Information Notice 2011-13, Official Exhibit - NYS000329-00-BD01 - NRC Information Notice 2011-13, Control Rod Blade Cracking Resulting in Reduced Design Lifetime (Jun 29, 2011) (NRC in 2011-13)

Official Exhibit - NYS000329-00-BD01 - NRC Information Notice 2011-13, Control Rod Blade Cracking Resulting in Reduced Design Lifetime (Jun 29, 2011) (NRC in 2011-13)

ML12335A479
Person / Time
Site:	Indian Point
Issue date:	06/29/2011
From:	Laura Dudes, Mcginty T Office of New Reactors, Division of Policy and Rulemaking
To:
SECY RAS
References
RAS 21619, 50-247-LR, 50-286-LR, ASLBP 07-858-03-LR-BD01 IN-11-013
Download: ML12335A479 (4)

United States Nuclear Regulatory Commission Official Hearing Exhibit NYS000329 Entergy Nuclear Operations, Inc.

In the Matter of:

(Indian Point Nuclear Generating Units 2 and 3) Submitted: December 22, 2011 c.,-VR REGU<..tr ASLBP #: 07-858-03-LR-BD01 l~"

Docket #: 05000247 l 05000286 Exhibit #: NYS000329-00-BD01 Identified: 10/15/2012

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UNITED STATES

NUCLEAR REGULATORY COMMISSION

OFFICE OF NUCLEAR REACTOR REGULATION

OFFICE OF NEW REACTORS

WASHINGTON, DC 20555-0001 June 29, 2011 NRC INFORMATION NOTICE 2011-13: CONTROL ROD BLADE CRACKING RESULTING

IN REDUCED DESIGN LIFETIME

ADDRESSEES

All holders of an operating license or construction permit for a nuclear power pressurized-water

reactor or boiling-water reactor (BWR) issued under Title 10 of the Code of Federal Regulations

(10 CFR) Part 50, "Domestic Licensing of Production and Utilization Facilities," except those

who have permanently ceased operations and have certified that fuel has been permanently

removed from the reactor vessel.

All holders of and applicants for a power reactor combined license, standard design certification, standard design approval under 10 CFR Part 52, "Licenses, Certifications, and Approvals for

Nuclear Power Plants."

PURPOSE

The U.S. Nuclear Regulatory Commission (NRC) is issuing this information notice (IN) to inform

addressees that GE Hitachi Nuclear Energy (GEH) has discovered severe cracking in Marathon

control rod blades (CRBs) near the end of their nuclear lifetime limits in an international BWR/6.

As a result of investigations into the cracking, GEH has determined that the design life of certain

Marathon CRBs may be less than previously stated and is revising the end-of-life depletion

limits of these CRBs. The NRC expects that recipients will review the information for

applicability to their facilities and consider actions, as appropriate, to avoid similar problems.

Suggestions contained in this IN are not NRC requirements; therefore, no specific action or

written response is required.

DESCRIPTION OF CIRCUMSTANCES

In August 2010, GEH, as part of its surveillance program to monitor Marathon CRB

performance, visually inspected four discharged CRBs at an international BWR/6 and found

cracks on all four CRBs. The cracks were much more numerous and had more material

distortion than those observed in previous inspections of Marathon CRBs. The cracks were

also more severe in that they resulted in missing boron-carbide capsule tube fragments from

two of the inspected CRBs. (A lost parts analysis determined that the missing fragments

caused no negative effect on plant performance.) Additionally, these cracks occurred at

locations of lower reported local boron-10 depletion than previously documented.

GEH attributed the cracking to irradiation-assisted stress-corrosion cracking that results when a

material that is susceptible to irradiation is in an aggressive environment from oxidizing BWR

ML 111380019 OAGI0001190_00001 water and experiences excessive stress because of boron-carbide swelling. GEH determined

that a significant contributor to the extensive cracking was a rapid thermal transient that

occurred when the automatic depressurization system actuated and injected cold water. GEH

does not anticipate the same severe extent of Marathon CRB cracking in other plants unless a

similar or more extreme thermal transient should occur. GEH further concluded that the

cracking phenomenon is confined to D-Iattice and S-Iattice BWR plants; no inspections to date

have identified cracks on C-Iattice Marathon CRBs. GEH attributed this to a difference in the

C-Iattice design that better accommodates boron-carbide swelling.

Based on the results of the investigation, GEH determined that the lifetimes of Marathon CRBs

in D-Iattice and S-Iattice plants may be less than previously stated. Therefore, GEH

recommended a lifetime reduction. The recommended Marathon CRB lifetime reduction

imposes a 60-percent local boron-10 depletion lifetime limit, or 54-percent for D-Iattice "V4 segment and 55-percent for S-Iattice "V4 segment lifetime limit.

