Asset Retirement Obligations

6 Months Ended

Mar. 31, 2018

Asset Retirement Obligation Disclosure [Abstract]

During the six months ended March 31, 2018, TVA's total asset retirement obligation ("ARO") liability increased $85 million as a result of revisions in estimates and periodic accretion, partially offset by settlement projects that were conducted during this period. The revisions in estimate are primarily related to changes in strategy of asset retirements at certain TVA facilities. The nuclear and non-nuclear accretion expenses were deferred as regulatory assets. During the six months ended March 31, 2018, $72 million of the related non-nuclear regulatory assets were amortized into expense as these amounts were collected in rates. See Note 6. TVA maintains investment trusts to help fund its decommissioning obligations. See Note 14 — Investment Funds and Note 17 — Contingencies — Decommissioning Costs for a discussion of the trusts' objectives and the current balances of the trusts.



Asset Retirement Obligation Activity⁽¹⁾
	Nuclear		Non-Nuclear			Total
Balance at September 30, 2017	$	2,859	$	1,445		$	4,304
Settlements	—		(42		)	(42		)
Revisions in estimate	—		45			45
Additional obligations	—		1			1
Accretion (recorded as regulatory asset)	65		16			81
Balance at March 31, 2018	$	2,924	$	1,465		$	4,389

Note

(1) The current portion of ARO in the amount of $142 million and $128 million is included in Accounts payable and accrued liabilities at March 31, 2018, and September 30, 2017, respectively.