WPD has recorded conditional AROs required by U.K. law related to treated wood poles, gas-filled switchgear and fluid-filled cables.

PPL Energy Supply has recorded AROs to reflect various legal obligations associated with the retirement of long-lived assets, the most significant of which relates to the decommissioning of the Susquehanna nuclear plant. The accrued nuclear decommissioning obligation was $342 million and $316 million at December 31, 2013 and 2012. The fair value of investments that are legally restricted for the decommissioning of the Susquehanna nuclear plant was $864 million and $712 million at December 31, 2013 and 2012, and is included in "Nuclear plant decommissioning trust funds" on the Balance Sheets. See Notes 18 and 23 for additional information on the nuclear decommissioning trust funds. Other AROs recorded relate to various environmental requirements for coal piles, ash basins and other waste basin retirements.

PPL Energy Supply has recorded several conditional AROs, the most significant of which related to the removal and disposal of asbestos-containing material. In addition to the AROs that were recorded for asbestos-containing material, PPL Energy Supply identified other asbestos-related obligations, but was unable to reasonably estimate their fair values. PPL Energy Supply management was unable to reasonably estimate a settlement date or range of settlement dates for the remediation of all of the asbestos-containing material at certain of the generation plants. If economic events or other circumstances change that enable PPL Energy Supply to reasonably estimate the fair value of these retirement obligations, they will be recorded at that time.

PPL Energy Supply also identified legal retirement obligations associated with the retirement of a reservoir that could not be reasonably estimated due to an indeterminable settlement date.

PPL Electric has identified legal retirement obligations for the retirement of certain transmission assets that could not be reasonably estimated due to indeterminable settlement dates. These assets are located on rights-of-way that allow the grantor to require PPL Electric to relocate or remove the assets. Since this option is at the discretion of the grantor of the right-of-way, PPL Electric is unable to determine when these events may occur.

LG&E's and KU's AROs are primarily related to the final retirement of assets associated with generating units. LG&E also has AROs related to natural gas mains and wells. LG&E's and KU's transmission and distribution lines largely operate under perpetual property easement agreements which do not generally require restoration upon removal of the property. Therefore, no material AROs are recorded for transmission and distribution assets. As described in Notes 1 and 6, LG&E's and KU's accretion and depreciation expense are recorded as a regulatory asset, such that there is no earnings impact. In 2013, AROs were revalued primarily due to updates in the estimated cash flows for ash ponds and CCR surface impoundments based on updated cost estimates.

		PPL				PPL Energy Supply
		2013		2012		2013		2012

ARO at beginning of period		$	552	$	497	$	375	$	359
	Accretion expense		38		36		29		28
	Obligations incurred		6		9		6		3
	Changes in estimated cash flow or settlement date		123		31		1		(7)
	Effect of foreign currency exchange rates		1		1
	Obligations settled		(15)		(22)		(7)		(8)
ARO at end of period		$	705	$	552	$	404	$	375

			LKE				LG&E				KU
			2013		2012		2013		2012		2013		2012

ARO at beginning of period			$	131	$	118	$	62	$	57	$	69	$	61
	Accretion expense			7		6		3		3		4		3
	Obligations incurred					6								6
	Changes in estimated cash flow
		or settlement date		122		15		17		5		105		10
	Obligations settled			(8)		(14)		(8)		(3)				(11)
ARO at end of period			$	252	$	131	$	74	$	62	$	178	$	69

Substantially all of the ARO balances are classified as noncurrent at December 31, 2013 and 2012.