EXHIBIT 10.74

AMENDMENT

to the
STOCK PURCHASE AGREEMENT

This Amendment to the Stock Purchase Agreement (this “Amendment”), dated as of
November 18, 2004, by and among Pinnacle West Capital Corporation, an Arizona
corporation (“PNW”), El Dorado Investment Company, an Arizona corporation (“El
Dorado” and, together with PNW, the “Seller Parties”), and USEC Inc., a Delaware
corporation (“Purchaser”). The Seller Parties and Purchaser are sometimes
referred to herein collectively as the “Parties” and each individually as a
“Party.”

WHEREAS, the Parties are also parties to that certain Stock Purchase Agreement,
dated as of July 29, 2004 (the “Agreement”); and

WHEREAS, the Parties desire to amend the Agreement to reflect the Parties’
agreement as to certain matters set forth below.

NOW, THEREFORE, in consideration of the foregoing and the mutual covenants and
agreements contained in this Amendment and the Agreement, and intending to be
legally bound hereby, the Parties agree as follows:

  1.   Terms used herein and not defined herein shall have the meanings ascribed
them in the Agreement.

  2.   Section 1.1 of the Agreement is hereby amended by inserting the following
terms in the appropriate alphabetical order:

"Assumed Margin Amount” means the present value of $1,173,000 (as calculated
pursuant to Schedule 2.8(c)(ii)), as of the date of the event giving rise to the
need to calculate the Assumed Margin Amount and assuming a discount rate of 10%,
which represents the Parties’ agreed-upon estimate of the present value of the
net margin anticipated as of the Closing Date on NAC Consulting business (other
than net margin resulting from the Existing NMMSS Contract) for calendar years
2006 through 2008 as if the Existing NMMSS Contract had been formally extended
for three (3) years on terms and conditions consistent with the NMMSS Base
Contract Terms.

"Contingent Contract Payment” has the meaning set forth in Section 2.8(c)(i).

"Contingent Contract Payment Threshold” has the meaning set forth in Section
2.8(e)(iii).

"Contingent Extension Payment” has the meaning set forth in Section 2.8(d).

"Contingent Payment” means a Contingent Contract Payment, Contingent Extension
Payment, Contingent Sale Payment or Contingent Termination Payment, as
applicable.

"Contingent Sale Payment” has the meaning set forth in Section 2.8(e)(vii).

"Contingent Termination Payment” has the meaning set forth in Section 2.8(h).

"Covered Period” means the period beginning on the Closing Date and ending on
the earlier of (i) the date a Contingent Sale Payment becomes payable to El
Dorado, and (ii) March 31, 2006; provided, that, if the Covered Period would
otherwise expire on March 31, 2006 and on such date the Subsidiary has a pending
NMMSS Contract Offer for a NMMSS Follow-On Contract before a Requesting Agency,
the Covered Period will be extended until such time as either (i) the Subsidiary
and the Requesting Agency execute such NMMSS Follow-On Contract or (ii) such
NMMSS Contract Offer is rejected or has expired and Purchaser gives written
notice to the Seller Parties that the Subsidiary in good faith has determined
that it will not submit another NMMSS Contract Offer in connection therewith.

"Escrow Agreement” means that certain Escrow Agreement, dated as of the date
hereof, by and among the Seller Parties, Purchaser and Wachovia Bank, National
Association, a national banking association, as Escrow Agent.

"Escrow Earnings” has the meaning set forth in Section 2.8(j).

"Escrow Funds” has the meaning given it in the Escrow Agreement.

"Estimated Payment Notice” means a written notice of a proposed Contingent
Payment amount, together with reasonable detail as to how the proposed amount
was determined.

"Excess Escrow Funds” has the meaning set forth in Section 2.8(i)(iv).

"Existing NMMSS Contract” means Contract No. DE-AC03-98SF21544, dated
September 28, 1998, as amended, between the Subsidiary and the DOE.

"Final NMMSS Award Date” has the meaning set forth in Section 2.8(e)(iv).

"Interim OCI Waiver” shall mean a written waiver granted by each of DOE and NRC
to the Subsidiary with respect to any Organizational Conflict of Interest under
the Existing NMMSS Contract arising out of Purchaser’s ownership of the
Subsidiary after the Closing or Purchaser’s status as an NRC licensee, on terms
and conditions that are, in Purchaser’s sole discretion, commercially
reasonable.

"NAC Consulting” has the meaning set forth in Section 2.8(e)(ii).

"NAC Consulting Sale” has the meaning set forth in Section 2.8(e)(ii).

"NAC Sale” has the meaning set forth in Section 2.8(e)(viii).

