approximately in height with an outside diameter of about . The containment has 42-inch thick concrete walls, has a flat foundation mat and a shallow torispherical dome. Post-tensioning is achieved by utilizing an outer array of horizontal tendons immediately adjacent to an inner array of vertical tendons that are embedded in the walls about 15 inches from the outside surface. Refueling outage, containment repairs and closure CR-3 went offline in September 2009 for RFO-16. While the reactor was down, the old steam generators were to be replaced. There are 426 steel tendons within the concrete walls of the reactor containment dome which reinforce the dome. Plan developer Sargent & Lundy specified that 97 tendons be loosened. Progress rejected that number as excessive. The next proposal was to loosen 74 tendons, which was typical of other nuclear plants doing the procedure. According to a Progress employee, "de-tensioning the tendons is a very expensive and time-consuming effort", so the number was further reduced to 65. Progress engaged Bechtel to provide a 3rd party review, which agreed that 65 was appropriate. However, when the work was performed, only 27 tendons were loosened, and a foreman and supervisor sent emails questioning the way the tendons were loosened. When workers began to cut the access hole for the steam generators, a crack formed. That crack was repaired, but more cracks appeared. Engineers noticed that parts of the concrete had delaminated. This was repaired, and the concrete re-tensioned, but the same problem was found in other areas. The plant had originally been due to restart in April 2011 following the uprate, but in June 2011 Progress Energy said that it did not expect it to restart until 2014. Preliminary cost estimates for the repairs was put at between $900 million and $1.3 billion, but this estimate was later called into question by Duke Energy. In October 2012 an independent review estimated the repair cost at $1.5 billion, with a worst-case scenario of $3.4 billion. In February 2013 Duke Energy announced that Crystal River would be permanently shut down and that they will recover $850 million in insurance claims. A Duke spokesperson stated, "The company sought input from numerous engineering experts — internally and externally — and used proven industry-accepted practices when determining how to replace the steam generators. Analysis has shown that the 2009 delamination (cracking) could not have been predicted. The U.S. Nuclear Regulatory Commission