1CAN061103, Response to Request for Additional Information Associated with Relief Request ANO1-R&R-014
| ML111610444 | |
| Person / Time | |
|---|---|
| Site: | Arkansas Nuclear  (DPR-051) |
| Issue date: | 06/09/2011 |
| From: | Pyle S Entergy Nuclear Operations |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| 1CAN061103 | |
| Download: ML111610444 (7) | |
Text
1CAN061103 June 9, 2011 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555
SUBJECT:
Response to Request for Additional Information Associated with Relief Request ANO1-R&R-014 Arkansas Nuclear One, Unit 1 Docket No. 50-313 License No. DPR-51
REFERENCE:
- 1. Entergy Letter dated October 26, 2010, Request for Use of Non-ASME Code Repair to Service Water Piping in Accordance with Generic Letter 90-05 Relief Request ANO1-R&R-014, (1CAN101005)
- 2. Email from Kaly Kalyanam (NRC) to Robert W. Clark (Entergy), dated February 10, 2011, RAI on the Relief Request ANO1-R&R-014
Dear Sir or Madam:
Entergy Operations, Inc. (Entergy) requested relief in accordance with 10 CFR 50.55a(a)(3)(i) for a temporary non-code repair to the Arkansas Nuclear One, Unit 1 (ANO-1) Service Water (SW) system via Reference 1. Justification for the temporary repair is based on the guidance provided in Generic Letter (GL) 90-05 and was provided in the referenced submittal.
During the review of the material provided in Reference 1, the NRC determined additional information was needed to complete the review (Reference 2). Attached is the Reference 2 Request for Additional Information (RAI) along with Entergys response.
There are no new commitments presented in this submittal.
If you have any questions or require additional information, please contact me.
Sincerely, Original signed by Stephenie L. Pyle SLP/rwc Entergy Operations, Inc.
1448 S.R. 333 Russellville, AR 72802 Tel 479-858-4710 Stephenie L. Pyle Acting Manager, Licensing Arkansas Nuclear One
1CAN061103 Page 2 of 2
Attachment:
Response to RAIs Related to Relief Request ANO1-R&R-014 cc:
Mr. Elmo Collins Regional Administrator U. S. Nuclear Regulatory Commission Region IV 612 E. Lamar Blvd., Suite 400 Arlington, TX 76011-4125 NRC Senior Resident Inspector Arkansas Nuclear One P.O. Box 310 London, AR 72847 U. S. Nuclear Regulatory Commission Attn: Mr. Kaly Kalyanam MS O-8 B1 One White Flint North 11555 Rockville Pike Rockville, MD 20852 Mr. Bernard R. Bevill Arkansas Department of Health Radiation Control Section 4815 West Markham Street Slot #30 Little Rock, AR 72205
Attachment To 1CAN061103 Response To RAIs Related To Relief Request ANO1-R&R-014
Attachment to 1CAN061103 Page 1 of 4 RESPONSE TO RAIs RELATED TO RELIEF REQUEST ANO1-R&R-014 By letter dated October 26, 2010, Entergy Operations, Inc. (Entergy) submitted Relief Request ANO-1-R&R-014. Entergy is requesting relief in accordance with 10 CFR 50.55a(g)(6)(i) for a temporary non-code repair to an ASME Code Class 3 pipe in the Arkansas Nuclear One, Unit 1 (ANO-1) Service Water (SW) system. The NRC staff has determined that additional information is needed to complete the review.
- 1.
Specify the ANO-1, fourth inservice inspection interval start and end dates.
The fourth 10-year inservice inspection interval for ANO-1 began May 31, 2008. This interval ends on May 30, 2017. Note that the interval was shortened one year, as permitted by IWA-2430(d).
- 2.
The leak is described as being in the flange weld. Is the pipe-to-flange weld a full penetration butt weld? If not, describe the configuration.
The pipe-to-flange weld is a full penetration butt weld.
- 3.
Were the ultrasonic thickness (UT) measurements made at a zero degree angle?
If so, was the crown of the weld removed to facilitate UT interrogation of the weld metal?
