NL-15-1621, Response to Request for Additional Information on Proposed In-Service Inspection Alternative to Install Four Full Structural Weld Overlays
| ML15258A551 | |
| Person / Time | |
|---|---|
| Site: | Hatch  |
| Issue date: | 09/15/2015 |
| From: | Pierce C Southern Co, Southern Nuclear Operating Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| NL-15-1621 | |
| Download: ML15258A551 (32) | |
Text
Charles R. Pierce Southern Nuclear Regulatory Affairs Director Operating Company, Inc.
40 Inverness Center Parkway Post Office Box 1295 Birmingham, AL 35242 Tel 205.992.7872 SOUTHERN . \ .
Fax 205.992.7601 NUCLEAR A SOUTHERN COMPANY S£P 1 5 2015 Docket Nos.: 50-321 NL-15-1621 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D. C. 20555-0001 Edwin I. Hatch Nuclear Plant Unit 1 Response to Request for Additional Information on Proposed In-Service Inspection Alternative to Install Four Full Structural Weld Overlays Ladies and Gentlemen:
By letter dated July 2, 2015 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML15183A354), Southern Nuclear Operating Company requested approval of a proposed In-Service Inspection (lSI)
Alternative (HNP-ISI-ALT-15-01) to install full structural weld overlays (FSWOL) on four welds at Edwin I. Hatch Nuclear Plant, Unit 1 during the Spring 2016 refueling outage.
In their letter dated August 18, 2015 (ADAMS Accession No. ML152248464),
NRC requested additional information to complete their review. The response to the NRC requested information is provided in the enclosure.
This letter contains no NRC commitments.
If you have any questions, please contact Ken McElroy at (205) 992-7369.
R2ilP;;tted, C. R. Pierce Regulatory Affairs Director CRP/OCV/
Enclosures:
- 1. Response to Request for Additional Information on Proposed lSI Alternative to Install Four Full Structural Weld Overlays
- 2. Figures
U.S. Nuclear Regulatory Commission NL-15-1621 Page 2 cc: Southern Nuclear Operating Company Mr. S. E. Kuczynski, Chairman, President & CEO Mr. D. G. Bost, Executive Vice President & Chief Nuclear Officer Mr. D. R. Vineyard, Vice President- Hatch Mr. M. D. Meier, Vice President- Regulatory Affairs Mr. D. R. Madison, Vice President- Fleet Operations Mr. B. J. Adams, Vice President- Engineering Mr. G. L. Johnson, Regulatory Affairs Manager - Hatch RType: CHA02.004 U.S. Nuclear Regulatory Commission Mr. W.M. Dean, Director, Office of Nuclear Reactor Regulations Mr. V. M. McCree, Regional Administrator Mr. L.D. Wert, Regional Administrator (Acting)
Mr. R. E. Martin, NRR Senior Project Manager- Hatch Mr. D. H. Hardage, Senior Resident Inspector- Hatch
Edwin I. Hatch Nuclear Plant Unit 1 Response to Request for Additional Information on Proposed lSI Alternative to Install Four Full Structural Weld Overlays Enclosure 1 SNC Responses
Enclosure 1 to NL-15-1621 SNC Responses REQUEST FOR ADDITIONAL INFORMATION (RAil SOUTHERN NUCLEAR OPERATING COMPANY, INC.
EDWIN I. HATCH NUCLEAR PLANT, UNITS 1 AND 2 By letter dated July 2, 2015 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML15183A354), Southern Nuclear proposed an In-service Inspection (lSI) Alternative to install full structural weld overlays (FSWOL) on four welds at Edwin I. Hatch Nuclear Plant, Unit 1 during the Spring 2016 refueling outage. The licensee has used a previously U.S. Nuclear Regulatory Commission (NRC)-approved lSI Alternative, HNP-ISI-ALT-08-02, through a majority of the fourth lSI interval for the installation of FSWOLs on both units. However, the licensee submitted the new lSI alternative, HNP-ISI-ALT-15-01, on the unique configuration of the four subject welds. In particular, existing weld overlay material is either adjacent to or located at those locations which are scheduled for the installation of new FSWOLs. To complete its review, the U.S. Nuclear Regulatory Commission (NRC) staff requests the following additional information.
NRC RAI No.1 In the cover letter dated July 2, 2015, the licensee states that the proposed lSI Alternative involves applying FSWOL on four welds. However, page 1 of Enclosure identifies only three welds, 1E11-1RHR-24A-R-12, 1B31-1RC-12BR-C-5 and 1831-1RC-12BR-E-5. Also, the last sentence on page 2 of the lSI Alternative states that "the RHR weld and two recirculation welds". The proposed lSI Alternative does mention weld 1E11-1RHR-24A-R-13 which has already been weld overlaid in 1984.
