ML093350526
| ML093350526 | |
| Person / Time | |
|---|---|
| Site: | McGuire  |
| Issue date: | 11/23/2009 |
| From: | Brandi Hamilton Duke Energy Carolinas |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| 09-MN-003 | |
| Download: ML093350526 (7) | |
Text
Duke YEnergye BRUCE H. HAMILTON Vice President McGuire Nuclear Station Duke Energy MG01 VP /12700 Hagers Ferry Road Huntersville, NC 28078 980-875-5333 980-875-4809 fax bruce. hamilton@duke-energy. com November 23, 2009 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001
SUBJECT:
Duke Energy Carolinas, LLC (Duke)
McGuire Nuclear Station, Unit 1 Docket Number 50-369 Relief Request 09-MN-003 Request for Additional Information On June 29, 2009 Duke submitted Relief Request 09-MN-003 pursuant to 10 CFR 50.55a(a)(3)(i), requesting NRC approval for an alternative to the reactor vessel inservice inspection interval requirements of the ASME Code,Section XI, IWB-2412.
On November 13, 2009, the NRC Staff electronically requested additional information regarding this relief request. This additional information, along with the Duke response, is attached.
If you have any questions or require additional information, please contact P. T. Vu at (980) 875-4302.
Sincerely,
[all Bruce H. Hamilton Attachment A-oy--7 k/g-A www. duke-energy. com
U. S. Nuclear Regulatory Commission November 23; 2009 Page 2 xc:
L. A. Reyes, Region II Administrator U. S. Nuclear Regulatory Commission Sam Nunn Atlanta Federal Center, 23 T85 61 Forsyth St., SW Atlanta, GA 30303-8931 J. H. Thompson, Project Manager U. S. Nuclear Regulatory Commission 11555 Rockville Pike Mail Stop 0-8G9A Rockville, MD 20852-2738 J. B. Brady NRC Senior Resident Inspector McGuire Nuclear Station
Relief Request 09-MN-003, Response to NRC Request for Additional Information Attachment, Page 1 of 5 ATTACHMENT Relief Request 09-MN-003 Response to NRC Request for Additional Information
Relief Request 09-MN-003, Response to NRC Request for Additional Information Attachment, Page 2 of 5 McGuire Unit 1 Response to NRC Request for Additional Information Question]: One flaw, in plate material B5012-1, with a through wall extent of 0.43 inches, exceeds the "allowable number of flaws" criteria in SECY-07-0104. Confirm from previous inspections whether any increase in flaw size has been observed.
Response
The detection of a flaw with a through-wall extent of 0.43 in. is attributed to the improvement of inspection technology, instead of an increase in flaw size. During the first 10-year reactor vessel inservice inspection (ISI) in 1992, examiners reported no flaw indications and recorded only geometric indications. During the second vessel ISI in 2001, examiners reported six indications on W12, the Middle to Lower Shell Circ. Weld, 1RPV-9-442. Changes in technology and methods between the two inspections include improvements in probe and calibration block designs, and the use of Performance Demonstration Initiative (PDI) qualified techniques.
Probes used for the first interval ISl were as follows:
45-degree shear wave, 1.0 MHz,, two 1.2 by 0.75 in. elements for full volume primary detection o
60-degree shear wave, 1.0 MHz, two 0.97 by 0.75 in. elements for full volume primary detection o
70-degree longitudinal wave, 1.0 MHz, two transmitting elements: 0.75 by 0.37 in., one receiving element: 1.5 by 0.75 in. for near surface primary detection Probes used for the second interval ISI were as follows:
45-degree shear wave, 1.0 MHz, one transmitting element: 1.2 by 0.75 in., one receiving element: 1.2 by 0.75 in. for full volume primary detection
" 45-degree longitudinal wave, 2.7 MHz, one transmitting element: 1.1 by 0.75 in., one receiving element: 1.1 by 0.75 in. for full volume primary detection 70-degree longitudinal wave, 1.3 MHz, two transmitting elements: 1.5 by 0.37 in., one receiving element: 1.5 by 0.75 in. for near surface primary detection.
