Text

Information Concerning Dissimilar Metal Weld in Pressurizer Safety Relief Nozzle-to-Safe-End Weld
	ML16069A020
Person / Time
Site:	Calvert Cliffs
Issue date:	03/05/2016
From:	George Gellrich; Exelon Generation Co
To:	; Document Control Desk, Office of Nuclear Reactor Regulation
References
	Download: ML16069A020 (16)
	v • d • e

George Gellrich Site Vice President

~Exe!.on Generation Calvert Cliffs Nuclear Power Plant 1650 Calvert Cliffs Parkway Lusby, MD 20657 410 495 5200 Office 717 497 3463 Mobile www. exeloncorp .com george.gellrich~exeloncorp.com March 5, 2016 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555 Calvert Cliffs Nuclear Power Plant, Unit No. 1 Renewed Facility Operating License No. DPR-53 NRC Docket No. 50-317

Subject:

Information Concerning Dissimilar Metal Weld in Pressurizer Safety Relief Nozzle-to-Safe-End Weld

References:

1. Letter from N. L. Salgado (NRC) to G. H. GelrInch (CCNPP), dated February 24, 2011, Relief from the Requirements of the ASME Code

2. Letter from D. T. Gudger (Exelon) to Document Control Desk (NRC), dated February 25, 2016, Report Concerning Dissimilar Metal Weld Flaw in Pressurizer Safety Relief Nozzle-to-Safe-End Weld In Reference 1, Calvert Cliffs Nuclear Power Plant, LLC was granted a relief from certain requirements of the American Society of Mechanical Engineers Code for dissimilar metal weld repairs. Reference 1 required that certain information related to a repair performed using this Code relief be provided to the Nuclear Regulatory Commission prior to entry into Mode 4 following the weld repair. A dissimilar metal weld on the Unit 1 pressurizer safety valve line was repaired during the current refueling outage using techniques approved by the subject Code relief. Attachments (1) and (2) contain the required weld overlay sizing analysis and the weld overlay material and size dimension drawing. The attached information, when combined with information previously submitted in Reference 2, meets the requirement to submit the required information prior to Unit 1 entry into Mode 4 conditions.

Document Control Desk March 5, 2016 Page 2 Should you have questions regarding this matter, please contact Mr. Larry D. Smith at (410) 495-5219.

Respectfully, George H. Gellinch Site Vice President G HG/KLG/psf Attachments: (1) Full Structural Weld Overlay Sizing for the Four-Inch Pressurizer Safety/Relief Valve Nozzles (2) Drawing 12024-0051 SH0001 cc: NRC Project Manager, Calvert Cliffs NRC Resident Inspector, Calvert Cliffs NRC Regional Administrator, Region I S. Gray, MD-DNR

ATTACHMENT (1)

FULL STRUCTURAL WELD OVERLAY SIZING FOR THE FOUR-INCH PRESSURIZER SAFETY/RELIEF VALVE NOZZLES Calvert Cliffs Nuclear Power Plant March 5, 2016

" DESCRIPTION¶ OF CONFIGURATION AND REPAIR PRocEss ""

The safety and relief ~alve nozles a're lociated in *the ulppe head of th~e pre~surzer and are fabricated with SA-50S Class 2 [7, Sectionhs 2-2-4 and 2-2-51 an~d are fitted with a SA-1 82 F3 16 Safe end [7, Sections 2-2-4 and 2-2-5]. The dissimilar metal weld (DMW) which joins the pressurizer safety/relief nozzles to the saf'e ends are fabricated using Alloy 821182 [10] nickel batsed weld metal.

The full structural overlay repair wiillbe performed using primary watet stress c:orrosion cracking (PWSCC) resistant Alloy 52M material depos~ited aro.und the circumference of dhe configuration. The overlay material will be deposited using the machine gas tungsten arc welding (GTAW) process. For the Alloy 52M weld overlay filler metal, the sele~cted material is. SB-166, Rod & Bar, Alloy 690 (S8Ni-29Cr-gFe) [6]. * ,. .. . .

