NRC has a performance indicator and inspection finding matrix webpage for each plant. There are separate pages for Unit 1 and Unit 2

June 30, 2007

New this week from NRC Public Document Room

* [2007-06-23] Bryon Station, Unit 2, 60-Day Response to NRC Bulletin 2004-01, "Inspection of Alloy 82/182/600 Materials Used in the Fabrication of Pressurizer Penetrations and Steam Space Piping Connections at Pressurized-Water Reactors." ML071650509 2007-06-13 5 05000455 NPF-066 BL-04-001 BYRON 2007-0068 2007-06-13 2007-06-22 Everon Generation Coiripany LLC Byron itatron 4450 !vort'r: Gzrman C'nuvci- Poad Byron, 11 61013-979.1 June 13,2007 LTR: BYRON 2007-0068 File: 1.10.01 01 United States Nuclear Regulatory Comm

June 23, 2007

New this week from NRC Public Document Room

* [2007-06-19] LER 07-001-00 from Byron Station Unit 2, re Reactor Pressure Vessel Head Control Rod Drive Mechanism Penetration Nozzle Weld Indication Due to an Initial Constructive Weld Defect Allowing the Initiation of Primary Water Stress Corrosion Cracking ML071590211 2007-06-08 4 05000455 NPF-066 BYRON 2007-0072 LER 07-001-00 2007-06-08 2007-06-18 Exekn~. Exe~onGeneration Company, LLC www.exeloncorp coin N 1 Byron Btation 4430 North German Church Road Byron, FL 61010-9794 June 8, 2007 LTR: BYRON 2007-0072 File: 1.10.0101 United Sta

June 16, 2007

New this week from NRC Public Document Room

* [2007-06-14] Byron Station, Unit 2, Closeout of Confirmatory Action Letter Requirements ML071560272 2007-06-04 5 05000455 NPF-066 BYRON 2007-0067 NRR-07-012 TAC MD4137 2007-06-04 2007-06-13 Exek,n. Exelon Generation Company, LLC www.exeloncorpconi Nuclear Byron Station 4450 North German Church Road Byron, ft 61010-9794 CAL No. NRR-07-012 June 4, 2007 LTR: BYRON 2007-

* [2007-06-14] U. S. Dept of Homeland Security/Updated Illinois Plan for Radiological Accidents (IPRA) - Byron, Volume VI, Dated 06/07 ML071580356 2007-06-07 1 05000454 05000455 NUREG-0654 2007-06-07 2007-06-13 C.S. Department of Homeland Securitj Washington, DC 20528 Homeland Security June 7,2007 Mr. Roland Lickus Chief, State & Government Affairs US. NRC Region I11 2443 Warrenville Road, Suite 2 10 Lisle, Illin

June 9, 2007

New this week from NRC Public Document Room

* [2007-06-09] 05/08/2007 - Summary of Public Meeting with Exelon Generation Company Management to Discuss the Byron Station, Units 1 & 2, End-of-Cycle Plant Performance Assessment ML071560306 2007-06-04 5 05000454 05000455 NPF-037 NPF-066 2007-06-04 2007-06-08 June 4, 2007 LICENSEE: Exelon Generation Company, LLC FACILITY: Byron Station, Units 1 and 2 SUBJECT: SUMMARY OF THE MAY 8, 2007, PUBLIC MEETING TO DISCUSS THE BYRON STATION, UNITS 1 AND 2, END-OF-CYC

June 2, 2007

New this week from NRC Public Document Room

* [2007-06-01] Ltr, 05/23/2007 Information Request for Byron, Units 1 and 2, Problem Identification and Resolution (PI&R) Inspection ML071440460 2007-05-23 6 05000454 05000455 NPF-037 NPF-066 2007-05-23 2007-05-31 May 23, 2007 Mr. Christopher M. Crane President and Chief Nuclear Officer Exelon Nuclear Exelon Generation Company, LLC 4300 Winfield Road Warrenville, IL 60555 SUBJECT: INFORMATION REQUEST TO SUPPORT

* [2007-05-31] Byron, Unit 2 - Evaluation of Proposed Alternatives for Inservice Inspection Examination Requirements ML071290011 2007-05-23 9 05000455 NPF-066 TAC MD5230 2007-05-23 2007-05-30 May 23, 2007 Mr. Christopher M. Crane President and Chief Nuclear Officer Exelon Generation Company, LLC 4300 Winfield Road Warrenville, IL 60555 SUBJECT: BYRON STATION, UNIT NO. 2 - RELIEF REQUEST I3R-14 F

