CP-201501103, Response to Request for Additional Information for Relief Request B-11 for the Second Ten-Year Inservice Inspection Interval from 10CFR50.55a Inspection Requirements Due to Physical Interferences (1998 Edition of ASME Code....)
| ML16020A066 | |
| Person / Time | |
|---|---|
| Site: | Comanche Peak  |
| Issue date: | 12/14/2015 |
| From: | Flores R, Thomas McCool Luminant Generation Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| CAC MF6554, CP-201501103, TXX-15157 | |
| Download: ML16020A066 (8) | |
Text
Rafael Flores Luminant Power Senior Vice President P0O Box 1002 Chief Nuclear Officer 6322 North FM 56 RafaeI.Flores@Lurninant.com Glen Rose, TX 76043 Luminant 258759 CP-201501103 Ref. # 10CFR50.55a(z)(1)
TXX-15157 December 14, 2015 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555
SUBJECT:
COMANCHE PEAK NUCLEAR POWER PLANT DOCKET NO. 50-446 RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION FOR RELIEF REQUEST B-li FOR UNIT 2 SECOND TEN YEAR INSERVICE INSPECTION INTERVAL FROM 10CFR50.55a INSPECTION REQUIREMENTS DUE TO PHYSICAL INTERFRENCES (1998 EDITION OF ASME CODE, SECTION XI, 2000ADDENDA THIRD INTERVAL START DATE: AUGUST 3, 2004 THIRD INTERVAL END DATE:
AUGUST 2, 2014) CAC NO. MF6554
REFERENCES:
- 1. Letter logged TXX-15118 dated August 3, 2015 from Rafael Flores to the NRC submitting Relief Request B-il for Unit 2 Second Ten Year Inservice Inspection Interval from 10CFR50.55a Inspection Requirements due to Physical Interferences
- 2. Email dated November 13, 2015 from Baiwant Singal of the NRC to Timothy Hope of Luminant Power requesting additional information regarding Relief Request B-il (CAC No. MF6554)
Dear Sir or Madam:
Per Reference 1, Luminant Generation Company, LLC (Luminant Power) submitted Relief Request B-li for Comanche Peak Unit 2 for the second ten year inservice inspection interval. 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 licensing basis commitments regarding Comanche Peak Unit 2.
U. S. Nuclear Regulatory Commission TXX-15157 Page 2 of 2 12/14/2015 Should you have any questions, please contact Mr. Jack Hicks at (254) 897-6725.
Sincerely, Luminant Generation Company LLC Rafael Flores B:Thomas
.c*o Vice President, Engineering and Support Attachment - Response to Request for Information Regarding Unit 2 Relief Request B-il Second Ten Year Interval Inspection Requirements due to Physical Interferences c -
Marc L. Dapas, Region IV*
Baiwant K. Singal, NRR Resident Inspectors, Comanche Peak Robert Free, TDLR Jack Ballard, ANII, Comanche Peak
Attachment to TXX-1 5157 Page 1 of 6 COMANCHE PEAK NUCLEAR POWER PLANT UNIT 2 RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION REGARDING RELIEF REQUEST B-li FOR SECOND TEN YEAR INTERVAL INSPECTION REQUIREMENTS DUE TO PHYSICAL INTERFERENCES (SECOND 10-YEAR IS1 INTERVAL END DATE: August 2, 2014)
CAC NO. MF6556 NRC REOUEST 1:
The NRC staff notes that in a single-sided access or a limited access to far-side, the "Best Effort" examination using the refracted longitudinal (L) waves may be performed as an extra effort to interrogate the requfred examination volume on the far-side particularly the root of weld and the heat affected zone (HAZ) of base materials typically susceptible to high stresses and potential degradation.
The L-waves have been shown capable of detecting planar flaws in the far-side volume of cast austenitic stainless steel and austenitic stainless steel weld and base materials in a single-sided examination. Given the reduced inspection coverage of the weld under consideration:
- a.
Please discuss whether the licensee performed the "Best Effort" examination as an extra effort to interrogate the examination volume on the far-side (particularly the root of weld and HAZ of base materials typically susceptible to high stresses and potential degradation).
