16. Long-term debt

  2012 2011
Debentures — Series C $299,265 $298,993
Debentures — Series D 496,566 496,152
Debentures — Series E 397,403
Debentures — Series F 99,206
Total $1,292,440 $795,145

On November 14, 2012, Cameco issued additional debentures (Series E and Series F) in the amounts of $400,000,000 and $100,000,000 respectively. The Series E debentures bear interest at a rate of 3.75% per annum (effective interest rate of 3.83%) and mature on November 14, 2022. The proceeds of the issue after deducting expenses were $397,400,000. The Series F debentures bear interest at a rate of 5.09% per annum (effective interest rate of 5.14%) and mature on November 14, 2042. The proceeds of the issue after deducting expenses were $99,200,000.

Cameco has $299,000,000 outstanding in senior unsecured debentures (Series C). These debentures bear interest at a rate of 4.70% per annum (effective interest rate of 4.79%) and mature on September 16, 2015.

Cameco has $497,000,000 outstanding in senior unsecured debentures (Series D). These debentures bear interest at a rate of 5.67% per annum (effective interest rate of 5.80%) and mature on September 2, 2019.

Cameco has a $1,250,000,000 unsecured revolving credit facility that is available until November 1, 2017. Upon mutual agreement, the facility can be extended for an additional year on the anniversary date. In addition to direct borrowings under the facility, up to $100,000,000 can be used for the issuance of letters of credit and, to the extent necessary, it may be used to provide liquidity support for the Company’s commercial paper program. The agreement also provides the ability to increase the revolving credit facility above $1,250,000,000 by no less than increments of $50,000,000, up to a total of $1,750,000,000. The facility ranks equally with all of Cameco’s other senior debt. As of December 31, 2012 there were no amounts outstanding under this facility.

Cameco has $698,814,000 ($410,917,000 and $289,374,000 (US)) in letter of credit facilities. Outstanding letters of credit at December 31, 2012 amounted to $672,224,000 ($405,421,000 and $267,879,000 (US)) (2011 - $664,575,000 ($395,606,000 and $264,186,000 (US))), the majority of which relate to future decommissioning and reclamation liabilities note 19.

Cameco is bound by a covenant in its revolving credit facility. The covenant requires a funded debt to tangible net worth ratio equal to or less than 1:1. Non-compliance with this covenant could result in accelerated payment and termination of the revolving credit facility. At December 31, 2012, Cameco was in compliance with the covenant and does not expect its operating and investing activities in 2013 to be constrained by it.

The table below represents currently scheduled maturities of long-term debt.

2013 2014 2015 2016 2017 Thereafter Total
$ — $ — $299,266 $ — $ — $993,174 $1,292,440