* [2007-05-30] Byron Station, Unit Nos. 1 and 2, Administrative Change and Order EA-06-037 Closeout Letter (TAC NOS. MD2203 and MD2204) ML071450247 2007-05-15 6 05000454 05000455 NPF-037 NPF-066 EA-06-037 TAC MD2203 TAC MD2204 2007-05-15 2007-05-29 OFFI.IA, USE ON6L, 6 WRCI'.' RELATED I, rWGRMd,;A--,,- ,~g REG&j( UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 May 15, 2007 Mr. Christopher

May 26, 2007

New this week from NRC Public Document Room

* [2007-05-24] Byron, Unit 2 - Westinghouse, Request for Withholding Information from Public Disclosure ML071290249 2007-05-16 7 05000455 NPF-066 TAC MD5230 2007-05-16 2007-05-23 May 16, 2007 Mr. Christopher M. Crane President and Chief Nuclear Officer Exelon Generation Company, LLC 4300 Winfield Road Warrenville, IL 60555 SUBJECT: WESTINGHOUSE ELECTRIC COMPANY, REQUEST FOR WITHHOLD

* [2007-05-24] IR 05000454-07-002; 05000455-007-002; on 01/01/2007-03/31/2007; Byron Station, Units 1 and 2; Equipment Alignment and Fire Protection ML071350661 2007-05-15 41 05000454 05000455 NPF-037 NPF-066 IR-07-002 2007-05-15 2007-05-23 May 15, 2007 Mr. Christopher M. Crane President and Chief Nuclear Officer Exelon Nuclear Exelon Generation Company, LLC 4300 Winfield Road Warrenville, IL 60555 SUBJECT: BYRON STATION, UNITS

May 19, 2007

New this week from NRC Public Document Room

* [2007-05-19] Byron Station, Unit 2, Plant Specific ECCS Evaluation Change - 10 CFR 50.46 Report. ML071300620 2007-05-10 6 05000455 NPF-066 RS-07-079 2007-05-10 2007-05-18 RS-07-079 10 CFR 50 .46 May 10, 2007 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 Byron Station, Unit 2 Facility Operating License No. NPF-66 NRC Docket No. STN 5

* [2007-05-15] Indications for B2R13 Pressurizer Weld Overlays. ML071240373 2007-05-04 1 05000455 NPF-066 2007-05-04 2007-05-14 ML071240366+ Indications for B2R1 3 Pressurizer Weld Overlays PORV PN-03 O~47~’ - O81~ 9.2 Laminar NOZZLE ID THICKNESS RANGE OF OVERLAY OVERLAY WIDTH INDICATION NUMBER INDICATION TYPE UTMEASURED DEPTH FROM OUTSIDE SUR

* [2007-05-15] 05/08/2007 Byron Licensee EOC Public Meeting Slides. ML071290272 2007-05-08 10 05000454 05000455 2007-05-08 2007-05-14 Exelon Nuclear Byron Generating Station U.S. NRC End-of-Cycle Public Meeting May 8, 2007 Byron Generating Station May 8, 2007 2 Byron Accomplishments – 2006 • Successful Unit 1 Refueling Outage • Completed Phases 1,

* [2007-05-15] 05/08/2007 Byron NRC Presentation EOC Public Meeting Slides. ML071290248 2007-05-08 20 05000454 05000455 2007-05-08 2007-05-14 Byron Annual Assessment Meeting Byron Annual Assessment Meeting Reactor Oversight Program Reactor Oversight Program - CY 2006 CY 2006 Nuclear Regulatory Commission Nuclear Regulatory Commission - Region III Region II

* [2007-05-15] Byron (EOC) Power Plant Assessment Letter (Report 05000454-07-001; 05000455-07-001). ML070610211 2007-03-02 6 2007-03-02 2007-05-14

* [2007-05-15] Byron, Unit 2, Pressurizer Weld Overlay Examination Results Related to Byron Station Relief Request 13R-08. ML071240370 2007-05-04 2 05000455 NPF-066 1.10.0101 BYRON 2007-0059 2007-05-04 2007-05-14 ML071240366+ Exekn~. Exelon Generation Company, LLC www.exeloncorp.com Nuci e Byron Station 4450 North German Church Road Byron, IL 61010—9794 May 4, 2007 LTR: BYRON 2007-0059 File: 1.10.0101