(a) It is not clear to the NRC staff exactly how many welds are affected. Confirm that the affected welds are welds 1E11-1RHR-24A-R-12, 1E11-1RHR-24A-R-13, 1B31-1RC-12BR-C-5 and 1831-1RC-12BR-E-5.
SNC Response to NRC RAI No. 1(a)
The four piping welds called out in the NRC RAJ Question 1{a) are affected by HNP-ISI-ALT 01 as described in the following paragraphs.
A new full structural weld overlay (FSWOL) is to be installed on Residual Heat Removal (RHR) system weld 1E11-1 RHR-24A-R-12 during the 1R27 outage due to configuration limitations.
RHR weld 1E11-1 RHR- 24A-R-13 has an existing weld overlay that was installed in 1984. Since the actual distance between original weld 12 and 13 centerlines is approximately 6-inches, the designer of the weld overlays (Structural Integrity Associates) has indicated that the weld overlay on weld 13 needs to be modified to support an adequate weld overlay installation on weld 12. The planned approach is to remove weld overlay material on weld 13 and then install one FSWOL that is applied to both welds 12 and 13. Therefore, Hatch considers this activity as affecting two RHR welds.
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Enclosure 1 to NL-15-1621 SNC Responses SNC Response to NRC RAI No. 1(a) (Cont'd.)
Welds 1831-1RC-12BR-C-5 and 1831-1RC-12BR-E-5 are safe-end to nozzle welds in the Reactor Recirculation (RC) system. These welds are on two separate RC system 12-inch riser loops and therefore, Hatch considers this activity as affecting two RC welds.
Therefore, a total of four piping welds will be affected by this lSI Alternative.
(b) Clarify whether the original weld 1E11-1RHR-24A-R-13 is made of Alloy 82/182 filler material or stainless steel filler material.
SNC Response to NRC RAI No. 1(b)
Weld 1E11-1 RHR-24A-R-13 is a stainless steel weld joining two sections of stainless piping material. See Figure RAI-1 b-1 A in Enclosure 2 for the physical layout.
NRC RAI No. 2:
Figures 1 and 2 in Appendix 6 present the weld configurations of the RHR piping and Recirculation riser line, respectively. Figure 1 shows the existing weld overlay on R-13 weld.
(a) Confirm that weld R-12 has no weld overlay at present.
SNC Response to NRC RAI No. 2(a)
Weld 1E11-1 RHR-24A-R-12 does not presently have a weld overlay. The purpose of the weld overlay to be installed during the 1R27 outage will be to enhance the examination of this dissimilar metal weld.
(b) Describe what represents the hash lines on the nozzle that is located horizontally in Figure 1.
SNC Response to NRC RAI No. 2(b)
Weld 1E11-1 RHR-24A-R-12 is a dissimilar metal weld joining the valve to the pipe. The hash lines indicate the lnconel buttering installed on the valve prior to joining the valve to the pipe piece. The F-No. 43 buttering is described in the Hatch design drawings which indicate that the minimum weld is 3/16-inch after machining.
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Enclosure 1 to NL-15-1621 SNC Responses (c) Figure 2 in Appendix 6 shows one weld is made of stainless steel and one weld is made of Alloy 82/182 material on the recirculation riser line. However, Page 1 of the lSI Alternative appears to suggest that both C-5 and E-5 are dissimilar metal welds. Clarify which of the two welds 1B31-1RC-12BR-C-5 and 1B31-1RC-12BR-E-5 is the alloy 82/182 weld and which is the stainless steel weld? Include both weld identification number on Figure 2.
SNC Response to NRC RAJ No. 2(c)
Welds 1831-1RC-12BR-C-5 and 1831-1RC-12BR-E-5 are both safe-end to nozzle welds on two separate 12-inch riser inlet lines on the Hatch-1 RC system. Weld No.4 is the stainless steel weld (pipe to safe-end) which is not part of this alternative. Two figures have been developed to assist the NRC reviewers. Figure RAI-2c-1 A notes both piping weld locations on the figure but it does not show the existing weld overlays. Figure RAI-3a-1 A shows the weld overlays that presently exist on the welds. Both figures are found in Enclosure 2.
(d) Page 1 of the lSI Alternative discusses the base materials that are adjacent to weld R-12, but not adjacent to weld R-13. Page 1 also discusses the base materials that are adjacent to C-5 or E-5, but it is not clear to the NRC staff the exact base materials that are associated with welds C-5 and E-5. Discuss the adjacent base materials to welds R-13, C-5 and E-5.
SNC Response to NRC RAJ No. 2(d)
Weld 1E11-1 RHR-24A-R-13 is a pipe to pipe weld. The short extension piece between Weld No. 13 and the valve is fabricated from F304 stainless steel, P No. 8. The other pipe section is Gr. 304 stainless steel.
Welds 1 831-1 RC-12BR-C-5 and 1831-1 RC-12BR-E-5 are both safe-end to nozzle welds on two separate 12-inch riser inlet lines on the Hatch-1 Recirculation system. The safe-end material is SA-182, F-304 (P No. 8) and the nozzle material is SA-508, CL. 2 (P No. 3).
