Vermont Yankee: On the Ground

by kfrego

Morrison-Knudsen bought a new state of the art P&H 90 ton truck mounted crane while constructing the nuclear plant at Vernon, VT. The crane came with two hundred feet of boom and a twenty foot jib section on top of the boom for light work. There were several cranes at Vernon that could pick more than 90 tons, but they didn’t have the mobility of a truck crane. The bright yellow and black truck crane was the best and the biggest in it’s class of crane. The crane arrived in Vernon and was assembled on site by local crews under the supervision of P&H factory representatives. The crane was continuously tested and documented during assembly. The final phases of testing were test picks of verified weight loads of 90 tons with a safety factor. As more boom sections were added the test picks verified the ability of the crane to safely handle designed load capacities. On Friday the crane was certified to be placed into service on site. It was rigged up with all the boom and the jib.

Early on Monday morning the crews started moving the 90 ton P&H from the assembly yard to the work area of the nuclear plant. The P&H would follow the west access road along the perimeter of the plant. The road was cluttered on each side with construction materials. Both sides of the road on the west side of the nuclear plant were lined with the crew shacks of the various trades and vendors on site. The P&H had to make a pretty tight turn on the access road to get onto the straight stretch going through the crew shacks. The crane was backing down the road. About half way through the corner the crane operator made a swing to line the boom up with the road. When he made an adjustment of angle with the boom, the boom brake failed. The crane operator beeped his horn to signal the driver in the truck cab to stop moving. As the boom fell it was out of control. The crane operator swung the crane to keep the boom lined up with the road between the crew shacks. The two hundred feet of boom and the jib made a tremendous crash when it hit the ground. It was ten minutes before start time of normal shifts. There were around 300 people in the shacks attending their safety meetings when the boom hit. Not one person was in a position to get hurt. The crane operator had his sliding door open. He grabbed the front door jamb with his left hand just as the boom hit. The door slammed forward and broke his hand. A subsequent investigation found a small defective weather strip had allowed rainwater to drip on the friction brake during a week end thunder storm. The boom and jib on the ground were nothing but wadded up scrap iron.

The smooth, smart, calm crane operator saved the day……………………he couldn’t do much for the boom.

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