SecProbe.io

July 25, 2011
 Via E-Mail

Darryl M. Bradford Senior Vice President and General Counsel Exelon Corporation 10 South Dearborn Street P.O. Box 805379 Chicago, Illinois 60680-5379
Re: Exelon Corporation
  Registration Statement on Form S-4
Filed June 27, 2011
  File No. 333-175162
  Form 10-K for Fiscal Year Ended December 31, 2010
  Filed February 10, 2011
Form 8-K  Filed April 27, 2011 File No. 001-16169

Dear Mr. Bradford:
 We have limited our review of your filings to  those issues we have addressed in our
comments.  In some of our comments, we may ask you to provide us with information so we may better understand your disclosure.

Please respond to this letter by amending your filings and providing the requested
information.  Where you do not believe our commen ts apply to your facts and circumstances or
do not believe an amendment is appropriate , please tell us why in your response.
 After reviewing any amendment to your re gistration statement and the information you
provide in response to these comments, we may have additional comments.

Form S-4 Registration Statement Filed June 27, 2011

 Unaudited Pro Forma Condensed Combined Consolidated Financial Statements, page 162

 Note 5.  Pro Forma Adjustments to Financial Statements, page 171

 1. Please tell us your basis in GAAP  for recognizing a re gulatory asset offset for the adjustment
to reflect Constellation’s third- party debt at estima ted fair value.  Please include a detailed
discussion of facts and circumstances supporti ng your conclusion including a discussion of
whether and how each regulatory jurisdiction incor porate interest or othe r debt-related costs

Darryl M. Bradford Exelon Corporation July 25, 2011 Page 2

 in base rates.  Please explain whether any of BGE’s regulatory jurisdictions utilize a
hypothetical debt structure a nd what effect you believe it will or should have on your
recording of a regulatory offset relating to  debt.  We may have further comment.
 2. Please tell us your basis in GAAP for recognizing Constellat ion’s regulatory assets and
liabilities, particularly those not earning a return, at carryi ng value as opposed to their
acquisition-date fair value.
 3. We note a number of blank spaces.  Please comp lete the information by filling in the blanks
prior to effectiveness.
 Form 10-K for Fiscal Year Ended December 31, 2010

 Item 7.  Management’s Discussion and Analys is of Financial Condition and Results of
Operations, page 63
 Critical Accounting Policies and Estimates, page 75

 Nuclear Decommissioning Asset Retirement Obligations (Exe lon and Generation), page 76

4. Please tell us the escalation pe rcentages you used to estimate future decommissioning costs
for the past three years and whether you use blen ded escalation factors or  separate escalation
factors for labor, equipment and other material s, energy, LLRW disposal  and other costs.
Please also tell us the indices upon which the es calation factors are based, if indices were
used.  In short, please show us why your  inflation assumptions related to future
decommissioning costs are supportable with hist orical experience and similar assumptions
used by other licensees.
 Item 8.  Financial Statements and Supplementary Data, page 150

 Combined Notes to Consolidated Financial Statements, page 178

 12.  Asset Retirement Obligations (Exel on, Generation, ComEd and PECO), page 260

 Nuclear Decommissioning Trust Fund Investments, page 262

 NRC Minimum Funding Requirements, page 264

 5. We note that you determine the ARO using multiple scenarios where decommissioning
activities are completed under th ree possible scenarios ranging fr om 10 to 70 years after the
cessation of plant operations.  Please tell  us your considerat ion of disclosing:

Darryl M. Bradford Exelon Corporation July 25, 2011 Page 3

  The degree to which any of the multiple scenar io based cost estimates are lower than the
Nuclear Regulatory Commissi on’s minimum formula amount, and if so, the reasons why
such estimates are lower than the NRC formula amount.

 The model you use and a sensitivity anal ysis of changes in assumptions.

Accounting Implications of the Regulatory Agreements with ComEd and PECO, page 265

 6. We note your disclosure that the NDT funds of each of the former ComEd units exceeded the
related decommissioning obligation for each of th e units, and for the purposes of making this
determination, the decommissioning obligati on referred to is the ARO reflected on
Generation’s Consolidated Balance Sheet at December 31, 2010 and is different from the
calculation used in the NRC minimum funding obligation fili ngs based on NRC guidelines.
Please tell us your consideration of disclosing: (i) whether NDT funds for each of the units is
greater than or less than the NRC minimum funding obligation; a nd (ii) if NDT funds for any
of the units is less than the NRC minimu m funding obligation and the reasons for the
difference.
 18.  Commitments and Contingencies (Exelon, ComEd and PECO), page 291