* [2007-05-15] IR 05000454-06-005, 05000455-06-005; 10/01/2006-12/31/2006; Byron Station, Units 1 and 2; Identification and Resolution of Problems. ML070430564 2007-02-12 51 2007-02-12 2007-05-14

* [2007-05-15] IR 05000455-07-007 on 02/05/2007 - 02/09/2007 for Exelon Generation Company, Byron Station, Unit 2; Supplemental Inspection for a White Performance Indicator in the Mitigating Systems Cornerstone. ML070710241 2007-03-09 16 2007-03-09 2007-05-14

* [2007-05-15] Byron June 2006 Initial Exam. ML062260233 2007-05-14

* [2007-05-15] Byron, Unit 2 - Review of the Spring 2005 Steam Generator Tube Inspection Reports. ML070590534 2007-03-19 6 2007-03-19 2007-05-14

* [2007-05-15] Byron, Unit 2, Pressurizer Weld Overlay Examination Results Related to Byron Station Relief Request 13R-08. ML071240366 2007-05-14 ML071240370+ML071240373+ FNWEBNAVIGATE=1.0 SYSTEMTYPE=MEZZANINE DOCUMENTID=071240366 STARTPAGE=1 LIBRARYNAME=ml_adams^hqntad01

* [2007-05-15] Byron, Unit 2, Relief, Evaluation of Relief Request I3R-08 Pertaining to Structural Weld Overlays. ML063530322 2007-03-19 18 2007-03-19 2007-05-14

* [2007-05-15] Byron, Units 1 and 2 - Facsimile transmission of draft request for additional information. ML070520195 2007-02-26 4 2007-02-26 2007-05-14

* [2007-05-15] Byron, Units 1 and 2, Relief, Evaluation of Relief Request 13R-06 for Control Rod Drive Canopy Seal Welds. ML070520480 2007-03-09 11 2007-03-09 2007-05-14

* [2007-05-15] Confirmatory Action Letter - Byron, Unit 2. ML070740325 2007-03-22 8 2007-03-22 2007-05-14

* [2007-05-15] Final As-Administered Administrative JPMS for the Byron Initial Examination - June 2006. ML062900374 2006-06-19 31 2006-06-19 2007-05-14

* [2007-05-15] Final As-Administered Scenarios for the Byron Initial Examination - June 2006. ML062900408 2006-06-19 73 2006-06-19 2007-05-14

* [2007-05-15] Final As-Administered Walkthrough JPMS for the Byron Initial Examination - June 2006. ML062900393 2006-06-19 64 2006-06-19 2007-05-14

* [2007-05-15] Initial Submittal of the Administrative JPMS for the Byron Initial Examination - June 2006. ML062900420 2006-06-19 26 2006-06-19 2007-05-14

* [2007-05-15] Initial Submittal of the Scenarios for the Byron Initial Examination - June 2006. ML062910346 2006-06-19 98 2006-06-19 2007-05-14

* [2007-05-15] Initial Submittal of the Walkthrough JPMS for the Byron Initial Examination - June 2006. ML062900467 2006-06-19 63 2006-06-19 2007-05-14

* [2007-05-15] Initial Submittal of the Written Exam for the Byron Initial Examination - June 2006, Questions 1 through 75 RO Examination, Questions 76 through 100 SRO Examination. ML062920438 2006-06-19 138 2006-06-19 2007-05-14

* [2007-05-15] Ltr. 02/22/07 Byron Notification of NRC Inspection and Request for Information. ML070530681 2007-02-22 9 2007-02-22 2007-05-14

* [2007-05-15] NRC Comments to the Proposed Written Examination, ES-401-9, for the Byron Initial Examination - June 2006. ML070230570 2007-01-22 16 2007-01-22 2007-05-14

* [2007-05-15] Transmittal Letter from United States Department of Homeland Security Re: Revision to the Illinois Plan for Radiological Accidents Volume VI-Byron, Dated 06/07. ML070430231 2007-02-07 1 2007-02-07 2007-05-14

