RA-24-0165, Response to Request for Additional Information (RAI) Regarding Proposed Alternative for the Fifth Ten-Year Inservice Inspection Interval Limited Examinations

Response to Request for Additional Information (RAI) Regarding Proposed Alternative for the Fifth Ten-Year Inservice Inspection Interval Limited Examinations

ML24208A108
Person / Time
Site:	Robinson
Issue date:	07/26/2024
From:	Ellis K Duke Energy Progress
To:	Office of Nuclear Reactor Regulation, Document Control Desk
References
RA-24-0165
Download: ML24208A108 (1)

Text

Kevin M. Ellis General Manager Nuclear Regulatory Affairs, Policy &

Emergency Preparedness Duke Energy 13225 Hagers Ferry Rd., MG011E Huntersville, NC 28078 843-951-1329 Kevin.Ellis@duke-energy.com Serial: RA-24-0165 10 CFR 50.55a July 26, 2024 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 H. B. ROBINSON STEAM ELECTRIC PLANT, UNIT NO. 2 DOCKET NO. 50-261 / RENEWED LICENSE NO. DPR-23

SUBJECT:

Response to Request for Additional Information (RAI) Regarding Proposed Alternative for the Fifth Ten-Year Inservice Inspection Interval Limited Examinations

REFERENCES:

1. Duke Energy letter, Fifth Ten-Year Inservice Inspection Interval Limited Examinations, dated February 15, 2024 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML24050A006)

2. NRC email, Request for Additional Information Regarding Duke's February 15, 2024, Relief Request RA-23-0300 for Robinson (EPID L-2024-LLR-0017), dated June 11, 2024 (ADAMS Accession No. ML24164A005)

Ladies and Gentlemen:

In Reference 1, pursuant to 10 CFR 50.55a(g)(5)(iii), Duke Energy Progress, LLC (Duke Energy) requested U.S. Nuclear Regulatory Commission (NRC) approval for relief from the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel (B&PV) Code,Section XI, 2007 Edition through the 2008 Addenda for the H. B. Robinson Steam Electric Plant, Unit No. 2. In Reference 2, the NRC staff requested additional information regarding Reference 1. Enclosure 1 provides Duke Energys response to the Reference 2 RAI.

( ~ DUKE ENERGY

U.S. Nuclear Regulatory Commission RA-24-0165 Page 2 No new regulatory commitments have been made in this submittal. If you have additional questions, please contact Ryan Treadway, Director - Nuclear Fleet Licensing, at (980) 373-5873.

Sincerely,

~vin M. Ellis General Manager - Nuclear Regulatory Affairs, Policy & Emergency Preparedness

Enclosures:

1. Response to Request for Additional Information Attachments:

cc:

1. Isometric Drawing HBR2-10618 Sheet 23 L. Dudes, Regional Administrator USNRC Region II L. Haeg, NRC Project Manager, NRR J. Zeiler, NRC Senior Resident Inspector RA-24-0165 Response to Request for Additional Information RA-24-0165 Page 1 of 5 NRC RAI-1

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Background===

Table 1 of Enclosure 1 (Page 10 of 12) to the submittal shows that weld 116B/18 in Examination Category B-J could not receive essentially 100% ultrasonic examination coverage due to the proximity of an adjacent weld. Under the Component Description column of Table 1, the weld joint is described as an elbow to pipe weld.

Issues

1. Report No. UT-15-020 on Page 56 of 90 of Enclosure 2 to the submittal shows a photo that appears to be the pressurizer spray nozzle with the filename of the photo given as 63300 63400 PZR Spray\\166B-18.jpg.

2. The Specific Technical Brief Sheet of Report No. UT-15-020 on Page 58 of 90 of to the submittal contains a partially legible handwritten note under Post-Job Comments stating, in part, Previous PT [dye penetrant testing] Inspection on these components identified [] issue.

Request A. Clarify whether the correct photo is attached or if the photo is mislabeled, and if weld 116B/18 is one of the pressurizer spray nozzle welds.

B. Confirm that the hand-written note is not reporting a PT indication and that the Remarks for weld 116B/18 on Page 10 of Enclosure 1 to the submittal: The surface examination achieved 100% coverage with no relevant indications noted, is still valid.

