

Asset Retirement Obligation Activity⁽¹⁾
	Nuclear		Non-Nuclear			Total
Balance at September 30, 2019	$	3,136	$	2,480		$	5,616
Settlements	—		(32		)	(32		)
Revisions in estimate	—		117			117
Accretion (recorded as regulatory asset)	35		15			50
Balance at December 31, 2019	$	3,171	$	2,580		$	5,751

Note

(1) The current portion of ARO in the amount of $163 million at both December 31, 2019, and September 30, 2019, is included in Accounts payable and accrued liabilities.

The revisions in non-nuclear estimates increased $117 million for the three months ended December 31, 2019. In November 2019, the Tennessee Department of Environment and Conservation ("TDEC") released amendments to its regulations which govern solid waste disposal facilities, including TVA's active Coal Combustion Residuals ("CCR") facilities covered by a solid waste disposal permit and those which closed pursuant to a TDEC approved closure plan. Such facilities are generally subject to a 30-year post-closure care period during which the owner or operator must undertake certain activities, including monitoring and maintaining the facility. The amendments will, among other things, add an additional 50-year period after the end of the post-closure care period, require TVA to submit recommendations as to what activities must be performed during this 50-year period to protect human health and the environment, and require TVA to submit revised closure plans every 10 years. This regulatory revision resulted in an increase of $129 million, of which $38 million was related to operating CCR facilities and $91 million was related to inactive or closed CCR facilities.