Information Notice 2011-13, New York State (NYS) Pre-Filed Evidentiary Hearing Exhibit NYS000329, NRC Information Notice 2011-13, Control Rod Blade Cracking Resulting in Reduced Design Lifetime (Jun 29, 2011) (NRC in 2011-13)
| ML11356A319 | |
| 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 | |
| Shared Package | |
| ML11356A318 | List: |
| References | |
| RAS 21619, 50-247-LR, 50-286-LR, ASLBP 07-858-03-LR-BD01 IN-11-013 | |
| Download: ML11356A319 (4) | |
UNITED STATES
NUCLEAR REGULA TORY 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
(1 0 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 NYS000329 Submitted: December 22, 2011 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-lattice and S-lattice BWR plants; no inspections to date
have identified cracks on C-lattice Marathon CRBs. GEH attributed this to a difference in the
C-lattice design that better accommodates boron-carbide swelling.
Based on the results of the investigation, GEH determined that the lifetimes of Marathon CRBs
in D-lattice and S-lattice 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 forD-lattice "V4 segment and 55-percent for S-lattice "V4 segment lifetime limit.
GEH recommends that all plants containing D-lattice and S-lattice 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-lattice and S-lattice 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-lattice and
S-lattice 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 for/
Timothy J. McGinty, Director
Division of Policy and Rulemaking
Office of Nuclear Reactor Regulation
Technical Contacts:
Shih-Liang Wu, NRR
301-415-3284 IRA by JTappert for/
Laura A. Dudes, Director
Division of Construction Inspection and
Operational Programs
Office of New Reactors
Arthur Kevin Heller, NRR
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, httj2://www.nrc.gov, under NRC Library.
OAGI0001190 00003
ML111380019 TAC ME5743 OFFICE
SNPB:NRR
Tech Editor
BC:SNPB:NRR
D:DSS
BC:SRSB:NRO
NAME
AHeller
JDougherty
AMendiola
SBahadur
JDonoghue
DATE
6/15/2011
5/25/11 e-mail
6/16/2011
6/17/2011
6/14/2011 OFFICE
LA:PGCB: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