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Asset Retirement Obligations
3 Months Ended
Dec. 31, 2018
Asset Retirement Obligation Disclosure [Abstract]  
Asset Retirement Obligations
Asset Retirement Obligations

During the three months ended December 31, 2018, TVA's total asset retirement obligations ("ARO") liability increased $20 million as a result of periodic accretion, partially offset by settlement activity from ongoing ARO projects at TVA facilities. The nuclear and non-nuclear accretion amounts were deferred as regulatory assets.  During the three months ended December 31, 2018, $36 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 14Investment Funds and Note 18ContingenciesDecommissioning 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, 2018
$
2,989

 
$
1,790

 
$
4,779

Settlements

 
(25
)
 
(25
)
Accretion (recorded as regulatory asset)
34

 
11

 
45

Balance at December 31, 2018
$
3,023

 
$
1,776

 
$
4,799

Note
(1) The current portion of ARO in the amount of $111 million and $115 million is included in Accounts payable and accrued liabilities at December 31, 2018, and September 30, 2018, respectively.

On January 25, 2019, TVA approved a change in the preferred closure method for the Allen West Impoundment from closure in place to closure by removal.  The cost impact of changing the closure method is expected to result in an increase of approximately $31 million to the non-nuclear AROs during the second quarter of 2019.  The method of final closure for this impoundment will depend on various factors, including the completion of all environmental reviews.