Asset Retirement Obligations (Tables)

9 Months Ended

Jun. 30, 2022

Asset Retirement Obligation Disclosure [Abstract]


Asset Retirement Obligation Activity
	Nuclear		Non-Nuclear		Total
Balance at September 30, 2021	$	3,428	$	3,574	$	7,002	(1)
Settlements	(2)		(195)		(197)
Revisions in estimate	3		237		240


Accretion (recorded as regulatory asset)	116		50		166

Balance at June 30, 2022	$	3,545	$	3,666	$	7,211	(1)

Note

(1) Includes $313 million and $266 million at June 30, 2022, and September 30, 2021, respectively, recorded in Current liabilities.

The revisions in non-nuclear estimates increased the liability balance by $237 million for the nine months ended June 30, 2022. TVA implemented revised depreciation rates during the first quarter of 2022 applicable to its completed plant as a result of the completion of a new depreciation study. The study included a decline in the service life estimates of TVA’s coal-fired plants based on current planning assumptions to potentially retire the remainder of the coal-fired fleet by 2035. As a result of the change in the service life estimates reflected in the depreciation study, TVA performed an assessment of the assumptions used in the timing of cash flows related to its non-nuclear AROs. Based on the assessment, TVA identified changes to its projections of timing of certain asset retirement activities, resulting in an increase of $47 million to the ARO. In addition, TVA completed an engineering review of its cost estimates for closure of certain areas containing coal fines at Paradise Fossil Plant, resulting in an increase of $119 million due to expected cost increases for necessary changes in activities associated with proper completion of the closure. During the second quarter of 2022, based on refined project cost assumptions and scope changes, TVA revised its AROs for the closure of certain coal yards at its fossil plants, resulting in an increase to AROs of $57 million. During the third quarter, coal combustion residual ("CCR") closure liabilities at Paradise and Cumberland Fossil Plants increased $82 million due to new vendor bids, modified closure designs, and revised estimates for construction costs. Partially offsetting these increases, was a reduction in expected CCR post-closure care costs for maintenance and monitoring at Paradise, Shawnee, and Colbert Fossil Plants resulting in a decrease in these liabilities of $53 million.