It has long been known in the prior art to employ a plug to effect a blockage of a normally open passage, when for some particular reason such action is deemed necessary. Moreover, the prior art is known to be replete with examples of various forms of plugs, which differ one from another in terms of configuration, mode of construction, etc. On the other hand, even though a multiplicity of plugs of different designs exist in the prior art, there continue to arise applications wherein it would be desirable to be able to employ a plug. However, due to the peculiar nature of the application, the plugs of known design are unsuitable for use therein.
One such application involves the accomplishment of the blockage of the inlet nozzle and/or the outlet nozzle of a steam generator, the latter being of the type that is suitable for employment in cooperative association with a nuclear reactor to form therewith a component part of a nuclear power generating system.
Periodically, there arises a need to conduct maintenance on and/or to effect minor repairs of the internal components of the steam generator. To accomplish such tasks, it is necessary for one or more persons to physically enter the steam generator. Ingress and egress from the steam generator by such persons is accomplished through suitable means such as for example an access port. While such persons are working in the steam generator, it is desirable that a blockage of the inlet and the outlet nozzle of the steam generator be effected to insure that there will be no fluid flow through the steam generator, which might imperil the lives of the people working therein.
One such design of a nozzle plug for a nuclear steam generator is disclosed in co-pending application Ser. No. 349,565 by Wentzell filed Feb. 17, 1982, entitled "Nozzle Plug For Submersible Vessel", which is herein incorporated by reference. This prior design is substantially comprised of a plurality of plate sections which are assembled within the steam generator to form the plug which is secured within the particular nozzle to be blocked. As this assembly and securing of the nozzle plug within the steam generator must be accomplished in an area where radioactivity may be present, it is desirable to be able to perform these operations as quickly and as efficiently as possible.