Summary of Significant Accounting Policies	12 Months Ended
Dec. 31, 2011
Accounting Policies [Abstract]
Basis of Presentation and Significant Accounting Policies	1. SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES Nature of Operations USEC Inc. ("USEC") is a global energy company and is a leading supplier of low enriched uranium ("LEU") for commercial nuclear power plants. LEU consists of two components: separative work units ("SWU") and uranium. SWU is a standard unit of measurement that represents the effort required to transform a given amount of natural uranium into two components: LEU having a higher percentage of U235 and depleted uranium having a lower percentage of U235. The SWU contained in LEU is calculated using an industry standard formula based on the physics of enrichment. The amount of enrichment deemed to be contained in LEU under this formula is commonly referred to as its SWU component and the quantity of natural uranium used in the production of LEU under this formula is referred to as its uranium component. Utility customers typically provide uranium to USEC as part of their enrichment contracts, and USEC delivers LEU to the customers and charges for the SWU component. In addition, USEC performs contract services through our subsidiary NAC International Inc. ("NAC") and for DOE and DOE contractors at the Paducah gaseous diffusion plant ("GDP") in Paducah, Kentucky and the site of the former Portsmouth GDP in Piketon, Ohio. Basis of Presentation The consolidated financial statements include the accounts of USEC Inc., its principal subsidiary, United States Enrichment Corporation, and its other subsidiaries including NAC. American Centrifuge Manufacturing, LLC, a joint company established by USEC (through its subsidiary American Centrifuge Holdings, LLC) and Babcock & Wilcox Technical Services Group, Inc., is also included in the consolidated financial statements. All material intercompany transactions are eliminated. Liquidity Risks and Uncertainties Key factors that can affect liquidity requirements for USEC's existing operations include the timing and amount of customer sales, power purchases, and purchases under the Russian Contract. In addition, USEC expects to make a number of decisions during 2012 that could have significant consequences for its business, including whether to continue enrichment operations of Paducah plant beyond May 2012 and the potential to demobilize the American Centrifuge project if DOE funding is not obtained for the RD&D program. These decisions, as well as actions that may be taken by vendors, customers, creditors and other third parties in response to USEC's decisions or based on their view of USEC's financial strengths and future business prospects, could give rise to events that individually, or in the aggregate, are likely to impose significant demands upon the company's liquidity. In light of these factors and USEC's desire to improve its credit profile, the company may pursue discussions with creditors and key stakeholders regarding the restructuring of its business and capital structure. USEC's sales backlog in its LEU segment is a source of stability for USEC's liquidity position. At December 31, 2011, USEC had contracts with customers aggregating an estimated $5.8 billion, including $1.5 billion expected to be delivered in 2012. Although sales prices under many of USEC's SWU contracts are adjusted in part based on changes in market prices for SWU and electric power, the impact of market volatility in these indices is generally mitigated through the use of market price averages over time. Additionally, changes in the power price component of sales prices are intended to mitigate the effects of changes in USEC's power costs. In order to enhance its liquidity and manage its working capital, USEC in light of anticipated sales and inventory levels and to respond to customer-driven changes, has been working with customers regarding the timing of their orders, in particular the advancement of those orders. Rather than selling material into the limited spot market for enrichment, USEC advanced orders from 2011 into 2010 and orders from 2012 into 2011. Based on USEC's outlook for demand and anticipated liquidity and working capital needs, USEC continues to work with customers to advance orders into 2012. The advancement of orders has the effect of accelerating receipt of cash from such advanced sales, although the amount of cash received from such sales may be reduced as a result of the terms mutually agreed with customers in connection with advancement. The shutdown of the Japanese reactors and the shutdown of reactors in other countries due to concerns raised by March 11 events have affected supply and demand for LEU over the next 2-4 years. This impact could grow more significant over time depending on the length and severity of delays or cancellations of deliveries. As a result, USEC has not been able to replace many of the order advancements that have been done in the past with additional sales, which has had the effect of reducing USEC's backlog as of December 31, 2011 compared to prior periods. Delays in decisions with respect to the extension of Paducah plant operations and delays in the deployment of the American Centrifuge project have also had a negative effect on USEC's backlog. Sales are a function of USEC's future supply, including potential supply from Paducah plant operations and from the American Centrifuge Plant ("ACP"). Looking out beyond the next 2-4 years, USEC expects an increase in uncommitted demand that could provide the opportunity to make additional sales to supplement USEC's backlog and thus decrease the need to advance orders in the future. However, the amount of any demand and USEC's ability to capture that demand is uncertain. USEC's ability to advance orders depends on the willingness of USEC's customers to agree to advancement on terms that USEC finds acceptable. In light of the order advancements that have been done in the past, additional order advancements are challenging, which could adversely affect USEC's liquidity. USEC needs significant additional financing in order to complete the American Centrifuge Plant. USEC applied for a $2 billion loan guarantee under the DOE Loan Guarantee Program in July 2008 and efforts since then and throughout most of 2011 have been focused on obtaining a conditional commitment for a loan guarantee so that the company could move forward with the commercialization of the American Centrifuge technology. However, DOE raised concerns regarding the financial and project execution depth of the American Centrifuge project that USEC was not able to overcome to DOE's satisfaction during 2011. USEC's spending on the American Centrifuge in 2011 was incrementally allocated as the company continuously evaluated its spending plan and a path toward a DOE loan guarantee commitment or other funding for the project. Beginning in October 2011, USEC reduced its monthly spending on the American Centrifuge project by approximately 30% (as compared to the average monthly rate of spending in the prior months of 2011) and also suspended a number of contracts with suppliers and contractors involved in the American Centrifuge. Instead of moving forward with a conditional commitment for a loan guarantee, in the fall of 2011, DOE proposed a two-year cost share research, development and demonstration ("RD&D") program for the project to enhance the technical and financial readiness of the centrifuge technology for commercialization. Under the cost-sharing arrangement, DOE's total contribution would be capped at $300 million. DOE indicated that USEC's application for a DOE loan guarantee would remain pending during the RD&D program. During late 2011 and early 2012, the American Centrifuge project efforts shifted to focus on the planning and implementation of the RD&D program and efforts that are currently underway in Piketon, Ohio and Oak Ridge, Tennessee are based upon the proposed program scope. USEC is currently building machines and parts that would be part of the complete demonstration cascade that would be built and operated as part of the RD&D program. In parallel, USEC has been working with DOE and Congress to secure funding for the RD&D program. However, DOE's share of funding for the program has not yet been provided and the source for such funding is uncertain. The current political environment in Washington has significantly slowed the legislative process. The two houses of Congress are each held by a different political party and in an election year the necessary bipartisan support will be difficult to achieve. Due to constraints on USEC's ability to continue to spend on the project, on March 13, 2012, USEC and DOE entered into an agreement that enables USEC to provide interim funding of $44 million. This funding was provided by DOE acquiring from us U.S. origin LEU in exchange for the transfer of quantities of our depleted uranium ("tails") to DOE. This enables USEC to release encumbered funds of approximately $44 million that were previously provided as financial assurance for the disposition of such depleted uranium. USEC expects that this LEU acquired by DOE could be returned to USEC as part of DOE's cost share under the RD&D program if government funding is provided for the RD&D program in government fiscal year 2012. However, if the RD&D program does not move forward, the LEU would not be returned to USEC, and DOE would not reimburse these ACP costs. The $44 million of funding enables USEC to fund the ACP program activities through the end of March 2012. In order to stay within the $44 million, USEC has further reduced its spending from the spending reductions implemented in October 2011. Continuation of the RD&D program beyond March 2012 will require additional funding. USEC is working with DOE and Congress to provide funding for government fiscal year 2012. Funding for the RD&D program beyond government fiscal year 2012 would be subject to future appropriations. USEC has no assurance that it will be able to reach agreement with DOE regarding any phase of the RD&D program or that any funding will be provided or that the LEU will be returned. USEC also has no assurance that it will ultimately be able to obtain a loan guarantee and the timing thereof. Any agreement for the RD&D program would likely require restructuring of the project and of USEC's investment. In light of USEC's inability to reach a conditional commitment for a DOE loan guarantee to date, and given the significant uncertainty surrounding USEC's prospects for finalizing an agreement and obtaining funding from DOE for an RD&D program and the timing thereof, USEC continues to evaluate its options concerning the American Centrifuge project. If USEC is unable to secure funding for the RD&D program beyond March 31, 2012 USEC would expect to begin demobilizing the project. Cash and Cash Equivalents Cash and cash equivalents include temporary cash investments with original maturities of three months or less. Inventories USEC holds uranium at the Paducah GDP in the form of natural uranium and as the uranium component of LEU. USEC holds SWU as the SWU component of LEU. USEC may also hold title to the uranium and SWU components of LEU at fabricators to meet book transfer requests by customers. Fabricators process LEU into fuel for use in nuclear reactors. Under inventory optimization arrangements between USEC and domestic fabricators, fabricators order bulk quantities of LEU from USEC based on scheduled or anticipated orders from utility customers for deliveries in future periods. As delivery obligations under actual customer orders arise, USEC satisfies these obligations by arranging for the transfer to the customer of title to the specified quantity of LEU at the fabricator. USEC's balances of SWU and uranium vary over time based on the timing and size of the fabricator's LEU orders from USEC. Balances can be positive or negative at the discretion of the fabricator. Fabricators have other inventory supplies and, where a fabricator has elected to order less material from USEC than USEC is required to deliver to its customers at the fabricator, the fabricator will use these other inventories to satisfy USEC's customer order obligations on USEC's behalf. In such cases, the transfer of title of LEU from USEC to the customer results in quantities of SWU and uranium owed by USEC to the fabricator. These obligations are presented in current liabilities, comprising most of the balance of inventories owed to customers and suppliers. The amounts of SWU and uranium owed to fabricators are satisfied as future bulk deliveries of LEU are made. Inventories of SWU and uranium are valued at the lower of cost or market. Market is based on the terms of long-term contracts with customers, and, for uranium not under contract, market is based primarily on published spot price indicators at the balance sheet date. SWU and uranium inventory costs are determined using the monthly moving average cost method. SWU costs are based on production costs and purchase costs. Production costs at the Paducah GDP consist principally of electric power, labor and benefits, depleted uranium disposition cost estimates, materials, depreciation and amortization and maintenance and repairs. USEC purchases SWU under a commercial agreement ("Russian Contract") with a Russian government entity known as OAO Techsnabexport ("TENEX"). The Russian Contract implements a government-to-government nonproliferation agreement between the United States and the Russian Federation. Under the agreement, USEC has been designated by the U.S. government to order LEU derived from dismantled Soviet nuclear weapons. The Russian Contract is expected to be completed in 2013. The cost of the SWU component of LEU purchased under the Russian Contract is recorded at acquisition cost plus related shipping costs. Underfeeding is a mode of operation that uses or feeds less uranium but requires more SWU in the enrichment process, which requires more electric power. The quantity of uranium that is earned or added to uranium inventory from underfeeding is accounted for as a byproduct of the enrichment process. Production costs are allocated to the uranium earned based on the net realizable value of the uranium, and the remainder of production costs is allocated to SWU inventory costs. Deferred Income Taxes USEC follows the asset and liability approach to account for deferred income taxes. Deferred tax assets and liabilities are recognized for the anticipated future tax consequences of temporary differences between the balance sheet carrying amounts of assets and liabilities and their respective tax bases. Deferred income taxes are based on income tax rates in effect for the years in which temporary differences are expected to reverse. The effect on deferred income taxes of a change in income tax rates is recognized in income when the change in rates is enacted in the law. A valuation allowance is provided if it is more likely than not that some or all of the deferred tax assets may not be realized. Property, Plant and Equipment Construction work in progress is recorded at acquisition or construction cost. Upon being placed into service, costs are transferred to leasehold improvements or machinery and equipment at which time depreciation and amortization commences. USEC leases the Paducah GDP located in Paducah, Kentucky and portions of the former Portsmouth GDP located in Piketon, Ohio from the U.S. Department of Energy ("DOE"). Leasehold improvements and machinery and equipment are recorded at acquisition cost and depreciated on a straight line basis over the shorter of the useful life of the assets or the expected productive life of the plant, which is 2016 for the Paducah GDP commensurate with the term of the lease agreement. Maintenance and repair costs are charged to production costs as incurred. Additional details related to capitalized costs included in property, plant and equipment, and related disposition obligations, are provided below in "Advanced Technology Costs" and "Lease Turnover Costs and Asset Retirement Obligations." Advanced Technology Costs Costs relating to the American Centrifuge technology are charged to expense or capitalized based on the nature of the activities and estimates and judgments involving the completion of project milestones. Costs relating to the demonstration of American Centrifuge technology are charged to expense as incurred. Demonstration costs include Nuclear Regulatory Commission ("NRC") licensing of the American Centrifuge Demonstration Facility located in Piketon, Ohio, engineering activities, and assembling and testing of centrifuge machines and equipment at centrifuge test facilities located in Oak Ridge, Tennessee and at the American Centrifuge Demonstration Facility. Advanced technology costs charged to expense include employee salaries and related benefits, contractor and third party costs, facility related costs, and other direct and indirect costs attributable to the American Centrifuge technology that are not capitalizable. Capitalized costs relating to the American Centrifuge technology include NRC licensing of the ACP in Piketon, Ohio, engineering activities, construction of centrifuge machines and equipment, leasehold improvements and other costs directly associated with the commercial plant. Capitalized American Centrifuge costs are recorded in property, plant and equipment primarily as part of construction work in progress. The continued capitalization of costs is subject to ongoing review and successful project completion. USEC's move during the second half of 2007 from a demonstration phase to a commercial plant phase in which significant expenditures are capitalized was based on management's judgment that the technology has a high probability of commercial success and meets internal targets related to physical