CP-201300143, Response to RAI for Unit 1 Relief Request No. B-2

Response to RAI for Unit 1 Relief Request No. B-2

ML13046A054
Person / Time
Site:	Comanche Peak
Issue date:	02/07/2013
From:	Madden F, Flores R Luminant Power, Luminant Generation Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
CP-201300143, TAC MF0507, TXX-13023
Download: ML13046A054 (7)

Text

Raifael Flores Luminant Power Senior Vice President P 0 Box 1002 RN &Chief Nuclear Officer 6322 North FM 56 Rafael.Flores@Luminant.com Glen Rose, TX 76043 Lum inant T 254 897 5550 C 817 559 0403 F 254 897 6652 CP-201300143 Ref. # 10CFR50.55a Log # TXX-13023 February 7, 2013 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555

SUBJECT:

COMANCHE PEAK NUCLEAR POWER PLANT DOCKET NO. 50-445 RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION FOR UNIT 1 RELIEF REQUEST NO. B-2 (TAC NO. MF0507)

REFERENCES:

1. Letter logged TXX-13003 dated January 16, 2013 from Rafael Flores to the NRC submitting Relief Request No. B-2 for the Unit I Reactor Vessel Hot Leg Nozzle Weld Examinations (Third Interval Start Date: August 13, 2010)(ML13029A592)

2. Email dated January 29, 2013 from Balwant Singal of the NRC to Timothy Hope of Luminant Power requesting additional information regarding Relief Request No. B TAC MF0507(ML13029A738)

Dear Sir or Madam:

Per reference 1, Luminant Generation Company LLC (Luminant Power) previously submitted a request for relief for inspection of the Unit 1 reactor pressure vessel leak-off flange. Per reference 2, the NRC provided a request for additional information regarding the subject relief request.

Attached is the Luminant Power response to the request for additional information.

This communication contains no new commitment regarding Comanche Peak Unit 1.

Should you have any questions, please contact Mr. Jack Hicks at (254) 897-6725.

Sincerely, Luminant Generation Company LLC Rafael Flores By:*-  %/QQ,,L Frred W. 1(4adden Director, Oversight & Regulatory Affairs A member of the STARS Alliance Callaway Comanche Peak Diablo Canyon

• Palo Verde

• San Onofre

• South Texas Project

• Wolf Creek ,o,1

U. S. Nuclear Regulatory Commission TXX-13023 Page 2 of 2 02/07/2013

Attachment:

Response to Request for Additional Information for Relief Request B-2

Enclosure:

Sketch for Response to RAI Question 1 c- E. E. Collins, Region IV Luis Ponce B. K. Singal, NRR Texas Department of Licensing and Regulation Resident Inspectors, Comanche Peak P. 0. Box 12157 Jack Ballard, ANII, Comanche Peak Austin, Texas 78711-2332

Attachment to TXX-13023 Page 1 of 3 RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION FOR RELIEF REQUEST NUMBER B-2 FOR THE UNIT 1 THIRD 10 YEAR IS1 INTERVAL (THIRD INTERVAL START DATE: AUGUST 13, 2010)

(THIRD INTERVAL END DATE: AUGUST 12, 2020)

(TAC NO. MF0507)

NRC Question I from Reference 2 Please provide a drawing of the nozzle, safe end, weld, and pipe showing the wall thickness dimensions or inside and outside diameter dimensions. If applicable, the drawing should show pipe inside surface cladding and provide cladding thickness and material specification. Please provide the material specification for the nozzle, affected welds, and pipe.

Luminant Power's Response to Question 1 A sketch of the outlet nozzle examination technique with dimensions is included as an attachment to this response. Referring to the sketch: (reading from left to right):

" Pipe material is cast stainless steel, SA-351-CF8A;

• Weld is stainless steel;

• Safe end is stainless steel, F-316L;

• DM weld is 182; nozzle is carbon steel, SA-508;

• Nozzle cladding is stainless steel.

In addition, the actual outlet nozzle safe-end dimensions are 34.82 inches OD x 27.88 inches ID with a wall thickness of 2.93 inches.

NRC Question 2 from Reference 2 Section 6 of the relief request states that the measured flaw size will be adjusted by adding the difference between the demonstrated Root-Mean Square (RMS) error (i.e., 0.189 inches) and the required RMS error (i.e., 0.125 inches). This implies that the measure flaw depth will be increased by 0.064 inches (0.189-0.125). The ASME Code,Section XI, IWA-3310 provides requirements under which a subsurface flaw must be considered as a surface-breaking flaw based on the flaw's proximity to the pipe surface. If a subsurface flaw is detected in the affected welds, nozzle, safe end, or pipe, the flaw would have two ends (crack tips). One end would be located closer to the inside surface of the pipe/weld and the other would be located closer to the outside surface of the pipe. (1) Please discuss how the 0.064-inch difference would be added to the measured flaw depth (e.g., to which crack tip would the 0.064-inch difference be added?)

(2) For flaws greater than 50 percent through-wall, the licensee stated that it will uses eddy current testing to verify whether the flaw is surface-breaking. Discuss whether eddy current testing will be used to verify whether any subsurface flaw regardless of depth, which is located close to the inside surface, is surface breaking. If eddy current will not be used in this situation, please explain why.

Luminant Power's Response to Question 2 (1) There is no Appendix VIII qualification for embedded flaws. Luminant's inspection vendor's procedure does address sizing of embedded volumetric (fabrication) flaws, with through-wall sizing determined by measurement of the -6dB (1/2 maximum response) limits of the flaw response, with no correction factor applied.

