Patent Number: 053234286
Section: summary

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to nozzles assemblies and more specifically to nozzle assemblies which enable quick and easy connection/disconnection in cramped and hazardous environments such as encountered in nuclear reactors. 2. Description of the Prior Art It is essential that a hermetic radiation proof seal be maintained between the interior and exterior of a pressure vessel such as a nuclear reactor. It is also necessary to monitor the operations of a reactor using In-Core-Instruments (ICI). However, this latter requirement necessitates the provision of nozzles through which the instruments can be sealingly introduced into the core. Examples of such an arrangements are shown in U.S. Pat. No. 4,723,795 issued on Feb. 9, 1988 in the name of Shenoy and U.S. Pat. No. 4,655,483 issued on Apr. 7, 1987 in the name of Margotta. The documents discloses techniques for providing fluid tight connections between a nozzle and a column which is concentrically supported within the nozzle. FIG. 1 shows a less preferred embodiment of the type of nozzle to which the present invention pertains. This arrangement is such as to provide a fluid tight radioactive proof seal for a plurality of ICI (In Core Instruments) and allows the operative connection with external controls and monitoring arrangements. This arrangement features the use of a Grayloc hub 10 which is clamped securely to a Grayloc flange 12 formed at the upper end of an ICI nozzle 14. However, with this arrangement when it is required to disassemble the same, the Grayloc clamp 16 is unbolted and each individual ICI nut 18 is then removed and the individual ICI's are then clustered together under a bullet nose. The above-mentioned Graylock hub and Graylock clamp are products of the Gray Tool Company, Houston, Tex. However, this induces the drawback that the disassembly process is both strenuous and time consuming. It is also carried out in very cramped conditions and in a radioactive environment. Accordingly, the operators are required to wear protective suiting and must be careful to watch the amount of time for which they are exposed to the radiation. Accordingly, there is a need for an arrangement which can reduce both the effort and time required to achieve the disassembly of an ICI nozzle which is carried out each time a refueling or instrument change is required, in order to reduce the reactor down time and more importantly to reduce the health risks associated with working the above mentioned hazardous environment. SUMMARY OF THE INVENTION It is an object of the present invention to provide a nozzle assembly for use with nuclear reactors and the like type of pressure vessels, which nozzle design enables very quick disassembly and which reduces the difficulty and amount of physical effort required to achieved said disassembly. In brief, seal arrangement which includes a Grayloc flange features a modified Grayloc hub in which a stepped bore receives a grafoil seal arrangement and a retaining nut which presses the grafoil seal into engagement with an inner wall portion of the hub and outer wall portion of an ICI (in core instrument) supporting column. A loading ring is threaded onto a portion of the column. Bolts associated with the ring are screwed down onto a belleville washer which is disposed between the loading ring and the top of the retaining nut for maintaining a desired amount of load on the seals irrespective of thermal variations. More specifically, a first aspect of the invention comes incomes in a device which features a hub which is clamped to a flange formed on the upper end of a nozzle in manner to establish a hermetic seal between the hub and the flange, the hub being formed with a stepped bore therein through which a column member extends; seal means disposed in the bore about the column member; a retaining nut threadedly received in the stepped bore, the retaining nut being adapted to press the seal means into sealing engagement with a wall portion of the stepped bore and a wall portion column member which is located within the stepped bore in a manner which establishes a hermetic seal between the hub and the column member; a resilient washer disposed on the upper side of the retaining nut; and an annular load ring which is threadedly received on a portion of the column, the load having a plurality through holes in which bolts are threadedly received and adjust the pressure applied by the resilient washer to the top of the retainer nut. A second aspect of the present invention comes in a sealing arrangement for device having a nozzle portion and a column member disposed through the nozzle portion, which features: a hub which is clamped to a flange formed on the upper end of the nozzle in manner to establish a hermetic seal between the hub and the flange, the hub being formed with a stepped bore through which the column member extends; seal means disposed in the bore about the column member, the seal being supported by a seal carrier; a retaining nut threadedly received in the stepped bore, the retaining nut being adapted to press the seal into sealing engagement with a wall portion of the stepped bore and a wall portion column member which is located within the stepped bore in a manner which establishes a hermetic seal between the hub and the column member; and an annular load ring which is threadedly received on a portion of the column, the load ring including means for selectively applying a force to the top of the retainer nut. A third aspect of the present invention comes in a nuclear reactor including an in-core-instrument, a head which is lifted when the reactor is refuelled, and a nozzle arrangement which includes a column arrangement through which the in-core-instrument is disposed, the nozzle comprising: a Grayloc flange which is associated with the nozzle; a Grayloc hub releasably connected to the Grayloc flange; a stepped bore formed in the Grayloc hub through which the column arrangement is disposed; a grafoil seal arrangement disposed in the stepped bore; a retaining nut which is threadedly received in the stepped bore and which can apply a pressure to the grafoil seal arrangement; loading means threadedly received on the column arrangement for applying pressure on the retaining nut. A further aspect of the invention comes in that the arrangement set forth above further features: an elastomeric spacer which can be inserted into the stepped bore when the retaining nut is removed, the elastomeric spacer protecting threads which are formed on the wall of the stepped bore and engaging the external wall of a bullet shaped cover which is placed over the top of the column arrangement when the nuclear reactor is conditioned for a predetermined operation.