control, technical achievement and economic viability. Beginning with the start of the fourth quarter of 2011, all project costs incurred have been expensed, including interest expense that previously would have been capitalized. Spending at the reduced levels relates primarily to development and maintenance activities rather than capital asset creation. USEC also expects to expense costs under the RD&D program as incurred. Capitalization of expenditures related to ACP has ceased until commercial plant deployment resumes. If conditions change, including if the current path to commercial deployment were no longer probable or our anticipated role in the project were changed, USEC could expense up to the full amount of previously capitalized costs related to the ACP. Refer to Note 4, "Property, Plant and Equipment" and Note 16, "Commitments and Contingencies" for further details and USEC's current assessment of the American Centrifuge project. In 2002, USEC and DOE signed an agreement in which both USEC and DOE made long-term commitments directed at resolving issues related to the stability and security of the domestic uranium enrichment industry. Discussion of USEC's commitments related to American Centrifuge project milestones under this agreement is provided in Note 16. Long-Lived Assets USEC evaluates the carrying value of long-lived assets by performing impairment tests whenever adverse conditions or changes in circumstances indicate a possible impairment loss. Impairment tests are based on a comparison of estimated undiscounted future cash flows to the carrying values of long-lived assets. If impairment is indicated, the asset carrying value is reduced to fair market value or, if fair market value is not readily available, the asset is reduced to a value determined by applying a discount rate to expected cash flows. Goodwill USEC's long-term assets include goodwill resulting from USEC's acquisition of NAC in 2004. USEC evaluates the carrying value of goodwill by performing an impairment test on an annual basis or whenever events or changes in circumstances indicate that its carrying amount may not be recoverable. The goodwill testing utilizes a two-step process, where the carrying value of the reporting unit is compared to its fair value. If the carrying value is less than the fair value, no impairment exists and the second step is not performed. However, if the carrying value is greater than the fair value, the second step is performed. An impairment charge would be recognized for the amount that the carrying value of the goodwill exceeds its fair value. The fair value of the reporting unit is estimated using the net present value of projected future cash flows. In its annual testing in the fourth quarter of 2011, USEC determined in the first step that there was no impairment. Financial Instruments and Fair Value Measurement Accounting standards define fair value as the price that would be received from selling an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. When determining the fair value measurements for assets and liabilities required or permitted to be recorded at fair value, consideration is given to the principal or most advantageous market and assumptions that market participants would use when pricing the asset or liability. Pursuant to accounting standards, USEC's credit facility term loan and convertible debt are recorded at face value and the fair value is disclosed. The estimated fair value of the term loan is based on the change in market value of an index of loans of similar credit quality based on published credit ratings. The estimated fair value of the convertible notes is based on the trading price as of the balance sheet date. Financing costs are generally deferred and amortized over the life of the instrument. Included in other long-term assets are deferred financing costs related to bank credit facility, convertible debt and the DOE Loan Guarantee Program. Fees related to the DOE loan guarantee application will be amortized over the life of the loan or, if USEC does not receive a loan, charged to expense. Pursuant to accounting standards, USEC's convertible preferred stock was initially recorded at fair value on a recurring basis. As of December 31, 2011, the convertible preferred stock can be converted at the holder's option and is classified as a current liability at the redemption value. Upfront costs and fees related to the issuance of the convertible preferred stock were expensed in the period of issuance, rather than deferred and amortized, since the preferred stock is classified as a liability and was initially recorded at fair value. The balance sheet carrying amounts for cash and cash equivalents, accounts receivable, accounts payable and accrued liabilities, and payables under the commercial agreement (the "Russian Contract") with a Russian government entity known as Techsnabexport ("TENEX") approximate fair value because of the short-term nature of the instruments. Lease Turnover Costs and Asset Retirement Obligations Property, plant and equipment assets related to the Paducah GDP are not subject to an asset retirement obligation. At the end of the lease, ownership of plant and equipment that USEC leaves at the GDP transfers to DOE, and responsibility for decontamination and decommissioning of the GDP remains with DOE. USEC estimates and accrues lease turnover costs. The balance of expected costs is being accrued over the expected productive life of the plant. Costs of returning the GDP to DOE in acceptable condition include removing nuclear material as required and removing USEC-generated waste. Liabilities for lease turnover costs are based on current-dollar cost estimates and are not discounted. USEC also leases facilities in Piketon, Ohio from DOE for the ACP. USEC owns all capital improvements and, unless otherwise consented to by DOE, must remove them by the conclusion of the lease term. At the conclusion of the lease, USEC is obligated to return these leased facilities to DOE in a condition that meets NRC requirements and in the same condition as the facilities were in when they were leased to USEC (other than due to normal wear and tear). Decontamination and decommissioning requirements for the ACP create an asset retirement obligation. As construction of the ACP takes place, the present value of the related asset retirement obligation (the initially determined fair value of the future obligation) is recognized as a long-term liability. An equivalent amount is recognized as part of the capitalized asset cost during the construction period. Upon commencement of commercial operations, the asset cost will be depreciated over the shorter of the asset life or the expected lease period. USEC has not recognized any changes to the capitalized asset cost related to the asset retirement obligation since the latter half of 2009, when USEC significantly reduced machine manufacturing and construction activities due to project funding uncertainty. The long-term liability for the asset retirement obligation is accreted, or increased, for the passage of time and the estimate also is revised for any changes in long-term inflation rate assumptions. The accretion, based on a time value of money calculation, is charged to cost of sales in the LEU segment. At the end of 2010, USEC reassessed the long-term liability and determined that the current fair value of the obligation was accrued at a sufficient amount based on construction progress and no further increase would be made until additional commercial plant deployment resumed. During each reporting period, USEC reassesses and revises the estimate of the asset retirement obligation based on construction progress, cost evaluation of future decommissioning expectations, and other judgmental considerations which impact the amount recorded in both construction work in progress and other long-term liabilities. Significant increases in asset retirement obligations and related capitalized asset costs would result when ACP construction is fully underway as part of any commercial plant deployment and plant operations. Environmental Compliance Costs Environmental compliance costs relating to operations are accrued and charged to inventory costs as incurred. Estimated environmental compliance costs, including depleted uranium disposition and waste disposal, are accrued where environmental assessments indicate that storage, treatment or disposal is probable and costs can be reasonably estimated. USEC stores depleted uranium at the Paducah GDP for future disposition. Changes in the estimated unit disposal cost result in charges to cost of sales for the accumulated quantity of depleted uranium. Liabilities for waste and depleted uranium disposition are based on current-dollar cost estimates and are not discounted. Concentrations of Credit Risk Credit risk could result from the possibility of a customer failing to perform or pay according to the terms of a contract. Extension