- b. Please provide percentage of coverage obtained from the "Best Effort" examination if this examination was performed.
- c.
Please clarify whether the ASME Code required ultrasonic testing (UT), (as well as the "Best Effort" examinations if performed) covered the regions that are typically susceptible to higher stresses and, therefore, potential degradation (i.e., the weld root and HAZ of the base material near the inside diameter surface of the joint).
LUMINANT POWER RESPONSE TO REQUEST 1:
- a.
Per Procedure TX-ISI-302 Revision 3 (The corresponding site procedure for EPRI Generic procedure PDI-UT-2) utilized at the time of inspection. Procedural step 6.7.2.1(b) states that a 70 degree shear shall be used when component thickness is less than 0.5 inches and a refracted longitudinal (RL) transducer is required for component thicknesses of greater than 0.5 inches. Based on EPRI PDI inspection techniques, a 70 degree shear wave technique has a better detection capability than a 70 degree RL wave for component thicknesses of less than 0.5 inches. Yes, the root area and HAZ were inspected to the fullest extent practical performing the "Best Effort" examination.
- b. The percentage of coverage obtained from the "Best Effort" examination was 50% of the required examination volume.
- c.
Yes, the root area and HAZ were inspected to the fullest extent practical performing the "Best Effort" examination.
Attachment to TXX-15157 Page 2 of 6 COMANCHE PEAK NUCLEAR POWER PLANT UNIT 2 RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION REGARDING RELIEF REQUEST B-li FOR SECOND TEN YEAR INTERVAL INSPECTION REQUIREMENTS DUE TO PHYSICAL INTERFERENCES (SECOND 10-YEAR ISI INTERVAL END DATE: August 2, 2014)
CAC NO. MF6556 NRC REQUEST 2:
Section 2 of the RR states; The applicable ASME Boiler and Pressure Vessel Code (hereafter referred to as the "Code")
edition and addenda is ASME Section XI, "Rule for Inservice Inspection of Nuclear Power Plant Components," 1998 Edition, through 2000 Addenda. In addition, as required by 10 CER [Title 10 of Code of Federal Regulations] 50.55a, ASME Section XI, 1995 Edition, 1996 Addenda is used for Appendix VIII, Performance Demonstration for Ultrasonic Examination System.
The NRC staff notes that pursuant to 10 CFR 50.55a(b)(2)(xv), "Section XI condition: Appendix VIII specimen set and qualification requirements," licensees using Appendix VIII in the 1995 Edition through the 2001 Edition of the ASME Code may elect to comply with all of the provisions in paragraphs (b)(2)(xv)(A) through (M) of 50.55a, except for paragraph (b)(2)(xv)(F) of 50.55a, which may be used at the licensee's option. Licensees using editions and addenda after 2001 Edition through the 2006 Addenda must use the 2001 Edition of Appendix VIII and may elect to comply with all of the provisions in paragraphs (b)(2)(xv)(A) through (M) of 50.55a, except for paragraph (b)(2)(xv)(F) of 50.55a, which may be used at the licensee's option.
- a.
Please clarify if 1998 Edition through 2000 Addenda to the ASME Code,Section XI, Appendix VIII, was used for ultrasonic testing (UT) personnel qualification and procedures demonstration.
- b. Please provide justification if other editions and addenda were used.
LUMINANT POWER RESPONSE TO REQUEST 2:
- a.
1998 Edition through 2000 Addenda to the ASME Code,Section XI, Appendix VIII, was used for ultrasonic testing (UT) personnel qualification and procedures demonstration.
- b. No other editions and addenda were used.
NRC REQUEST 3:
Please provide the following information:
- a.
Material specifications (e.g., austenitic stainless steel pipes SA-376, TP-304 and austenitic stainless steel ER-308 weldment) for the welds and associated components (e.g., pipe, and valves).
- b. Thickness of each pipe.
Attachment to TXX-1 5157 Page 3 of 6 COMANCHE PEAK NUCLEAR POWER PLANT UNIT 2 RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION REGARDING RELIEF REQUEST B-li FOR SECOND TEN YEAR INTERVAL INSPECTION REQUIREMENTS DUE TO PHYSICAL INTERFERENCES (SECOND 10-YEAR ISI INTERVAL END DATE: August 2, 2014)
CAC NO. MF6556 LUMINANT POWER RESPONSE TO REQUEST 3:
- a.