May 12, 2007

New this week from NRC Public Document Room

* [2007-05-12] Byron Station, Unit No. 1 - Pressurizer Surge, Spray, Safety, And Relief Nozzle Weld Susceptibility To Primary Water Stress Corrosion Cracking (TAC No. MD4136). ML071030261 2007-05-07 5 05000454 NPF-037 tac md4136 2007-05-07 2007-05-11 May 7, 2007 Mr. Christopher M. Crane President and Chief Nuclear Officer Exelon Generation Company, LLC 4300 Winfield Road Warrenville, IL 60555 SUBJECT: BYRON STATION, UNIT NO. 1 - PRESSURIZER SURGE, SPRAY

* [2007-05-09] Byron Station, Units 1 & 2 - Annual Dose Report for 2006. ML071200272 2007-04-30 1 05000454 05000455 NPF-037 NPF-066 1.10.0101 BYRON 2007-0054 2007-04-30 2007-05-08 Exek%n. Exelon Generation Company, LLC wwvv.exeIoncorp~com Nuciear Byron atation 4450 North German Church Boa Byron, IL 650i0~9794 10 CFR 20.2206(c) April 30, 2007 LIR: BYRON

* [2007-05-09] Byron Station, Units 1 and 2, 2006 Annual Radioactive Effluent Release Report. ML071200276 2007-04-30 95 05000454 05000455 NPF-037 NPF-066 BYRON 2007-0052 2007-04-30 2007-05-08 Exek,n. Con~pany,LLC www.exe]oncorpconi Nuclear Byron Stafion 4LL5Q North Gernian Church Road Byron, W 61050-9794 April 30, 2007 10CFR 50.36a LTR: BYRON 2007-0052 File: 1.10.0101 Unite

* [2007-05-09] G20070226/LTR-07-0221 - Letter to Robert Meyer, re Professional Reactor Operator Society. ML071030236 2007-04-30 3 G20070226 LTR-07-0221 TAC MD5165 2007-04-30 2007-05-08 ML071030331+ April 30, 2007 Robert Meyer, Founder Professional Reactor Operator Society P.O. Box 1074 Byron, IL 61010 Dear Mr. Meyer: On behalf of the U.S. Nuclear Regulatory Commission (NRC), I am res

May 5, 2007

New this week from NRC Public Document Room

* [2007-05-05] Press Release-III-07-019 - NRC to Discuss 2006 Performance Assessment for Byron Nuclear Power Plant. ML071240258 2007-05-04 2 05000454 05000455 Press Release-III-07-019 2007-05-04 2007-05-04 NRC NEWS U.S. NUCLEAR REGULATORY COMMISSION 2443 Warrenville Road Lisle IL 60532 Web Site: http://www.nrc.gov E-mail: opa3@nrc.gov No. III-07-019 May 4, 2007 CONTACT: Viktoria Mitlyng (630) 8

* [2007-05-02] Byron Station, Unit Nos. 1 and 2, and Braidwood Station, Unit 1 and 2 - NRC Generic Letter 2006-01: Steam Generator Tube Integrity and Associated Technical Specifications (TAC No. MD0066, MD0067, MD0068 and MD0069). ML071000026 2007-04-24 3 05000454 05000455 05000456 05000457 TAC MD0066 TAC MD0067 TAC MD0068 TAC MD0069 2007-04-24 2007-05-01 April 24, 2007 Mr. Christopher M. Crane President and Chief Nuclear Officer Exelon Generation Company, LLC 4300 Winfield Road Warrenville, IL 60555 SUBJEC

* [2007-05-01] 05/08/2007 - Notice of Public Meeting with Exelon Generation Company Re: Byron Plant Performance Annual Assessment. ML071100276 2007-04-20 4 05000454 05000455 NPF-037 NPF-066 2007-04-20 2007-04-30 April 20, 2007 Mr. Christopher M. Crane President and Chief Nuclear Officer Exelon Nuclear Exelon Generation Company, LLC 4300 Winfield Road Warrenville, IL 60555 SUBJECT: PUBLIC MEETING TO REVIEW 200

* [2007-05-01] G20070187/LTR-07-0186 - Ltr. Rep. Donald A. Manzullo re: 10 CFR Part 26 - Fitness for Duty Rule, Byron. ML070810746 2007-03-15 4 05000454 05000455 NPF-037 NPF-066 10 CFR Part 26 G20070187 LTR-07-0186 2007-03-15 2007-04-30 ML070871199+ EDO Principal Correspondence Control FROM: DUE: 04/10/07 EDO CONTROL: G20070187 DOC DT: 03/15/07 FINAL REPLY: Representative Donald A. Manzullo TO: Ha

