In early August, a couple of subject experts from the Defense Nuclear Facilities Safety Board were at the Y-12 nuclear weapons plant to observe a contractor survey of “structural cracking” at the Highly Enriched Uranium Materials Facility — which houses the nation’s stockpile of bomb-grade uranium.
According to a spokeswoman at B&W Y-12, the government’s managing contractor at Y-12, the cracks are not unexpected or a major concern at this time. That analysis was confirmed by others familiar with the situation. But it apparently it is an issue that bears watching for the years ahead to see how it evolves, because the HEUMF — constructed at a cost of $549 million, with loading of uranium in 2010-11 — is supposed to last a long, long time.
“Exterior walls of HEUMF are fabricated from concrete, and shrinkage cracks have occurred in some locations since the end of construction,” B&W said in an email response to questions. “The concrete walls are periodically monitored, and these cracks are documented and evaluated. The existing cracks pose no structural concerns for the HEUMF building. Cracks are due to the concrete shrinking as it cures. This is normal and expected that concrete buildings will develop shrinkage cracks that are minor and of no structural significance.”
I talked with others who said that while that’s true, the weather conditions can affect the cure rate and also potentially expand or exacerbate the cracking over time. That apparently is why the situation has to be monitored over years to make sure the cracks — interior or exterior — don’t grow or cause a situation where water infiltrating the concrete causes the rebar to rust and weaken.
Asked if B&W was repairing the cracks, spokeswoman Ellen Boatner responded, “We have done no repair work to any cracks because none require repair at this time. We continue to monitor the cracks.”
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