Vermont Yankee: Grouted
While working on the concrete crew at Vernon we had lots of fun with Johnny Joe Kaska. We placed concrete for the reactor containment building on a regular basis. This is the large domed shaped building which encloses the massive steel reactor of a nuclear power plant. We had a new truck mounted hydraulic concrete pump parked at the edge of the building. Five inch concrete slickline pipe delivered the concrete to the various placements. We were always several hundred feet away from the pump and could never see the pump. An electric signal bell was used for pump operator communication. The slickline pipe ran up, over, and around many obstacles to get the concrete to us. We often had to spread the reinforcement steel with come-a-longs to get the line inside a placement. The slickline was installed with a ten foot rubber flex hose on the end. We could place the concrete accurately with the flex hose. As the forms were filled we would remove ten feet of solid pipe and reinstall the rubber flex hose on the end.
When the slickline is charged with concrete a lubricant has to go ahead of the concrete. The lubricant was normally a very thin sand cement grout with water. The concrete would not get through the dry pipe without plugging if the lubricant wasn’t ahead of it. We were starting a concrete placement near the top of the circular dome around the reactor. We had massive amounts of #18 reinforcing bars on both sides of the placement. The rebar followed the curvature of the reactor and had about four feet of open space in the middle. Our slickline was close to the end of the placement. Johnny Joe was tagging the flex line as we rang the pump operator to send our grout followed by the concrete. When we got the grout we would bend the flex hose in a wide arc to flow the wet grout behind us. The grout would act as a slurry between the new and existing concrete. We would signal the pump off to put the flex hose back in position to place the concrete.
We started getting grout. Johnny Joe picked the end of the flex hose straight up about five feet and flopped it backwards. He had a hard kink right in the middle of the hose. As he flopped the hose back he knocked our signal bell off the rebar where we couldn’t reach it. The grout stopped coming because of the kink. Each time the concrete pump stroked the flex hose behind the kink got a little bigger. So did John’s eyes. There was no way for us to get to John to help him. We couldn’t get to the bell to shut off the pump. Finally the pressure lifted John off his feet, the kink came out, and grout went twenty feet in the air out of a five inch hose. A large area and thirty to forty people below us with all their tools got covered with grout. The only reason we didn’t get our butts kicked was because they couldn’t get to us.
We were lucky none of us got hurt…………………and nobody killed Johnny Joe.