor head is lifted. As will be noted, in this instance a nylon thread protector 122 is inserted into the upper section of the stepped bore to ensure that insertion of the lower open end of the bullet nose 120 does not damage the threads and reduce the integrity of the sealing effect which is provided thereby. FIG. 8 is a partially sectional view of a detector seal plug which forms part of the instant embodiment. As shown, this device includes a support tube 124 which is welded to a swaged detector 126 and includes a plurality of leads which are brazed to a header in the manner illustrated. As this element is not directly connected with the invention, no further disclosure will be given for brevity. It will be appreciated that the present invention is not limited to the exact construction which as been described above and which is illustrated in the accompanying FIGS. 2-5, and that various modifications and changes can be made without departing from the scope thereof.