 Environmental Issues, page 300

 Section 316(b) of the Clean Water Act, page 301

 7. We note that you revised the economic useful li fe of Oyster Creek used in determining
depreciation and the asset retirement obligation to  reflect your decision to  retire Oyster Creek
by December 31, 2019 and the execution of the Ad ministrative Consent Order with the New
Jersey Department of Environm ental Protection.  Based on the e xpiration date of the current
operating license, it appears th at the Nuclear Regulatory Comm ission previously approved an
extension of the initial 40-year  operating license for Oyster Creek.  If our assumption is
incorrect please advise in detail.  If our assu mption is correct, please tell us (i) when the
operating license was extended (ii) whether you re vised the useful life of Oyster Creek used
in determining depreciation and the asset reti rement obligation and (iii) when and how you
revised the useful life and the facts and circumstances you considered, including your
consideration of the impact of New Jersey state-level permit programs.  If you did not
anticipate the early retirement of  Oyster Creek, please discuss the events and circumstances
between the date the Nuclear Regulatory Commission approved the extension of the
operating license and/or the date  you revised the useful life of Oyster Creek and the decision
to cease generating operations by December 31, 2019.
 Litigation and Regulatory Matters, page 306

 8. We note your disclosure regarding asbestos personal injury clai ms and the savings plan claim
and regarding various other litigation matters, and in particular your disclosure that the

Darryl M. Bradford Exelon Corporation July 25, 2011 Page 4

 ultimate outcome of such matters  is uncertain and may have a material impact on your results
of operations, cash flows or financial position.  Please tell us your cons ideration of disclosing
an estimate of the reasonably possible loss or range of loss for each matter, or in the
aggregate, or providing a statement that such  estimates cannot be made in accordance with
ASC 450-20-50-4.  In addition, for those ma tters where you are unable to estimate the
possible loss or range of loss, please tell us the procedures you undertake on a quarterly basis
to attempt to develop a range of reasonably possible loss.
 Form 8-K Filed April 27, 2011

 9. We note that you present a full income statement in your reconciliations of adjusted (non-
GAAP) operating earnings to GAAP consolidated statement of operations.  Presenting a full
non-GAAP income statement may attach undue prominence to the non-GAAP information.  As such, please revise your reconciliations in future filings to simply reconcile net income to adjusted (non-GAAP) operating earnings.  Please refer to Question 102.10 of our
Compliance and Disclosure Interpretati ons: Non-GAAP Financial Measures.

We urge all persons who are responsible for th e accuracy and adequacy of the disclosure
in the filing to be certain that the filing incl udes the information the Securities Act of 1933 and
all applicable Securities Act rules require.  Since the company and its management are in
possession of all facts relating to a company’s disc losure, they are responsible for the accuracy
and adequacy of the disclosures they have made.
Notwithstanding our comments, in the event you request acceleration of  the effective date
of the pending registration statement please pr ovide a written statement from the company
acknowledging that:

 should the Commission or the staff, acting purs uant to delegated authority, declare the
filing effective, it does not foreclose the Co mmission from taking any action with respect
to the filing;

 the action of the Commission or the staff, acting pursuant to delegated authority, in
declaring the filing effective, does not relieve the company from its full responsibility for
the adequacy and accuracy of the disclosure in the filing; and

 the company may not assert staff comments a nd the declaration of effectiveness as a
defense in any proceeding initiated by the Commission or any person under the federal
securities laws of the United States.  Please refer to Rules 460 and 461 regarding re quests for acceleration.  We will consider a
written request for acceleration of  the effective date of the regi stration statement as confirmation
of the fact that those reques ting acceleration are aware of thei r respective responsibilities under
the Securities Act of 1933 and the Securities Excha nge Act of 1934 as they relate to the proposed
public offering of the securities specified in th e above registration stat ement.  Please allow

Darryl M. Bradford Exelon Corporation July 25, 2011 Page 5

 adequate time for us to review any amendment prior to the requested effective date of the
registration statement.
 You may contact Ta Tanisha Meadows, Sta ff Accountant, at (202) 551-3322 or William
Thompson, Accounting Branch Chief, at (202)  551-3344 if you have questions regarding
comments on the financial statements and re lated matters.  Please contact Ramin Olson,
Attorney-Advisor, at (202) 551-3331 or me at (202) 551-3720 if you have any other questions.

Sincerely,
        / s /  M a r a  L .  R a n s o m  f o r
James Allegretto Senior Assistant Chief Accountant