NRC RAJ No.3 Fourth paragraph on page 3 of the lSI Alternative states that " .. .In the present configuration, the lnconel weld overlay does not completely cover the weld and buttering but tapers to approximately the centerline of the weld. These two weld overlays have seen continuous service since that outage with UT examinations performed during several outages ... " Figure 2 of Appendix 6 does not show the existence of the current weld overlay.
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Enclosure 1 to NL-15-1621 SNC Responses (a) Provide a sketch or draw on Figure 2 of the current weld overlay configuration on 1831*1 RC-128R*C-5 and 1831*1 RC-128R-E-5 including dimensions.
SNC Response to NRC RAI No. 3(a)
Figure RAI-3a-1A shows the present weld overlay configuration (i.e., prior to the 1R27 outage) of welds 1B31-1RC-12BR-C-5 and 1B31-1RC-12BR-E-5. The two weld locations have essentially the same configuration and one drawing covers both. SNC has also enclosed pictures to show the weld overlays on these two welds.
(b) Clarify where the two existing weld overlays are located as referenced in the above quote SNC Response to NRC RAI No. 3(b)
Figure RAI-3a-1 A in Enclosure 2 shows that the weld overlay is located on the safe-end side of the dissimilar metal weld based on an axial ultrasonic (UT) indication noted on each weld during the 1988 Hatch-1 outage. Based on the issues associated with installing a weld overlay on ferritic nozzles at that time, the designer of these weld overlays (Structural Integrity) proposed that the weld overlays taper down onto these two dissimilar metal welds.
NRC RAI No.4 Discuss the maximum and minimum design thickness of the proposed FSWOL.
SNC Response to NRC RAI No. 4 The maximum and minimum design thicknesses for the proposed FSWOLs are provided for the benefit of the installer. The maximum and minimum dimensions allow the installer to apply the overlay within a practically achievable set of dimensional boundaries which meet the design requirements.
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Enclosure 1 to NL-15-1621 SNC Responses NRC RAI No.5 Section 1.0 of the lSI Alternative states that " ...The surface of the existing weld overlays will be ground to prepare the surface for receipt of a new Alloy 52M overlay... After performance of a satisfactory liquid penetrant surface examination, a stainless steel buffer layer (ER308L) will be deposited over the stainless steei...The portion of the overlay deposited over the low alloy steel material will be applied directly at ambient temperature using the temper bead technique and the Alloy 182 butt weld will be spanned and tied into the stainless steel material using a single layer of Alloy 82 ... "
(a) Identify the stainless steel surfaces that the buffer layer will be applied on Figures 1 and 2 of Appendix 6 (or on sketches) of the four weld configurations and draw the buffer layer on the diagrams.
SNC Response to NRC RAI No. S(a)
The two RHR system welds in their present configuration are combined onto Figure RAI-5a-1A.
In Figure RAI-Sa-1 8, the removal of part of the existing weld overlay is shown. The next figure, Figure RAI-Sa-1 C shows the locations of the stainless steel buffer layer using ER308L.
Since welds 1831-1 RC-128R-C-5 and 1831-1 RC-128R-E-5 are essentially identical, Figure RAI-5a-2A shows the present configuration of both welds. In Figure RAI-Sa-28, the removal of part of the existing weld overlay is shown. The addition of the stainless steel buffer layer is not needed for these welds since the existing stainless steel material already has a buffer layer that was installed previously. The referenced figures are found in Enclosure 2.
(b) Provide a step-by-step welding of how the Alloy 82, Alloy 182, and Alloy 52M layers are deposited on the subject welds. Illustration these layers on Figures 1 and 2 of Appendix 6 (or on sketches).
SNC Response to NRC RAI No. S(b)
An additional figure has been added to show the installation process for the weld overlay on the RHR system using Figure RAI-Sa-1 D.
Similarly, an additional figure has been added to show the installation process for the weld overlay on the RC system using figure number RAI-5a-2C. These figures are found in .
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Enclosure 1 to NL-15-1621 SNC Responses NRC RAI No.6 Section 1.0(b), second paragraph states that: "... Depending on the chemical composition of the base materials where the weld overlay is to be applied, there may be different ways to apply the first layer of weld material ... " Explain the "different ways" to apply the first layer of weld material (different from standards?).
SNC Response to NRC RAI No. 6 The initial overlays were all deposited entirely over austenitic material substrates and weld deposits and did not require temper bead welding procedures. In the case of the RHR location, the butt weld is a stainless steel to stainless steel weld that was mitigated in a prior outage. The overlay filler material deposit was Type 308L stainless steel. The recirculation riser inlet nozzle location included a combination of austenitic materials eventually joined to the low alloy steel nozzle- the austenitic substrate includes the forged stainless steel safe-end (SA 182 F304), the lnconel 182 buttering on the end of the safe-end, and the lnconel182 butt weld. The end of the low alloy steel nozzle (SA 508 Class 2 forging which has a current designation of SA 508 Grade 2 Class 1) was also buttered with lnconel182. The existing lnconel82 weld overlay was truncated intentionally on the lnconel 182 butt weld. The existing overlay thickness will be reduced and prepared for the new overlay.