* [2007-05-01] G20070187/LTR-07-0186 - Ltr. Donald A. Manzullo re: 10 CFR Part 26 - Fitness for Duty Rule, Byron. ML070871199 2007-04-30 ML070810746+ML070871126+ FNWEBNAVIGATE=1.0 SYSTEMTYPE=MEZZANINE DOCUMENTID=070871199 STARTPAGE=1 LIBRARYNAME=ml_adams^hqntad01

April 28, 2007

New this week from NRC Public Document Room

* [2007-04-28] Byron Station, Unit Nos. 1 & 2, RAI, Request For Additional Information Related To Request To Change The Tornado Missile Protection Methodology (TAC Nos. MD2371 & MD2372). ML071060029 2007-04-26 5 05000454 05000455 TAC MD2371 TAC MD2372 2007-04-26 2007-04-27 April 26, 2007 Mr. Christopher M. Crane President and Chief Nuclear Officer Exelon Generation Company, LLC 4300 Winfield Road Warrenville, IL 60555 SUBJECT: BYRON STATION, UNIT NOS. 1 AND 2 - RE

* [2007-04-28] G20070187/LTR-07-0186 -Ltr to Donald A. Manzullo from Luis Reyes Re.: 10 CFR Part 26 - Fitness for Duty Rule, Byron. ML070871126 2007-04-17 2 10 CFR Part 26 G20070187 LTR-07-0186 TAC MD4919 2007-04-17 2007-04-27 April 17, 2007 The Honorable Donald A. Manzullo United States House of Representatives Washington, DC 20515 Dear Congressman Manzullo: I am responding to your March 15, 2007, letter to M

* [2007-04-27] Closure Of the Review of Exelon Generation Company's And Amergen Energy Company's Response To Generic Letter 2006-03, " Potentially Nonconforming HEMYC And MT Fire Barrier Configurations," For Byron Station Unit Nos. 1 and 2. ML071000347 2007-04-20 9 05000010 05000219 05000237 05000249 05000254 05000261 05000265 05000277 05000278 05000289 05000352 05000353 05000373 05000374 05000454 05000455 05000456 05000457 TAC MC1557 TAC MD1558 TAC MD1594 TAC MD1595 TAC MD1608 TAC MD1613 TAC MD1614 2007-04-20 2007-0

* [2007-04-26] Byron Station, Unit 2 Cycle 14 Core Operating Limits Report. ML071070443 2007-04-17 16 05000455 NPF-066 1.10.0101 BYRON 2007-0050 2007-04-17 2007-04-25 Exel™n,. Exelon Generation Company, LLC www.ex&oncorpcorn Byron Station r 4450 North German Church Road Byron, ft 61010-~9794 April 17, 2007 LTR: BYRON 2007-0050 File: 1.10.0101 United States

* [2007-04-26] Byron Station, Unit 2, Reactor Coolant System (RCS) Pressure and Temperature Limits Reports (PTLR). ML071070447 2007-04-17 26 05000455 NPF-066 BYRON 2007-0051 2007-04-17 2007-04-25 Exekrn,. Ex&on Generation Company, LLC www.exeloncorpcorn N Byron Station 4450 North German Church Road Byron, ft 61010Ñ9794 April 17, 2007 LTR: BYRON 2007-0051 File: 1.10.0101 United States Nuclear Re

* [2007-04-24] Braidwood, Units 1 & 2, Byron, Units 1 & 2, Annual Report of the Emergency Core Cooling System Evaluation Model Changes and Errors Required by 10 CFR 50.46, "Acceptance Criteria for Emergency Core Cooling Systems for Light-Water Nuclear Power Reactors." ML071030399 2007-04-13 14 05000454 05000455 05000456 05000457 NPF-037 NPF-066 NPF-072 NPF-077 RS-07-052 2007-04-13 2007-04-23 Exelor Generation wvvw.exeloncorp_com 4300 Vd ;nfield Road Warrenville, IL 60555 RS-07-052 April 13, 2007 United States Nuclear Regulatory Commission ATTN:

* [2007-04-24] Byron Unit 2 Inservice Inspection Relief Request I3R-14: Alternative Requirements for the Repair of a Reactor Vessel Head Penetration. ML071030180 2007-04-13 9 05000455 NPF-066 RS-07-055 2007-04-13 2007-04-23 Exek,n~. Exelon Generation Company, LLC wwwexeloncorp.com N 1 Byron Station 4450 North German Church Road ¥Byron, IL 61010Ñ9794 10 CFR 50.55a RS-07-055 April 13, 2007 U. S. Nuclear Regulatory Commission ATTN

