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Asset Retirement Obligations (Tables) | 3 Months Ended
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Dec. 31, 2021
Asset Retirement Obligation Disclosure [Abstract] |
Asset Retirement Obligation Activity |
Asset Retirement Obligation Activity |
| Nuclear |  | Non-Nuclear |  | Total |
Balance at September 30, 2021 | $ | 3,428 |  |  | $ | 3,574 |  |  | $ | 7,002 |  | (1)
Settlements | — |  |  | (61) |  |  | (61) |  |
Revisions in estimate | — |  |  | 163 |  |  | 163 |  |
Accretion (recorded as regulatory asset) | 38 |  |  | 17 |  |  | 55 |  |
Balance at December 31, 2021 | $ | 3,466 |  |  | $ | 3,693 |  |  | $ | 7,159 |  | (1)
Note (1) Includes $301 million and $266 million at December 31, 2021, and September 30, 2021, respectively, recorded in Current liabilities. The revisions in non-nuclear estimates increased the liability balance by $163 million for the three months ended December 31, 2021. 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 includes 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 asset retirement obligation. 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.

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- Definition Tabular disclosure of the carrying amount of a liability for asset retirement obligations. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 410 -SubTopic 20 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6392692&loc=d3e7535-110849 + Details
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