RA-21-0067, Response to Request for Additional Information - Relief Request, Service Water Pinhole Leak in a Socket Weld, Inservice Inspection Program, Fourth Ten-Year Interval

Response to Request for Additional Information - Relief Request, Service Water Pinhole Leak in a Socket Weld, Inservice Inspection Program, Fourth Ten-Year Interval

ML21056A625
Person / Time
Site:	Harris
Issue date:	02/25/2021
From:	Dills J Duke Energy Progress
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
RA-21-0067
Download: ML21056A625 (4)

Text

John R. Dills tf_~ DUKE Plant Manager Shearon Harris Nuclear Power Plant

~ ENERGY 5413 Shearon Harris Rd New Hill NC 27562-9300 984 .229.2000 10 CFR 50.55a February 25, 2021 Serial: RA-21-0067 ATTN : Document Control Desk U.S. Nuclear Regulatory Commission Washington, DC 20555-0001 Shearon Harris Nuclear Power Plant, Unit 1 Docket No. 50-400/Renewed License No. NPF-63

Subject:

Response to Request for Additional Information - Relief Request, Service Water Pinhole Leak in a Socket Weld , lnservice Inspection Program , Fourth Ten-Year Interval Ladies and Gentlemen:

By letter dated November 4, 2020 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML20309A774), Duke Energy Progress, LLC (Duke Energy) submitted a relief request to defer implementation of American Society of Mechanical Engineers (ASME)

Code repairs of a through-wall leak in the Emergency Service Water (ESW) System , to no later than the next scheduled refueling outage for the Shearon Harris Nuclear Power Plant, Unit 1 (HNP) .

The NRC staff reviewed the rel ief request and determined that additional information is needed to complete their review. By letter dated February 5, 2021 (ADAMS Accession No. ML21036A114), the NRC provided a request for additional information (RAI) on the subject. The RAI response is provided in the enclosure to this letter.

This letter contains no new regulatory commitments. Please refer any questions rega rding this submittal to Chuck Yarley, HNP Regulatory Affairs, at (984) 229-2477.

Sincerely,

Enclosure:

Response to Request for Additional Information cc: J. Zeiler, NRC Senior Resident Inspector, HNP M. Mahoney, NRC Project Manager, HNP NRC Regional Administrator, Region II

U.S. Nuclear Regulatory Commission RA-21-0067 Enclosure Shearon Harris Nuclear Power Plant, Unit 1 Docket No. 50-400/Renewed License No. NPF-63 Service Water Pinhole Leak in a Socket Weld, Inservice Inspection Program, Fourth Ten-Year Interval Enclosure Response to Request for Additional Information

U.S. Nuclear Regulatory Commission Page 1 of 2 RA-21-0067 Enclosure By letter dated November 4, 2020 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML20309A774), Duke Energy Progress, LLC (Duke Energy) submitted a relief request to defer implementation of American Society of Mechanical Engineers (ASME)

Code repairs of a through-wall leak in the Emergency Service Water (ESW) System, to no later than the next scheduled refueling outage for the Shearon Harris Nuclear Power Plant, Unit 1 (HNP).

The NRC staff reviewed the relief request and determined that additional information is needed to complete their review. By letter dated February 5, 2021 (ADAMS Accession No. ML21036A114), the NRC provided a request for additional information (RAI) on the subject.

Response to this request is provided below.

RAI-1

On Page 3 (of 5) of the request, the licensee states, in part:

A flaw diameter of 0.100 inches was used to further evaluate the defect.

Ultrasonic testing (UT) measurements indicate some wall thinning, with pipe wall thickness varying between 0.150 inch and 0.167 inches around the pipe circumference. The lowest reading obtained was 0.137 inches at the root of the socket weld.

Additionally, in Enclosure 2 of the request, the licensee states, in part:

The pipe wall thickness varies between 0.150 inches and 0.167 inches around the pipe circumference with the lowest reading measured at 0.137 inches. Since the UT measurements indicate some wall thinning, the minimum wall thickness is also calculated.

a. Does the referenced measurement range of 0.150 in (inches) to 0.167 in refer to the pipe wall thickness, which has a nominal pipe wall thickness of 0.179 in (for 1-inch schedule 80 pipe)?

b. Is the measurement of 0.137 in the thickness of the sockolet? If so, what is the nominal thickness of the sockolet, in the location of the weld?

c. Has the licensee assessed the loss of wall-thickness in the pipe, sockolet, and the return line, in the area where the sockolet is attached? Provide a basis for the determination that structural integrity is maintained.

d. From the description in the request, it appears that the flaw is at the weld/sockolet interface originating from the root area. Confirm the location of the flaw.

Duke Energy Response to RAI-1

a. Yes, the referenced measurement range of 0.150 inches to 0.167 inches refers to the pipe wall thickness, which has a nominal pipe wall thickness of 0.179 inches (for 1-inch schedule 80 pipe). This range is based on the measurements from the original scope of the UT that utilized a one-inch by one-inch grid along the length of the pipe to establish a representative minimum wall thickness. At the request of site Engineering, additional pipe wall thickness

U.S. Nuclear Regulatory Commission Page 2 of 2 RA-21-0067 Enclosure measurements were taken along the sockolet to pipe interface to determine the lowest reading, which was found to be 0.137 inches.

b. No, the 0.137 inches is also related to the wall thickness of the pipe, as discussed in the response to part a. above.

c. The evaluation provided in the relief request is of the 1-inch pipe (line number 3SW1-141SB-1) and socket weld. Additional UT thickness measurements were collected on February 15, 2021, on the return line (line number 3SW24-73SB-1) and sockolet.

The pipe wall thickness of return line 3SW24-73SB-1, a 24-inch pipe with a nominal thickness of 0.375 inches, was measured in eight places around the circumference of the attached sockolet. The pipe wall thickness measurements varied between 0.376 inches and 0.402 inches (with coatings removed), all of which are greater than the nominal wall thickness. Therefore, no structural evaluation is needed for the return line.

The thickness of the sockolet was measured in four places around the circumference of the sockolet, with wall thickness varying between 0.289 inches and 0.301 inches. These measurements are greater than the nominal wall thickness of 0.179 inches for the 1-inch pipe. Therefore, no structural evaluation is needed for the sockolet.

d. The flaw appears to be at the stop-start interface of the socket weld and is likely the result of a lack of fusion or other defect at this location following installation.

RAI-2

On Page 3 (of 5) of the request, the licensee states, in part:

An accurate measurement of the pinhole diameter could not be obtained since the size of the pinhole leak is small (less than 1/16-inch diameter). The area of the leak was observed dripping at approximately 1 drop per minute.

a. Describe the current state of the leakage.

Duke Energy Response to RAI-2 A compensatory action is in place for Operations to monitor the current leak rate daily and log the results. This daily monitoring indicates that the leak rate is currently less than 1 drop per minute.