Austenitic stainless steel SA-376 Type 316 pipe to SA-182 F316 valve with ER-316 weldment material.
- b.
3" Schedule 160 Stainless Steel Pipe (0.437 inches thick).
NRC REQUEST 4:
Please describe the following:
- a.
The inservice inspection (ISI) history (i.e., inspection years, disposition of detected flaws, extent of condition assessment, and corrective actions).
- b.
Whether the licensee identified any indications during construction and preservice inspections (i.e.,
radiographic testing or surface examination, or both) on the volume not covered by UT.
- c.
Disposition of identified flaws.
LUMINANT POWER RESPONSE TO REQUEST 4:
- a.
The first inservice inspection of weld TCX-1-4504-11 (Ultrasonic examination) was performed in 2RE12 which was the Second Interval, Second Period, Third Outage in 2011 with no identified flaws or corrective actions required.
- b.
Construction inspections (Radiographic testing and surface examination) of weld TCX-1-4504-11 were satisfactorily performed with no identified flaws. Preservice inspection (surface examination) was also satisfactorily performed with no identified flaws.
- c.
No flaws have been identified in weld TCX-1-4504-11. Therefore, no disposition has been required.
NRC REQUEST 5:
Given the reduced inspection coverage of the welds under consideration, please discuss the following:
- a.
Any walkdowns (e.g., under Boric Acid Corrosion Control Program or normal operator rounds) usually performed to monitor and identify leakage in an unlikely event of a through wall leak.
- b.
Reactor coolant system leakage detection capabilities at the plant, or any measures taken, to monitor and identify leakage during operation in an unlikely event of a through wall leak in the weld under consideration.
Attachment to TXX-15157 Page 4 of 6 COMANCHE PEAK NUCLEAR POWER PLANT UNIT 2 RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION REGARDING RELIEF REQUEST B-li FOR SECOND TEN YEAR INTERVAL INSPECTION REQUIREMENTS DUE TO PHYSICAL INTERFERENCES (SECOND 10-YEAR ISI INTERVAL END DATE: August 2, 2014)
CAC NO. MF6556 LUMINANT POWER RESPONSE TO REQUEST 5:
- a.
There are several programs at CPNPP that examine the area in question each refueling outage.
These programs are as follows:
TCX-1-4504-11 is within the examination scope of the Boric Acid Control Program walk down prior to each Refueling Outage.
TCX-1-4504-11 is also included in the scope of the Class 1 System Leakage Test prior to plant startup following each refueling outage as required by ASME Section XI.
- b.
CPNPP has a Leakage-detection system with design objectives in accordance with the requirements of 10 CFR Part 50, GDC 30, and NRC Regulatory Guide 1.45. The leakage-detection systems are capable of detecting leakage as low as 0.1-gpm using the air particulate monitor and as low as 1-gpm using the condensate flow rate and the sump level alarm. The sensitivity is reasonably adequate to detect an increase in unidentified leakage rate. The following are also plant indications of evidence of leakage that are procedurally monitored at CPNPP: Containment humidity high or increasing, Containment radiation levels high or increasing, Containment temperature high or increasing, Containment pressure high or increasing and Containment dew point increasing. An RCS water inventory balance is also performed daily by operations for evidence of RCS leakage.
NRC REQUEST 6:
In an unlikely event of a potential though wall flaw and leakage, please discuss significance of the leak and potential for structural failure of the subject weld.
LUMINANT POWER RESPONSE TO REQUEST 6:
Based on the containment leakage detection as discussed in RAI 5 above, a potential through wall flaw of the weld should be detected and the plant would be shut down before significant weld failure could occur. Then corrective action would be performed as required.
NRC REQUEST 7:
Please discuss any industry or plant-specific operating experience regarding potential degradation (e.g.,
stress corrosion cracking, corrosion, and fatigue) and potential severe loading (e.g., vibration, water hammer, and overloading) for the subject weld and associated components.
