Regulatory Assets and Liabilities

Regulatory assets generally represent incurred costs that have been deferred because such costs are probable of future recovery in customer rates. Regulatory liabilities generally represent obligations to make refunds to customers for previous collections for costs that are not likely to be incurred or deferrals of gains that will be credited to customers in future periods. Components of regulatory assets and regulatory liabilities are summarized in the table below:



Regulatory Assets and Liabilities
	At December 31, 2016		At September 30, 2016
Current regulatory assets
Deferred nuclear generating units	$	237	$	237
Unrealized losses on commodity derivatives	104		122
Fuel cost adjustment receivable	41		98
Environmental agreements	27		34
Environmental cleanup costs - Kingston ash spill	42		42
Other current regulatory assets	3		3
Total current regulatory assets	454		536

Non-current regulatory assets
Deferred pension costs and other post-retirement benefits costs	5,330		5,385
Unrealized losses on interest rate derivatives	1,106		1,547
Nuclear decommissioning costs	935		938
Deferred nuclear generating units	915		850
Non-nuclear decommissioning costs	863		819
Environmental cleanup costs - Kingston ash spill	288		299
Unrealized losses on commodity derivatives	32		56
Environmental agreements	15		18
Other non-current regulatory assets	244		252
Total non-current regulatory assets	9,728		10,164
Total regulatory assets	$	10,182	$	10,700

Current regulatory liabilities
Fuel cost adjustment tax equivalents	$	151	$	148
Unrealized gains on commodity derivatives	22		6
Total current regulatory liabilities	173		154

Non-current regulatory liabilities
Unrealized gains on commodity derivatives	6		3
Total non-current regulatory liabilities	6		3
Total regulatory liabilities	$	179	$	157

Deferred Nuclear Generation Units. On November 14, 2016, following a public auction, TVA entered into a contract to sell substantially all of the Bellefonte Nuclear Plant ("Bellefonte") site for $111 million. The net book value of the Bellefonte assets to be sold and the related asset retirement costs are collectively $121 million and are included in Regulatory asset-Deferred nuclear generating units on TVA’s Consolidated Balance Sheet at December 31, 2016, as approved by the TVA Board. TVA received $22 million on November 14, 2016, which is recorded as a long-term liability on TVA’s Consolidated Balance Sheet at December 31, 2016, with the remaining $89 million due at closing. The buyer has up to two years to close on the property. Proceeds received from the sale will be recorded as a reduction to the regulatory asset upon closing and will reduce amounts collected in future rates. Any subsequent losses resulting from the disposition or impairment of Bellefonte will be recovered in future rates until fully recovered based upon the TVA Board-approved recovery of the Regulatory asset-Deferred nuclear generating units in future rates at an amount of $237 million per year until fully recovered.