Nuclear reactor vessel decontamination systems
First Claim
1. A decontamination system adapted to being temporarily installed by being raised above and thereafter lowered progressively into an upright open-topped cylindrical nuclear reactor vessel during a decontamination operation being performed on the interior of the vessel, comprising guide means installed within the reactor vessel, a circular horizontal track smaller than the diameter of the vessel, means on the track for engaging the guide means to center the track in the vessel, a pair of oppositely directed arms supported and guided on the track, a high pressure nozzle assembly on each arm, each assembly including a pair of nozzles spaced apart from each other in a vertical direction, at least one of the nozzles being formed to direct a generally cylindrical jet toward the wall and at least one other nozzle being formed to direct a generally fan shaped sweeping pattern toward the wall, means for imparting a rotary motion to the arms in a full circle around the track with the nozzle assemblies in close proximity to the interior wall of the vessel and means for targeting fluid under high pressure through the nozzles at the interior wall.
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Abstract
There is disclosed in the present application, a decontamination system for reactor vessels. The system is operatable without entry by personnel into the contaminated vessel before the decontamination operation is carried out and comprises an assembly which is introduced into the vertical cylindrical vessel of the typical boiling water reactor through the open top. The assembly includes a circular track which is centered by guideways permanently installed in the reactor vessel and the track guides opposed pairs of nozzles through which water under very high pressure is directed at the wall for progressively cutting and sweeping a tenacious radioactive coating as the nozzles are driven around the track in close proximity to the vessel wall. The whole assembly is hoisted to a level above the top of the vessel by a crane, outboard slides on the assembly brought into engagement with the permanent guideways and the assembly progressively lowered in the vessel as the decontamination operation progresses. The assembly also includes a low pressure nozzle which forms a spray umbrella above the high pressure nozzles to contain radioactive particles dislodged during the decontamination.
69 Citations
7 Claims
- 1. A decontamination system adapted to being temporarily installed by being raised above and thereafter lowered progressively into an upright open-topped cylindrical nuclear reactor vessel during a decontamination operation being performed on the interior of the vessel, comprising guide means installed within the reactor vessel, a circular horizontal track smaller than the diameter of the vessel, means on the track for engaging the guide means to center the track in the vessel, a pair of oppositely directed arms supported and guided on the track, a high pressure nozzle assembly on each arm, each assembly including a pair of nozzles spaced apart from each other in a vertical direction, at least one of the nozzles being formed to direct a generally cylindrical jet toward the wall and at least one other nozzle being formed to direct a generally fan shaped sweeping pattern toward the wall, means for imparting a rotary motion to the arms in a full circle around the track with the nozzle assemblies in close proximity to the interior wall of the vessel and means for targeting fluid under high pressure through the nozzles at the interior wall.
Specification