The UT measurements were made at a zero degree angle. The crown of the weld was not removed.
- 4.
Was weld metal interrogated at the 5 additional inspection locations?
Weld metal was not interrogated. The five additional locations were pipe samples adjacent to welds with similar service conditions and corrosion susceptibility.
- 5.
Would the UT measurements have been able to determine if the leak was from a through wall crack or linear flaw?
The UT measurements were not for planar flaws. The visible flaw, after the paint was removed, was noted to be a pit approximately 0.20 inches long by 0.050 inches wide.
- 6.
On what basis was the root cause determination of Microbiologically Influenced Corrosion (MIC) made?
The MIC determination was based on the pit-like flaw characterization and initial ultrasonic thickness readings.
Attachment to 1CAN061103 Page 2 of 4
- 7.
What are the dimensions of the defect (include NDE uncertainties and limitations)?
The flaw was identified as having a physical dimension, based on visual surface examination following paint removal, of ~ 0.20 inches by 0.050 inches. The pit could not be sized with UT due to the irregular surface at the edge of the weld.
The UT examinations recorded the lowest readings obtainable as follows:
Date Condition of Component Lowest Reading Obtained May 26, 2010 Initial scan, as found with paint intact 0.096 May 27, 2010 Rescan for Code Case 513 evaluation 0.176 August 26, 2010 First periodic examination, paint removed at flaw 0.078 November 18, 2010 Second periodic examination 0.078 February 17, 2011 Third periodic examination 0.072 The resolution capabilities of the UT instrumentation as reported by the manufacturer are listed as 0.001 inches to 0.010 inches. The resolution is dependent on many factors, but is certainly influenced by the surface condition and geometry of the portion under examination. Typically, resolution accuracy of +/- 0.005 inches is achievable on portions having parallel surfaces without geometry limitations.
- 8.
Provide details of the through-wall analysis calculation.
Below are the details from the spreadsheet that was used to perform the through-wall analysis calculation. The specific calculations use the equations provided in Enclosure 1, Section C.3.a, of Generic Letter (GL) 90-05.
The value for the through-wall flaw length, 2a, is conservatively assumed to be 0.5 inches.
This is acceptable since all wall thickness measurements reported are greater than the Code-required minimum wall thickness, tmin, which is 0.0718 inches. The nominal wall thickness is 0.375 inches. Based on the UT results (reference NDE Report No. 1-BOP-UT-10-025), the minimum average wall thickness is 0.371 inches. Conservatively, 0.370 inches was used in the calculation.
Attachment to 1CAN061103 Page 3 of 4 INPUT VALUES Flaw size, 2a 0.500 inches Outside diameter of pipe 18.000 inches Design pressure 120.0 psi Initial wall thickness 0.375 inches Initial section modulus 91.4912 cubic inches Material allowable stress 15000.00 psi y (constant) 0.40 New pipe wall properties Average wall thickness 0.370 inches Average section modulus 90.3226 cubic inches Existing Pipe Stress (reference CALC-89-D-1036-01, Rev. 4)
Deadweight 1382 psi Seismic 1393 psi Thermal 3649 psi Total 6424 psi CALCULATED RESULTS ASME Section III/ B31.1, Equation 3, tmin = 0.0718 inches Mean pipe radius R = 8.8150 A / 3.1415972 (R) c = 0.009028 R / Equation 3 r = 122.82233 A = 2054.25636 B = -5255.32958 C = 5175.01480 Adjusted Pipe Stress For Thinned Wall 6507 psi Adjusted Pressure Stress 1459 psi Adjusted Total Stress 7967 psi Geometry Factor F = 2.72167 Notes:
- 1.
15% of pipe circumference is 8.4823 inches. The flaw size is under 3 inches (or within 15% of the pipe circumference).
- 2.
K = 26902, which is less than 35000 psi.
Attachment to 1CAN061103 Page 4 of 4 In support of the above, GL 90-05 states:
It is noted that the rate of degradation is not considered in this approach because the flaw is assumed to have grown through the pipe wall and the temporary non-Code repair is applicable, at maximum, until the next scheduled refueling outage.