Talen Energy Corp

8. Asset Retirement Obligations and Accrued Environmental Costs

Certain subsidiaries of the Company have legal retirement obligations for the decommissioning and environmental remediation costs associated with our current and former generation sites. Most of these obligations, except remediation of some ash impoundments, are not expected to be paid until several years, or decades, in the future. The Company’s most significant obligations are associated with the: (i) decommissioning of Susquehanna, which the NDT is expected to fund; and (ii) coal ash disposal units of legacy coal-fired generation facilities which, for certain obligations, the Company has posted surety bonds (some of which have been collateralized with LCs). The carrying value of these AROs include assumptions of estimated future retirement and remediation cash expenditures, cost escalation rates, probabilistic cash flow models, and discount rates.

The Company may be required to revise or recognize new AROs as a result of regulatory changes by the NRC, EPA, Montana Department of Environmental Quality (the “MDEQ”) or other regulatory entities. Additionally, revisions may result from scope of work amendments to remediation activities as well as changes to remediation costs and other assumptions. If the assumptions underlying any ARO estimates do not materialize as expected, actual cash expenditures and costs could be materially different than currently estimated.

As of March 31, 2026, the fair values of certain conditional AROs as a result of the EPA CCR Rule cannot be determined. See Note 9 for additional information on a recent EPA proposal to rescind certain provisions of the EPA CCR Rule.

The carrying value of AROs and accrued environmental costs were:

(a)Presented as “Other current liabilities” on the Consolidated Balance Sheets.

The changes of the ARO carrying value during the period were:

The disaggregation of ARO carrying values on the Consolidated Balance Sheets was:

(a)Obligations are expected to be settled with available funds in the NDT at the time of decommissioning. See Note 6 for additional information on the NDT.

(b)Certain obligations are: (i) partially supported by surety bonds, some of which have been collateralized with LCs; or (ii) partially prefunded under phased installment agreements.