ASME CODIE CRITER.A "

The applicable ASME Code,Section XI edition for Calvert Cli~ffs Nuc~lear Power Plant, Units. Iand 2 is the 2004 Edition [3] per Section 1.4 of Reference 11. The basis for FSWOL sizing is the ASME Code, Section Xl, Code Case N-740-2 [ I] and the ASME Code,Section XI, Division 1, Class 1 [31 rules for allowable flaw sizes in austenitic .andferritic piping (IWB-364.0). The ASME Code, Section.X11 Code Case N-740-2 [1] incorporates the weld repair by overlay approach documented in Code Case N-504-3

[4], and the temper bead welding app~roach documecnted in Code Case N-638-1 [8], and applies these to similar and dissimilar metal welds. To determine the overlay thickness, Code Case N-740-2 refers to the requirements of ASME Code, Section XlIWB-3640. IWB-3640 at' the applicable Code refers to Appendix C, which contains the specific methodology for meeting the allowable flaw sizes. The overlays are to be applied using the OTAW process, which is a nonflux process. Therefore, for cirumferential flaws, the source equations in Appendix C, Section C-5320 (limit load c:riteria) are the controlling allowable flaw size equations for *combinedloading (membrane plus bending) and membrane-only loading. These equations are valid for flaw depth-to-thickness ratios for flaw lengths ranging from 0 to 100% of the circumference as defined in Section C-5320 of Appendix C. For purposes of designing the overlay, a circumferential flaw is assumed to be 100% through the original wall thickness for the entire circumference of the item being overlaid.

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The overlay is sized by iusing the souirce equations iii Siection C-5320 [3]. :, .'

The allowable bending strs's unider combined membrane plus bending loads is given by the equation:

..i ... *.: . .. . S F--~.-o l LS J-- IJ ... . C-5321.

where..3 . . . . *=2>(2:)iP In e,f or(+/3) ,,

The allowable rm..brahe stress is given, by. thie equation ........ .

o' C-5322.

-°. (a

G' 2qzl. : . . ..

where,:

9' = arcsin{0.5(.*)sin 0],

and S,

aeb = allowable b ending strss for a circumfer'entially

= bending "stressatincipient pl ti.tcolla"pse.c flawed

?" .:.::pip~e"i". .....

. ' : + "

S~in = safety factor for membrane i+'Strssbased on Service Lev'el as shown in Table 1 [3, C-26211 SF,, = sf'ety factor for bendiig stress based on Service Level*as sown in Table 1 [3, C.262 I]

a =fotlwall thicns icue vra hcnsi h+* '*::+'

t, = toalowable thicknes (snclude ovrlay thicknmessn this clawed)i

=alloabl membrane stress a in foiri pastircwnfrollype flwe pipe : :': .. "+""

Ou = membrlawanlest 3,s atiniiguet plas10-i] 18°ollapse 0 l irufretalfa O = halflflaw angtea[3,xFigurefC-43d10i1] inIY o rfrad an10sfl ci.um.renia flaw:

,= angletoeneutral axismoryflawedpipe intresadihefans oai~

.+= flow stress = (s, + sa)/2 [3, C-8200(a)J +' .. .. ..

Si, *=Specifiedvalue for materiafl .yield strengt [6] at th!e. evaluation (operating) temperature s.= specified valu~e for material ultimate strength [6] at the evaluation (operating) temperature Safety factors are provided in Appendix C of Section Xl for evaluation of flaws in austenitic stainless steel piping. The safety factors used for the weld overlay sizing are shown in Table 1 and are taken from C-2621 [31.

2' II

Table 1: Safety Factors for Sizing- Circumferential Flaw Service .. Membrane Stress Safety Bending Stress

,, Level'*+!** Faictor 8P S,. Saifet Fac~tor, SFb* .

A 2.7 2.3

.....B 2.4 2.0

... C ].8 1.* . 1.6 D 1.I.3 .. 1.4 The overlay thickness must be established so that ithe flaw assu~mption herein meets the allowable.

flaw depth-to-thickness ratio requirement of te source equatons [3, C-5320], for the thickness of the weld-overlaid item, considering primary ebrane-plus-bending stresses, as well as membr'ane only stresses, per the source equations defined previously. Since the weld overlay is austenitic material and applied With a. nonflux welding process, which has hiigh fracture toughness, the limit load failure mode .isapplicable [3, Figure C-42i0-1 for nonflux welds] ad, hence, limit load e*,ijiaitioifi*'*'***

techniques are used here.