The new overlays in both cases will be dissimilar metal overlays. The portion of the new overlays that extends over the ferritic materials will utilize a temper bead welding procedure.
The existing recirculation riser nozzle overlays are made with Alloy 82 filler metal and currently extend over the stainless steel spool piece truncating on to the lnconel butt weld; therefore the Alloy 52M overlay material can be deposited directly on the remnant overlay and proceed directly on to the nozzle using a temper bead procedure. However, the remnant stainless steel overlay on the RHR does not cover all of the stainless steel pipe spool joined to the carbon steel valve. A stainless steel (ER308-L) buffer layer will be required over the uncovered stainless steel pipe spool but will be truncated approximately 1/8 inch short of the dissimilar metal weld (lnconel 182). This is done to avoid hot cracking in the stainless steel deposit. Accordingly a bridge deposit is required to "bridge the gap" and join the stainless steel buffer material to the lnconel 182 butt weld. Alloy 82 is selected for this purpose because of its better resistance to hot cracking than the Alloy 52M overlay design material. Alloy 52M is selected for the overlay design because of the excellent corrosion resistance imparted by its high chromium content (29%Cr minimum). Hot cracking is a known issue with Alloy 52M weld deposits when applied over stainless steel substrates when they contain elevated levels of sulfur, phosphorus, and silicon. A variety of welding techniques have been developed by industry that minimize weld dilution. The aggressiveness of the mitigation techniques needed to avoid hot cracking is determined by evaluating the composition of the stainless steel substrate. In some cases E1-6
Enclosure 1 to NL-15-1621 SNC Responses SNC Response to NRC RAI No. 6 (Cont'd.)
welding parameters that minimize dilution (use of low Power Ratios) combined with the use of a stainless steel (EA308-L) buffer layer is effective. Situations where high levels of contaminants are present may require more than a single stainless steel buffer layer. In addition, the intersection of stainless steel and lnconel 182 butter can be a concern because the stainless steel buffer deposit must be stopped short of the lnconel 182 butter or butt weld. This is why the bridge deposit is necessary. Note that the bridge layer is initiated on the lnconel butt weld and the bridge beads are deposited first on the butt weld then progress towards the buffer layer.
This technique limits uptake of contaminants into the weld deposit to avoid hot cracking. The Alloy 52M overlay layers start on the stainless steel safe-end side and progress toward the nozzle.
NRC RAI No.7 Section 2, page 6 states that "This report will be submitted within 90 days after plant startup." Confirm that the report is referring to the crack growth calculation of the postulated flaw(s).
SNC Response to NRC RAI No. 7 The crack growth calculation for the postulated flaw(s) will be submitted within 90 days after plant startup.
NRC RAI No.8 Section 3, under the Pre-Overlay Examination heading, the licensee stated that " ... For welds overlaid because of unacceptable indications, the flaw size would be defined by qualified ultrasonic examinations ... " This statement appears that the licensee will perform a pre-overlay examination. However, on page 12 of the lSI Alternative the licensee stated that it will not perform ultrasonic examination of the weld prior to FSWOL application.
(a) Clarify whether a pre-overlay ultrasonic examination will be performed. If not, explain why a pre-overlay examination will not be performed.
Since RHR weld 1E11-1 RHR-24A-R-12 is being overlaid to address an inspectability issue and no UT indications were seen previously, Hatch does not plan on performing a pre-overlay examination.
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Enclosure 1 to NL-15-1621 SNC Responses SNC Response to NRC RAI8(a) (Cont'd)
The three welds with previous indications were overlaid during the outage when the UT indications were first observed. Since that time, UT examinations have been performed to show that the weld overlays are performing their function. The UT examination is qualified for the weld overlay and the outer 25% of the original piping. In the case of the two RC weld overlays, the ultrasonic indication on each weld was observed beneath the outer 25 % of base material. In the case of the RHR weld overlay with an initial UT indication of about 50 %
through wall, the existing UT indication was not observed (the indication was beyond the outer 25% examination volume). These examinations are confirmation that the weld overlays are performing their function. These examinations are located in high radiation dose areas, and the dose required for an additional UT examination is not warranted since the weld overlays at Hatch and throughout the industry are mitigating intergranular stress corrosion cracking.
NRC RAI No.9 Sections 3(a)4 and 3(b)2 state that: " ... Reexamination per IWB-2420 is not required because unacceptable indications will be removed and the volume will be re-welded ... "
Explain why re-examination is not required after an unacceptable indication is removed and the excavated volume is backfilled.