"Net Proceeds” means, with respect to a NAC Consulting Sale, (i) the sum of
(A) the cash, market value of marketable equity securities or interests, fair
value of unmarketable equity securities or interests, and face amount of
straight and convertible debt instruments or obligations issued to Purchaser or
any Affiliate of Purchaser in connection with the NAC Consulting Sale, (B) the
amount of indebtedness (excluding trade payables) of the Company or the
Subsidiary assumed directly or indirectly by the acquiring Person or any
Affiliate of the acquiring Person in connection with the NAC Consulting Sale and
(C) the value of any contingent payment obligations, including earn-outs, when
and if actually received by Purchaser, less (ii) Transaction Costs.

"NMMSS Base Contract Terms” has the meaning set forth in Section 2.8(b).

"NMMSS Contract Offer” has the meaning set forth in Section 2.8(b).

"NMMSS Contract Solicitation” has the meaning set forth in Section 2.8(b).

"NMMSS Follow-On Contract” has the meaning set forth in Section 2.8(b).

"NMMSS Losses” means those losses incurred by the Subsidiary in connection with
the termination of the Existing NMMSS Contract, including the related severance
costs actually incurred by the Subsidiary; the present value of the loss of fees
to be earned by the Subsidiary under the Existing NMMSS Contract; the direct and
indirect costs previously allocated to the Existing NMMSS Contract that will no
longer be covered, after taking into account any cost reduction measures taken
by the Subsidiary; and the present value of the reduced net margin on other NAC
Consulting business expected to be achieved in calendar years 2006 through 2008
as compared to the Assumed Margin Amount (as calculated in accordance with
Schedule 2.8(c)(ii)).

"NMMSS Program Services” means the services being performed by the Subsidiary
under the scope of work of the Existing NMMSS Contract as of the Closing.

"Requesting Agency” has the meaning set forth in Section 2.8(b).

"Restricted Sale Period” has the meaning set forth in Section 2.8(e)(i).

"Sale Consent” has the meaning set forth in Section 2.8(e)(ii).

"Transaction Costs” means, with respect to a NAC Consulting Sale, transaction
costs, including, but not limited to, fees of attorneys’, financial advisors,
accountants, consultants and other advisors incurred in connection with such
transaction, including any costs of transferring NAC Consulting to a separate
legal entity.

3. Section 2.2 of the Agreement is hereby amended and restated as follows:

The purchase price for the Company Shares will be cash in the amount of Ten
Million Dollars ($10,000,000) plus up to Six Million Dollars ($6,000,000)
payable in whole or in part upon the terms and conditions set forth in
Section 2.8 (collectively, the “Purchase Price”), subject to adjustment as
determined pursuant to the provisions of Section 2.7.

  4.   Section 2.5 of the Agreement is hereby amended by deleting the word “and”
at the end of Section 2.5(o), by designating the original Section 2.5(p) as
Section 2.5(q), and by adding a new Section 2.5(p) as follows:

  (p)   the Escrow Agreement, duly executed by the Seller Parties; and

5. Section 2.6(d) of the Agreement is hereby amended and restated as follows:

payment by wire transfer of immediately available U.S. funds to the bank account
designated by the Seller Parties in writing no later than five (5) Business Days
prior to the Closing in the amount of Ten Million Dollars ($10,000,000), plus or
minus, as applicable, the Estimated Working Capital Adjustment;

  6.   Section 2.6 of the Agreement is hereby further amended by deleting the
word “and” at the end of Section 2.6(e), by designating the original
Section 2.6(f) as Section 2.6(g), and by adding a new Section 2.6(f) as follows:

(f) the Escrow Agreement, duly executed by Purchaser; and

7. The Agreement is hereby amended by adding a new section after Section 2.7 as
follows:

2.8 Contingent Payment.

(a) Escrow Agreement. Concurrently with the Closing, the Seller Parties and
Purchaser will enter into the Escrow Agreement and, pursuant thereto, Purchaser
will deliver to the escrow agent thereunder the sum of Six Million Dollars
($6,000,000) to fund the Contingent Payment, to the extent payable, on the terms
and subject to the conditions set forth in this Section 2.8.