of credit is based on an evaluation of each customer's financial condition. USEC regularly monitors credit risk exposure and takes steps to mitigate the likelihood of such exposure resulting in a loss. SWU and Uranium Revenue Revenue is derived from sales of the SWU component of LEU, from sales of both the SWU and uranium components of LEU, and from sales of uranium. Revenue is recognized at the time LEU or uranium is delivered under the terms of contracts with domestic and international electric utility customers. Some customers take title and delivery of LEU at the Paducah GDP, and revenue is recognized when delivery of LEU to the customer is complete. Most customers take title and delivery of LEU at fuel fabricators. USEC ships LEU to nuclear fuel fabricators for scheduled or anticipated orders from utility customers. Based on customer orders, USEC arranges for the transfer of title of LEU from USEC to the customer for the specified quantity of LEU at the fuel fabricator. Revenue is recognized when delivery of LEU to the customer occurs at the fuel fabricator. In a number of sales transactions, title to uranium or LEU is transferred to the customer and USEC receives payment under normal credit terms without physically delivering the uranium or LEU to the customer. This may occur because the terms of the agreement require USEC to hold the uranium to which the customer has title, or because the customer encounters brief delays in taking delivery of LEU at USEC's facilities. In such cases, recognition of revenue does not occur at the time title to uranium or LEU transfers to the customer but instead is deferred until LEU to which the customer has title is physically delivered. Certain customers make advance payments to be applied against future orders. Advances from customers are reported as deferred revenue, and revenue is recognized as product is delivered or services are provided. Contract Services Revenue USEC performs services and earns revenue from contract work through our subsidiary NAC and from contract work for DOE and DOE contractors at the Paducah GDP and the Portsmouth site. Revenue from NAC sales related to fixed-price contracts is recognized as services are provided based on milestones or events defined in the work scope. Revenue is recorded on time-and-materials contracts as the work is performed based on agreed-upon hourly rates and allowable costs. U.S. government contract revenue includes billings for fees and reimbursements for allowable costs that are determined in accordance with the terms of the underlying contracts. Revenue is recognized as work is performed and as fees are earned. Allowable costs include direct costs as well as allocations of indirect plant and corporate overhead costs determined in accordance with government cost accounting standards. Amounts representing contract change orders or final billing rates based on incurred costs are accrued and included in revenue when they can be reliably estimated and realization is probable. Allowable costs are subject to audit by the Defense Contract Audit Agency ("DCAA"), or such other entity that DOE authorizes to conduct the audit. The final settlement of amounts submitted by USEC for reimbursement is subject to acceptance by DOE. Revenue resulting from final billing rates is recognized upon completion of the government audits and notice by DOE authorizing final billing. This process has been completed for fiscal 2002, USEC's first year as a federal contractor under government cost accounting standards. In addition, as of December 31, 2011, USEC has finalized and submitted to DOE the billable incurred costs for contract work for the six months ended December 31, 2002 and the years ended December 31, 2003, 2004, 2005, 2006, 2007, 2008, 2009 and 2010. Government audits for these periods have either not started or have not been completed. The additional revenue that would result from USEC's final billing rates for these periods has not been recognized due to uncertainty related to the unperformed audits. DOE funded a portion of the work at the Portsmouth site through an arrangement whereby DOE transferred to USEC uranium which USEC immediately sold. USEC completed six competitive sales of uranium between the fourth quarter of 2009 and the first quarter of 2011. USEC's receipt of the uranium was not considered a purchase by USEC and no revenue or cost of sales was recorded upon its sale. This was because USEC had no significant risks or rewards of ownership and no potential profit or loss related to the uranium sale. The value of the contract work was based on the cash proceeds from the uranium sales less our selling and handling costs. The net value from the uranium sale was recorded as deferred revenue, and revenue was recognized in our contract services segment as services are provided. Stock-Based Compensation USEC has stock-based compensation plans available to grant restricted stock, restricted stock units, non-qualified stock options, performance awards and other stock-based awards to key employees and non-employee directors. Stock-based compensation cost is measured at the grant date, based on the fair value of the award, and is recognized over the requisite service period, which is either immediate recognition if the employee is eligible to retire, or on a straight-line basis until the earlier of either the date of retirement eligibility or the end of the vesting period. Use of Estimates The preparation of consolidated financial statements in conformity with accounting principles generally accepted in the United States requires management to make estimates and assumptions that affect reported amounts presented and disclosed in the consolidated financial statements. Significant estimates and judgments include, but are not limited to, pension and postretirement health and life benefit costs and obligations, costs for the conversion, transportation and disposition of depleted uranium, accounting treatment for expenditures on the American Centrifuge project, plant lease turnover costs, the tax bases of assets and liabilities, the future recoverability of deferred tax assets, and determination of the valuation allowance for deferred tax assets. Actual results may differ from such estimates, and estimates may change if the underlying conditions or assumptions change. New Accounting Standards In May 2011, the Financial Accounting Standards Board ("FASB") amended its guidance on fair value measurements and related disclosures. The amendments represent the converged guidance of the FASB and the International Accounting Standards Board and provide a consistent definition of fair value and common requirements for measurement and disclosure of fair value between generally accepted accounting principles in the U.S. ("GAAP") and International Financial Reporting Standards ("IFRS"). The new amendments also change some fair value measurement principles and enhance disclosure requirements related to activities in Level 3 of the fair value hierarchy. The new provisions are effective for fiscal years and interim periods beginning after December 15, 2011 and are applied prospectively. This requirement will become effective for USEC beginning with the first quarter of 2012. USEC does not expect the adoption of the amended guidance will have a material effect on its consolidated financial statements. In June and December 2011, the FASB issued guidance on the presentation of comprehensive income. The new guidance requires companies to present the components of net income and other comprehensive income either in a single statement below net income or in a separate statement of comprehensive income immediately following the income statement. The provisions of this new guidance are effective for fiscal years and interim periods beginning after December 15, 2011 and are applied retrospectively for all periods presented. This requirement will become effective for USEC beginning with the first quarter of 2012. The new guidance relates to financial statement presentation and will have no effect on USEC's results of operations, cash flows or financial position. In September 2011, the FASB amended its guidance on testing goodwill for impairment. Under the revised guidance, companies testing goodwill for impairment have the option of first performing a qualitative assessment to determine whether further quantitative assessments are warranted. In assessing qualitative factors, companies are to determine whether it is more likely than not that the fair value of a reporting unit is less than its carrying amount as a basis for determining whether it is necessary to perform the two-step goodwill impairment test prescribed in the existing guidance. The provisions of this new guidance are effective for fiscal years and interim periods beginning after December 15, 2011. USEC does not expect the adoption of the new guidance will have a material effect on its consolidated financial statements.

1. SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES

Nature of Operations

USEC Inc. ("USEC") is a global energy company and is a leading supplier of low enriched uranium ("LEU") for commercial nuclear power plants. LEU consists of two components: separative work units ("SWU") and uranium. SWU is a standard unit of measurement that represents the effort required to transform a given amount of natural uranium into two components: LEU having a higher percentage of U235 and depleted uranium having a lower percentage of U235. The SWU contained in LEU is calculated using an industry standard formula based on the physics of enrichment. The amount of enrichment deemed to be contained in LEU under this formula is commonly referred to as its SWU component and the quantity of natural uranium used in the production of LEU under this formula is referred to as its uranium component. Utility customers typically provide uranium to USEC as part of their enrichment contracts, and USEC delivers LEU to the customers and charges for the SWU component.

In addition, USEC performs contract services through our subsidiary NAC International Inc. ("NAC") and for DOE and DOE contractors at the Paducah gaseous diffusion plant ("GDP") in Paducah, Kentucky and the site of the former Portsmouth GDP in Piketon, Ohio.

Basis of Presentation

The consolidated financial statements include the accounts of USEC Inc., its principal subsidiary, United States Enrichment Corporation, and its other subsidiaries including NAC. American Centrifuge Manufacturing, LLC, a joint company established by USEC (through its subsidiary American Centrifuge Holdings, LLC) and Babcock & Wilcox Technical Services Group, Inc., is also included in the consolidated financial statements. All material intercompany transactions are eliminated.

Liquidity Risks and Uncertainties

Key factors that can affect liquidity requirements for USEC's existing operations include the timing and amount of customer sales, power purchases, and purchases under the Russian Contract. In addition, USEC expects to make a number of decisions during 2012 that could have significant consequences for its business, including whether to continue enrichment operations of Paducah plant beyond May 2012 and the potential to demobilize the American Centrifuge project if DOE funding is not obtained for the RD&D program. These decisions, as well as actions that may be taken by vendors, customers, creditors and other third parties in response to USEC's decisions or based on their view of USEC's financial strengths and future business prospects, could give rise to events that individually, or in the aggregate, are likely to impose significant demands upon the company's liquidity. In light of these factors and USEC's desire to improve its credit profile, the company may pursue discussions with creditors and key stakeholders regarding the restructuring of its business and capital structure.

USEC's sales backlog in its LEU segment is a source of stability for USEC's liquidity position. At December 31, 2011, USEC had contracts with customers aggregating an estimated $5.8 billion, including $1.5 billion expected to be delivered in 2012. Although sales prices under many of USEC's SWU contracts are adjusted in part based on changes in market prices for SWU and electric power, the impact of market volatility in these indices is generally mitigated through the use of market price averages over time. Additionally, changes in the power price component of sales prices are intended to mitigate the effects of changes in USEC's power costs.

In order to enhance its liquidity and manage its working capital, USEC in light of anticipated sales and inventory levels and to respond to customer-driven changes, has been working with customers regarding the timing of their orders, in particular the advancement of those orders. Rather than selling material into the limited spot market for enrichment, USEC advanced orders from 2011 into 2010 and orders from 2012 into 2011. Based on USEC's outlook for demand and anticipated liquidity and working capital needs, USEC continues to work with customers to advance orders into 2012. The advancement of orders has the effect of accelerating receipt of cash from such advanced sales, although the amount of cash received from such sales may be reduced as a result of the terms mutually agreed with customers in connection with advancement. The shutdown of the Japanese reactors and the shutdown of reactors in other countries due to concerns raised by March 11 events have affected supply and demand for LEU over the next 2-4 years. This impact could grow more significant over time depending on the length and severity of delays or cancellations of deliveries. As a result, USEC has not been able to replace many of the order advancements that have been done in the past with additional sales, which has had the effect of reducing USEC's backlog as of December 31, 2011 compared to prior periods. Delays in decisions with respect to the extension of Paducah plant operations and delays in the deployment of the American Centrifuge project have also had a negative effect on USEC's backlog. Sales are a function of USEC's future supply, including potential supply from Paducah plant operations and from the American Centrifuge Plant ("ACP"). Looking out beyond the next 2-4 years, USEC expects an increase in uncommitted demand that could provide the opportunity to make additional sales to supplement USEC's backlog and thus decrease the need to advance orders in the future. However, the amount of any demand and USEC's ability to capture that demand is uncertain. USEC's ability to advance orders depends on the willingness of USEC's customers to agree to advancement on terms that USEC finds acceptable. In light of the order advancements that have been done in the past, additional order advancements are challenging, which could adversely affect USEC's liquidity.

USEC needs significant additional financing in order to complete the American Centrifuge Plant. USEC applied for a $2 billion loan guarantee under the DOE Loan Guarantee Program in July 2008 and efforts since then and throughout most of 2011 have been focused on obtaining a conditional commitment for a loan guarantee so that the company could move forward with the commercialization of the American Centrifuge technology. However, DOE raised concerns regarding the financial and project execution depth of the American Centrifuge project that USEC was not able to overcome to DOE's satisfaction during 2011. USEC's spending on the American Centrifuge in 2011 was incrementally allocated as the company continuously evaluated its spending plan and a path toward a DOE loan guarantee commitment or other funding for the project. Beginning in October 2011, USEC reduced its monthly spending on the American Centrifuge project by approximately 30% (as compared to the average monthly rate of spending in the prior months of 2011) and also suspended a number of contracts with suppliers and contractors involved in the American Centrifuge.

Instead of moving forward with a conditional commitment for a loan guarantee, in the fall of 2011, DOE proposed a two-year cost share research, development and demonstration ("RD&D") program for the project to enhance the technical and financial readiness of the centrifuge technology for commercialization. Under the cost-sharing arrangement, DOE's total contribution would be capped at $300 million. DOE indicated that USEC's application for a DOE loan guarantee would remain pending during the RD&D program. During late 2011 and early 2012, the American Centrifuge project efforts shifted to focus on the planning and implementation of the RD&D program and efforts that are currently underway in Piketon, Ohio and Oak Ridge, Tennessee are based upon the proposed program scope. USEC is currently building machines and parts that would be part of the complete demonstration cascade that would be built and operated as part of the RD&D program. In parallel, USEC has been working with DOE and Congress to secure funding for the RD&D program. However, DOE's share of funding for the program has not yet been provided and the source for such funding is uncertain. The current political environment in Washington has significantly slowed the legislative process. The two houses of Congress are each held by a different political party and in an election year the necessary bipartisan support will be difficult to achieve.

