BYRON 2002-0109, Response to NRC Bulletin 2001-01, Circumferential Cracking of Reactor Pressure Vessel Head Head Penetration Nozzles

Response to NRC Bulletin 2001-01, Circumferential Cracking of Reactor Pressure Vessel Head Head Penetration Nozzles

ML023080075
Person / Time
Site:	Byron
Issue date:	10/25/2002
From:	Lopriore R Exelon Nuclear
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
BYRON 2002-0109, BL-01-001
Download: ML023080075 (6)

Text

Exelon Generation Company, LLC www exeloncorp com Exelkn.s Byron Station Nuclear 4450 North German Church Road Byron, IL 61010-9794 October 25, 2002 LTR: BYRON 2002-0109 File: 1.10.0101 United States 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 50-455 Subject Byron Station Unit 2 Response to NRC Bulletin 2001-01, "Circumferential Cracking of Reactor Pressure Vessel Head Penetration Nozzles" On August 3, 2001, the NRC issued NRC Bulletin 2001-01, "Circumferential Cracking of Reactor Pressure Vessel Head Penetration Nozzles". This bulletin requires that the following information be submitted to the NRC within 30 days after plant restart following the next refueling outage:

- a description of the extent of reactor pressure vessel head penetration nozzle leakage and cracking detected, including the number, location, size, and nature of each crack detected; and

- if cracking is identified, a description of the inspections, repairs, and other corrective actions taken to satisfy applicable regulatory requirements.

Pursuant to 10 CFR 50.54, "Conditions of Licenses," paragraph (f), Attachment I to this letter provides the Byron Station Unit 2 30-day response. This response is due to the NRC by November 6, 2002.

October 25, 2002 U.S. Nuclear Regulatory Commission Page 2 If you have any questions or desire additional information regarding this letter, please contact William Grundmann, Regulatory Assurance Manager, at (815) 406-2800.

sptfully, Ocard P.' Loprior Site Vice Presiden Byron Nuclear Generating Station RPLJMR/rah

Enclosures:

Attachment 1, Byron Station Unit 2 Response to NRC Bulletin 2001-01 cc: Regional Administrator- NRC Region III NRC Senior Resident Inspector- Byron Station NRC Project Manager- NRR - Byron Station Office of Nuclear Facility Safety - Illinois Department of Nuclear Safety

STATE OF ILLINOIS )

COUNTY OF OGLE )

IN THE MATTER OF EXELON GENERATION COMPANY, LLC ) Docket Numbers BYRON STATION UNIT 2 ) STN 50-455

SUBJECT:

Byron Station Unit 2 Response to NRC Bulletin 2001-01, "Circumferential Cracking of Reactor Pressure Vessel Head Penetration Nozzles" AFFIDAVIT I affirm that the content of this transmittal iitýe and correct to the best of my knowledge, information and belief.

ý-Acfard P. L~p 'lr Site Vice Presidet Byron Nuclear Ge erating Station Subscribed and sworn to before me, a Notary Public in and for the State above named, this . . day of 0 20 0 Notary Public

,N8trPtda Hayenga YPbcState of Jlnf E:W0My omsi q1res 3/2lj

ATTACHMENT I Byron Station Unit 2 Response to NRC Bulletin 2001-01 "Circumferential Cracking of Reactor Pressure Vessel Head Penetration Nozzles"

Attachment I Byron Station Unit 2 Response to NRC Bulletin 2001-01 On August 3, 2001, the NRC issued NRC Bulletin 2001-01, "Circumferential Cracking of Reactor Pressure Vessel Head Penetration Nozzles". This bulletin requires that the following information be submitted to the NRC within 30 days after plant restart following the next refueling outage:

5. Addressees are requested to provide the following information within 30 days afterplant restartfollowing the next refueling outage:

a. a descriptionof the extent of vessel headpenetration (VHP) nozzle leakage and cracking detected at your plant, including the number, location,size, and nature of each crack detected;

b. if cracking is identified, a descriptionof the inspections (type, scope, qualification requirements,and acceptance criteria),

repairs,and othercorrective actions you have taken to satisfy applicableregulatoryrequirements. This information is requested only if there are any changes from priorinformation submitted in accordancewith this bulletin.

Byron Station Unit 2 Response

a. a description of the extent of VHP nozzle leakage and crackingdetected at your plant, including the number, location, size, and nature of each crack detected;

Response

No VHP nozzle leakage or cracking was detected during refueling outage B2R10 in Fall 2002. The following inspections were performed on the reactor pressure vessel (RPV) head during refueling outage B2R10:

Pre and post-outage VT-2 examinations of the accessible areas on top of the RPV head (i.e., control rod drive mechanism housings) were performed at normal reactor coolant system pressure. No evidence of leakage, boric acid residue, or degradation of material due to corrosion was identified during these inspections.

VT-1 examinations were performed on the core exit thermocouple clamp assemblies. There was no evidence of erosion, corrosion, or wear of the bolting material, and there were no instances of bolting material degradation due to corrosion. These connections, which are disassembled each refueling outage, were specifically examined for leakage by VT-2 qualified personnel during unit startup and no abnormal conditions were identified.

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Attachment I A 100% bare metal RPV head examination was completed. This examination consisted of visual examinations (3600) of the RPV head vent penetration and all RPV head nozzles (78) at the annulus region to determine if any boric acid leakage was evident. In addition, the bare metal RPV head was visually examined for general condition and to ensure no RPV head wastage was present. These examinations found no evidence of boric acid leakage from the nozzles or degradation of the RPV head.

b. if cracking is identified, a descriptionof the inspections (type, scope, qualification requirements,and acceptance criteria),repairs,and other corrective actionsyou have taken to satisfy applicable regulatory requirements. This information is requested only if there are any changes from priorinformationsubmitted in accordancewith this bulletin.

Response

No VHP nozzle leakage or cracking was identified during refueling outage B2R10; therefore, no inspections, repairs, or other corrective actions were required.

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