SNC Response to NRC RAI 9 In order to clarify the SNC response, the entire paragraph is quoted below from lSI Alternative HNP-ISI-ALT-15-01: "Planar flaws shall meet the preservice examination standards of Table IWB-3514-2. In applying the acceptance standards, wall thickness "tw" shall be the thickness of the weld overlay. For weld overlay examination volumes with unacceptable indications, the unacceptable indications will be removed and the volume will be re-welded. Reexamination per IWB-2420 is not required because unacceptable indications will be removed and the volume will be re-welded."
The scenario described in this paragraph discusses the acceptance examination of the weld overlay. Hatch is committing to compare any UT indication found to the IWB-3514-2 table. In addition, Hatch is stating that if an unacceptable UT indication exists, the flaw will be removed and the volume will be re-examined to address the acceptance examination of the weld overlay.
Section XI Subarticle IWB-2420, titled Successive Examinations, does not apply to this situation since the flaw was removed in the outage when the weld overlay was installed. The requirement for future examinations will be performed per Appendix 8 of the lSI Alternative.
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Enclosure 1 to NL-15-1621 SNC Responses NRC RAI No. 10 Section 3(c) states that inservice examinations of the FSWOLs will be performed in accordance with Q-4300 and 431 0 of Appendix Q to the 2004 Edition of Section XI with Addenda through 2005 with modifications. Appendix 8 presents the modified lnservice examination requirements.
(1) Clarify whether paragraphs (a), (b), and (c) as stated in the Modified Q-4300 lnservice Flaw Evaluation Requirements will replace paragraphs (a) and (b) in the existing Q-4300 lnservice Examination Requirements of the ASME Code,Section XI.
SNC Response to NRC RAI No. 10(1)
SNC indicated in their two lSI alternatives that Q-4300(a) and Q-4300(b) were being replaced with the paragraphs listed in Appendix 8 of the lSI Alternatives ALT-08-02 and ALT-15-01. In reality, both Q-4300(a) through (f) and Q-4310 were replaced with Appendix 8 in these two lSI Alternatives as stated under Section 3(c).
(2) If the Modified Q-4300 requirements will replace the existing Q-4300(a) and Q-4300(b),
discuss when the subject overlaid welds will receive their first ultrasonic examination after weld overlay installation.
SNC Response to NRC RAI No. 10(2) lSI Alternative ALT-15-01 requires both an acceptance examination and a baseline UT examination for each weld overlay to be performed during the 1R27 outage.
The first lSI examination of these weld overlays will be performed in one of the two next refueling outages for Hatch-1 (i.e., either the 1R28 outage in Spring 2018 or the 1R29 outage in Spring 2020). The timing decision will be made after the 1R27 outage.
(3) Modified Q-4300 lnservice Examination Requirement Paragraphs (b) and (c) mention the "unacceptable indications". What are the acceptance criteria for the unacceptable indications and based on which subarticle of the ASME Code?
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Enclosure 1 to NL-15-1621 SNC Responses SNC Response to NRC RAI No. 10(3)
As stated in the modified Q-4300 of the Hatch lSI Alternative, "unacceptable indications" require removal. An "unacceptable indication" occurs when a new or existing crack propagates into the weld overlay. SNC indicated in their lSI Alternatives that "the weld overlay (or the portion of the weld overlay containing the unacceptable indication) shall be removed and corrected by a repair/replacement activity in accordance with IWA-4000." There is no ASME Code subarticle to reference.
(4) ASME Code,Section XI, Q-4300 contains paragraphs a, b, c, d, e, and f. Discuss whether Q-4300 paragraphs c, d, e and f will be followed because Modified Q-4300 did not mention these four subparagraphs.
SNC Response to NRC RAI No. 10(4)
As noted in the response to NRC RAI No. 10(1), SNC indicated that Q-4300(a) and Q-4300(b) were being replaced with the paragraphs listed in Appendix 8 of the lSI Alternatives ALT-08-02 and ALT-15-01. In reality, both Q-4300(a) through (f) and Q-431 0 were replaced with Appendix 8 in these two lSI Alternatives as stated under Section 3(c ).
NRC RAI No. 11 Appendix 8, Modified Q-4300 Re-examination Requirements (b) specifies that " .. .If inservice examinations reveal acceptable crack growth or new cracking in the upper 25%
of the original weld or base materials ... " Discuss whether the crack is caused by stress corrosion cracking or some other degradation mechanism. The NRC staff noted that paragraph (c) provides requirements of the non-SCC flaws. However, Paragraph (b) does not reference whether the flaws are caused by sec.
