Machine and method for decontaminating nuclear steam generator channel head

Claim 1

A decontamination machine for decontaminating substantially all of the interiorly facing walls on one side of a divider wall in a channel head of a nuclear steam generator having a manway, comprising: a first assembly comprising a vertical post and a carriage track carrying a movable carriage, said carriage track being pivotally secured to the upper end portion of said post to permit the assembly to be collapsed to a size permitting entry through said manway into said channel head, said assembly being sufficiently lightweight to permit the manipulation and installation thereof in said channel head by no more than two individuals in a location in which said vertical post is closely adjacent the vertical center line of said divider wall; a horizontal support beam including fastener means at its radially inner end adapted to be separably secured to the upper end portion of said vertical post; a curved track shaped to complete a generally quadrantal shaped frame also including said post and said beam, said curved track means including fastener means at both ends adapted to be separably secured to the radially outer end of said horizontal beam and the lower end portion of said vertical post, said curved track engaging the outer end of said carriage track in movable relation; both said beam and said curved track also being sufficiently ligthweight to permit their manipulation and attachment to said first assembly by no more than two individuals; adjustable decontamination blaster means attached to said carriage; and means for moving said carriage along said carriage track, and means for swinging said carriage track both horizontally and vertically so that said decontamination means has the capability of sweeping past substantially all said interiorly facing walls of said channel head.

Claim 10

The method for decontaminating substantially all the interiorly facing walls of a space defined by an upper tube sheet, a divider wall and a channel head wall of a nuclear steam generator, with a directionally adjustable blast nozzle carried by a carriage on a track, with the blast nozzle being movable radially in and out on the track by one drive, and the track being swingable horizontally by a second drive, and swingable vertically by a third drive, comprising: traversing the area of said tube sheet by energizing said second drive for successive sweeps at a rate according to the radial position of said carriage on said track, and energizing said one drive between successive sweeps to position said carriage on said track; traversing the area of said divider wall by energizing said third drive for successive sweeps at a rate according to the radial position of said carriage on said track, and energizing said one drive between these successive sweeps to position said carriage on said track; positioning said carriage at its radially outer position and then traversing the area of said channel head wall by energizing said second drive for successive sweeps at a rate according to the length of each of these sweeps along the channel head wall, and energizing said third drive between these successive sweeps to successively step said track between opposite generally horizontal and generally vertical positions.

Claim 11

The method for decontaminating substantially all the interiorly facing walls of a space defined by an upper tube sheet, a divider wall and a channel head wall of a nuclear steam generator, with a directionally adjustable blast nozzle carried by a carriage on a track, with the blast nozzle being movable radially in and out on the track by one drive, and the track being swingable horizontally by a second drive, and swingable vertically by a third drive, comprising: traversing the area of said tube sheet by energizing said second drive for successive sweeps at a rate according to the radial position of said carriage on said track, and energizing said one drive between successive sweeps to position said carriage on said track; traversing the area of said divider wall by energizing said third drive for successive sweeps at a rate according to the radial position of said carriage on said track, and energizing said one drive between these successive sweeps to position said carriage on said track; positioning said carriage at its radially outer position and then traversing the area of said channel head wall by energizing said second drive for successive sweeps at a rate according to the length of each of these sweeps along the channel head wall, and energizing said third drive between these successive sweeps to successively step said track between opposite generally horizontal and generally vertical positions.