The NRC staff notes that due to recent operating experience regarding thermal fatigue cracking in some plants, the Electric Power Research Institute (EPRI) issued an interim guidance, "EPRI-MRP [Material Reliability Program] Interim Guidance for Management of Thermal Fatigue," (ADAMS Accession Number ML15189A100), that supplemented the existing industry thermal fatigue guidelines (e.g., MRP-1461 and MRP-192 2) to better manage thermal fatigue cracking. Please discuss whether the licensee will SMaterials Reliability Program: Management of Thermal Fatigue in Normally Stagnant Non-Isolable Reactor Coolant System Branch Lines (MRP-146) (Non-Publically Available)
Attachment to TXX-15157 Page 5 of 6 COMANCHE PEAK NUCLEAR POWER PLANT UNIT 2 RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION REGARDING RELIEF REQUEST B-11 FOR SECOND TEN YEAR INTERVAL INSPECTION REQUIREMENTS DUE TO PHYSICAL INTERFERENCES (SECOND 10-YEAR ISI INTERVAL END DATE: August 2, 2014)
CAC NO. MF6556 take any compensatory measures to better manage thermal fatigue cracking in the subject weld to ensure structural integrity and leak tightness since essentially 100 coverage was not achieved by the UT.
LUMINANT POWER RESPONSE TO REQUEST 7:
CPNPP has determined that weld TCX-1-4504-11 is not within the scope of the industry thermal fatigue guidelines MRP-146 and MRP-192. As stated in 5a above TCX-1-4504-11 is within the examination scope of the Boric Acid Control Program walk down prior to each Refueling Outage and also included in the scope of the Class 1 System Leakage Test prior to plant startup following each refueling outage as required by ASME Section XI. CPNPP feels that with the limited Ultrasonic examination as outlined in Relief Request B-il (Agencywide Documents Access and Management System (ADAMS) Accession Number ML15224B364) and the routine inspection of this weld area via the Boric Acid Control Program and the Class 1 System Leakage Test no further compensatory measures are required.
A review of industry and plant-specific operating experience databases did not identify any other operating experience regarding potential degradation and potential severe loading for the subject weld.
NRC REQUEST 8:
Please discuss whether use of alternative volumetric examination techniques (e.g., the radiographic testing and phased array UT) would increase examination coverage.
LUMINANT POWER RESPONSE TO REQUEST 8:
No radiographic testing was performed due to the configuration limitations and radiological conditions associated with performing the radiographic testing. Phased Array techniques would not have increased examination volume percentages.
NRC REQUEST 9:
It appears that the licensee reported in Attachments 1 and 2 to the P.R that the UT was performed only in axial direction. Given that the licensee preformed a single-sided examination due to the valve body, please clarify whether scanning was done in both circumferential and axial directions, and the 50 percent coverage reported in Section 4 of the P.R is the aggregate coverage of all ASME Code required UT performed in a single-sided examination (i.e., scanning of the weld in the circumferential and axial directions).
2 Materials Reliability Program: Assessment of Residual Heat Removal Mixing Tee Thermal Fatigue in PWR [Pressurized Water Reactor] Plants (MRP-1 92) (Non-Publically Available)
Attachment to TXX-15157 Page 6 of 6 COMANCHE PEAK NUCLEAR POWER PLANT UNIT 2 RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION REGARDING RELIEF REQUEST B-li FOR SECOND TEN YEAR INTERVAL INSPECTION REQUIREMENTS DUE TO PHYSICAL INTERFERENCES (SECOND 10-YEAR ISI INTERVAL END DATE: August 2, 2014)
CAC NO. MF6556 LUMINANT POWER RESPONSE TO REQUEST 9:
Per Relief Request B-il (Agencywide Documents Access and Management System (ADAMS) Accession Number ML15224B364) Attachment 2 Page 1 of 3, the 45 degree shear wave was performed in both the axial and circumferential directions. The calibration requirement only requires an axial scan for calibration. The scan area depicts that both axial and circumferential directions were performed utilizing the 45 degree. The 60 and 70 degree shear wave transducers were only utilized for axial scanning for circumferential flaws. Therefore, yes the 50 percent coverage reported in Section 4 is the aggregate coverage of ASME Code Required UT exams.