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Enclosure 1 to NL-15-1621 SNC Responses SNC Response to NRC RAI No. 11 The treatment of flaws discovered by inspections is the same regardless of whether they are the result of SCC or fatigue. When inspections indicate that flaws penetrate into the 25% inspection zone, they are analyzed for both SCC and fatigue extensions over the prescribed service duration. The only differences in the analysis treatment are the rates of growth that are used and the driving functions for crack extension by each mechanism. Both are evaluated. The original design assumes a crack at least 75% through wall (original pipe, safe end wall thickness) or other thickness if the inspection crack sizing so indicates. If the acceptance inspection indicates a crack depth greater than assumed for the design, a reanalysis of the projected crack growth is performed.
NRC RAI No. 12 Provide a sketch or diagram of each subject weld that is applied with a FSWOL demonstrating that the ultrasonic examination of the overlaid weld will achieve 100 percent coverage of the required volume per the lSI Alternative. The sketch/diagram should include lines that represent the ultrasonic beam angles and signal path that cover the required volume.
SNC Response to NRC RAI No. 12 A figure has been developed for both the RC welds and the RHR welds showing the expected coverage. The RC weld overlay is designated as Figure RAI-12-1A while the RHR weld overlay is Figure RAI-12-1 B. Both figures are found in Enclosure 2.
NRC RAI No.13 Appendix 9 presents the inspection history and results of all 4 subject welds. Welds 1E11-1RHR-24A-R-13, 1B31-1RC-12BR-C-5 and 1B31-1RC-12BR-E-5 have previously detected indications. The indications in welds E-5 and R-13 have considerable depth with respect to the wall thickness.
(a) Discuss whether these indications will be removed or reduce in size prior to applying FSWOL. If not, justify.
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Enclosure 1 to NL-15-1621 SNC Responses SNC Response to NRC RAI No. 13(a)
The position of SNC is that these UT indications do not need to be removed or reduced in size.
As documented in the Reply to the Inquiry for ASME Code Case N-740, ASME provides two options for the repair of a defect in austenitic stainless steel or austenitic nickel alloy piping:
- Use of IWA-441 0 and IWA-4611 or
- A defect may be reduced to a flaw of acceptable size by the addition of a repair weld overlay.
Hatch has installed weld overlays previously and has determined that the best option in these cases is to re-work the existing weld overlays as described in this lSI Alternative. The response to RAI No.8 provides the SNC position about this and is repeated below for clarity.
The three welds with previous indications were overlaid during the outage when the UT indications were first observed. Since that time, UT examinations have been performed to show that the weld overlays are performing their function. The UT examination is qualified for the weld overlay and the outer 25 % of the original piping. In the case of the two RC weld overlays, the ultrasonic indication on each weld was observed beyond the outer 25 % of base material. In the case of the RHR weld overlay with an initial UT indication of about 50%
through wall, the existing UT indication was not observed {the indication was beyond the outer 25% examination volume). These examinations are confirmation that the weld overlays are performing their function. These examinations are located in high radiation dose areas and Hatch doesn't believe the dose is warranted when the weld overlays at Hatch and throughout the industry are mitigating intergranular stress corrosion cracking.
(b) Page 12 of the lSI Alternative states that ultrasonic examination will not be performed prior to FSWOL application. The indications in the above 3 welds were detected in 1984 and 1988. Without performing the ultrasonic testing prior to the FSWOL application, the current indication size would not be known. Section 2 of the lSI Alternative requires a crack growth calculation based on an initial flaw size. However, the indications in these three welds may have grown since the initial detection in the 1980's. Explain how the crack growth calculation can be performed if the initial flaw size is not known prior to the FSWOL application.
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Enclosure 1 to NL-15-1621 SNC Responses SNC Response to NRC RAI No. 13(b)
Hatch has worked with the designer of the weld overlays (Structural Integrity) to use 75 %
through wall calculation prior to the application of the weld overlays. After these weld overlays are completed, the UT examination results are reviewed by Structural Integrity to determine if a new crack growth calculation needs to be performed. Therefore, the criteria for the crack growth calculation is based on the UT examination after the weld overlay is applied ensuring that the latest information is used for the calculation.
NRC RAI No. 14 Appendix 3 to the lSI Alternative presents the preservice examination volume which is illustrated in Figure 3. Figure 3 identifies Note 1. However, Note 1 is not shown in Figure 3, nor Appendix 3. Clarify SNC Response to NRC RAI No. 14 For clarification, the correct Appendix 3 sketch is Figure 2.
SNC originally developed HNP-ISI-ALT-08-02 using guidance from ASME Code Case N-740 which has a corresponding figure (Figure 2) which included a reference to Note 1: "For axial and circumferential flaws, the axial extent of the examination volume shall extend at least %-
inch (13 mm) beyond the as-found flaw and at least ¥2-inch (13 mm) beyond the toes of the original weld end butter, where applied." In addition, the same note is in Appendix Q of the 2004 Edition with 2005 Addenda. In both of the lSI Alternatives, SNC included the note on Figure 2 but did not include the actual note as part of the package. SNC has satisfied the requirements of this note for previous examinations per lSI Alternative HNP-ISI-ALT-08-02 as documented on the NDE data sheets.