Duke Energy Response to NRC RAI-1 A. The attached photo within report number UT-15-020 is correct. The photo filename is mislabeled and says 166B-18 instead of 116B/18. The image is labeled with a hyphen since use of a / is prohibited for file names of jpeg images. The photograph identifies the subject elbow to pipe weld labeled Weld 18 (116B/18). Beneath weld 116B/18 is the adjacent pipe to safe end weld (116B/19), and beneath 116B/19 is the safe end to pressurizer spray nozzle weld (116B/19DM). See isometric drawing HBR2-10618 SH00023 in Attachment 1 for weld configuration.

B. The last sentence on the post job comments of data report number UT-15-020 reads, "Previous PT inspection on these components identified equip tagging issue". This note was not related to any relevant indications associated with the PT examination. The results of the PT examination were satisfactory achieving 100% coverage with no relevant indications.

Therefore, the remarks for weld 116B/18 on Page 10 of Enclosure 1 within the submittal (RA-23-0300) remain valid.

RA-24-0165 Page 2 of 5 NRC RAI-2

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Background===

Section 3.2 of Enclosure 1 to the submittal states that Examination Category C-C welded attachments require surface examination. The rationale provided by the licensee under Section 6.3 of Enclosure 1 to the submittal includes discussion regarding the coverage obtained by magnetic particle testing (MT) examination. However, the Exam Requirements Figure No. and (Method) column on Page 11 of Enclosure 1 to the submittal, along with the nondestructive testing (NDT) Report No. PT-13-001 provided as Pages 59-60 of Enclosure 2 to the submittal, indicate that weld joint 204/AWS-1-ATT received a PT examination.

Issue The technical rationale provided in Section 6.3 of Enclosure 1 to the submittal only discusses MT coverage but one of the subject weld joints received a PT examination.

Request Discuss if the statement regarding MT in Section 6.3 of Enclosure 1 to the submittal is accurate or whether discussion of PT examination coverage results should be provided.

Duke Energy Response to NRC RAI-2 The existing discussion of MT coverage results in Section 6.3 of Enclosure 1 to the submittal (RA-23-0300) is applicable, since two other Category C-C welded attachments (212/MS-1A-6017-ATT and 213/MS-1B-1003-ATT) received MT examinations.

Duke Energy agrees that welded attachment 204/AWS-1-ATT received a PT examination.

Discussion of PT coverage results is appropriate. The volume of coverage obtained during the PT examination of 204/AWS-1-ATT and an acceptable interval VT-3 examination of the support in addition to periodic system leakage tests provides adequate assurance that any flaw that might have propagated through the subject welded attachment is identified and repaired prior to returning the plant to power operation. Thus, an acceptable level of quality and safety will have been achieved and public health and safety will not be endangered by allowing the proposed alternative examinations in lieu of the Code requirement.

RA-24-0165 Page 3 of 5 NRC RAI-3

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Background===

Section 3.2 of Enclosure 1 to the submittal states that Examination Category C-C welded attachments require surface examination.

Issues Neither the rationale in Section 6.3 of Enclosure 1 to the submittal nor the Remarks column on Page 11 of Enclosure 1 to the submittal discuss whether the surface examinations found any indications. The PT and MT reports on Pages 59, 61, and 64 of Enclosure 2 to the submittal do not report indications but the Comments for Report No. PT-13-001 on Page 59 notes, in part, Observed tool marks, weld overlap, undercut.

Request Discuss how the issues identified on Report No. PT-13-001 were dispositioned.

Duke Energy Response to NRC RAI-3 As indicated on Report No. PT-13-001, no recordable indications (NRI) were detected during the Liquid Penetrant examination of component 204/AWS-1-ATT. The Level II examiner recorded the exam results as satisfactory (acceptable). The examination was dispositioned as acceptable per procedural requirements by the Level III reviewer. The surface conditions noted in the comments were not indicative of service induced degradation and did not impact exam results.

RA-24-0165 Page 4 of 5 NRC RAI-4

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Background===

Section 6.4 of Enclosure 1 to the submittal states that Examination Category F-A supports require visual examination.

Issues The comments on Pages 68, 76, and 84 of Enclosure 2 to the submittal indicate that boron was identified throughout. The sub-section Historic Findings on Page 68 states, in part:

Reference RNP RO-32 historic documents EC 418725: Attachments A through C, "Structural Engineering Review and Comparison of RX Vessel Support Material Condition" for background information pertaining to history of identified cavity leakage within the Reactor Vessel Support areas.

