Nuclear performance for IndecoPublished 18/12, 2017 at 16:09
Indeco attachments are playing a key role in the demolition of the nuclear power plant in Zion, Illinois. The project is being conducted by Manafort Brothers, one of the most important contractors in the US, specialized in nuclear decommissioning.
The Zion nuclear power plant is located on the shores of Lake Michigan about 64km from Chicago. Completed in 1973, the plant started producing electricity between December 1973 from the first reactor and September 1974 from the second.
The Zion power plant was part of the Commonwealth Edison (ComEd) network serving the Chicago metropolitan area and that part of the state along the lake. In February 1997, following the shut down of Reactor 1, electricity production was suspended. In February 1998, ComEd, decided to stop electricity production and decommission the plant.
In August 2010 the Nuclear Regulatory Commission allowed ComEd to transfer the license to Energy Solutions, a company specializing in the decommissioning of nuclear power plants and cleanup of industrial sites. By late 2026, the Energy Solutions project aims to restore the entire area to a Greenfield status of environmental conditions and landscape that characterized it 50 years ago before construction of the nuclear plant was started.
A long and complex decommissioning process
Energy Solutions, through the subsidiary Zion Solutions, is responsible for removal of the plants, demolition of the structures, as well as for transport of all debris to a site it owns. Decommissioning started in 1998 with removal of the nuclear fuel from the reactors. In 2011 decontamination and demolition of the structures began. Soil remediation also started at the same time. This process will take about ten years, requiring 200 specialized workers per year, and have a total project cost estimated at about US $1bn (€0.84bn.) The demolition of the reinforced concrete and steel structures could only be done by mechanical demolition techniques. The use of explosives was banned due to the potential risk of an uncontrolled release of contaminated dust into the air.
To execute the demolition process, the project was assigned to a contractor with proven experience and expertise. In 2014, Zion Solutions contracted the works to Manafort Brothers of New Britain, Connecticut, a company with a 100-year old history and a national reputation, since it was the only company that has performed demolition of two nuclear power plants on the East Coast of the US.
Manafort Brothers started with the turbine and generator building, and then proceeded with the interior of the two towers that housed Reactor 1 and Reactor 2. This was followed by dismantling the auxiliary plants building. After evaluation of demolition equipment, Manafort Brothers decided to use Indeco hammers, a pulveriser and shears.
The hammers are two HP 25000s, three HP 13001s and an HP 8000 mounted on an excavator fitted with a long boom for demolition and ISS 30/50 shears and an IRP1250 rotating pulveriser. Some of the attachments have been used on an ongoing basis for more than a year. “In Zion, as with all demolitions of this kind, there is a whole set of problems to deal with, primarily the health and safety of our workers, the compliance with environmental regulations and the need to properly plan and execute the different stages of demolition, so we can access areas not immediately reachable because they are concealed by other structures,” said Manafort Brothers site manager John Carville. “For an idea of how much reinforced concrete is present at the site, let’s just say that by the time we’ve finished the job, we’ll have produced over 113,000t of debris, all transported by train to a special site in the desert in Clive, Utah owned by Energy Solutions. And besides the concrete, we have to count the thousands of tons of ferrous and non-ferrous materials that come out of the demolition process.”
All the major internal and external structures in reinforced concrete varying from 1m to 4m, with 32-36mm diameter rebar and mesh. The biggest thicknesses were in the structures that go down to almost 18m below ground level containing the pumping plants and in the structures that held the reserve of nuclear fuel, and the foundations.
“Manafort Brothers is the only company on the East Coast that has experience in the demolition of decommissioned nuclear power plants,” said Carville. “Before Zion, we did the demolition of the Connecticut Yankee plant at Haddam Neck, Connecticut and the Maine Yankee plant in Wiscasset, Maine, so we know how to handle these projects, but to be honest, I had never encountered reinforced concrete with a compressive strength of 60-90MPa like here in Zion. That’s why the choice of hammers and other demolition equipment was absolutely critical. The decision for Indeco equipment was based not only on the good experience with the HP 8000 we were already using, but also the result of a comparison of other manufacturers’ products. The two HP 13001 are the models we operate the most, but it’s the two HP 25000 that allow us to tackle the most challenging situations. The HP 25000 has impressive power, and with its 25,000joules it is the most productive and powerful hammer on the market today. In certain conditions, it really is the only one that can be a valid alternative to blasting. All the models get top marks for reliability and durability. The pulveriser and the shears are delivering excellent productivity too. The rotating pulveriser has particularly stood out for a favourable ratio between power and size.”
At the Zion site the hammers are subjected to a heavy-duty use over a long period. “Our satisfaction with the Indeco hammers, the pulveriser and the shears is not only attributed to their production output, but also the service provided by Indeco North America, who has consistently given a rapid and efficient response to all our needs, almost all relating to routine maintenance,” said Carville. “We intend to order another two HP 13001s to finish the job.”