(b) Bid for NMMSS Follow-On Contract. Subject to Section 2.8(e), Purchaser
agrees that, during the Covered Period, it will cause the Subsidiary, or any
successor to the Subsidiary, unless prohibited by the DOE and/or other
applicable governmental agency (the “Requesting Agency”), to make in response to
each Requesting Agency request for bid, proposal or other solicitation of an
offer to perform all or a significant portion of the NMMSS Program Services (a
“NMMSS Contract Solicitation”) a good faith, timely bid, proposal or similar
offer (a “NMMSS Contract Offer”) for a contract to perform such NMMSS Program
Services (each, a “NMMSS Follow-On Contract”), on terms that are commercially
reasonable and, to the extent consistent with the related NMMSS Contract
Solicitation, meet the terms and conditions set forth in Schedule 2.8(b) hereto
(the “NMMSS Base Contract Terms”), and, if so requested by the Requesting
Agency, to engage in good faith negotiations with the Requesting Agency for each
such NMMSS Follow-On Contract; provided, that nothing herein will preclude
Purchaser from bidding or proposing or negotiating commercially reasonable terms
other than the NMMSS Base Contract Terms to the extent necessary, in Purchaser’s
commercially reasonable judgment, to help improve the Subsidiary’s chances of
securing a NMMSS Follow-On Contract; provided, further, that nothing herein will
preclude Purchaser from teaming with one or more Persons in making a NMMSS
Contract Offer to the extent necessary, in Purchaser’s sole discretion, to
improve the Subsidiary’s chances of securing a NMMSS Follow-On Contract; and
provided, further, that Purchaser will have no obligation to make a NMMSS
Contract Offer in response to a NMMSS Contract Solicitation if the Existing
NMMSS Contract is terminated by the DOE prior to September 30, 2005 and
Purchaser reasonably concludes that it is not commercially reasonable under the
circumstances for the Subsidiary to pursue a NMMSS Follow-On Contract. Purchaser
will provide the Seller Parties with a draft of each NMMSS Contract Offer and,
to the extent practicable, give the Seller Parties a reasonable opportunity to
comment thereon.

(c) Execution of NMMSS Follow-On Contract.

(i) In the event that, in response to a NMMSS Contract Offer made during the
Covered Period, the Subsidiary and a Requesting Agency execute one or more NMMSS
Follow-On Contracts on terms and conditions that, in the reasonable judgment of
Purchaser, collectively result (upon consideration of the economic benefits
accruing under the base contract term but not beyond December 31, 2009) in an
economic benefit to the Subsidiary that is at least as favorable to the
Subsidiary as if the Existing NMMSS Contract had been formally extended for
three (3) years on terms and conditions consistent with the NMMSS Base Contract
Terms, then, within ten (10) Business Days of any such mutual execution and
delivery of a NMMSS Follow-On Contract(s), payment will be made to El Dorado in
an amount equal to Six Million Dollars ($6,000,000) less any amounts paid to El
Dorado pursuant to Section 2.8(d) or Section 2.8(h) (such payment, including as
it may be reduced pursuant to Section 2.8(c)(ii), the “Contingent Contract
Payment”) pursuant to the Escrow Agreement, if the Escrow Agreement has not been
terminated, or, if the Escrow Agreement has been terminated, directly by
Purchaser.

(ii) In the event that, in response to a NMMSS Contract Offer made during the
Covered Period, the Subsidiary and a Requesting Agency execute one or more NMMSS
Follow-On Contracts on terms and conditions that, in the reasonable judgment of
Purchaser, collectively result (upon consideration of the economic benefits
accruing under the base contract term but not beyond December 31, 2009) in an
economic benefit to the Subsidiary that is less favorable to the Subsidiary than
if the Existing NMMSS Contract had been formally extended for three (3) years on
terms and conditions consistent with the NMMSS Base Contract Terms, then El
Dorado will be entitled to payment of an equitably reduced Contingent Contract
Payment (if, after the equitable reduction, the Contingent Contract Payment
amount is a positive amount), which reduction will reflect, among other things:
the severance costs actually incurred by the Subsidiary as a result of the
reduced scope of the NMMSS Follow-On Contract(s); the present value of the
reduction in fees to be earned by the Subsidiary under the Existing NMMSS
Contract; the direct and indirect costs previously allocated to the Existing
NMMSS Contract that will no longer be covered, after taking into account any
cost reduction measures taken by the Subsidiary; and the present value of the
reduced net margin on other NAC Consulting business expected to be achieved in
calendar years 2006 through 2008 as compared to the Assumed Margin Amount (as
calculated in accordance with Schedule 2.8(c)(ii)). Within ten (10) Business
Days of any such mutual execution and delivery of one or more such NMMSS
Follow-On Contracts, Purchaser will deliver to the Seller Parties an Estimated
Payment Notice, including a copy of the NMMSS Follow-On Contract(s). Thereafter,
the Parties will follow the resolution and payment procedures set forth in
Section 2.8(f) and Section 2.8(g).

(iii) If the Subsidiary will share the financial benefits of any NMMSS Follow-On
Contract with one or more Persons (other than a subsidiary of Purchaser)
pursuant to a teaming arrangement in which the Subsidiary is participating
(whether as the prime contractor on behalf of the other Persons in such
arrangement or as a subcontractor of another Person serving as the prime
contractor), only the financial benefits accruing to the Subsidiary will be
considered in determining the Contingent Contract Payment. The Seller Parties
will be entitled to a percentage of the Contingent Contract Payment that would
have been payable had no such teaming arrangement occurred and such percentage
will correspond to the percentage of the economic benefit under the NMMSS
Follow-On Contract allocable to the Subsidiary, as compared to the economic
benefit to the Subsidiary under such NMMSS Follow-On Contract had no such
teaming arrangement occurred.