Due to constraints on USEC's ability to continue to spend on the project, on March 13, 2012, USEC and DOE entered into an agreement that enables USEC to provide interim funding of $44 million. This funding was provided by DOE acquiring from us U.S. origin LEU in exchange for the transfer of quantities of our depleted uranium ("tails") to DOE. This enables USEC to release encumbered funds of approximately $44 million that were previously provided as financial assurance for the disposition of such depleted uranium. USEC expects that this LEU acquired by DOE could be returned to USEC as part of DOE's cost share under the RD&D program if government funding is provided for the RD&D program in government fiscal year 2012. However, if the RD&D program does not move forward, the LEU would not be returned to USEC, and DOE would not reimburse these ACP costs. The $44 million of funding enables USEC to fund the ACP program activities through the end of March 2012. In order to stay within the $44 million, USEC has further reduced its spending from the spending reductions implemented in October 2011.

Continuation of the RD&D program beyond March 2012 will require additional funding. USEC is working with DOE and Congress to provide funding for government fiscal year 2012. Funding for the RD&D program beyond government fiscal year 2012 would be subject to future appropriations. USEC has no assurance that it will be able to reach agreement with DOE regarding any phase of the RD&D program or that any funding will be provided or that the LEU will be returned. USEC also has no assurance that it will ultimately be able to obtain a loan guarantee and the timing thereof. Any agreement for the RD&D program would likely require restructuring of the project and of USEC's investment. In light of USEC's inability to reach a conditional commitment for a DOE loan guarantee to date, and given the significant uncertainty surrounding USEC's prospects for finalizing an agreement and obtaining funding from DOE for an RD&D program and the timing thereof, USEC continues to evaluate its options concerning the American Centrifuge project. If USEC is unable to secure funding for the RD&D program beyond March 31, 2012 USEC would expect to begin demobilizing the project.

Cash and Cash Equivalents

Cash and cash equivalents include temporary cash investments with original maturities of three months or less.

Inventories

USEC holds uranium at the Paducah GDP in the form of natural uranium and as the uranium component of LEU. USEC holds SWU as the SWU component of LEU. USEC may also hold title to the uranium and SWU components of LEU at fabricators to meet book transfer requests by customers. Fabricators process LEU into fuel for use in nuclear reactors. Under inventory optimization arrangements between USEC and domestic fabricators, fabricators order bulk quantities of LEU from USEC based on scheduled or anticipated orders from utility customers for deliveries in future periods. As delivery obligations under actual customer orders arise, USEC satisfies these obligations by arranging for the transfer to the customer of title to the specified quantity of LEU at the fabricator. USEC's balances of SWU and uranium vary over time based on the timing and size of the fabricator's LEU orders from USEC. Balances can be positive or negative at the discretion of the fabricator. Fabricators have other inventory supplies and, where a fabricator has elected to order less material from USEC than USEC is required to deliver to its customers at the fabricator, the fabricator will use these other inventories to satisfy USEC's customer order obligations on USEC's behalf. In such cases, the transfer of title of LEU from USEC to the customer results in quantities of SWU and uranium owed by USEC to the fabricator. These obligations are presented in current liabilities, comprising most of the balance of inventories owed to customers and suppliers. The amounts of SWU and uranium owed to fabricators are satisfied as future bulk deliveries of LEU are made.

Inventories of SWU and uranium are valued at the lower of cost or market. Market is based on the terms of long-term contracts with customers, and, for uranium not under contract, market is based primarily on published spot price indicators at the balance sheet date. SWU and uranium inventory costs are determined using the monthly moving average cost method.

SWU costs are based on production costs and purchase costs. Production costs at the Paducah GDP consist principally of electric power, labor and benefits, depleted uranium disposition cost estimates, materials, depreciation and amortization and maintenance and repairs. USEC purchases SWU under a commercial agreement ("Russian Contract") with a Russian government entity known as OAO Techsnabexport ("TENEX"). The Russian Contract implements a government-to-government nonproliferation agreement between the United States and the Russian Federation. Under the agreement, USEC has been designated by the U.S. government to order LEU derived from dismantled Soviet nuclear weapons. The Russian Contract is expected to be completed in 2013. The cost of the SWU component of LEU purchased under the Russian Contract is recorded at acquisition cost plus related shipping costs.

Underfeeding is a mode of operation that uses or feeds less uranium but requires more SWU in the enrichment process, which requires more electric power. The quantity of uranium that is earned or added to uranium inventory from underfeeding is accounted for as a byproduct of the enrichment process. Production costs are allocated to the uranium earned based on the net realizable value of the uranium, and the remainder of production costs is allocated to SWU inventory costs.

Deferred Income Taxes

USEC follows the asset and liability approach to account for deferred income taxes. Deferred tax assets and liabilities are recognized for the anticipated future tax consequences of temporary differences between the balance sheet carrying amounts of assets and liabilities and their respective tax bases. Deferred income taxes are based on income tax rates in effect for the years in which temporary differences are expected to reverse. The effect on deferred income taxes of a change in income tax rates is recognized in income when the change in rates is enacted in the law. A valuation allowance is provided if it is more likely than not that some or all of the deferred tax assets may not be realized.

Property, Plant and Equipment

Construction work in progress is recorded at acquisition or construction cost. Upon being placed into service, costs are transferred to leasehold improvements or machinery and equipment at which time depreciation and amortization commences.

USEC leases the Paducah GDP located in Paducah, Kentucky and portions of the former Portsmouth GDP located in Piketon, Ohio from the U.S. Department of Energy ("DOE"). Leasehold improvements and machinery and equipment are recorded at acquisition cost and depreciated on a straight line basis over the shorter of the useful life of the assets or the expected productive life of the plant, which is 2016 for the Paducah GDP commensurate with the term of the lease agreement. Maintenance and repair costs are charged to production costs as incurred.

Additional details related to capitalized costs included in property, plant and equipment, and related disposition obligations, are provided below in "Advanced Technology Costs" and "Lease Turnover Costs and Asset Retirement Obligations."

Advanced Technology Costs

Costs relating to the American Centrifuge technology are charged to expense or capitalized based on the nature of the activities and estimates and judgments involving the completion of project milestones. Costs relating to the demonstration of American Centrifuge technology are charged to expense as incurred. Demonstration costs include Nuclear Regulatory Commission ("NRC") licensing of the American Centrifuge Demonstration Facility located in Piketon, Ohio, engineering activities, and assembling and testing of centrifuge machines and equipment at centrifuge test facilities located in Oak Ridge, Tennessee and at the American Centrifuge Demonstration Facility. Advanced technology costs charged to expense include employee salaries and related benefits, contractor and third party costs, facility related costs, and other direct and indirect costs attributable to the American Centrifuge technology that are not capitalizable.