The non-overlaid piping stresses for use in the equa~tion! are, usually obtained from the applicable stress reports for the items to be overlaid. However, in this calculation, since the stresses are not provided, they are calculated based on; forces* and moimenta at the welds using equations from C-2500 of Section XI, Appendix C as described below.i Primary membrane stress (o'm) is given by:

Cm= pD/(4t), where:

p = maximum operating pressure for the.Sevicee.Level being considered ,**i D =- outside diameter of the component including the oveirlay.

t =t'hickness, consistent with the locatio*n ati whichl theo0Utside diameter is taken -

Sincluding the overlay (note that any inside diameter (ID) cladding is not counted Primary bending stress (ci)is given by:i -* -;. .:.' *: "-:

Gb=DM/(2[), where: .... :' .. * ; :'

D =outside diameter othcmpnnt includng t eo ly d = inside diameter consstent *with the point at which the outside diameter is taken

..."(note that ID cladding is not counted towar'd the inside, diameter)* i..

Mb =resultant moment for theappropriate primary load combination for each Service Level (square root of the sum of the squares (SRSS) of three moment components in X, Y, and Z diections) ,".

I =' moment of inertia, (ir/64) (D4'-d 4). " ; .. .." . -. - .

The contribution of axial .and shear forces toofpiping, stress XI, (other moments) is not included basd on C-2500 Section than force couples contributing to Appendixt C [3]; . .*,, -,, ,

The following l!oad co~mbinations are u~sed for"the full structural weld overlay. These are equivalent to the load co

m bination s defin ed in R eference ::2 (P age 13) v * *: : . . *- . "... * *. , , .; ,,. i .

",' service Level A (ormal): Pressure (P)'+Deadweight (DW)..* *... .*'*.-.....:."-

SerVice Level B (upset)*:* *' P +,OW S[kSS(Relief valve di.scharge transient (PORV) +

Operating basis..eart.hquake (ORE))

Service Level C (Emergency): P + DW + SRSS (PORV*i+ Delgignbasis earthqual~e (DBE))

Service Level D (Faulted): P,.+/- DW..+ SRSS (Safety v alv3e discharge: transient (SRV) or Once

, :7! :,*, **- 'through core cooling transient (OTCC) + DBE)*,*, :

Reference 2 (Page 13) states that the dynamic loads (pORV, OBE, DeE, SRV, OTCC) are combined, Service..Le~el* .A., B, C, and D in the ASM* Code [3] are alternatively referred as Normal, Upset,--

Emergency, and FaUlted conditions, respectively, in-this evajuation. .Per ASME Ccse,*Section XI,,:..

C-5-3 11. for theCombined Loading case, test conditions!shall be included with the Service L*eve B Load Combination. However, the hydro~static pressure test is notoapplic:able to the weld ov¢erlay: repair and is not included in the FSWOL design. In addition, the leak test requitement per, ASME Cod;,Section XI, IWB-5220 is included, in the design of the FSWOL sincee the.leak test pressure (2250 ps.ia given in :

Table I-1, Pressure Vessels of Reference 7) is the same as the operating pressure of 2250 psia

[Table I- I, Pressure veisael, of ReferenceT],. Tlicefore, no aidditional test condition nieeds to be ::.

included with the Service Level B Load Combination,** .. ::-.*..:*; *,*-**.-:*.:!-. '-

The weld overlay sizing is an ite rative process, in which the allowable stre~sse are calculated and then*

compared to the stresses in the overlaid component. 'If de stresses in the component are larger thian the allowable stresses in the component then the overlay thicknss is inc~reased, and theprocess Is repeated until it converges to an overlay thickness which meets the allowable Stresses.

