Brian Bradley
NS&D Monitor
8/7/2015
Structural engineers at the Y-12 National Security Complex have begun preliminary design work to stabilize a concrete beam found with vertical and horizontal cracks, according to a letter sent last month from the Energy Department’s Oak Ridge site office to the Defense Nuclear Facilities Safety Board and released this week. The beam is 36 inches deep and 16 inches wide, and had a vertical crack midspan “appearing to be almost the full depth of the beam and roughly 3/8 in. wide,” the letter states. Y-12 contractor Consolidated Nuclear Security became aware of the issue in June after a structural engineer inspected the area upon receiving reports of chips of spalled concrete falling from the ceiling. The engineer also found horizontal cracks about 5 feet in length near the level of the lower reinforcing bar.
Another same-sized beam had horizontal cracks and a thinner vertical crack. “The ceiling area has staining on the concrete indicative of solution leaks from legacy processing that was conducted on the floor above years ago,” the letter states. “The CNS structural engineer informed the shift manager of the cracks, who directed the area to be cordoned off to prevent unauthorized entry.”
According to the July 10 letter, the area below the beam with the wider vertical crack is “heavily congested,” so a design solution will involve more than installing a simple vertical column and might include constructing a structural steel support frame. CNS did not respond to a request for comment on the matter.
