DOE and USEC provide pro-rata cost sharing support for continued American Centrifuge activities under our June 2012 cooperative agreement, as amended, including in March 2013. The agreement provides for 80 percent DOE and 20 percent USEC cost sharing for work performed during the period June 1, 2012, through December 31, 2013, with a total estimated cost of $350 million. DOE’s total contribution would be up to $280 million and our contribution would be up to $70 million. The cooperative agreement is being incrementally funded, and $177.8 million of DOE funding has been provided. As of December 31, 2012, we made qualifying American Centrifuge expenditures of $115.1 million. DOE’s pro-rata share of 80 percent, or $92.1 million, is recognized as other income in 2012.
At December 31, 2012, USEC had a cash balance of $292.9 million compared to $37.6 million at December 31, 2011. Cash flow from operations in 2012 was $142.9 million compared to cash flow from operations of $56.3 million in the previous year. Positive cash flow resulted from a $238.7 million reduction in inventories due to monetization of inventory produced in the prior year. Capital expenditures were $4.3 million during 2012 compared to $152.8 million in 2011. USEC ceased capitalizing spending on the ACP as of September 30, 2011.
On March 14, 2013, we amended our existing $230.0 million credit facility that was scheduled to mature on May 31, 2013, now extended to September 30, 2013. The amended revolving credit facility totals $110.0 million (including letters of credit of up to $50.0 million or $25.0 million upon cessation of enrichment at the Paducah GDP). The term loan under the credit facility, which had declined to $78.1 million outstanding, was repaid in connection with the amendment.Sale of NAC International Revenue for the contract services segment was derived primarily from NAC in 2012. This wholly owned subsidiary was acquired by USEC in 2004 and provides transportation and storage systems for spent nuclear fuel and provides nuclear and energy consulting services. On March 15, 2013, USEC sold NAC to a subsidiary of Hitachi Zosen Corporation for $42.4 million, subject to final working capital adjustment.