Notes to Consolidated Financial Statements  Years ended December 31, 2012 and 2011 17. Debt (continued)  a) Notes Issued and Retired in 2012 In February 2012, we issued US$500 million of senior unsecured notes due March 2019 and US$500 million of senior  unsecured notes due March 2042. The 2019 notes bear interest at 3.00% per annum and were issued at 99.705% of  face value. The 2042 notes bear interest at 5.20% per annum and were issued at 99.533% of face value. In August 2012, we issued US$500 million of senior unsecured notes due February 2018, US$750 million of senior  unsecured notes due February 2023 and US$500 million of senior unsecured notes due February 2043. The 2018 notes  bear interest at 2.50% per annum and were issued at 99.690% of face value. The 2023 notes bear interest at 3.75%  per annum and were issued at 99.188% of face value. The 2043 notes bear interest at 5.40% per annum and were  issued at 99.808% of face value. Net proceeds from these issues were US$2.7 billion after underwriting discounts and issue costs. The majority of  the net proceeds, in addition to cash on hand, was used to redeem US$530 million of the 9.75% notes due 2014,  US$659.5 million of the 10.25% notes due 2016, US$1.04 billion of the 10.75% notes due 2019 and to settle the  7.00% notes that matured in September 2012. The total payment, including the premium for the repurchase, was  US$2.85 billion. We recorded an accounting charge of US$965 million in the year in connection with the redemptions. In July 2011, we issued US$300 million of senior unsecured notes due January 2017, US$700 million of senior  unsecured notes due January 2022, and US$1.0 billion of senior unsecured notes due July 2041. The 2017 notes  bear interest at 3.15% per annum and were issued at 99.964% of face value. The 2022 notes bear interest at 4.75%  per annum and were issued at 99.843% of face value. The 2041 notes bear interest at 6.25% and were issued at  99.715% of face value. Net proceeds from these three issues were US$1.98 billion after underwriting discounts and issue costs. The Antamina revolving credit facility is our proportionate share of Antamina’s five-year revolving term bank facility  with full repayment due at maturity in 2015 and is the obligation of Antamina. The facility, which is denominated  in U.S. dollars, is non-recourse to us and the other Antamina project sponsors and may be renewed and extended  annually with the concurrence of the participating banks. The outstanding amount under the facility bears interest  at LIBOR plus a margin. All of our outstanding notes are callable at any time by repaying the greater of the principal amount plus accrued interest  and the present value of the principal and interest amounts discounted at a comparable treasury yield plus a stipulated  spread. The 2023, 2042 and 2043 notes issued in 2012 are callable at 100% at any time on or after November 1, 2022,  September 1, 2041 and August 1, 2042 respectively. The 2022 and 2041 notes issued in 2011 are callable at 100% at any  time on or after October 15, 2021 and January 15, 2041 respectively. The 2021 notes are callable at 100% on or after  October 15, 2020 and the 2040 notes are callable at 100% on or after February 15, 2040. At December 31, 2012 we had committed revolving credit facilities aggregating $1.1 billion, of which $1.0 billion is  available until 2016 and $100 million is available until 2013, and a $150 million uncommitted demand revolving credit  facility. Net of $178 million of letters of credit issued, the unused portion of these credit facilities is $1.1 billion at  December 31, 2012. In addition, we have issued stand-alone letters of credit for $685 million at December 31, 2012  in respect of environmental and other bonding requirements.  Teck 2012 Annual Report 104 e) Revolving Facilities d) Optional Redemptions c) Antamina Facility b) Notes Issued in 2011