Maine Yankee Containment Dome Brought Down By Dynamite

Maine Yankee Containment Dome Brought Down By Dynamite

The Loizeaux Group, LLC

Two years of preparatory demolition culminated September 17th in the detonation of 1,100 lb of carefully placed dynamite, dropping the containment dome of 900-MW Maine Yankee Nuclear Unite 1. The 85-ft. drop put the heavily reinforced concrete dome within easy reach of ground-based demolition equipment.

“We brought the dome down to where we could reach it with specialty equipment”, says Justin Manafort, Vice President of Manafort Brothers, Inc., Plainville, Connecticut. A typical excavator can reach 30 to 35 ft., but the contractor modified its excavators to reach up to 100 ft. for this project.

At 150 ft. tall, “the dome was too big to take down mechanically”, says Doug Loizeaux, Vice President of Controlled Demolition, Inc., Phoenix, Maryland, Manafort’ s subcontractor. Instead, Manafort attacked the 85-ft-tall vertical walls, cutting away 25 to 35-ft-wide sections in the 530-ft circumference and leaving the dome standing on nine columns ranging from 17 to 21 ft. wide. Workers cut out the liner between the columns just before demolishing them.

The 170-ft-diameter cylinder’s concrete wall, tapering from 4.5 ft. to 2.5 ft., was reinforced with five mates of #18 rebar. Workers cut it into 5-ft. lengths for shipment from the Wiscasset, Maine, Site to a disposal site in Utah. The 3/8-in. steel liner, left in place during demolition, allowed workers inside to continue removing the steam generator, piping and internal structures.

“We couldn’t have any flying debris,” says Loizeaux. “We just took away the compressive capability of the concrete and allowed the columns to crush under the weight of the 10-million-lb dome.” Nuclear contamination was not an issue because all contaminated equipment and materials had been cleaned or removed well before demolition.

Manafort has been on site since 1999, and its fixed-price contract has grown from $11 million to $30 million through condition changes and additions to the scope. Dome demolition will take about a month more.