The thickness of the weld overlay is determined through an iterative process* The thickness of the...

overlay (t01) is assumed resulting in total thicktness of(t,+-t01) where t* is the original pipe tlickness,,

The applied flaw size-to-thickness ratio based on~ aFSWOL (flawed through the original pipe wall, thickness, tp) is tp/(tp + t01). The allowable stresses are then determined from the source equations (see Section 3.0). If this allowable stress value is greater than the calculated stress for the overlaid component, the overlay thickness (to,) is reduced. On the other hand, if the allowable stress value is less than the calculated stress for the overlaid component, the overlay thickness (td) is increased. The process is repeated until the assumed overlay thickness results insa stress ratio of the calculated stress to the allowable stress that is equal or less than 1.0. As the maximum allowed value for alt is-0.75 [3, C-5320], t01 is initially set as t,,/3. If the overlay thickness of tp/3 meets the allowable stresses for pure membrane and combined membrane plus bending stresses, then no more iterations are performed.

If the allowable stresses are not met, then the overlay thickness is increased until the ratio of the computed stress to the allowable stress is less than or equal to 1.0.

WELD OVRA(Umc'S M* "-

The operatng pressure ([7,Table lI*.!i d~enislons [5 and overlay thicknes. ar shown in Table 4. At the thickness 6ftheIlD I*bittrlng)eseFgik*il). An* Ihitial, alt value of (f.75 (thu limiti~ng value 3600 flaw .resiitslr.!#f I .aWleng t.i

i*io 6f 1.0. Fi* 1 sf~ows the locations for fall structurai we*l- o"*rlay (FSWit)*sizinj: ;;*-**..... }... * .... '

"/ "*" i i*.';i'*,IA /lB " ."

. . ... . .... . . ... . . . . - '. .. -.. . 3..

"l ii 1 "'" If I " L ] i lJJ

. V A..*.. J.Z RE iE ... .. ..'*

.. L.....

I II

..... .. W

.AFE...*

.r

- E... .

()

FigUre 1: Locationa Exanited for FSqwoL Sizing . . .

"Table 4: Di~mensions fo'r Overlay Slzh*.I :'-: -"*. .. :*

Lo~atranlA, Loaton 1B L..atlon 2"

_______ (,dbtt.) (uo buttef Weid p, p$1g 2235 2235 2235.

tr 1 , In 1.313 t.094 1.313 lt o75

0. 0.75 0.75 toll In 0.38 0.3515 0.4a0 tprplii, In 1.78 1.48 1.75 D:lo, In e.938 e,792 8.93e t, !n4 105.5 93,38 108.855 Pipe + Owdy___ _______

The final calculated membrane stresses (cv,,n) and bending stresses (at) at each service level for the pipe +

overlay configuration are shown in Table 5. This table also shows the ratio of the membrnme stress (arm) to the flow stress (C'r)at the selected Locations. The material properties are evaluated at the normal operating temperature of 6530 F (7, Table I-I] using Section 11, Part D of the ASME Code [6].

