ML18352A805
| ML18352A805 | |
| Person / Time | |
|---|---|
| Site: | McGuire, Mcguire  |
| Issue date: | 12/18/2018 |
| From: | Michael Mahoney Plant Licensing Branch II |
| To: | Zaremba A Duke Energy Carolinas |
| References | |
| L-2017-LLA-0414 | |
| Download: ML18352A805 (4) | |
Text
1 NRR-DMPSPEm Resource From:
Mahoney, Michael Sent:
Tuesday, December 18, 2018 9:51 AM To:
Art Zaremba Cc:
'Hentz, Lee A'; 'Edwards, Nicole D'; Mahoney, Michael
Subject:
Request for Additional Information - McGuire Nuclear Station, Units 1 and 2 - MRP-227 Review (EPID L-2017-LLA-0414)
- Art, By letter dated December 13, 2017, as supplemented by letter dated May 9, 2018 (Agencywide Documents Access and Management System (ADAMS) Accession Nos. ML17356A184 and ML18135A087, respectively),
Duke Energy Carolinas, LLC (Duke Energy or the licensee) submitted Aging Management Program (AMP) and Inspection Plan for the McGuire Nuclear Station, Units 1 and 2 Reactor Vessel Internals (RVIs). The McGuire RVI AMP and Inspection Plan is based on MRP-227-A, Materials Reliability Program: Pressurized Water Reactor Internals Inspection and Evaluation Guidelines (ADAMS Accession No. ML120170453).
The McGuire RVI AMP and Inspection Plan was submitted to fulfill the inspection commitment in Section 18.2.23 of the McGuire Updated Final Safety Analysis Report, which was originated from License Renewal Commitment 14 for the McGuire units, as documented in Appendix D of NUREG-1772, Safety Evaluation Report Related to the License Renewal of McGuire Nuclear Station, Units 1 and 2, and Catawba Nuclear Station, Units 1 and 2 (ADAMS Accession No. ML030830181).
The NRC staff has reviewed the application and, based upon this review, determined that additional information is needed to complete our review. Please provide a response on the docket within 45 days of this correspondence.
Request for Additional Information (RAI)-1 The licensee stated, in part, in Section 6.2.2 in Attachment 1 (ADAMS Accession No. ML17356A178) of its December 13, 2017 letter, that a detailed tabulation of the McGuire RVI components was completed and compared to typical Westinghouse PWR RVI components in Table 4-4 of MRP-191, Screening, Categorization and Ranking of Reactor Internals Components for Westinghouse and Combustion Engineering PWR Design (ADAMS Accession No. ML091910130). This effort identified one McGuire RVI component (access plug assembly spring) that has no corresponding MRP-191 component.
Further assessment of Attachment 1 in the May 9, 2018 supplement (ADAMS Package No. ML18135A087),
indicated that the McGuire access plug assembly spring is made of Inconel X-750, and no degradation mechanisms were identified through the process of MRP-191. Attachment 1 of the May 9, 2018 supplement also indicated that the McGuire anti-vibration sleeves are made of 304 stainless steel (SS), and although several degradation mechanisms have been identified, the [McGuire-specific expert] panel considered the likelihood of failure and damage to be low.
Please address the following:
In its consideration of the acceptability of MRP-191, as a basis for MRP-227, the NRC staff performed three tasks: 1) assessed the nature and qualifications of the expert panel used in developing MRP-191;
- 2) assessed the process used by the expert panel in screening, categorization, and ranking the RVI components, and 3) developed an independent assessment of the MRP-191 disposition for verification.
The NRC staff intends to review those items applicable to McGuire that were not included in MRP-191 in the same manner as it reviewed MRP-191. To permit the NRC staff to perform its analysis, please
2 compare the makeup and processes used by the McGuire expert panel to those used by the MRP-191 expert panel.
The above conclusion on McGuire anti-vibration sleeves was made in Attachment 1 of the May 9, 2018 supplement, without justification. Please provide justification regarding this conclusion (e.g., negligible stresses, absence of hostile environment, or negligible neutron fluence).
RAI-2
Regarding the core barrel and lower former plate plugs, Attachment 2 of the May 9, 2018 supplement states that the McGuire core barrel and lower former plate plugs is made of Type 316L SS; and irradiation embrittlement (IE), irradiation-enhanced stress relaxation and creep (ISR/IC), fatigue, and wear were identified as degradation mechanisms for them through the process of MRP-191. The NRC staff notes that the interface (contact) pressure between the plugs and the hosting components could be lost due to stress relaxation. To address this, the attachment states that the minimum required stress ratios were calculated for the core barrel plugs and the lower former plate plugs based on their respective loads and required interface pressure for 60 years. The licensee states in section 3.3.2 of Attachment 2 of the May 9, 2018, letter, these stresses ratios were less than the estimated stress ratios based on laboratory studies for these two types of plugs.