Capitalized costs relating to the American Centrifuge technology include NRC licensing of the ACP in Piketon, Ohio, engineering activities, construction of centrifuge machines and equipment, leasehold improvements and other costs directly associated with the commercial plant. Capitalized American Centrifuge costs are recorded in property, plant and equipment primarily as part of construction work in progress. The continued capitalization of costs is subject to ongoing review and successful project completion. USEC's move during the second half of 2007 from a demonstration phase to a commercial plant phase in which significant expenditures are capitalized was based on management's judgment that the technology has a high probability of commercial success and meets internal targets related to physical control, technical achievement and economic viability. Beginning with the start of the fourth quarter of 2011, all project costs incurred have been expensed, including interest expense that previously would have been capitalized. Spending at the reduced levels relates primarily to development and maintenance activities rather than capital asset creation. USEC also expects to expense costs under the RD&D program as incurred. Capitalization of expenditures related to ACP has ceased until commercial plant deployment resumes. If conditions change, including if the current path to commercial deployment were no longer probable or our anticipated role in the project were changed, USEC could expense up to the full amount of previously capitalized costs related to the ACP. Refer to Note 4, "Property, Plant and Equipment" and Note 16, "Commitments and Contingencies" for further details and USEC's current assessment of the American Centrifuge project.

In 2002, USEC and DOE signed an agreement in which both USEC and DOE made long-term commitments directed at resolving issues related to the stability and security of the domestic uranium enrichment industry. Discussion of USEC's commitments related to American Centrifuge project milestones under this agreement is provided in Note 16.

Long-Lived Assets

USEC evaluates the carrying value of long-lived assets by performing impairment tests whenever adverse conditions or changes in circumstances indicate a possible impairment loss. Impairment tests are based on a comparison of estimated undiscounted future cash flows to the carrying values of long-lived assets. If impairment is indicated, the asset carrying value is reduced to fair market value or, if fair market value is not readily available, the asset is reduced to a value determined by applying a discount rate to expected cash flows.

Goodwill

USEC's long-term assets include goodwill resulting from USEC's acquisition of NAC in 2004. USEC evaluates the carrying value of goodwill by performing an impairment test on an annual basis or whenever events or changes in circumstances indicate that its carrying amount may not be recoverable. The goodwill testing utilizes a two-step process, where the carrying value of the reporting unit is compared to its fair value. If the carrying value is less than the fair value, no impairment exists and the second step is not performed. However, if the carrying value is greater than the fair value, the second step is performed. An impairment charge would be recognized for the amount that the carrying value of the goodwill exceeds its fair value. The fair value of the reporting unit is estimated using the net present value of projected future cash flows. In its annual testing in the fourth quarter of 2011, USEC determined in the first step that there was no impairment.

Financial Instruments and Fair Value Measurement

Accounting standards define fair value as the price that would be received from selling an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. When determining the fair value measurements for assets and liabilities required or permitted to be recorded at fair value, consideration is given to the principal or most advantageous market and assumptions that market participants would use when pricing the asset or liability.

Pursuant to accounting standards, USEC's credit facility term loan and convertible debt are recorded at face value and the fair value is disclosed. The estimated fair value of the term loan is based on the change in market value of an index of loans of similar credit quality based on published credit ratings. The estimated fair value of the convertible notes is based on the trading price as of the balance sheet date. Financing costs are generally deferred and amortized over the life of the instrument. Included in other long-term assets are deferred financing costs related to bank credit facility, convertible debt and the DOE Loan Guarantee Program. Fees related to the DOE loan guarantee application will be amortized over the life of the loan or, if USEC does not receive a loan, charged to expense.

Pursuant to accounting standards, USEC's convertible preferred stock was initially recorded at fair value on a recurring basis. As of December 31, 2011, the convertible preferred stock can be converted at the holder's option and is classified as a current liability at the redemption value. Upfront costs and fees related to the issuance of the convertible preferred stock were expensed in the period of issuance, rather than deferred and amortized, since the preferred stock is classified as a liability and was initially recorded at fair value.

The balance sheet carrying amounts for cash and cash equivalents, accounts receivable, accounts payable and accrued liabilities, and payables under the commercial agreement (the "Russian Contract") with a Russian government entity known as Techsnabexport ("TENEX") approximate fair value because of the short-term nature of the instruments.

Lease Turnover Costs and Asset Retirement Obligations

Property, plant and equipment assets related to the Paducah GDP are not subject to an asset retirement obligation. At the end of the lease, ownership of plant and equipment that USEC leaves at the GDP transfers to DOE, and responsibility for decontamination and decommissioning of the GDP remains with DOE. USEC estimates and accrues lease turnover costs. The balance of expected costs is being accrued over the expected productive life of the plant. Costs of returning the GDP to DOE in acceptable condition include removing nuclear material as required and removing USEC-generated waste. Liabilities for lease turnover costs are based on current-dollar cost estimates and are not discounted.

USEC also leases facilities in Piketon, Ohio from DOE for the ACP. USEC owns all capital improvements and, unless otherwise consented to by DOE, must remove them by the conclusion of the lease term. At the conclusion of the lease, USEC is obligated to return these leased facilities to DOE in a condition that meets NRC requirements and in the same condition as the facilities were in when they were leased to USEC (other than due to normal wear and tear).

Decontamination and decommissioning requirements for the ACP create an asset retirement obligation. As construction of the ACP takes place, the present value of the related asset retirement obligation (the initially determined fair value of the future obligation) is recognized as a long-term liability. An equivalent amount is recognized as part of the capitalized asset cost during the construction period. Upon commencement of commercial operations, the asset cost will be depreciated over the shorter of the asset life or the expected lease period.

USEC has not recognized any changes to the capitalized asset cost related to the asset retirement obligation since the latter half of 2009, when USEC significantly reduced machine manufacturing and construction activities due to project funding uncertainty.

The long-term liability for the asset retirement obligation is accreted, or increased, for the passage of time and the estimate also is revised for any changes in long-term inflation rate assumptions. The accretion, based on a time value of money calculation, is charged to cost of sales in the LEU segment. At the end of 2010, USEC reassessed the long-term liability and determined that the current fair value of the obligation was accrued at a sufficient amount based on construction progress and no further increase would be made until additional commercial plant deployment resumed.

During each reporting period, USEC reassesses and revises the estimate of the asset retirement obligation based on construction progress, cost evaluation of future decommissioning expectations, and other judgmental considerations which impact the amount recorded in both construction work in progress and other long-term liabilities. Significant increases in asset retirement obligations and related capitalized asset costs would result when ACP construction is fully underway as part of any commercial plant deployment and plant operations.

Environmental Compliance Costs

Environmental compliance costs relating to operations are accrued and charged to inventory costs as incurred. Estimated environmental compliance costs, including depleted uranium disposition and waste disposal, are accrued where environmental assessments indicate that storage, treatment or disposal is probable and costs can be reasonably estimated. USEC stores depleted uranium at the Paducah GDP for future disposition. Changes in the estimated unit disposal cost result in charges to cost of sales for the accumulated quantity of depleted uranium. Liabilities for waste and depleted uranium disposition are based on current-dollar cost estimates and are not discounted.