NRC RAI No.15 In Section 2.1, "Procedure qualifications," on page 16, paragraph (g) of the July 2, 2015 submittal, the licensee stated:
"The average lateral expansion value of the heat affected zone (HAZ) Charpy V-notch specimens shall be equal to or greater than the average lateral expansion value of the three unaffected base metal specimens. However, if the average lateral expansion value of the HAZ Charpy V-notch specimens is less than the average value of the unaffected base metal specimens and the procedure qualification meets all the other requirements of the Appendix 1 of the submittal, either of the following shall be performed:
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Enclosure 1 to NL-15-1621 SNC Responses (1) The welding procedure shall be requalified.
{2) An Adjustment Temperature for the procedure qualification shall be determined in accordance with the applicable provisions of NB-4335.2 of Section Ill, 2001 Edition with 2002 Addenda. The RTNoT or lowest service temperature of the materials for which the welding procedure will be used shall be increased by a temperature equivalent to that of the Adjusted Temperature."
Based on the above information, the staff requests that the licensee provide the following information:
(a) Identify whether aforementioned option (1) or option {2) was used in the temperbead weld qualification for Hatch weld overlays.
SNC Response to NRC RAI No. 15(a)
The procedure qualification coupon testing resulted in impact samples that exhibited higher average lateral expansion in the HAZ than in the base material. Therefore, the qualification coupon did not require an adjustment temperature per option (2) nor did it require requalification per option (1 ).
(b) If the welding procedure specification (WPS) was qualified with option {2), provide the value for the new Adjusted Temperature for the vessel component (where temperbead structural overlay is to be applied). Identify if this Adjusted Temperature value was considered in the evaluation of the vessel integrity analyses (e.g., pressure-temperature curves-if applicable).
SNC Response to NRC RAI No. 15(b)
Based on the response to RAI No. 15(a), this question does not apply.
E1-14
Edwin I. Hatch Nuclear Plant Unit 1 Response to Request for Additional Information on Proposed lSI Alternative to Install Four Full Structural Weld Overlays Enclosure 2 Figures to NL-15-1621 Figures STAINLESS STEEL CARBON STEEl VPJ.VE e.o* -~
~25,50 HATCH-1 RHR VALVE WOL PRE-1R27 OUTAGE CONFIGURATION FIGURE RAI-1b-1A 1E11*1 RHR*24A*R-12 1E11*1RHR-24AoR-13 E2-1 to NL-15-1621 Figures LOW ALLOY STEEL SA.CO!I ClASS 2 INCONEL 821182
. . , - - - BUTTER AND WELD (WCLDS)
-<= STAINLESS STEEL WELD (WELD4)
FOR INFORMATION ONLY 3116" STAIN..ESS STEEL CLADDING HATCH-1 RECIRCULATION SYSTEM INLET NOZZLE CONFIGURATION RECIRC VALVE WOL (TYPICAL CONFIGURATION FOR 1J NOZZLES)
FIGURE RAI-2c-1A 18::11-1RC.12BR-C-5 18::11-1RC.12BR-E-6 E2-2 to NL-15-1621 Figures EXISTING WOL REM NANT
[ -
STAINLESS STEEL ~ 5 I~ CARBON STEEL NOZZLE
- W ELl}' SAFE-END
\ 4/ CLADDING I I I ~------ ' '
WELDN0,4 FOR REFERENCE ONLY PIPE TO SAFE-END WELD HATCH*1 PRE*1R27 OUTAGE CONFIGURATION 12" RECIRC RISER PIPING FIGURE RAJ-3a-1A AT NOZZLE 1B31-1RC-12SR..C-5 1831*1RC-12BR-E*5 E2-3
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to NL-15-1621 Figures Nominal thickness of existing weld overlay is 0.23 inches.
1 - - -- 3,7
- I STAINLESS STEEL STAINLESS STEEL
- - -- - - - - e,o,*_- - - - - - - -
Ql25.50 HATC~1 RHR VALVE WOl PRE*1R27 OUTAGE CONFIGURATION FIOURE RAI-5a-1A 1E11-1RHR-24A*R*12 1E11-1RHR-24A*R*13 E2-6 to NL-15-1621 Figures DURING THE 1R27 OUTAGE, THE EXISTING OVERLAY THICKNESS WILL BE REDUCED AND PREPARED FOR THE NEW OVERLAY. A SURFACE EXAMINATION WILL THEN BE PERFORMED.
STAINLESS STEEL STAINLESS STEEL 1- -------6.0'-------- -1 Ql25,50 HATCH-1 RHR VALVE WOL INITIAl. WORK ON EXISTING WELD OVERLAY FIGURE RAI-Oa-18 1E11*1 RHR*24A*R-12 1E 11-1 RHR-.24A.R-13 E2-7 to NL-15-1621 Figures AFTER THE SURFACE EXAMINATION HAS BEEN PERFORMED ON THE WELD OVERLAY ON WELD #13 AND THE ADJACENT BASE MATERIAL, ER308L WILL BE INSTALLED AS A BUFFER LAYER (NON-CREDITED) AS SHOWN BELOW. AN ALLOY 52 MATERIAL BRIDGE IS ALSO INSTALLED.