April 21, 2007

New this week from NRC Public Document Room

* [2007-04-21] 05/08/2007 - Notice of Public Meeting with Exelon Generation Company Re: Byron Station Plant Performance Annual Assessment. ML071100250 2007-04-20 3 05000454 05000455 2007-04-20 2007-04-20 April 20, 2007 NOTICE OF SIGNIFICANT MEETING THIS MEETING IS OPEN TO PUBLIC ATTENDANCE Name of Licensee: Exelon Generation Company, LLC Name of Facility: Byron Station, Units 1 and 2 Docket Nos: 50-454; 50-455 Date a

March 16, 2007

* Inspection Report 50-455/2007-7 documents Byron senior resident inspector's recent follow-up of three failures of the 'B' aux feedwater pump at Byron-2 between March 3, 2005 - Jan 5, 2006. The report discusses the plant's internal review of each of the events individually, and also discusses the role of effectiveness reviews and the type of combined review that the inspector was performing. The inspector notes that the plant's initial review of the March 2005 failure was not extensive enough to rule out common mode type of failure.

March 4, 2007

Byron - NRC asks about Probabilistic Risk Assessment process

Last month, NRC and Byron discussed the plant's request to employ risk-informed selection and examination criteria for certain pressure retaining welds. After the discussion, NRC eliminated some of the questions in formal request for additional information, and added one item. The new RAI item is "Please provide a summary of how changes to the PRA are developed and reviewed." Other requested information includes:

* "Please provide the risk impact of implementing" the risk-informed inservice inspection (RI-ISI) program proposed for the third 10-year ISI program interval instead of the American Society of Mechanical Engineers inspection program that was replaced by RI-ISI.

* "According to your submittal dated November 17, 2000, and the NRC staff's safety evaluation dated February 5, 2002, the Byron probabilistic risk assessment (PRA) had not undergone a peer review prior to development of the second interval's RI-ISI program. Instead, the submittal states that you used the results of the peer review on the sister plant Braidwood Station, Units 1 and 2, to address potential PRA quality issues. Please indicate when the peer review was performed on the Byron PRA. Please provide the A and B level facts and observations from the Byron PRA peer review and the resolution of each observation or an explanation about why resolving the observation is not expected to significantly affect the proposed RI-ISI program."

* "Please provide ... [t]he ... base core damage frequency (CDF) and large early release fraction (LERF) of the Byron PRA model used to perform the risk ranking of pipe segments and change in risk evaluation ..."

* The newer versions of the ASME Code have reduced the exempted portions of Auxiliary Feedwater piping from nominal pipe size (NPS) 4 to NPS 11/2. This reduction in exempted piping has caused other licensees to add ASME Class 2 and/or Class 3 Auxiliary Feedwater piping to the scope of their RI-ISI programs, and to implement their chosen RI-ISI methodology to classify, risk-rank, and to select, as necessary, additional locations for the next ISI interval. Please describe how you treated this issue in your RI-ISI program for the third 10-year ISI interval when you updated your code of record from the 1989 edition to the 2001 edition with 2003 addenda."

An NRC memo, dated February 26, 2007, describes the conference call and includes a January 31 version of the RAI questions. The memo with attachment is available as ADAMS ACN ML070520195.

September 12, 2006

Byron - mechanic's allegation re: retaliation not substantiated by NRC A Senior Mechanic at Byron alleged that Exelon discriminated against him for raising safety issues. NRC's Region III Office of Investigations initiated investigation into the allegation on September 8, 2005. On September 12, 2006, NRC reported their conclusion that the allegation was not substantiated. The letter and synopsis of OI report 3-2005-027 was released via ADAMS as ACN ML062560212.