For an embedded planar flaw, the 0.064-inch correction factor will be added to the bottom tip (nearest to the ID) response. The total through-wall extent and near surface tip or "S" dimension, used for determination of surface proximity, will also add the adjusted conservative measurement value of 0.064-inches to the computed flaw depth.

Attachment to TXX-13023 Page 2 of 3 RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION FOR RELIEF REQUEST NUMBER B-2 FOR THE UNIT 1 THIRD 10 YEAR IS1 INTERVAL (THIRD INTERVAL START DATE: AUGUST 13, 2010)

(THIRD INTERVAL END DATE: AUGUST 12, 2020)

(TAC NO. MF0507)

(2) Eddy current is used for the examination of the entire ID surface of the inspection area during the detection scans. The eddy current results will be used to help verify the ID surface connectivity of all reported flaws.

NRC Question 3 from Reference 2 Section 6 of the relief request (page 3) states that "...for planar indications that are connected to the inside surface, an IWB-3600 evaluation will be performed..." (1) The Code of Record, 1998 Edition through 2000 Addenda of the ASME Code,Section XI, permits a detected flaw to be dispositioned by the acceptance standards of IWB-3514. The licensee does not need to perform a flaw evaluation if the flaw is accepted by IWB-3514. However, if the flaw is connected to the inside surface of the nickel-based dissimilar metal weld, the NRC staff believes that the flaw needs to be evaluated regardless of size, even if it is accepted by IWB-3514. The NRC staff is concerned regarding crack growth of primary stress corrosion cracking affecting the structural integrity of the nickel-based dissimilar metal weld. Also, starting from the 2007 Edition of ASME Section XI, the acceptance standards of IWB-3514 are not applicable to flaws connected to the inside surface of the nickel-based dissimilar metal welds. Therefore, confirm that an IWB-3600 evaluation will be performed for any size flaw as long as it is connected to the inside surface of the nickel-based dissimilar metal weld. (2) Please confirm that when performing a flaw evaluation based on IWB-3600 for an inside surface-connected flaw, the flaw growth will be calculated based on the degradation mechanisms of primary stress corrosion cracking and fatigue.

Luminant Power's Response to Question 3 (1) The statement in Section 6 of the relief request is not meant to suggest that ID surface connected flaws will not be compared to the acceptance standards of IWB-3500. The intent is that all flaws, either ID connected or embedded will be compared to the acceptance standards of IWB-3500. Additionally, any flaw determined to be ID surface connected will also be evaluated per IWB-3600, whether or not an evaluation per IWB-3500 requires an IWB-3600 analytical evaluation. IWB-3600 evaluations will be performed.

(2) A flaw evaluation based on IWB-3600 for an inside surface-connected flaw will calculate flaw growth based on the degradation mechanisms of primary stress corrosion cracking and fatigue.

Attachment to TXX-13023 Page 3 of 3 RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION FOR RELIEF REQUEST NUMBER B-2 FOR THE UNIT 1 THIRD 10 YEAR IS1 INTERVAL (THIRD INTERVAL START DATE: AUGUST 13, 2010)

(THIRD INTERVAL END DATE: AUGUST 12, 2020)

(TAC NO. MF0507)

NRC Question 4 from Reference 2 Section 6 of the relief request (page 2) stated that a demonstrated or measured RMS error of 0.189 inches will be used. Section 6 (page 3) further stated that if the examination vendor demonstrates an improved depth sizing RMS (i.e., smaller error) prior to the examination, the excess of that improved RMS error over the 0.125 inch RMS error requirement will be added to the measured flaw depth. Please discuss which demonstrated RMS error will be used to compare with the required RMS error of 0.125 inches if the demonstrated RMS error prior to actual examination is greater (i.e., data scatter become worse) than 0.189 inches.

Luminant Power's Response to Question 4 Luminant's inspection vendor will not be attempting any further Appendix VIII qualification demonstrations prior to the 1RF16 refueling outage. Therefore, the demonstrated or measured RMS error of 0.189 inches will be used.

NRC Question 5 from Reference 2 (1) Please clarify whether the proposed relief request is applicable for the spring 2013 refueling outage 1RF16 only, or for the remaining third 10-year inservice inspection interval. (2) Provide the end date of the third 10-year inservice inspection interval and the month of 2013 refueling outage 1RF16.

Luminant Power's Response to Question 5 (1) The proposed relief request is for 1RF16 refueling outage and for future similar examinations of the reactor vessel hot leg nozzle DM welds that may occur during the third 10-year inservice inspection interval for Unit 1.

(2) The end date for the third 10-year inservice inspection interval for Unit 1 is August 12, 2020.

Refueling outage 1RF16 is scheduled to begin on March 30, 2013, with the reactor vessel nozzle dissimilar metal weld examinations to occur in April, 2013.

ENCLOSURE TO TXX-13023 SKETCH FOR RESPONSE TO RAI QUESTION 1

Detection Scan Increments Axial Scan Scanner Input = 0.98° (0.25')

Circ. Scan Scanner Input = 0,08' n~ i Ur) I NOZZLE DM WELD z OUTLET 2 22' TBX-1-4400-1 2:x *E OUTLET @ 158' TBX-1-4300-1 OUTLET 2 202* TBX-1-4200-1 DISTANCE FROM OUTLET 2 338' TBX-1-4100-1 VESSEL g_

CD UN Sizing Scan Increments Axial Scan Scanner Input = 0.49° (0.125')

Circ, Scan Scanner Input = 0.08' R 14.50 d-d 0i CDQ* Cud C) Lj <£ COMANCHE PEAK UNIT 1 - TBX Uý) = zW 2J X 5--i 2013 EXAMINATION PROGRAM PLAN In x4£ OUTLET SAFE-END DETECTION & SIZING I WESDYNE 6 OF 61