(d) Extension of Existing NMMSS Contract. In the event that the DOE extends the
Existing NMMSS Contract or any portion thereof more than three (3) months beyond
September 30, 2005, then El Dorado will be entitled to a payment (the
“Contingent Extension Payment”) that equitably reflects the value of such
extension from September 30, 2005, consistent with the terms of this
Section 2.8, including but not limited to the reduction factors listed in
Section 2.8(c)(ii), and which will not exceed Six Million Dollars ($6,000,000).
Within ten (10) Business Days of the Subsidiary’s receipt of notice of any such
extension, Purchaser will promptly deliver to the Seller Parties an Estimated
Payment Notice, including the terms of the extension. Thereafter, the Parties
will follow the resolution and payment procedures set forth in Section 2.8(f)
and Section 2.8(g). The maximum Contingent Contract Payment payable pursuant to
Section 2.8(c) will be reduced by the amount of any Contingent Extension Payment
made pursuant to this Section 2.8(d).

(e) Sale or Transfer Events.

(i) During the period (the “Restricted Sale Period”) from and after the Closing
until the earlier of (A) expiration of the Covered Period and (B) such time as
one or more Contingent Contract Payments, Contingent Extension Payment and/or
Contingent Termination Payment that, when taken together, equal or exceed Three
Million Dollars ($3,000,000) (the “Contingent Contract Payment Threshold”) have
been paid or are payable to El Dorado, Purchaser may not enter into, or permit
the Company or the Subsidiary to enter into, an agreement (x) relating to a NAC
Consulting Sale (as defined below) with any Person, or (y) to assign or
otherwise transfer all or any portion of the Existing NMMSS Contract to any
Person, except as set forth in this Section 2.8(e); provided that Purchaser will
be permitted to transfer all or any portion of NAC Consulting (as defined
below), including the Existing NMMSS Contract, to a direct or indirect
wholly-owned subsidiary of Purchaser to help facilitate a possible NAC
Consulting Sale, in which event references to the Subsidiary in this Section 2.8
will also be deemed to refer to such transferee, as applicable. After the
expiration of the Restricted Sale Period, there will be no limitations on
Purchaser’s ability to take any of the actions described in (x) and (y) above,
and no Contingent Sale Payment (as defined below) or other payment will be
payable in connection therewith, except pursuant to Section 2.8(e)(iii) or
Section 2.8(e)(iv).

(ii) During the Restricted Sale Period, subject to Section 2.8(e)(iv), Purchaser
will be entitled to sell (a “NAC Consulting Sale”), directly or indirectly, all
or substantially all of the Subsidiary’s consulting line of business (which
includes, but is not limited to, those assets associated with the administration
of the Existing NMMSS Contract) (“NAC Consulting”) only with the prior written
consent of the Seller Parties (which consent will not be unreasonably withheld,
conditioned or delayed) (a “Sale Consent”).

(iii) Upon the closing of a NAC Consulting Sale pursuant to an agreement or
agreements of sale executed by the prospective purchaser or purchasers prior to
the expiration of the Restricted Sale Period (unless, between such execution and
closing, payments owing to El Dorado pursuant to this Section 2.8 will have
reached the Contingent Contract Payment Threshold, whereupon no Contingent Sale
Payment will thereafter be payable pursuant to this Section 2.8(e) or
otherwise), El Dorado will be entitled to cash in an amount equal to (A) Three
Million Dollars ($3,000,000) plus (B) fifty percent (50%) of the Net Proceeds in
excess of Three Million Dollars ($3,000,000), if any, up to an aggregate payment
to El Dorado of Six Million Dollars ($6,000,000) less any Contingent Contract
Payment, Contingent Extension Payment or Contingent Termination Payment. Within
ten (10) Business Days following any such closing of a NAC Consulting Sale,
Purchaser will deliver to the Seller Parties an Estimated Payment Notice,
including a copy of the NAC Consulting Sale transaction agreement(s).
Thereafter, the Parties will follow the resolution and payment procedures set
forth in Section 2.8(f) and Section 2.8(g).

(iv) Notwithstanding anything to the contrary herein, at any such time that one
or more NMMSS Follow-On Contracts with respect to all significant NMMSS Program
Services for which one or more NMMSS Contract Solicitations were issued during
the Covered Period have been entered into by one or more Persons other than the
Subsidiary (or a Person other than another subsidiary of Purchaser teaming with
the Subsidiary to secure a NMMSS Follow-On Contract) during the Restricted Sale
Period (such time, the “Final NMMSS Award Date”), Purchaser will be entitled to
effect a NAC Consulting Sale without any Sale Consent. Upon the closing of such
a NAC Consulting Sale pursuant to an agreement or agreements of sale executed by
the prospective purchaser or purchasers prior to the expiration of the
Restricted Period (unless, between such execution and closing, payments owing to
El Dorado pursuant to this Section 2.8 will have reached the Contingent Contract
Payment Threshold, whereupon no Contingent Sale Payment will thereafter be
payable pursuant to this Section 2.8(e) or otherwise), if the Net Proceeds from
such NAC Consulting Sale (A) equal or exceed Six Million Dollars ($6,000,000),
then El Dorado will be entitled to a Contingent Sale Payment in an amount
calculated in accordance with Section 2.8(e)(iii), or (B) are less than Six
Million Dollars ($6,000,000), then El Dorado will be entitled to payment in cash
in an amount equal to fifty percent (50%) of the Net Proceeds. Within ten
(10) Business Days following any such closing of a NAC Consulting Sale,
Purchaser will deliver to the Seller Parties an Estimated Payment Notice,
including a copy of the NAC Consulting Sale transaction agreement(s).
Thereafter, the Parties will follow the resolution and payment procedures set
forth in Section 2.8(f) and Section 2.8(g).