Please provide detailed information and data regarding these laboratory studies and explain why the data can be used in this application for the McGuire core barrel and lower former plate plugs.
RAI-3
Regarding Applicant/Licensee Action Item 7 in the NRC safety evaluation of MRP-227-A, dated June 22, 2011 (ADAMS Accession No. ML111600498), there is new NRC staff guidance on the threshold limits for thermal embrittlement (TE) and IE of Cast Austenitic Stainless Steel (CASS). The bases for the NRC staff's new consensus on the threshold limits are described in NRC Position on Aging Management of CASS Reactor Vessel Internal Components (ADAMS Accession No. ML14163A112), as amended in the NRC staffs SE of the Boiling Water Reactor Vessel Internals Project (BWRVIP)-234, Thermal Aging and Neutron Embrittlement Evaluation of Cast Austenitic Stainless Steel for BWR Internals, June 22, 2016 (ADAMS Accession No. ML16096A002).
- a. Please address any difference between the new guidance and the evaluation performed for McGuire, Units 1 and 2. In particular, please address, the new screening guidelines of CASS materials for loss of fracture toughness of highly irradiated components (i.e., components susceptible to IE), in addition to TE. If any changes to the evaluation are necessary, please submit the re-evaluation, if not, please explain why not. This evaluation could affect some of the CASS components that are listed as susceptible to TE in Tables 6-2 and 6-3 of Attachment 1 of the December 13, 2017, letter, for McGuire, Units 1 and 2, respectively.
- b. The NRC staff notes that MRP-191, Rev. 1 has not been reviewed by the NRC. Therefore, placing the following CF8 components in Category A in accordance with MRP-191, Rev. 1, is not considered by the NRC staff as having sufficient support:
CF8 upper guide tube enclosures CF8 intermediate flanges CF8 Brackets, clamps, terminal blocks, and conduit straps Please demonstrate that the screening and the failure modes, effects and criticality analyses and ranking considerations in MRP-191, Rev. 1 are equivalent or better than MRP-191, Rev. 0, to support the Category A determination for these three RVI components.
- c. Section 6.2.7 states, The lower support column bodies are not CASS material for either McGuire Unit 1 or Unit 2. WCAP-17397-NP, PWR Vessel Internals Program Plan for Aging Management of Reactor
3 Internals at Salem Nuclear Generating Station, Salem 1, states that, The lower internals assembly column cap is a CASS piece welded onto the top of the core support column shaft. These two pieces together constitute the lower internals assembly - column body. For Salem 1, only the lower support column caps were identified as CASS. To ensure that McGuire units do not have the same lower support column bodies as Salem 1, please confirm that the lower support column caps are not CASS material. If this cannot be confirmed, please provide an explanation of how aging degradation due to TE and IE of the lower support column caps is being managed and will be managed during the period of extended operation because the NRC staffs initial review indicated that, in addition to TE, the lower support column caps are also susceptible to IE.
Once this email is added to ADAMS, I will provide the accession number for your reference.
Thanks Mike Michael Mahoney McGuire and Catawba Project Manager, Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation U. S. Nuclear Regulatory Commission Desk: (301)-415-3867 Email: Michael.Mahoney@NRC.GOV
Hearing Identifier:
NRR_DMPS Email Number:
714 Mail Envelope Properties (DM6PR09MB2619202305E96420395EF546E5BD0)
Subject:
Request for Additional Information - McGuire Nuclear Station, Units 1 and 2 -
MRP-227 Review (EPID L-2017-LLA-0414)
Sent Date:
12/18/2018 9:50:52 AM Received Date:
12/18/2018 9:50:55 AM From:
Mahoney, Michael Created By:
Michael.Mahoney@nrc.gov Recipients:
"'Hentz, Lee A'" <Lee.Hentz@duke-energy.com>
Tracking Status: None
"'Edwards, Nicole D'" <Nicole.Edwards@duke-energy.com>
Tracking Status: None "Mahoney, Michael" <Michael.Mahoney@nrc.gov>
Tracking Status: None "Art Zaremba" <Arthur.Zaremba@duke-energy.com>
Tracking Status: None Post Office:
DM6PR09MB2619.namprd09.prod.outlook.com Files Size Date & Time MESSAGE 8074 12/18/2018 9:50:55 AM Options Priority:
Standard Return Notification:
No Reply Requested:
No Sensitivity:
Normal Expiration Date:
Recipients Received: