NL-17-1194, Submittal of Response to Request for Information Fourth Interval Relief Requests RR-13, RR-14, RR-18, RR19, RR-23, and RR-24

Submittal of Response to Request for Information Fourth Interval Relief Requests RR-13, RR-14, RR-18, RR19, RR-23, and RR-24

ML17191B036
Person / Time
Site:	Hatch
Issue date:	07/10/2017
From:	Hutto J Southern Nuclear Operating Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
NL-17-1194
Download: ML17191B036 (10)

Text

J . J. Hutto 40 Inverness Center Parkway

~ Southern Nuclear Regulatory Affairs Director Post Office Box 1295 Birmingham , AL 35242 205 992 5872 tel 205 992 7601 fax jjhutto@southernco.com July 10, 2017 Docket Nos.: 50-321 NL-17-1194 50-366 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D. C. 20555-0001 Edwin I. Hatch Nuclear Plant Units 1 and 2 Response to Request for Information Fourth Interval Relief Requests RR-13, RR-14, RR-18, RR-19, RR-23. and RR-24 Ladies and Gentlemen:

By letter dated December 27, 2016 (Agencywide Documents Access and Management System Accession No. ML16362A273), Southern Nuclear Operating Company (SNC) submitted 11 Requests for Relief associated with the fourth 10-year Interval lnservice Inspection (lSI) Program for the Edwin I. Hatch Nuclear Plant, Units 1 and 2. The Nuclear Regulatory Commission (NRC) staff reviewed the information provided by SNC regarding relief requests RR-13, RR-14, RR-18, RR-19, RR-23, and RR-24 and requested additional information requested to complete its evaluation. The Enclosure provides the SNC response to the NRC requests.

This letter contains no NRC commitments. If you have any questions, please contact Ken McElroy at 205.992.7369.

Respectfully submitted, J. J. Hutto JJH/RMJ

Enclosure:

SNC Response to NRC Requests Cc: Regional Administrator, Region II NRR Project Manager- Hatch Senior Resident Inspector- Hatch RTYPE: CHA02.004

Edwin I. Hatch Nuclear Plant Units 1 and 2 Response to Request for Information Fourth Interval Relief Requests RR-13, RR-14, RR-18, RR-19, RR-23, and RR-24 Enclosure SNC Response to NRC Requests

Enclosure to NL-17-1194 SNC Response to NRC Requests RR-13 NRC RAI #1:

Relief Request RR-13 states "Subsection IWB of ASME Section XI of the 2001 Edition through

• the 2003 Addenda does not address the examination of weld overlays nor is this detail in later editions of ASME Section XI." It is not clear to the staff which Code requirements are applicable for the subject weld. Please clarify the Code requirements for the subject weld for which you are requesting relief.

SNC Response to NRC RAI #1:

SNC is requesting relief from Table IWB-2500-1 for category B-J welds, the weld in question is categorized as a B-J weld. Specifically, footnote 4 which states "Includes essentially 100% of the weld length." This is interpreted to mean essentially 100% of examination volume of the weld. Based upon the configuration of the overlay, as described in ISI-RR-13, this is not achievable.

NRC RAI #2:

The weld overlay was constructed to the requirements of NUREG-0313, Revision 2 "Technical Report on Material Selection and Process Guidelines for BWR Coolant Pressure Boundary Piping." NUREG-0313, Revision 2 states that 308L weld metal and cast stainless steel with less than 0.035% carbon and a minimum of 7.5% ferrite are adequately resistant to sensitization by welding. Please confirm that the cast valve is in compliance with NUREG-0313, Revision 2 (i.e.

the cast austenitic steel is less than 0.035% carbon and has a minimum of 7.5% ferrite)

SNC Response to NRC RAI #2:

The material specification for the valve adjacent to Weld 1B31-F031 B is A351-CF8M cast austenitic stainless steel (CASS). The chemical composition is shown below:

c Mn p s Si Ni Cr Mo N 0.05 0.53 .032 .007 1.12 9.47 19.03 2.22 0.04*

• Consistent w1th NUREG 7185 (ML 1522A007), mtrogen percentage 1s assumed to be 0.04 as 1t was not spec1f1ed for the valve body.

The ferrite content is determined by using the Hall's equivalent method [1] as specified in the GALL Report [2] and the Grimes Letter [3]. The Hall equivalent method is presented in Equations 1 through 4 below.

Creq = Cr + 1.21Mo + 0.48Si- 4.99 (1)

Nieq = Ni + O.llMn- 0.0086Mn 2 + 18.4N + 24.SC + 2.77 (2)

X= Creq (3)

Nieq OFe = 100.3X 2 -170.72X + 74.22 (4)

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Enclosure to NL-17-1194 SNC Response to NRC Requests From Equations 1 through 4, the ferrite content for the valve is calculated as 14.6%.

The carbon content of 0.05% exceeds the maximum value of 0.035% specified in NUREG-0313, Revision 2 while the ferrite content of 14.6% far exceeds the minimum of 7.5% specified in NUREG-0313, Revision 2. The limits on the carbon content and the ferrite content specified in NUREG-0313, Revision 2 ensure adequate resistance to intergranular stress corrosion cracking (IGSCC) resulting from sensitization by welding. Although the carbon content of the valve does not meet the criterion in NUREG-0313, Revision 2, studies have shown that CASS material with a higher carbon content can have adequate IGSCC resistance if it is compensated by higher ferrite content. The most comprehensive study on IGSCC resistance in CASS piping was performed in Reference [4] by a group of researchers from General Electric Nuclear Energy (GENE). The study was performed on several CASS grades which are typically used for BWR piping. This study developed a relationship between the carbon content and the ferrite content to provide adequate IGSCC resistance as shown in Figure 1. Lower carbon contents require a relatively small amount of ferrite for IGSCC resistance while higher carbon contents require more ferrite to provide IGSCC resistance.

OIO r-------------------------------------------------------~

CLGIID I~- 1G1CC OI'IN IYiiiiO&. - NO 1G1CC UO.IJ Al,..UINT LOW(" ~DAllY CW STAlS$ ~o:IQH fAILUAU HAL' raLUD IYUtol -IGICC- AT LlAST QHf IAWU CROSS MA1CMI D ITUI~- IIJNOA ENVI"CHMlNTAL l'<<fLUlNCt 001 OIJ e *

-OOJ 0011 l

~ 0 &li-e; IIIIG"fln411 3 004 0 t> 10110. . , ...

iU-WI LDl D AW

• LTl A!lf

• 1>0

'i/ STH UTI HAIItiiSUII J ACID OCI:I t>

0 0 ocn 0 00 0 001 0

Figure 1: IGSCC Resistance of CASS Based on Carbon Content and Ferrite Content [4]

As can be seen from Figure 1, at a ferrite content of 14.6%, a maximum carbon content of 0.08% can provide adequate IGSCC resistance in a welded component (top line on graph). The lower line represents items that are stress relieved in furnace and is not applicable in SNC's application. As such, the valve adjacent to Weld 1B31-F031 Bat Hatch Unit 1 with a carbon content of 0.05% is considered resistant to IGSCC and meets the intent of NUREG-0313, Revision 2.

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Enclosure to NL-17-1194 SNC Response to NRC Requests References

1. NUREG/CR-4513, Revision 2, "Estimation of Fracture Toughness of Cast Stainless Steels during Thermal Aging in LWR Systems," May 2016.

2. NUREG-1801, Rev. 2, Generic Aging Lessons Learned (GALL) Report, XI.M12, "Thermal Aging Embrittlement of Cast Austenitic Stainless Steel (CASS)," December 2010.

3. Letter from C. I. Grimes (USNRC) to D. J. Walters (NEI), "License Renewal Issue No.

98-0030, Thermal Aging Embrittlement of Cast Austenitic Stainless Steel Components,"

dated May 19, 2000.

4. N. R. Hughes, W. L. Clarke, and D. E. Delwiche, "lntergranular Stress-Corrosion Cracking of Austenitic Stainless Steel Castings," Stainless Steel Castings, ASTM STP 756, V. G. Behal and A. S.Melilli, Eds., American Society for Testing and Materials, 1982, pp. 26-47, ISBN-13: 978-0-8031-0740-3.

RR-14 NRC RAI #3:

Please provide the materials of construction for the subject welds and adjacent components (i.e., nozzle, safe end).

SNC Response to NRC RAI #3 The materials of construction for the subject welds and adjacent components are provided below:

component . I Mater.a Nozzle SB-166-600 Nozzle Butter lnconel Rod 182 Nozzle to Safe End Weld lnconel Rod 182 Safe End SA-182 F304 RR-18 NRC RAI #4:

Were any relevant indications identified during the examinations of welds 2E11-1 RHRM-24A-1 0 and 2E11-1 RHRM-248-10?

SNC Response to NRC RAI #4:

No recordable indications were found during the examination on 2E11-1RHRM-24A-10 or 2E11-1RHRM-248-1 0.

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Enclosure to NL-17-1194 SNC Response to NRC Requests NRC RAJ #5:

Figure RR-18-3 depicts the coverage achieved for axial flaws. Moreover, it appears that the coverage obtained does not include the subject weld. Please confirm. In addition, please provide the area of the weld that is contained within the American Society of Mechanical Engineers (ASME)-required 0.90 square inches.

SNC Response to NRC RAJ #5:

The 0.90 square inches was determined using the Figure IWB-2500-8 shown below. Volume C-D-E-F is the required examination volume.

114 *" I r-114**

I 1-CE*am vo*

E - F...,

Ccl NPS 4 er Laro-FIG IWB-2500-8 SIMILAR AND DISSIMILAR METAL WELDS IN COMPONENTS, NOZZLES, AND PIPING CCONT'Dl C1.'.! ln. = 13 mm, 1/ 4 tn. = 6 mml The ASME required volume is shown in the green box and represents the inner 1/3 of the thickness. This is the same for axial and circumferential directions. The two graphics below, included in the Relief request, show the coverage obtained by the axial and circumferential scans.

'I Ax. I

\ n

' - - - - - - - - - - - ' 0 90 sq In r: ulred ASMf coverase Circumferential

'------~---------~-~ os9~inamkNR The axial scan obtained 100% of the volume required (calculated to be 0.90 sq in). The circumferential scan obtained 0.59 sq in. This equates to 65% coverage on the circumferential scan. When the two scans are averaged together the coverage obtained is 82.5% as indicated in the Relief Request.

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Enclosure to NL-17-1194 SNC Response to NRC Requests RR-19 NRC RAI #6 Please provide the materials of construction for the eight austenitic piping components and welds.

SNC Response to NRC RAI #6 The materials of construction for the eight austenitic piping components and welds are provided below:

WeldiD Component Material 1 B31-1 RC-4A-1 OA/C Cap Note 1 Weld Note 1 Branch connection ASTM A 182 Gr 304 1 B31-1 RC-12BR-E-1/C Pipe ASTM A240 Gr A304 Weld ER308 Branch connection ASTM A 182 Gr 304 1 E21-1 CS-1 OB-20A/C Safe End ASTM A-182 Gr 316(note 2l Weld ER308L or E308L Safe End Extension ASTM A-182 Gr 316(note 2 l 1G31-1 RWCUM-6-0-5/A Valve A351 GR CF-8M Weld ER308 Elbow ASTM A-403 Gr WP304 1G31-1 RWCUM-6-D- Penetration SA-182 Gr F304 16/Table 6 Weld ER308 Pipe ASTM A-376 Gr TP304 2B31-1 RCM-22A-1/A Cross Low Carbon GE Type 316 NG(Note3)

Weld E308L Manifold Low Carbon GE Type 316 NG(Note3) 2B31-1 RCM-28AD-5/A Pipe Low Carbon GE Type 316 NG(Note3)

Weld E308L Cross Low Carbon GE Type 316 NG(Note3) 2B31-1 RCM-28BD-5-A Pipe Low Carbon GE Type 316 NG(Note3)

Weld E308L Cross Low Carbon GE Type 316 NG(Note3)

Note 1- Unable to locate the material for the cap and weld which was installed when the 4" diameter recirculation bypass line was cut and capped in 1980. The material would have been specified as equal to or better than the original material which was ASTM A240 Gr 304.