AFTER THIS BUFFER LAYER IS INSTALLED A SURFACE EXAMINATION WILL BE PERFORMED, STAINLESS STEEL STAINLESS STEEL
- -- - - - - - - e.a
- : - - - - - - - -1
- 1 25,!;0 HATCH-1 ADDITION OF BUFFER LAYER RHRVALVE WOL FIGURE RAI-5a-1 C 1E11*1 RHR*24A*R-12 1E 11-1 RHR..24A-~ 1 3 E2-8 to NL-15-1621 Figures AFTER THE SURFACE EXAMINATION HAS BEEN PERFORMED ON THE BUFFER LAYER AND THE ADJACENT BASE MATERIAL.
THE WELD OVERLAY IS TO BE INSTALLED USING ALLOY 52M MATERIAL.
AFTER THIS WELD OVERLAY IS INSTALLED. BOTH A SURFACE AND A VOLUMETRIC EXAMINATION ARE TO BE PERFORMED PER THE lSI ALTERNATIVE, STAINLESS STEEL STAINLESS STEEL CARBON STEEL 1 - - - - - - - - 6,0::.....__ _ _ _ _ __
CZ12!:,50 HATCH-1 RHR VALVE WOt INSTALLATION OF WELD OVERLAY USING ALLOY 52M FIGURE RAI-Sa-10 1E11*1RHR-24A*R-12 1E11*1RHR-24A-R-13 E2-9 to NL-15-1621 Figures Nominal thickness of existing weld overlay is 0.12 inches.
4,80-"- - - - -
STAINLESS STEEL CARBON STEEL NOZZLE SAFE-END WELD N0.4 FOR REFERENCE ONLY PIPE TO SAFE-END WELD HATCH*1 PRE-1R27 OUTAGE CONFIGURATION 12" RECIRC RISER PIPING FIGURE RAI-6a-2A AT NOZZLE 1B31-1RC.12BR-C-5 1831-1RC.12BR-E.O E2-10 to NL-15-1621 Figures DURING THE 1R27 OUTAGE, THE EXISTING OVERLAY THICKNESS WILL BE REDUCED AND PREPARED FOR THE NEW WELD OVERLAY ON BOTH RC WELDS. A SURfACE EXAMINATION WILL BE PERFORMED.
EXISTING WOL REMNANT
[ -~ - ~;L- ~ --- STAINLESS STEEL SAFE-END CARBON STEEL NOZZLE
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WELD N0.4 FOR REFERENCE ONLY PIPE TO SAFE-END WELD HATCH*1 12" RECIRC RISER PIPING INITIAL WORK ON EXISTING WELD OVERLAY AT NOZZLE FIGURE RAI-5&-2B 1B31-1 RC-128 R.C-5 1 831* 1RC* 12BR-E* S E2-11 to NL-15-1621 Figures AFTER THE SURFACE EXAMINATION HAS BEEN PERFORMED ON EXISTING WELD OVERLAY AND THE ADJACENT BASE MATERIAL, THE WELD OVERLAY IS TO BE INSTALLED USING ALLOY 52M MATERIAL AFTER THIS WELD OVERLAY IS INSTALLED, BOTH A SURFACE AND A VOLUMETRIC EXAMINATION ARE TO BE PERFORMED PER THE lSI ALTERNATIVE.
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- BU n Eqi*IG FOR REF'ERErlCE DN!.Y PII'E TO !II.J"f.*EHO 't\'ElO HATCH-1 12" RECIRC RISER PIPING INSTALLATION OF WELD OVERLAY USING ALLOY 52M AT NOZZLE FIGURE RAI-5a*2C 1B31-1RC-12BR-C-5 1821-1RC-12BR-E-5 E2-12 to NL-15-1621 Figures Illustrative only The weld overlay examination volume Includes the weld overlay and the outer 25%
of the original base material, and at least 1/2 Inch from the weld toes, Including the buttering. The width Is wide enough to provide adequate scanning.
LOV ALLOY STEEL SA-508 CL 2 IJELD 4
<FOR REFERENCE ONLY>
Ha "t c h 1 N2C 8x N2E ND E w DL I ll ustro t ion Figure RM !A E2-13 to NL-15-1621 Figures Illustrative Only The examination volume includes the weld overlay and the outer 25% of the original base material, and at least 1/2 inch from the weld toes, Including the buttering. The width will be wide enough to provide adequate scanning.
Valve 1 - - - - - - - -6.0000 I Hatch 1 RHR NDE WOL Illustration Figure RAI-12-18 E2-14