(v) Upon receipt by Purchaser of a Sale Consent, Purchaser will use its
reasonable efforts to promptly consummate a NAC Consulting Sale, and, assuming
Purchaser is not in breach of its foregoing obligation and subject to Section
2.8(e)(vi), (A) Purchaser will have no obligation to cause the Subsidiary to
make any NMMSS Contract Offer, (B) the Seller Parties will cease to have any
rights to any payment pursuant to Section 2.8(c) (other than any payment payable
at the time such Sale Consent was given), without regard to whether the
Subsidiary enters into a NMMSS Follow-On Contract, and (C) in the event that a
NAC Consulting Sale is not consummated, the Seller Parties will not be entitled
to any payments pursuant to this Section 2.8(e) in respect of such unconsummated
sale.

(vi) Notwithstanding anything to the contrary herein, during the Restricted Sale
Period, in the event that a Sale Consent is given by the Seller Parties but a
NAC Consulting Sale is not consummated, and the Restricted Sale Period has not
yet expired upon termination or expiration of the agreement(s) of sale relating
to the unconsummated NAC Consulting Sale, (A) the Seller Parties will be
entitled to any Contingent Contract Payment otherwise payable pursuant to
Section 2.8(c) in connection with any NMMSS Follow-On Contract executed by the
Subsidiary and a Requesting Agency in respect of a NMMSS Contract Offer that was
pending before such Requesting Agency at the time the Sale Consent was given or
that Purchaser made during the Restricted Sale Period at its own election after
the Sale Consent was given, and (B) to the extent still practicable,
commercially reasonable and responsive to a pending NMMSS Contract Solicitation,
and to the extent not prohibited by a Requesting Agency, Purchaser will cause
the Subsidiary to make a NMMSS Contract Offer in accordance with the provisions
of Section 2.8(b) and any Contingent Contract Payment payable in connection
therewith shall be made in accordance with Section 2.8(c); provided that fifty
percent (50%) of Purchaser’s Transaction Costs in connection with the
unconsummated NAC Consulting Sale shall be deducted from any Contingent Contract
Payments payable pursuant to clause (A) and (B) above.

(vii) Upon the making of all payments to El Dorado required by the terms of
Section 2.8(e)(iii) or Section 2.8(e)(iv) or in connection with a NAC Sale (a
“Contingent Sale Payment”), El Dorado will cease to have any rights to further
payments pursuant to this Section 2.8 or to the Escrow Funds, and Purchaser and
the Seller Parties will promptly cause the Escrow Funds to be released to
Purchaser.

(viii) Upon the request of Purchaser, the Parties will agree in good faith upon
terms that will apply in the event that Purchaser desires to sell all of the
outstanding Company Shares or Subsidiary Shares or all or substantially all of
the assets of the Subsidiary (a “NAC Sale”).

(f) Resolution Procedures.

(i) Within ten (10) Business Days after the Seller Parties’ receipt of an
Estimated Payment Notice, the Seller Parties will notify Purchaser in writing of
the Seller Parties’ acceptance or rejection of Purchaser’s proposed Contingent
Payment. Any Rejection Notice by the Seller Parties must include reasonable
detail as to the reasons for such rejection and the Seller Parties’ proposed
calculation of the Contingent Payment. If (A) by written notice to Purchaser,
the Seller Parties accept the proposed Contingent Payment as set forth in the
Estimated Payment Notice, or (B) the Seller Parties fail to deliver any notice
of acceptance or rejection of the proposed Contingent Payment within the
prescribed ten (10) Business Day period, the determination of the Contingent
Payment as set forth in the Estimated Payment Notice will be deemed accepted by
the Seller Parties and will be final and binding on the Parties.

