ML15271A046

Summary of Public Meeting with Indiana Michigan Power Company Regarding Donald C. Cook Nuclear Plant, Units 1 and 2

ML15271A046
Person / Time
Site:	Cook
Issue date:	10/05/2015
From:	Dietrich A Plant Licensing Branch III
To:
Dietrich A, NRR/DORL/LPLIII-1
References
TAC MF0050, TAC MF0051
Download: ML15271A046 (7)

Text

UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 October 5, 2015 LICENSEE: Indiana Michigan Power Company, LLC FACILITY: Donald C. Cook Nuclear Plant, Units 1 and 2

SUMMARY

OF SEPTEMBER 23, 2015, PUBLIC MEETING WITH INDIANA MICHIGAN POWER COMPANY REGARDING DONALD C. COOK NUCLEAR PLANT, UNITS 1 AND 2 (TAC NOS. MF0050 and MF0051)

On September 23, 2015, a Category I public meeting was held between the U.S. Nuclear Regulatory Commission (NRC) and representatives of Indiana Michigan Power Company (l&M, the licensee). This meeting was open to members of the public.

The purpose of the meeting was to discuss the reactor vessel internals aging management program for Donald C. Cook Nuclear Plant (CNP), Units 1 and 2, which is currently under review by the NRC staff. The meeting notice and agenda, dated September 11, 2015, are available at Agencywide Documents Access and Management System (ADAMS) Accession No. ML15257A289. A list of attendees is provided as Enclosure 1 to this meeting summary.

The handout used during the meeting is provided as Enclosure 2.

The NRC staff discussed a follow-up request for additional information (RAl)-2(b), which was sent to the licensee on May 5, 2015 (ADAMS Accession No. ML15119A339), and to which a response was received on August 6, 2015 (ADAMS Accession Nos. ML15223A435 and ML15223A436, respectively). The NRC staff discussed the licensee's response, the staff's evaluation of the response, and the supplemental information needed in order for the staff to complete its review of the CNP aging management program.

The NRC staff requested elaboration on four statements made by the licensee in its response to RAl-2(b). Those statements are related to the fracture toughness of thermally-embrittled cast austenitic stainless steel components, the redundancy of the control rod guide tube guide cards, the periodic monitoring of control rod functionality, and the ability of VT-3 inspections to detect cracking. The licensee stated that it will submit a supplement that provides amplification regarding these items.

No regulatory decisions were made during the meeting. Members of the public were in attendance via telephone and had no comments. Public Meeting Feedback forms were not received.

Please direct any inquiries to me at 301-415-2846, or Allison.Dietrich@nrc.gov.

_A'u!l~

Allison W. Dietrich, Project Manager Plant Licensing Branch 111-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos. 50-315 and 50-316

Enclosures:

1. List of Attendees

2. Handout cc w/encl: Distribution via Listserv

LIST OF ATTENDEES SEPTEMBER 23. 2015, PUBLIC MEETING WITH l&M, LLC DONALD C. COOK NUCLEAR PLANT, UNITS 1AND2 REACTOR VESSEL INTERNALS AGING MANAGEMENT PROGRAM Name Organization Allison Dietrich NRC Chris Sydnor NRC John J. McHale NRC Tom Wengert NRC Ganesh Cheruvenki NRC Jeffrey Poehler NRC David Dijamco NRC Q. Shane Lies* l&M Michael Scarpello* l&M Helen Kish* l&M Danielle Burgoyne* l&M Kevin Kalchik* l&M April Lloyd* l&M Cheryl Boggess* Westinghouse Josh McKinley* Westinghouse Randy Locks* Westinghouse Kyle Amberge* Electric Power Research Institute Rebecca Siegrist* PSEG Nuclear Krishan Garg* PSEG Nuclear Al Mason* Robinson Nuclear Plant

• Participated by telephone Enclosure 1

September 23. 2015. Public Meeting with Indiana Michigan Power Company (l&M)

Donald C. Cook Nuclear Plant. Units 1 and 2 Reactor Vessel Internals Aging Management Program Cast Austenitic Stainless Steel (CASS) Control Rod Guide Tube (CRGT) Guide Cards Docket Nos. 50-315 and 50-316 TAC Nos. MF0050 and MF0051 BACKGROUND

• MRP-191 Failure modes, effects, & criticality analysis (FMECA) are the basis for the MRP-227-A inspection guidelines.

