NEW YORK--(BUSINESS WIRE)--Fitch Ratings expects to assign a rating of 'BBB-' to AES Gener S.A.'s (AES Gener) proposed senior unsecured debt issuance of up to USD450 million with a 10-year bullet maturity. Proceeds from the 144A/RegS bond issuance will be used to refinance existing debt and will not result in additional significant indebtedness. Funds from the issuance will go towards refinancing USD308 million of existing Nueva Ventanas project finance debt with a maturity of 2022, unwinding r