The probes used for the second interval ISI reflected the optimization required to successfully demonstrate a PDI qualified procedure. Using the 45-degree longitudinal probe with a higher frequency and calibrating on smaller side drilled holes increased the sensitivity of the examination to identification of flaws. The longitudinal wave allowed the sound energy to better penetrate the cladding, increasing the ability to interrogate for flaws within the component. The increased size of the transmitting elements of the 70-degree longitudinal probe for the near surface region increases penetration and reduces beam spread, increasing the ability of the examination to detect a flaw.
The calibration blocks for the first interval ISI contained the following structures:
Relief Request 09-MN-003, Response to NRC Request for Additional Information Attachment, Page 3 of 5 o
Full volume calibration block #50377:
o Clad thickness of 0.255 in.
o Side drilled hole of 0.375 in. dia.
o Near surface calibration block #50304:
o Clad thickness of 0.180 in.
o Side drilled hole of 0.0625 in. dia.
The calibration blocks for the second interval 181 contained the following structures:
o Full volume calibration block #RPV-95001:
o Clad thickness of 0.250 in.
o Side drilled hole of 0.125 in. dia.
o Near surface block #RPV-95001 o
Clad thickness 0.250 in.
o Side drilled hole of 0.0625 in. dia.
Calibration on the full Volume block with the smaller diameter holes increased the sensitivity and detection capability for the inspection method used during the second interval examination. For the near surface blocks, calibrating on holes of the same diameter through a thicker cladding increased the sensitivity and detection capability for the second interval examination.
Finally, the largest flaw was measured as being 0.43 in. through wall. The calculated aspect ratio (a/t) of 2.4% was well below the acceptance limit of 7.6%. The analyst characterized the flaw to be sub-surface, meaning it is judged to be due to fabrication and not attributed to a service related degradation mechanism.
Question 2: The licensee proposed to defer the ASME Code required volumetric examination of the McGuire Unit 1 reactor pressure vessel full penetration pressure retaining Category B-A and B-D welds for the third in-service inspection interval until 2020. The methodology used to demonstrate the acceptability of extending the inspection intervals for Category B-A and B-D welds was based on the methodology used in WCAP-16168-NP-A, Revision 2, "Risk-Informed Extension of Reactor Vessel In-Service Inspection Interval." The submittal attachment, Relief Request (RR) 09-MN-003, included the nozzle-to-vessel welds and the nozzle inside radius section. Table 4.2-1, "Evaluation of Upper Shelf Energy for McGuire Unit I Beltline Region Materials at 54 Effective Full Power Years (EFPY)," of the Application to Renew the Operating Licenses of McGuire Nuclear Station Units 1 & 2 and Catawba Nuclear Station Units 1 and 2, Technical Information (ML0116601450), identified beltline nozzle materials which were not included in Table 3, "Details of TWCF Calculation - Performed for 60 Effective Full Power Years," of the RR. These materials are as follows: nozzle shell plate B5453-2, nozzle shell plate B5011-2, nozzle shell plate B5011-3, nozzle shell longitudinal weld seams 1-422A, B, C, and the nozzle shell to intermediate shell circumferential weld seam. Analysis of these beltline materials must be added to Table 3.
Response
While the pilot plant analyses in WCAP-1 6168-NP-A, Revision 2, and in NUREG-1874 (References 4 and 5 of RR 09-MN-003), the technical basis for the alternate PTS Rule (1 OCFR50.61 a), did not consider materials outside of those immediately adjacent to the reactor core, the nozzle shell course materials identified in question 2, along with their appropriate properties and fluence values, have conservatively been added to a revised Table 3 below.
Relief Request 09-MN-003, Response to NRC Request for Additional Information Attachment, Page 4 of 5 Due to the low fluence that these materials are subjected to, their resulting shifts in reference temperature due to irradiation damage are not sufficient to cause them to have limiting RTMAX-XX values. Since the TWCF calculation is affected solely by the limiting RTMAX-XX values, the addition of these materials has no impact on the TWCF calculations for the McGuire Unit 1 reactor vessel.