GEH recommends that all plants containing D-Iattice and S-Iattice Marathon CRBs remove the

blades from service before they exceed the revised lifetime limits. For any Marathon CRB that

exceeds the revised lifetime limit while in use, GEH advises that reactor operation can continue, but the licensee should monitor reactor coolant boron and tritium concentrations in accordance

with normal plant procedures. If no significant increase is observed in these concentrations, GEH recommends that reactor operation can continue until the end of the cycle before removing

the CRBs from service. GEH recommends that licensees contact GEH if they detect a

significant increase in boron or tritium concentration or both.

The U.S. plants that may contain D-Iattice and S-Iattice Marathon CRBs and that; therefore, are

potentially affected are Browns Ferry-1, -2 and -3, Cooper, Clinton, Dresden-2 and -3, Duane Arnold, Grand Gulf, Fitzpatrick, Hatch-1 and -2, Monticello, Nine Mile Point-1, Oyster Creek, Peach Bottom-2 and -3, Perry, Pilgrim, River Bend, Quad Cities-1 and -2, and

Vermont Yankee.

DISCUSSION

GEH's Marathon CRBs consist of a series of absorber tubes, each containing capsules filled

with boron carbide (a neutron absorber), welded together to form the control rod blades.

Absorber tube cracks allow water to enter both the outer absorber tube and the boron-carbide

capsules, whereupon boron carbide may leach into the reactor coolant, which could result in

reduced control rod worth. Licensees must maintain control rods in an operable condition as

required by plant technical specifications. Technical specification requirements for reactivity

anomalies give a limit for the difference between predicted versus measured core reactivity

during power operation to ensure that a reactivity anomaly, such as change in control rod worth, does not result in a loss of shutdown margin or exceeding specified acceptable fuel design

limits. In addition, GEH advised plant operators to continue monitoring for reactor coolant boron

and tritium concentrations in accordance with normal plant procedures to detect CRB cracking

and to follow the GEH Marathon CRB surveillance program, particularly for D-Iattice and

S-Iattice plants.

OAGI0001190 00002

CONTACT

This IN requires no specific action or written response. Please direct any questions about this

matter to the technical contacts listed below or to the appropriate Office of Nuclear Reactor

Regulation (NRR) project manager.

IRA by CRegan fori IRA by JTappert fori

Timothy J. McGinty, Director Laura A. Dudes, Director

Division of Policy and Rulemaking Division of Construction Inspection and

Office of Nuclear Reactor Regulation Operational Programs

Office of New Reactors

Technical Contacts: Shih-Liang Wu, NRR Arthur Kevin Heller, NRR

301-415-3284 301-415-8379 E-mail: Shih-Liang.Wu@nrc.gov E-mail: Kevin.Heller@nrc.gov

Note: NRC generic communications may be found on the NRC public Web site, htt(2:1lwww.nrc.gov, under NRC Library.

OAGI0001190 00003

CONTACT

This IN requires no specific action or written response. Please direct any questions about this

matter to the technical contacts listed below or to the appropriate Office of Nuclear Reactor

Regulation (NRR) project manager.

IRA by CRegan fori IRA by JTappert fori

Timothy J. McGinty, Director Laura A. Dudes, Director

Division of Policy and Rulemaking Division of Construction Inspection and

Office of Nuclear Reactor Regulation Operational Programs

Office of New Reactors

Technical Contacts: Shih-Liang Wu, NRR Arthur Kevin Heller, NRR

301-415-3284 301-415-8379 E-mail: Shih-Liang.Wu@nrc.gov E-mail: Kevin.Heller@nrc.gov

Note: NRC generic communications may be found on the NRC public Web site, htt(2:1lwww.nrc.gov, under NRC Library.

ADAMS Accession No.: ML111380019 TAC ME5743 OFFICE SNPB:NRR Tech Editor BC:SNPB:NRR D:DSS BC:SRSB:NRO

NAME AHelier JDougherty AMendiola SBahadur JDonoghue

DATE 6/15/2011 5/25/11 e-mail 6/16/2011 6/17/2011 6/14/2011 OFFICE LAPGCB:NRR PM:PGCB:NRR BC:PGCB:NRR D:DCIP:NRO D:DPR:NRR

NAME CHawes DBeaulieu SRosenberg LDudes (JTappert for) TMcGinty (CRegan for)

OFFICE 6/22/11 6/22/2011 06/22/11 06/27/11 06/29/11 OFFICIAL RECORD COpy

OAGI0001190 00004