September 11, 2006

* Braidwood and Byron head (RPV) inspection - alternative method approved

Recent NRC inspections

* Byron problem ID and resolution report 50-454-2003-9

* Byron e-plan report 50-454-2003-10

* Byron report 50-454-2003-2

* Byron report 50-454/2002-7

February 16, 2006

* Tritium contamination found at Dresden and Byron too (that makes three, counting Braidwood)

* 2005-03-28: Exelon Byron 1 nuke exits refuel in Illinois
Reuters

January 7, 2005

Exelon announcement of management personnel changes:

* Mike Pacillio to be promoted to Senior Vice President for Midwest Operations responsible for Braidwood, Byron, Clinton, Dresden, LaSalle, Quad Cities and Zion stations

December 31, 2004

Summary of lant Operations - Oct 1 through Dec 31, 2004

Unit 1 operated at or near full power throughout the inspection except: on October 17, 2004, when power was reduced about 14 percent for a turbine throttle valve and governor valve surveillance test; on November 21, 2004, when power was reduced about 6 percent for a feedwater pump swap; and on December 14, 2004, when power was reduced by about 3 percent to conduct moderator temperature coefficient measurement at power.

Unit 2 operated at or near full power throughout the inspection period except: on October 3, 2004, when power was reduced about 11 percent for a turbine throttle valve and governor valve surveillance test; on October 31, 2004, when power was reduced about 8 percent for a feedwater pump swap; and on November 13, 2004, when power was reduced about 7 percent due to an unexpected feedwater heater transient.

[Source: R. Skokowski (NRC senior resident inspector) et al., Inspection at Byron Station, Units 1 and 2 conducted October 1 through December 31, 2004, NRC Region III inspection report 50-454/2004-9, January 27, 2005, pp. 1, 9-11]

December 4, 2003

Operating Experience Related to Power Uprates:
Abnormalities in Ultrasonic Flow Meter Instrumentation Readings

On August 28, 2003, Exelon informed the staff that it was reducing the operating power of Byron Units 1 and 2 by 32 MWe and 22 MWe, respectively. The decision was made following analysis of feedwater flow data derived from the Advanced Measurement and Analysis Group (AMAG) ultrasonic flow meters (UFMs) in use at Byron and Braidwood. Exelon reported that there were signal abnormalities from some of the UFMs, and on Byron 1, there were statistical differences between the total feedwater flow and the sum of the flows from the four individual feedwater lines. On September 1, 2003, the power at Braidwood Unit 2 was reduced for similar reasons. Westinghouse issued Technical Bulletin (TB) 03-6 on September 5, 2003, to inform its customers of the abnormalities experienced at the Byron and Braidwood plants. TB 03-6 also provides recommendations for plants to monitor their instrumentation to identify promptly any such abnormalities at their plants. The staff met with Westinghouse on September 26, 2003, to discuss efforts Westinghouse has taken to identify the cause of these abnormalities.

Westinghouse has not completed its root-cause evaluation of the problems, but currently believes that plant equipment near the instruments could have caused contamination in the signal, thus leading to incorrect readings by the flow meter. Westinghouse has also preliminarily concluded that this issue is limited to Byron and Braidwood. Based on current information, the staff does not believe that this issue poses an immediate safety concern. The staff is closely following this issue for Byron and Braidwood, as well as any implications on instrument installations for MUR power uprates.

[Source: "Monthly Status Report On The Licensing Activities And Regulatory Duties Of The United States Nuclear Regulatory Commission, September 2003", enclosure to Nils J. Diaz (Chairman, NRC), letter to Sen. George V. Voinovich (Chairman, Subcommittee on Clean Air, Climate Change and Nuclear Safety, Senate Committee on Environment and Public Works), November 25, 2003, ACN ML032900350]

September 26, 2003

Signal contamination of flow measurements used as basis for power uprates

On September 26, 2003, NRC staff met with Westinghouse representatives to discuss their root cause analysis related to the Byron Unit 1 assumed overpower condition regarding crossflow ultrasonic flowmeter (UFM) signal contamination. A portion of the meeting was closed when proprietary information was presented. Special tests indicated frequency contamination that affected the operation of the UFM. The signal contamination was traced to acoustic resonant frequencies in the piping. However, the source of the resonant frequencies is still unknown. Possible sources included feedwater and pumps or other nearby equipment. Westinghouse is still evaluating UFM performance at other plants and plans to respond to the staff questions by the end of October.

The staff advised Westinghouse: (1) to verify the integrity of the information contained in previously-approved topical reports for generic applications of the crossflow UFM; (2) to establish and publish guidelines instructing users how to operate their system; and (3) that future UFM applications for Appendix K power uprates will receive greater scrutiny with respect to signal contamination and assurance that signal contamination is not present. Byron has indicated that they will gather information using UFMs, but will not use the correction factor until the root cause analysis is complete.