U.S. independent power producer Calpine Corp. plans to issue about $2.8 billion in senior unsecured notes with 2023 and 2025 maturities to replace by tender an equal amount of existing senior secured notes with maturities in 2020 and 2021, but possibly those in 2019 as well. We assigned a 'B' debt rating and '5' recovery rating to the planned senior unsecured notes. Calpine also plans to increase its revolving credit facility to $1.5 billion from $1 billion. The planned change in Calpine's capitalization does not affect our 'B+' corporate credit rating on the company. We revised the recovery rating on the existing senior secured debt to a '1' from a '2', reflecting a lower amount of debt after the tender