Concentrations of Credit Risk

Credit risk could result from the possibility of a customer failing to perform or pay according to the terms of a contract. Extension of credit is based on an evaluation of each customer's financial condition. USEC regularly monitors credit risk exposure and takes steps to mitigate the likelihood of such exposure resulting in a loss.

SWU and Uranium Revenue

Revenue is derived from sales of the SWU component of LEU, from sales of both the SWU and uranium components of LEU, and from sales of uranium. Revenue is recognized at the time LEU or uranium is delivered under the terms of contracts with domestic and international electric utility customers. Some customers take title and delivery of LEU at the Paducah GDP, and revenue is recognized when delivery of LEU to the customer is complete. Most customers take title and delivery of LEU at fuel fabricators. USEC ships LEU to nuclear fuel fabricators for scheduled or anticipated orders from utility customers. Based on customer orders, USEC arranges for the transfer of title of LEU from USEC to the customer for the specified quantity of LEU at the fuel fabricator. Revenue is recognized when delivery of LEU to the customer occurs at the fuel fabricator.

In a number of sales transactions, title to uranium or LEU is transferred to the customer and USEC receives payment under normal credit terms without physically delivering the uranium or LEU to the customer. This may occur because the terms of the agreement require USEC to hold the uranium to which the customer has title, or because the customer encounters brief delays in taking delivery of LEU at USEC's facilities. In such cases, recognition of revenue does not occur at the time title to uranium or LEU transfers to the customer but instead is deferred until LEU to which the customer has title is physically delivered. Certain customers make advance payments to be applied against future orders. Advances from customers are reported as deferred revenue, and revenue is recognized as product is delivered or services are provided.

Contract Services Revenue

USEC performs services and earns revenue from contract work through our subsidiary NAC and from contract work for DOE and DOE contractors at the Paducah GDP and the Portsmouth site. Revenue from NAC sales related to fixed-price contracts is recognized as services are provided based on milestones or events defined in the work scope. Revenue is recorded on time-and-materials contracts as the work is performed based on agreed-upon hourly rates and allowable costs. U.S. government contract revenue includes billings for fees and reimbursements for allowable costs that are determined in accordance with the terms of the underlying contracts. Revenue is recognized as work is performed and as fees are earned. Allowable costs include direct costs as well as allocations of indirect plant and corporate overhead costs determined in accordance with government cost accounting standards. Amounts representing contract change orders or final billing rates based on incurred costs are accrued and included in revenue when they can be reliably estimated and realization is probable. Allowable costs are subject to audit by the Defense Contract Audit Agency ("DCAA"), or such other entity that DOE authorizes to conduct the audit. The final settlement of amounts submitted by USEC for reimbursement is subject to acceptance by DOE. Revenue resulting from final billing rates is recognized upon completion of the government audits and notice by DOE authorizing final billing. This process has been completed for fiscal 2002, USEC's first year as a federal contractor under government cost accounting standards. In addition, as of December 31, 2011, USEC has finalized and submitted to DOE the billable incurred costs for contract work for the six months ended December 31, 2002 and the years ended December 31, 2003, 2004, 2005, 2006, 2007, 2008, 2009 and 2010. Government audits for these periods have either not started or have not been completed. The additional revenue that would result from USEC's final billing rates for these periods has not been recognized due to uncertainty related to the unperformed audits.

DOE funded a portion of the work at the Portsmouth site through an arrangement whereby DOE transferred to USEC uranium which USEC immediately sold. USEC completed six competitive sales of uranium between the fourth quarter of 2009 and the first quarter of 2011. USEC's receipt of the uranium was not considered a purchase by USEC and no revenue or cost of sales was recorded upon its sale. This was because USEC had no significant risks or rewards of ownership and no potential profit or loss related to the uranium sale. The value of the contract work was based on the cash proceeds from the uranium sales less our selling and handling costs. The net value from the uranium sale was recorded as deferred revenue, and revenue was recognized in our contract services segment as services are provided.

Stock-Based Compensation

USEC has stock-based compensation plans available to grant restricted stock, restricted stock units, non-qualified stock options, performance awards and other stock-based awards to key employees and non-employee directors. Stock-based compensation cost is measured at the grant date, based on the fair value of the award, and is recognized over the requisite service period, which is either immediate recognition if the employee is eligible to retire, or on a straight-line basis until the earlier of either the date of retirement eligibility or the end of the vesting period.

Use of Estimates

The preparation of consolidated financial statements in conformity with accounting principles generally accepted in the United States requires management to make estimates and assumptions that affect reported amounts presented and disclosed in the consolidated financial statements. Significant estimates and judgments include, but are not limited to, pension and postretirement health and life benefit costs and obligations, costs for the conversion, transportation and disposition of depleted uranium, accounting treatment for expenditures on the American Centrifuge project, plant lease turnover costs, the tax bases of assets and liabilities, the future recoverability of deferred tax assets, and determination of the valuation allowance for deferred tax assets. Actual results may differ from such estimates, and estimates may change if the underlying conditions or assumptions change.

New Accounting Standards

In May 2011, the Financial Accounting Standards Board ("FASB") amended its guidance on fair value measurements and related disclosures. The amendments represent the converged guidance of the FASB and the International Accounting Standards Board and provide a consistent definition of fair value and common requirements for measurement and disclosure of fair value between generally accepted accounting principles in the U.S. ("GAAP") and International Financial Reporting Standards ("IFRS"). The new amendments also change some fair value measurement principles and enhance disclosure requirements related to activities in Level 3 of the fair value hierarchy. The new provisions are effective for fiscal years and interim periods beginning after December 15, 2011 and are applied prospectively. This requirement will become effective for USEC beginning with the first quarter of 2012. USEC does not expect the adoption of the amended guidance will have a material effect on its consolidated financial statements.

In June and December 2011, the FASB issued guidance on the presentation of comprehensive income. The new guidance requires companies to present the components of net income and other comprehensive income either in a single statement below net income or in a separate statement of comprehensive income immediately following the income statement. The provisions of this new guidance are effective for fiscal years and interim periods beginning after December 15, 2011 and are applied retrospectively for all periods presented. This requirement will become effective for USEC beginning with the first quarter of 2012. The new guidance relates to financial statement presentation and will have no effect on USEC's results of operations, cash flows or financial position.

In September 2011, the FASB amended its guidance on testing goodwill for impairment. Under the revised guidance, companies testing goodwill for impairment have the option of first performing a qualitative assessment to determine whether further quantitative assessments are warranted. In assessing qualitative factors, companies are to determine whether it is more likely than not that the fair value of a reporting unit is less than its carrying amount as a basis for determining whether it is necessary to perform the two-step goodwill impairment test prescribed in the existing guidance. The provisions of this new guidance are effective for fiscal years and interim periods beginning after December 15, 2011. USEC does not expect the adoption of the new guidance will have a material effect on its consolidated financial statements.