~ The guide card metal is evaluated as wrought product - 304 stainless steel (SS) in MRP-191.

• As 304 SS, the guide cards screen in for Wear. Fatigue. and stress corrosion cracking of the welds. Accordingly, they are FMECA Group 3 and Category C, per MRP-191.

~ FMECA Group 3 - High Likelihood of Failure and Medium Likelihood of Core Damage If There Are Failures

~ Category C: " ... components for which aging effects are above screening levels, which have moderate or high susceptibility to degradation, and have not yet been demonstrated to be sufficiently tolerant to remain functional relative to aging degradation significance ... "

• MRP-227-A primary components' guidelines require VT-3 exams for Wear every 10 years of 20% of CRGT assemblies. All guide cards in each selected CRGT assembly are to be examined.

• Certified material test reports (CMTRs) or other records are not available for identifying the type of material for the CRGT guide cards at Donald C. Cook, Unit 1 (CNP-1 ).

• Design drawing for the CNP-1 guide cards states that the material is either 304 SS or CASS. Therefore licensee assumes the guide cards are CASS at CNP-1.

• For the assumed CASS CRGT guide cards at CNP-1, the licensee is assuming they are susceptible to thermal embrittlement (TE) given that Ferrite content is unknown (i.e.,

ferrite content is assumed to be> 20%).

• Thermally em brittled CASS material has lower fracture toughness and greater susceptibility to fracture than non-CASS (wrought) material.

Enclosure 2

BACKGROUND (Cont.)

• May 2015 - NRC staff issued a follow-up RAl-2(b) (Agencywide Documents Access and Management System (ADAMS) Accession No. ML15119A339):

~ Evaluate the susceptibility of the guide cards to cracking given that these components are more likely to fail if cracks are present.

~ If guide cards are susceptible, propose plant-specific inspection criteria sufficient to detect cracking, or

~ Provide an evaluation to justify that no additional inspections, other MRP-227-A VT-3 exams, are necessary.

• August 2015 response to follow-up RAl-2(b) states that, as CASS, the guide cards screen in for Wear Fatigue, SCC of the Welds, and TE. (ADAMS Accession Nos. ML15223A435 and ML15223A436, respectively).

• The response to follow-up RAl-2(b) states that cracking would not be more of a concern for CASS guide cards than 304 SS guide cards because:

~ Stress, Function, and Geometry of the part are the same for 304 SS and CASS.

~ Welds on CASS are similar to welds on 304 SS.

~ TE of CASS doesn't result in total loss of fracture toughness.

~ Redundancy of guide cards; multiple failures are necessary for CR to slip out of place.

~ Periodic monitoring of CR functionality, per plant procedures.

~ VT-3 for wear would detect gross failures.

• Follow-up RAl-2(b) response indicates that the addition of TE for CASS does not increase susceptibility enough to justify changes to the current MRP-227-A inspection requirements - i.e., VT-3 exams for wear of 20% of CRGT assemblies are still adequate.

STATUS OF NRC STAFF'S EVALUATION

• Thermally embrittled CASS guide card material is more susceptible to flaw propagation and fracture than 304 SS guide card material.

• NRC staff confirms that the guide card welds are already analyzed as susceptible to SCC in MRP-191 FMECA, and the welds are not any more susceptible to SCC if they are welded to CASS base metal.

• NRC staff also confirms that the susceptibility of the base metal to sec is not a greater concern for CASS.

• CASS guide cards may be no more susceptible to the formation of new cracks via SCC and fatigue, compared to wrought guide cards.

~ However, due to the lower fracture toughness of em brittled CASS material, CASS guide cards would have less flaw tolerance than wrought guide cards.

• Therefore, even if the pre-existing flaw assumptions and flaw loading/crack driving force parameters are the same for CASS and wrought material, then the lower intrinsic fracture toughness of thermally-embrittled CASS material (compared to 304 SS) makes it more susceptible to the propagation of a pre-existing flaw.

• Currently, the NRC staff does not have the information needed to determine that there is adequate assurance that the VT-3 exams will detect cracking in time to prevent fracture of the guide cards.

ML15271A046 OFFICE DORL/LPL3-1/PM DORL/LPL3-1/LA DE/EVIB/BC DORL/LPL3-1 /BC DORL/LPL3-1 /PM NAME ADietrich MHenderson JMcHale DPelton ADietrich DATE 09/28/15 9/30/15 10/4/15 10/5/15 10/5/15