RC-18-0090, (Vcsns), Unit 1 - Relief Request RR-4-16, Request for Alternative to Implement Code Case N-513-4, Evaluation Criteria for Temporary Acceptance of Flaws in Moderate Energy Class 2 or 3 Piping Response to Request.
| ML18193B111 | |
| Person / Time | |
|---|---|
| Site: | Summer  |
| Issue date: | 07/12/2018 |
| From: | Lippard G South Carolina Electric & Gas Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| RC-18-0090 | |
| Download: ML18193B111 (4) | |
Text
George A. Lippard Vice President, Nuclear Operations 803.345.4810 July 12, 2018 A SCANA COMPANY Document Control Desk U.S. Nuclear Regulatory Commission Washington, DC 20555
Dear Sir / Madam:
Subject:
VIRGIL C. SUMMER NUCLEAR STATION (VCSNS), UNIT 1 DOCKET NO. 50-395 OPERATING LICENSE NO. NPF-12 RELIEF REQUEST RR-4-16, REQUEST FOR ALTERNATIVE TO IMPLEMENT CODE CASE N-513-4, "EVALUATION CRITERIA FOR TEMPORARY ACCEPTANCE OF FLAWS IN MODERATE ENERGY CLASS 2 OR 3 PIPING" RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION Letter from George A. Lippard to NRC Document Control Desk dated July 11, 2018. "RELIEF REQUEST RR-4-16, REQUEST FOR ALTERNATIVE TO IMPLEMENT CODE CASE N-513-4, "EVALUATION CRITERIA FOR TEMPORARY ACCEPTANCE OF FLAWS IN MODERATE ENERGY CLASS 2 OR 3 PIPING" Email from Shawn A. Williams to Sara Beth Dalick dated July 12, 2018. "VC Summer SW Leak RAIs" South Carolina Electric & Gas Company (SCE&G), acting for itself and as agent for South Carolina Public Service Authority, submitted a Relief Request for the use of an alternative to implement Code Case N-513-4," Evaluation Criteria for Temporary Acceptance of Flaws in Moderate Energy Class 2 or 3 Piping" (Reference 1). The NRC staffs review of the Relief Request determined additional information was required and a request for additional information (RAI) was issued (Reference 2).
Enclosed is SCE&G's response to these RAIs.
References:
- 1.
- 2.
V. C. Summer Nuclear Station
- P. 0. Box 88
- Jenkinsville, South Carolina
- 29065
- F (803) 941-9776
- www.sceg.com
Document Control Desk CR-18-02797 RC-18-0090 Page 2 of 2 If you have any questions or require additional information, please contact Beth Dalick at (803) 605-5428.
Very truly yours, BAB/GAL/bd
Enclosure:
Response to Request for Additional Information c:
J.E. Addison NRC Resident Inspector K.M. Sutton NSRC RTS (CR-18-02797)
File (810.19-2)
PRSF (RC-18-0090)
W.K. Kissam J. B. Archie J. H. Hamilton G. J. Lindamood W. M. Cherry C. Haney S. A. Williams
Document Control Desk Enclosure CR-18-02797 RC-18-0090 Page 1 of 2 VIRGIL C. SUMMER NUCLEAR STATION (VCSNS) UNIT 1 DOCKET NO. 50-395 OPERATING LICENSE NO. NPF-12 ENCLOSURE Response to Request For Additional Information For RR-4-16, REQUEST FOR ALTERNATIVE TO IMPLEMENT CODE CASE N-513-4, "EVALUATION CRITERIA FOR TEMPORARY ACCEPTANCE OF FLAWS IN MODERATE ENERGY CLASS 2 OR 3 PIPING" During the NRC review, the staff identified two areas where insufficient information was provided in the Relief Request to conduct the detailed review of the Relief Request. These areas are as follows:
RAI No. 1 Generic Letter 90-05, Enclosure 1, B 1. Scope, states "...., pumps, valves, heat exchangers, and components other than piping are excluded." The NRC staff also notes that Equation 1 of GL 90-05 Enclosure 1 is a piping equation that does not include elements that take into account the more complicated stress field of the reinforced area of a branch Tee. Provide a technical basis for using the evaluation procedures given in GL 90-05 on Flaw Number 2 in the reinforced area of the Tee.
SCE&G Response The GL 90-05 through-wall flaw evaluation, contained in Enclosure 2 Attachment 5, was conservatively used to accept Flaw #2 (not a through wall flaw), which partially extends into the reinforced region of the pipe branch tee. The design pressure was conservatively used in calculating both minimum wall thickness and performing the GL 90-05 through-wall flaw evaluation. The pipe stresses used in the calculation were intensified stresses to specifically account for the pipe branch tee fitting. The GL 90-05 evaluation utilizes Linear Elastic Fracture Mechanics (LEFM) acceptance criteria in which the stress intensity factor of the flawed region is compared to the fracture toughness of the material. The use of LEFM is conservative since principles of limit load controlled by plastic collapse and Elastic Plastic Fracture Mechanics are not applied. The fracture toughness limit in GL 90-05 is also conservatively restrictive. Utilizing a reasonable lower bound fracture toughness of the branch tee material would provide a higher allowable fracture toughness. Therefore, using the conservative inputs and the conservative through-wall evaluation provides the technical basis for accepting this non-through-wall flaw, which extends into the reinforced region of the branch tee, until the scheduled refueling outage RF-24.
Document Control Desk Enclosure CR-18-02797 RC-18-0090 Page 2 of 2 RAI No. 2 The third paragraph on page 4 of the relief request states that for flaw Number 1: "...A compensatory action of daily walkdowns of the area will be completed to quantify the leakage. UT examinations of no more than 30-day intervals will be performed around the degraded area to characterize flaw growth..." The fourth paragraph on page 4 of the relief request discusses flaw number 2 without discussing a similar compensatory action for flaw Number 2. The NRC staff notes that the first paragraph on page 3 of the relief request states that "...VCSNS will follow all requirements of the code case and Generic Letter, and will take no exceptions..." However, it is not clear to the NRC staff whether compensatory action in Generic Letter 90-05 or N-513-4 will be performed to monitor flaw number 2. Discuss whether specific compensatory actions will be performed for flaw number 2. If yes, provide the specific compensatory actions. If no, provide justifications.
SCE&G Response Yes, the station will perform specific compensatory actions to monitor Flaw #2. The specific compensatory actions are provided in the updated Section 5.7 Compensatory Actions below:
5.7 Compensatory Actions CR-18-02797-002 - Interim Action: Operations to quantify the leakage from the pin hole leak at least once every 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> until the leak is repaired and observe Flaw #2 location for any new through-wall leaks. Note: If significant change in leakage is noted, additional UTs are required to characterize the flaw growth.
CR-18-02797-003 - Interim Action: Gather UT data to characterize Flaw #1 and Flaw
- 2 growth prior to 8/09/2018.
CR-18-02797-004 - Interim Action: Gather UT data to characterize Flaw #1 and Flaw
- 2 growth prior to 9/08/2018.
CR-18-02797-005 - Interim Action: Gather UT data to characterize Flaw #1 and Flaw #2 growth prior to 10/08/2018.