(ii) If the Seller Parties deliver a Rejection Notice to Purchaser under
Section 2.8(f)(i), the Seller Parties and Purchaser will promptly attempt in
good faith to agree upon a Contingent Payment. If the Seller Parties and
Purchaser are unable to agree upon a Contingent Payment within thirty (30) days
after the date of the Rejection Notice, then the Seller Parties and Purchaser
will refer the dispute to Independent Accountants for review and final
determination of the Contingent Payment, and, in connection therewith, will
submit their final respective proposals for the amount of the disputed
Contingent Payment; provided, that the Parties agree that any undisputed portion
of a Contingent Payment will be paid to El Dorado in accordance with Section
2.8(g). The Independent Accountants may request of the Seller Parties or
Purchaser such documents and information as may be necessary or appropriate for
proper determination of the matter, and the Seller Parties and Purchaser will
cooperate to promptly satisfy any such request. Any such documents provided to
the Independent Accountants shall be provided on a confidential basis and shall
be concurrently provided to the other Parties. The Independent Accountants will
be instructed by the Seller Parties and Purchaser to select as the Contingent
Payment either the amount last proposed by Purchaser or the amount last proposed
by the Seller Parties and not any other amount. The determination by the
Independent Accountants of the Contingent Payment will be final and binding on
the Seller Parties and Purchaser. The reasonable costs and expenses of the
Independent Accountants will be paid by the Party whose proposal for the amount
of the Contingent Payment is not selected by the Independent Accountants.

(g) Payment of Contingent Payment. Within ten (10) Business Days of the date of
the final agreement of the Seller Parties and Purchaser, the final determination
by the Independent Accountants or the deemed acceptance by the Seller Parties,
as the case may be, with respect to a Contingent Payment or any portion thereof,
Purchaser will pay El Dorado, or Purchaser and the Seller Parties will request
payment to be made to El Dorado pursuant to the Escrow Agreement of, as
applicable, an amount equal to any such Contingent Payment or portion thereof
that has not previously been paid pursuant to the other provisions of this
Section 2.8. In the event that the Escrow Agreement has terminated, any
Contingent Payment or portion thereof otherwise payable hereunder to El Dorado
pursuant to the Escrow Agreement will then be paid directly by Purchaser to El
Dorado. In the event that a portion of the Escrow Funds has been released to
Purchaser and the remaining Escrow Funds are not sufficient to pay any
Contingent Payment or portion thereof otherwise payable hereunder to El Dorado
pursuant to the Escrow Agreement, then an amount equal to the difference between
the Contingent Payment amount and the Escrow Funds will be paid directly by
Purchaser to El Dorado.

(h) Existing NMMSS Contract Termination. In the event that the Existing NMMSS
Contract is terminated by the DOE prior to September 30, 2005 and, in connection
therewith, the Subsidiary receives from the DOE termination payments, then USEC
shall pay to El Dorado cash in an amount equal to the amount, if any, by which
the amount of such termination payments exceeds the NMMSS Losses, but not more
than Six Million Dollars ($6,000,000) (the “Contingent Termination Payment”).
Within ten (10) Business Days of the Subsidiary’s receipt of any such
termination payment, Purchaser will promptly deliver to the Seller Parties an
Estimated Payment Notice. Thereafter, the Parties will follow the resolution and
payment procedures set forth in Section 2.8(f) and Section 2.8(g). The maximum
Contingent Contract Payment payable pursuant to Section 2.8(c), and the maximum
Contingent Sale Payment payable pursuant to Section 2.8(e), if any and as
applicable, will be reduced by the amount of any Contingent Termination Payment
made pursuant to this Section 2.8(h).

(i) Expiration of the Covered Period; Other Release of Escrow Funds.

(i) Upon the expiration of the Covered Period, (A) Purchaser will have no
obligation to secure any required consent of the Seller Parties under this
Section 2.8, or to submit a NMMSS Contract Offer or otherwise make any further
effort to secure any NMMSS Follow-On Contract, (B) the Seller Parties will cease
to have any right to any payment pursuant to this Section 2.8 or to the Escrow
Funds, other than with respect to any payment owed but unpaid pursuant to this
Section 2.8, and (C) if the Escrow Funds have not previously been released to
Purchaser, Purchaser and the Seller Parties will promptly cause the Escrow Funds
to be released to Purchaser.

(ii) At any time and at its sole discretion, Purchaser may direct that all
unpaid Escrow Funds, in an amount not to exceed Six Million Dollars ($6,000,000)
less any Contingent Termination Payment, be paid to El Dorado, and the Seller
Parties will cooperate in making such direction under the Escrow Agreement. Upon
El Dorado’s receipt of such Escrow Funds, Purchaser will have no obligation to
secure any required consent of the Seller Parties under this Section 2.8, or to
submit a NMMSS Contract Offer or otherwise make any further effort to secure any
NMMSS Follow-On Contract, and the Seller Parties will have no further right to
any Contingent Payment from Purchaser under this Section 2.8.

(iii) In the event that (A) the Existing NMMSS Contract is terminated by the DOE
prior to September 30, 2005, (B) the Subsidiary receives written notification
from a Requesting Agency that it is not entitled to respond to a NMMSS Contract
Solicitation or the Subsidiary does not qualify to submit a NMMSS Contract Offer
pursuant to a NMMSS Contract Solicitation or (C) the Final NMMSS Award Date
occurs, then, if the Escrow Funds have not previously been released to
Purchaser, upon delivery by Purchaser to the Seller Parties of a written notice
indicating that one of the events specified in this Section 2.8(i)(iii) has
occurred, Purchaser and the Seller Parties will promptly cause the Escrow Funds
to be released to Purchaser.

(iv) Purchaser and the Seller Parties will cause Escrow Funds to be released to
Purchaser in connection with the execution of any NMMSS Follow-On Contract by a
Requesting Agency and any Person other than the Subsidiary (or a Person teaming
with the Subsidiary to secure a NMMSS Follow-On Contract) to the extent that the
balance of Escrow Funds as of the date of such execution exceeds the collective
economic benefit to the Subsidiary were it to enter into one or more Follow-On
Contracts with respect to all NMMSS Program Services not then covered by
executed NMMSS Follow-On Contracts (the “Excess Escrow Funds”). Purchaser and
the Seller Parties will attempt in good faith to agree upon the amount of the
Excess Escrow Funds and cause any such undisputed amount to be promptly released
to Purchaser.

(v) Purchaser and the Seller Parties will cause the Escrow Funds to be released
to Purchaser if, by September 30, 2005, the Subsidiary and a Requesting Agency
have not executed a NMMSS Follow-On Contract and the Existing NMMSS Contract has
not been formally extended beyond September 30, 2005.

(vi) In the event that, as of September 30, 2005, the Subsidiary and a
Requesting Agency have not executed a NMMSS Follow-On Contract and the Existing
NMMSS Contract has been formally extended beyond September 30, 2005 on terms and
conditions that, in the reasonable judgment of Purchaser, collectively result in
an economic benefit to the Subsidiary that is less favorable to the Subsidiary
than if the Existing NMMSS Contract had been formally extended for three
(3) years on terms and conditions consistent with the NMMSS Base Contract Terms,
then Purchaser and the Seller Parties will cause Escrow Funds to be released to
Purchaser in an amount equal to the difference between (A) the collective
economic benefit to the Subsidiary anticipated as of the Closing Date if the
Existing NMMSS Contract had been formally extended for three (3) years on terms
and conditions consistent with the NMMSS Base Contract Terms and (B) the
collective economic benefit to the Subsidiary of the actual extension of the
Existing NMMSS Contract as of September 30, 2005. Purchaser and the Seller
Parties will attempt in good faith to agree upon such amount to be released and
cause any such undisputed amount to be promptly released to Purchaser.

(vii) The release of any Escrow Funds to Purchaser pursuant to Section
2.8(i)(iii), Section 2.8(i)(iv), Section 2.8(i)(v) or Section 2.8(i)(vi) will
not affect Purchaser’s payment obligations hereunder, other than as provided in
the last two sentences of Section 2.8(g).

(j) Maximum Payment. Under no circumstance will the aggregate of all payments
payable to El Dorado pursuant to this Section 2.8 (including, but not limited
to, Contingent Payments) exceed Six Million Dollars ($6,000,000) plus any Escrow
Earnings (as defined below). Notwithstanding anything to the contrary herein, to
the extent any payments made to El Dorado pursuant to this Section 2.8 are made
out of the Escrow Funds (without giving effect to the penultimate sentence of
Section 2.8(g)), on the Termination Date (as defined in the Escrow Agreement),
El Dorado will also be entitled to payment from the Escrow Funds of an amount
equal to the product of (i) the aggregate net interest or income earned on the
Escrow Funds during the term of the Escrow Agreement less any amounts
distributed to Purchaser pursuant to the Escrow Agreement to pay Taxes thereon
and (ii) a fraction, the numerator of which is the aggregate amount of Escrow
Funds otherwise paid or then payable to El Dorado and the denominator of which
is Six Million Dollars ($6,000,000) (such product, the “Escrow Earnings”), and
Purchaser and the Seller Parties will cause payment of such Escrow Earnings to
be made pursuant to the Escrow Agreement.

(k) Information. Upon the written request of a Party, the other Parties will
promptly provide such requesting Party with any information reasonably required
to verify the determination of, or otherwise to calculate, any proposed
Contingent Payment amount. In addition, from time to time, Purchaser will
provide the Seller Parties with such additional information regarding the
Existing NMMSS Contract, any NMMSS Follow-On Contract (including the bidding
process therefor), NAC Consulting, and the status of any prospective or pending
NAC Consulting Sale or NAC Sale as the Seller Parties may reasonably request.

(l) Good Faith Efforts. The Parties will use their respective good faith efforts
to carry out their respective obligations under this Section 2.8.

