Exhibit 4.31
 Fourth Amendment to
 Alion Science and Technology Corporation
Employee Ownership, Savings and Investment Plan
     1.
    
    Section 2.2 is hereby amended by adding the following sentences to the end
thereof:
  2.
    
    Section 2.11 is hereby amended in its entirety to read as follows:
 Common Stock.




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3.
    
    Subsection 2.13(a)(4) is hereby amended, effective as of October 1, 2006, by
deleting the following phrase therefrom:
    4.
    
    The last two sentences of Section 2.69 are hereby amended in their entirety to
read as follows:
  5.
    
    The last sentence of subsection 4.6(b) is hereby amended in its entirety to
read as follows:
  6.
    
    The second sentence of subsection 4.10(c)(2) is hereby amended, effective as of
October 1, 2006, in its entirety to read as follows:
  7.
    
    The second sentence of subsection 4.10(d) is hereby amended, effective as of
October 1, 2006, in its entirety to read as follows:
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8.
    
    The second sentence of subsection 4.12(d) is hereby amended, effective as of
October 1, 2006, in its entirety to read as follows:
  9.
    
    The fourth sentence of subsection 4.12(f) is hereby amended, effective as of
October 1, 2006, in its entirety to read as follows:
  10.
    
    A new subsection 5.6(a)(2) is hereby added to read as follows:
  11.
    
    Subsection 5.7(a) is hereby amended by adding the following sentence to the end
thereof:
  12.
    
    Subsection 5.7(d) is hereby amended in its entirety to read as follows:
  13.
    
    Subsection 5.8(b) is hereby amended in its entirety to read as follows:
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14.
    
    The first sentence of Section 5.8(c) is hereby deleted in its entirety.15.
    
    Section 5.9 is hereby amended in its entirety to read as follows:[Reserved.]16.
    
    Section 5.12 is hereby amended in its entirety to read as follows:
   (A)
    
    Shares of stock
in an S Corporation that are allocated to a
Participants ESOP Accounts;(B)
    
    Such
Participants share of the Common Stock of an S
Corporation that is held by the ESOP Component but is
not allocated to the ESOP Accounts of any Participant or
Beneficiary; and(C)
    
    Synthetic Equity
Shares.
   (A)
    
    The aggregate
number of Deemed-Owned Shares of such person and the
persons Members of the Family is at least twenty
percent (20%) of the number of Deemed-Owned Shares of
stock in the S Corporation; or(B)
    
    In the case of a
person other than one described in paragraph (1)
immediately above, a Deemed 10% Shareholder.
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(A)
    
    The spouse of the
individual;(B)
    
    An ancestor or
lineal descendant of the individual or the individuals
spouse;(C)
    
    A brother or
sister of the individual or the individuals spouse and
any lineal descendant of the brother or sister; and(D)
    
    The spouse of any
individual described in paragraphs (B) or (C)
immediately above.
   (A)
    
    The Plan holds
Company Stock consisting of shares of stock in an S
Corporation; and(B)
    
    Disqualified
Persons own at least fifty percent (50%) of the number
of shares of stock in the S Corporation. For purposes
of this paragraph (B), stock includes Company Stock
owned directly by the Disqualified Person, Deemed-Owned
Shares of the Disqualified Person, and Synthetic Equity
of the Disqualified Person.
  (i)
    
    The rules of
Section 318(a) of the Code shall apply for purposes of
determining ownership except that:
 (I)
    
    In applying paragraph (1) of Section 318(a) of
the Code, the members of an individuals family
shall include Members of the Family; and(II)
    
    Paragraph (4) of Section 318(a) of the Code
thereof shall not otherwise apply; and
 (ii)
    
    Notwithstanding
the employee trust exception in Code Section
318(a)(2)(B)(i), an individual shall be
treated as owning Deemed-Owned Shares of the
individual.
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(A)
    
    any rights to
future payments (payable in cash or any other form other
than stock of the S Corporation) (e.g., stock
appreciation rights, phantom stock units, or similar
rights to future cash payments) based on the value of
such stock or appreciation in such value;(B)
    
    any rights to
acquire stock or other similar interests in a related
entity if such interests in the related entity are the
only significant asset of the S Corporation and the S
Corporation is the only significant owner of the related
entity (e.g., partnership, trust, or Qualified
Subchapter S Subsidiary under Section 1361(b)(3)of the
Code);(C)
    
    any remuneration
for services rendered to the S Corporation, or a related
entity, to which Section 404(a)(5) of the Code applies
(including remuneration for which a deduction would be
permitted under Section 404(a)(5) of the Code if
separate accounts were maintained);(D)
    
    any rights to
receive property (to which Section 83 of the Code
applies) in a future year for the performance of
services to an S Corporation, or a related entity;(E)
    
    any transfers of
property (to which Section 83 of the Code applies) in
connection with the performance of services to an S
Corporation, or a related entity, to the extent that the
property is not substantially vested within the meaning
of Treas. Reg. §1.83-3(i) by the end of the Plan Year in
which transferred; and(F)
    
    any remuneration
for services rendered to an S Corporation, or a related
entity, under a plan, or method or arrangement,
deferring the receipt of compensation to a date that is
after the 15th day of the 3rd
calendar month after the end of the entitys taxable
year in which the related services are rendered, other
than a plan that is an eligible retirement plan within
the meaning of Section 402(c)(7)(B) of the Code.
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ab initio
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17.
    
    Effective as of October 1, 2006, a new sentence is hereby added between the
third and fourth sentences of subsection 9.2(c) to read as follows:
  18.
    
    The second and third sentences of subsection 9.14(d) are hereby amended in
their entirety to read as follows:
  19.
    
    The last sentence of subsection 9.15(a)(1) is hereby amended in its entirety to
read as follows:
  20.
    
    Subsection 9.15(a)(2) is hereby amended in its entirety to read as follows:
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21.
    
    A new subsection 9.15(b)(6) is hereby added to read as follows:
  22.
    
    The last sentence of Section 12.5(a) is hereby amended, effective as of October
1, 2006, by deleting the following phrase therefrom:
    th
 Alion Science and Technology CorporationBy:
    /s/ Bahman AtefiIts:  Chief Executive Officer  10