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Enclosure to NL-17-1194 SNC Response to NRC Requests Note 2- Material was specified as ASTM A182 Gr. F316 with a maximum' carbon content on 0.02%.

Note 3-The GE type 316 NG is an austenitic stainless steel with a high resistance to IGSCC in the BWR environment due to its low carbon content and the addition of molybdenum. This material has a carbon content not exceeding .02 weight percent. In addition, the nitrogen content of this alloy is controlled to counterbalance the loss in strength due to the relatively low carbon content. Increased pitting and sensitization resistance is provided by the addition of molybdenum.

RR-23 NRC RAI #7:

It is stated that "scans for axial flaws were not required for these ferritic welds." Please explain why examinations for axial flaws were not required by ASME Section XI, Table IWC-2500-1.

SNC Response to NRC RAI #7 This statement was in error. Scans for axial flaws were performed.

NRC RAI #8 It appears that some of the figures do not correspond to information listed in Tables RR-23-1 and RR-23-2. Please confirm the figures are correct. In addition, please clarify the following:

SNC Response to NRC RAI #8 The figures contained in the relief request are correct. One of the components related to figure 1 was mistakenly omitted from Table 2. The revised section of the table is listed below.

NRC RAI #8.a Figure 1 does not appear to correspond to any weld discussed in RR-23 SNC Response to NRC RAI #8.a Table RR-23-2 should have contained weld 2E41-2HPCI-16-TS-18. The modified table is shown below.

Table RR-23*2 Hatch-2 Weld Number I Description I Coverage I Basis for Limited Coverage 2E11-2RHR-6B-TSP-5 I 45' Elbow to Pipe 1 2R21

• 2011 I 78.9% I A restraint limited the examination of this weld (Fiaure 4).

i2E41-2HPCI-16-TS-1 6 I 45" Elbow to Tee/2R20.2009 I 60.0% l !..lmlted due to la!!er on lee and weld crown lfioure 1\

NRC RAI #8.b Is the circular protrusion in Figure 2 the welded attachment" that is referred to in Table RR-23-1?

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Enclosure to NL-17-1194 SNC Response to NRC Requests SNC Response to NRC RAI #8.b Yes, the circular protrusion in Figure 2 is the "welded attachment that is referred to in Table RR-23-1.

NRC RAI #B.c It is not clear to the staff where the "restraint discussed in Table RR-23-2 is depicted in Figure 4.

SNC Response to NRC RAI #B.c The photograph depicting the configuration limitation is below. The photograph shows a section of a restraint for an adjacent pipe.

RR-24 NRC RAI #9:

Were any relevant indications found within the 50% coverage that was obtained in the surface examinations?

SNC Response to NRC RAI #9 No recordable indications were found during the surface examinations.

NRC RAI #10 Please provide the materials of construction for the subject weld and adjacent components (i.e.,

nozzle elbow, flange).

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Enclosure to NL-17-1194 SNC Response to NRC Requests SNC Response to NRC RAI #1 0 The materials of construction for the subject weld and adjacent components (i.e., nozzle elbow, flange) are provided below:

2E21-2CS-POP-A-2 Component Material Nozzle Elbow SA-234 Gr WPB Weld E7018 Note4 Flange SA-350 Note 4- The weld material is proprietary information from the Original Equipment Manufacturer and was not available. The pump outlet assembly was fabricated at the pump manufacturer; however, this P1 to P1 weld is likely E7018 or equivalent filler material.

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