EC 418725 concluded that the condition of the Reactor Vessel supports are acceptable for continued service based on structural review of past inspection images, engineering change packages, condition reports, examination of critical structural parameters.

Request Discuss why the presence of boron is not a concern to the structural integrity of the reactor vessel supports.

Duke Energy Response to NRC RAI-4 Pages 67-90 of Enclosure 2 to the submittal (RA-23-0300) document acceptable VT-3 Visual Examinations with no rejectable indications associated with the A, B, and C Reactor Pressure Vessel (RPV) Cold Leg Supports during Refueling Outage 33 (R2R33). After extensive cleaning efforts and visual examination, the three cold leg supports were noted to have light/moderate residual boron accumulation and general surface corrosion. No visual evidence of the following relevant condition attributes was identified:

Structural deformation or degradation threatening to the purposeful intent of the component Detached, broken, loosened component support items Misalignment of existing support component items Material wastage The RPV cold leg supports are constructed of carbon and low alloy steel, a 2 1/2 thick plate as the base, a 4 thick plate as the top, separated by 12 wide flange I-beams and 3/4 web plates.

The transverse web plates have 3 1/2 diameter holes and openings top and bottom that allow air passage. The I-beams are oriented radially, flanges flat on the plates, and channel the air through the supports into the HVAC ducts. The design does not provide enclosures for pools of water and allows all the inside surfaces to be exposed to the air being pulled through the ducts by the Reactor Vessel Support Cooling System. Additionally, the supports are welded, sand blasted and painted with one coat of "Carbozinc", a generic reference to Carboline CZ11. This coating was specifically applied to prevent corrosion of the low alloy steel substrates.

RA-24-0165 Page 5 of 5 The potential sources of leakage have been identified as the Reactor Cavity Seal and the Reactor Cavity Seal Access Ports (Sand Plugs). Both sources of leakage are not active during normal plant operation because they only provide a potential pathway for borated water to reach the cold leg supports whenever the reactor cavity is flooded. Furthermore, a Permanent Cavity Seal Plate was installed in 2013 to minimize the potential for cavity seal leakage. If leakage were to occur during refueling outage activities and contact the cold leg supports, the residual Reactor Cavity water would evaporate during normal plant operation due to normal support ventilation and surrounding air temperature. The support structure surfaces, coated with Carbozinc, are not expected to exhibit significant corrosion from residual boron deposits, since there is no continuous replenishment of borated water during normal plant operation. In accordance with the EPRI Boric Acid Corrosion Guidebook (Reference 1), laboratory tests and field experience have shown that dry boric acid deposits produce very little corrosion. Historical Inservice Inspections (ISI) of RPV cold leg supports have consistently reported no visual evidence of significant corrosion which is consistent with EPRI lab tests and field experience.

Continued ISI visual VT-3 examinations of all three RPV cold leg supports are scheduled commensurate with ASME Section XI, Category F-A requirements (References 2 & 3).

In conclusion, the presence of the observed residual boron is not a concern to the structural integrity of the RPV supports.

References:

1.

EPRI Boric Acid Corrosion Guidebook, TR 1025145, Revision 2.

2.

2007 Edition of ASME XI Code through 2008 Addenda,Section XI Code of Record for 5th Interval ISI exam of RPV cold leg support.

3.

2017 Edition ASME XI Code,Section XI Code of Record for 6th ISI Interval at RNP.

of Enclosure 1 RA-24-0165 of Enclosure 1 Isometric Drawing HBR2-10618 Sheet 23

ATTACHMENT 1 RA-24-0165 PAGE 1 OF 1

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4-RC-28 CONT'D. ON CPL-116A 4-RC-29 CONT'D. ON CPL-116 PRESSURIZER NOTES:

1. DM = DISSIMILAR METAL Weld 18 was examined (elbow to pipe). It is very close in proximity to weld 19 as depicted in the picture included in the data package resulting in the documented limitation. Weld 19DM is the safe end to pressurizer spray nozzle weld.

2. -

= DATUM POINT REFERENCE

3. WR = WHIP RESTRAINT 2

REV DATE EC 66637 REF. DWGS.

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DESCRIPTION PROFESSIONAL ENGINE[

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