Asset Retirement Obligations

6 Months Ended

Mar. 31, 2024

Asset Retirement Obligation Disclosure [Abstract]

During the six months ended March 31, 2024, TVA's total asset retirement obligations ("ARO") liability increased $103 million primarily due to revisions in estimate to non-nuclear AROs and increases from periodic accretion, partially offset by revisions in estimate to nuclear AROs and settlements related to retirement projects that were conducted during the period. The nuclear and non-nuclear accretion amounts were deferred as regulatory assets. During the six months ended March 31, 2024, $94 million of the related regulatory assets were amortized into expense as these amounts were collected in rates. See Note 8 — Regulatory Assets and Liabilities. TVA maintains investment trusts to help fund its decommissioning obligations. See Note 14 — Fair Value Measurements — Investment Funds and Note 20 — Contingencies and Legal Proceedings — Contingencies — Decommissioning Costs for a discussion of the trusts' objectives and the current balances of the trusts.


Asset Retirement Obligation Activity (in millions)
	Nuclear		Non-Nuclear		Total
Balance at September 30, 2023	$	3,808	$	3,681	$	7,489	(1)
Settlements	(3)		(119)		(122)
Revisions in estimate	(161)		253		92


Accretion (recorded as regulatory asset)	86		47		133

Balance at March 31, 2024	$	3,730	$	3,862	$	7,592	(1)

Note

(1) Includes $311 million and $272 million at March 31, 2024, and September 30, 2023, respectively, in Current liabilities.

Revisions in non-nuclear estimates increased the liability balance by $253 million for the six months ended March 31, 2024. The increase was primarily attributable to a change in closure liabilities of $184 million at Gallatin Fossil Plant based on new vendor bids associated with final closure and $76 million at Cumberland based on scope changes to the interim closure plan and updated cost estimates for activities associated with final closure.