  8.   Section 6.2 of the Agreement is hereby amended by deleting the word “and”
at the end of Section 6.2(a), by replacing the period at the end of
Section 6.2(b) with a semicolon and the word “and,” and by adding a new
Section 6.2(c) as follows:

(c) Without limiting the foregoing, to the extent required, the Parties will, as
promptly as practicable, use reasonable efforts to obtain, or cause to be
obtained, the Interim OCI Waiver, and will coordinate and cooperate with the
other Parties in obtaining the Interim OCI Waiver.

9. Section 9.4(c) of the Agreement is hereby amended and restated as follows:

the aggregate Liability of the Seller Parties for all Losses claimed by
Purchaser Indemnitees under Section 6.5(a), Section 9.2(a), Section 9.2(b)
(other than for breach of the Seller Parties’ obligations under Section 6.10(a))
or Section 9.2(d) will not exceed an amount equal to (i) thirty-five percent
(35%) of the Purchase Price, less (ii) the amount of Escrow Funds, if any,
released to Purchaser up to Six Million Dollars ($6,000,000), plus (iii) any
Escrow Earnings or Contingent Payment paid to the Seller Parties by Purchaser
other than from the Escrow Funds; provided, however, that the aggregate
liability of the Seller Parties for all Losses claimed by Purchaser Indemnitees
as a result of any violation of Section 3.2, Section 4.4, or Section 4.5 will
not exceed an amount equal to (i) the Purchase Price, less (ii) the amount of
Escrow Funds, if any, released to Purchaser up to Six Million Dollars
($6,000,000), plus (iii) any Escrow Earnings or Contingent Payment paid to the
Seller Parties by Purchaser other than from the Escrow Funds; and

10. Section 9.4(d) of the Agreement is hereby amended and restated as follows:

the aggregate liability of Purchaser for all Losses claimed by Seller
Indemnitees under Section 9.3(a), Section 9.3(b) (other than for breach of
Purchaser’s obligations under Section 6.10(b) or Section 6.13) or Section 9.3(d)
will not exceed an amount equal to (i) thirty-five percent (35%) of the Purchase
Price, less (ii) the amount of Escrow Funds, if any, released to Purchaser up to
Six Million Dollars ($6,000,000), plus (iii) any Escrow Earnings or Contingent
Payment paid to the Seller Parties by Purchaser other than from the Escrow
Funds; provided, however, that the aggregate liability of Purchaser for all
Losses claimed by Seller Indemnitees as a result of any violation of Section 5.2
will not exceed an amount equal to (i) the Purchase Price, less (ii) the amount
of Escrow Funds, if any, released to Purchaser up to Six Million Dollars
($6,000,000), plus (iii) any Escrow Earnings or Contingent Payment paid to the
Seller Parties by Purchaser other than from the Escrow Funds.

  11.   The Agreement is hereby amended by adding Schedule 2.8(b) in the form
set forth in Attachment 1 hereto, and Schedule 2.8(c)(ii) in the form attached
as Attachment 2 hereto, to the Schedules to the Purchase Agreement.

  12.   Notwithstanding anything in this Amendment or the Purchase Agreement to
the contrary, if any Party refuses or fails to perform its obligations under
this Amendment or the Escrow Agreement, in addition to any other remedy which
may be available to the other Party at law or in equity, such other Party will
be entitled to seek specific performance and injunctive relief, without posting
bond or other security, and without the necessity of proving actual or
threatened damages, which remedy such Party will be entitled to seek in any
court of competent jurisdiction. Further, a Party shall be reimbursed by the
other Parties for its reasonable attorneys’ fees incurred in connection with
successfully enforcing its rights under this Amendment and/or under the Escrow
Agreement.

  13.   Except where inconsistent with the express terms of this Amendment, all
provisions of the Agreement as originally entered into will remain in full force
and effect.

  14.   This Amendment (including the Attachments hereto), taken together with
the Agreement and the Escrow Agreement, constitutes the entire and complete
agreement between the Parties with respect to the subject matter hereof and
supercedes all prior agreements, commitments, communications, representations
and understandings, both written and oral, between the Parties with respect to
the subject matter hereof.

  15.   This Amendment will be governed in all respects, including as to
validity, interpretation and effect, by the internal laws of the State of
Delaware, without giving effect to the conflict of laws rules thereof.

  16.   This Amendment may be executed in several counterparts and delivered in
original form or by electronic facsimile, each of which will be deemed an
original and all of which will together constitute one and the same instrument.

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IN WITNESS WHEREOF, the Parties have duly executed this Amendment as of the date
first above written.

PINNACLE WEST CAPITAL CORPORATION

By:
/s/ Donald E. Brandt

      Name: Donald E. Brandt
Title: Executive Vice President and
Chief Financial Officer

EL DORADO INVESTMENT COMPANY

By:

/s/ Donald E. Brandt

      Name: Donald E. Brandt

Title: Treasurer

USEC INC.

By:

/s/ Ellen C. Wolf

      Name: Ellen C. Wolf
Title: Senior Vice President and
Chief Financial Officer

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