New Enclosure for Chernobyls 4th reactor,
While Japan struggles to stabilise its wrecked Fukushima nuclear plant, engineers in Ukraine are only now starting construction of a new enclosure for Chernobyl’s fourth reactor, almost exactly 25 years after it exploded causing immense human and environmental damage in the region and globally. (ENR November 24, 2008, page. 80)
It's too early to say whether the Japanese will need their version of Chernobyl’s $1.4 billion, 29,000-tonne steelwork safe confinement in which to clear away their nuclear ruins. But the hard lessons learnt in Ukraine’s $2.2-billionthe shelter implementation plan following the 26 April 1986 disaster could give Japan’s clean-up a running start.
Chernobyl’s shelter implementation plan should have been completed a few years ago according to tentative schedules made in the mid 1990s. Now, everybody’s working to a mid-2015 deadline for the new confinement to be in place.
The combination of nuclear hazards and engineering difficulties puts the Chernobyl project in a class of its own, believes Novak. The indicative early schedule was conditional on findings of subsequent research into previously unknown areas, he adds. “We got to the point where we could understand the scope (only) in the summer of 2003”.
Even then, “procurement took longer than we anticipated in 2003 and the design of the new safe confinement took longer,” adds Novak. “The issues were first of a kind for everybody,” he says. The involvement of national and international experts and regulators added further complications.
Now at last the new confinement’s design is on course for securing regulatory approval, probably this autumn, says Eric Schmieman, senior technical advisor with the shelter implementation plan’s project management unit. The unit includes Chernobyl staff and specialists from a consortium including Bechtel National Inc., San Francisco, Battelle Memorial Institute, Columbus, Ohio.
With a span of 257-m, the 150-m-long arching confinement will rise 105-m to enclose the entire reactor building. The confinement will have a 100-year design life and accounts for two thirds of the shelter plan’s budget. It is the main goal of the 22 work packages in the plan.
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“Most of the preparatory works have been completed,” says Schmieman. Putting up a new vent stack over the reactor building next year, removing the old one in 2013 and strengthening walls in the turbine generator hall next to the new confinement are among major pieces of work still to be done, he adds.
At the new confinement's erection site, just west of the reactor building, earthmoving is largely done. Piling is under way for the two large ground beams along which the turnkey consortium Novarka will slide the preassembled confinement into place. Concrete foundation pads for cranes to be used in the vault erection are also being cast.