There were two errors identified in Table 3 during the development of the response to question
- 2. The column headers for Chemistry Factor (C.F) and Regulatory Guide (R.G) 1.99 Position were interchanged. Also, Table 3 identified axial welds 3-442A, B, and C as intermediate shell welds when in fact these are lower shell welds. These errors have been corrected in the Table 3 below.
Relief Request 09-MN-003, Response to NRC Request for Additional Information Attachment, Page 5 of 5 Table 3 Details of TWCF Calculation - Performed for 60 Effective Full Power Years (EFPY)
Inputs Reactor Coolant System Temperature, TRCs[°F]:
N/A Twaii [inches]:
8.84 Ni R.G.
Un-Fluence [10lY Region/Component Material /
Cu Ni C.F.
2 1.99 Irradiated Neutron/cm2 Description Flux Type
[wt%]
[wt%]
[OF]
RTNDT ['F]
E> 1.0 MeV]
pos.RTD[F]
E>10MV 1
Int. Plate B5012-1 A 533B 0.110 0.610 2.1 62.5 34.0 3.80 2
Int. Plate B5012-2 A 533B 0.140 0.610 1.1 100.3 0.0 3.80 3
Int. Plate B-5012-3 A 533B 0.110 0.660 1.1 74.9
-13.0 3.80 4
Low. Plate B5013-1 A 5833B 0.140 0.580 1.1 99.1 0.0 3.63 5
Low. Plate B5013-2 A 533B 0.100 0.510 1.1 65.0 30.0 3.63 6
Low. Plate 5013-3 A 533B 0.100 0.550 1.1 65.0 15.0 3.63 7
Int. Ax. Weld 2-442A Linde 1092 0.199 0.846 2.1 156.5
-50.0 2.16' 8
Int. Ax. Weld 2-442B Linde 1092 0.199 0.846 2.1 156.5
-50.0 3.09 9
Int. Ax. Weld 2-442C Linde 1092 0.199 0.846 2.1 156.5
-50.0 3.09 10 Low. Ax. Weld 3-442A Linde 1092 0.213 0.867 2.1 194.4
-50.0 2.96 11 Low. Ax. Weld 3-442B Linde 1092 0.213 0.867 2.1 194.4
-50.0 2.06 12 Low. Ax. Weld 3-442C Linde 1092 0.213 0.867 2.1 194.4
-50.0 2.96 13 Int./Lower Circ. Weld 9-442 Linde 1091 0.051 0.096 1.1 37.5
-70.0 3.59 14 Noz. Shell Plate B5453-2 A 533B 0.14 0.58 1.1 99.1 15 0.113 15 Noz. Shell Plate B5011-2 A 533B 0.10 0.54 1.1 65.0 27 0.113 16 Noz. Shell Plate B5011-3 A 533B 0.13 0.56 1.1 89.8 0
0.113 17 Noz. Ax Weld 1-442A N/A 0.199
.846 1.1 200.4
-50 0.092 18 Noz. Ax. Weld 1-442B N/A 0.199
.846 1.1 200.4
-50 0.064 19 Noz. Ax. Weld 1-442C N/A 0.199
.846 1.1 200.4
-50 0.092 20 Int./Noz. Circ Weld 8-442 Linde 1092 0.183 0.704 1.1 174.3
-56 0.113 Outputs Methodology Used to Calculate AT 30:
Regulatory Guide 1.99, Revision 2 Controlling Material Fluence [1019 FF RTMAx-XX2 Region #
R Neutron/cm 2, (Fluence AT3o ['F]
TWCF 95-XX (From E > 1.0 MeV]
Factor)
Above)
Axial Weld - AW 12 659.91 2.96 1.287 250.22 2.88E-09 Circumferential Weld - CW 2
593.32 3.59 1.332 133.63 5.52E-29 Plate - PL 2
594.59 3.80 1.345 134.90 1.23E-12 TWCF95-TOTAL (cAwTWCF95-AW + OXpLTVWCF95-PL + ocwTWCF95-cw):
6.60E-09