SO /

~~~Table 5: Calculgted Stresses *, *=

., Locution "A

.... t... 18* Lo iati '

.of, psI 53744. 83744 53.744

______ am/o*= .O.,*lt 0.048 0,041 A " No.=rm~al ~bmpsi 7......

01 . ... . 78.5 ..... 701 B ,. Up~set db, ps~iI ... '1553 . 17**t.40 *553 1f 0 Faulted 0 b,pai.. .. 2108 . 238. .210.8 Tablemembrane The 6 shows the andallowable stresses from bending stresses as determ*ined fro~m Table 5 are the source compared to theequations allowable discussed stresses inasSection shown 3.0.

by the ratios in Table 6. The limiting cases for the membrane and bending stresses arc shown in bold. In the limit load analyses, the flow stress of the Alloy, 52M weld overlay material is used, consistent with the assumption of a full 360° flaw through the original pipe wall for the design of the full structural weld overlay ... " ' . " ' "" " ..

~5oI~ ii

l e6: Al owbl T a b. le"6:- . A l l owa bl e.. ..: .t-re se

' . s"se

, "S lS es~eu Rai o

-s,.. t r e sss R a t ioal ore bnlelc

.. C a lc u l.'a"t. e d, S t r e;s- to.. A...Tb a..an d,

_______ ~ p t.*Si 052470. .~0,166 0.5247

_____ ______________ 0;!142e' '0..h66 . l0.428 Letel A Normal S,, psi 4920 738! ... 7921 Lewilc Emergency 8t, p8i 1474118146 12407.4 LewI 0 Faitlted Si, psi 14733S .. .. 422f' .. 14733 0...*t,., .....

Lewi B LewiC (( Upse~t o*h/S, Emereny om/St 0.3957 0.2967- .

J .*. 0,.4648 0.3488'-' J 0.3957 0'.2967' Lewei O Fautd Gtn1 t 0.2143 0,2518 0.2143 Notes: o,' -Bending strss 3So-Allowable ldidgn tes ['3,plasti"c at IncipIent colapse [-3, :..

C.5320];,. C,5320]

S.-Allowable membrane stress [3, C-5320],

e" -Membrane stress at incipient plastic collapse [3, C-5320]

...(All terms defined InSection3'.0).,. .:.:

The weld overlay length must consider three requirements: (I) length required for structural**.'

reinforcement, (2) length required for preservice examination access of the overlaid weld, and"(3) limitation on the area of the nozzle surface that can be. overlaid, Structural Reinforcement Structural reinforcement requirements are expected to be satisfied if the weld overlay length is 0.75.J'*

on either side of the susceptible weld being overlaid [1], where R is outside radius of the item arnd t is the nominal thickness of the item at the applicable side of the overlay. However, to assure ASME Code,Section III, NB-3200 [9] compliance, detailed shear stress calculations are instead performed to determine the minimum required structural length.

7oF Ii

The sc~tio, .alpngthel lengtitem.

h of the overlay is ovaluated for axial S*uipargrph NW-3shear due[9]

227.2 to transfer imitsf pure of axial shear load and due to moment from *he.overla~id. to.the overay.*

Design L~oadings, Test Load'in' or; an" Service Level loadings except Service Level D to 0.6Smn.

Therefore, O.6s,~i~i ds for serIce Levels A, l, and .C. *or Service Level D (Faulted) coniditions, the stress intensityI im*it is theilesserof 4m or 0,7s* [,[NB-3225 andI Appendix F], equivalent to the lesser of 1.ZSm, or,o.35Su* br shear stres,*Thpe v'alues ire shown in Table 7 for the safe end, nozzle and weld Shear stress* around the~circumferencee at the overlay-base material interface due to axial force and moment loading equals: .... . -!.. ..

w here: " l: * "* ' .. . : ".... .." ... ... . . . . ..

=outside radius of overlaid item at crack ! !. ... i :I Li=' length of ovrlay at outside surface of overlaid item on one side of crack

,4= shear area, ,2iR 0 L., " ....

P, = pressure, psig.<. : '. * .:,- . . .

M. = resultanit momment from piping interf'ace loads at crack.. ..

Thus =-PiiR02/(2azR 0 L) +M(dL)', .... ' " ": '...' '"

Solvhing for L and equating r with tlhe allowable shear stress (Sdtw yields: .

L [PR11 2 + 4/(*l2)]/Sio, where:. , " . .

= 0.63.(Service Levels A, B nd C) .":i* . .

=Lesser of 1.2Sm and 0,358. (Service ILevel D).'

The evaluation for required length is documented in Table 7 for the-pressurizer sa~fety/relief valve nozzles and safe ends. The overlay weld metal is also evaluated (at the s;mallest diameter) as it may control if the base metal has a higher value Of Sin. The greater yalue of the required Overlay length will be taken. The material properties are evaluated at the normal operating temperatur of 6530 F [7, Table 1-11 using Section II, Part D of the ASME Code [6]. * '* :*' . ...

f'ro /1

.* Table 7: Mniamum Required Ov/erlay Length*: *'r

..., i *'*"Location 1A,1B

Location 2. Location.A16162 R0, in i 3.03 3.03 3.03 Material.Class 28'0 SA-182 F316 Alloy 52M Sen*csLewi A O.6St,* kal ...... 18.02 9..

.95 ..... 13.98" Ser~ce ~li C0.6Sm, kela* *. 16..4.02 ... .9.95 ... : 13.98*-..

SI4Ce

- LeVil D *-1;2Smi ksl . .. 32.04-. +*+++ 19.90 ,.27.90, Ser*¢ae Level D0O.35S0, icat 28* 25.13 28.00 ...

Serdce Leel A 1, in 0.258 0,415 0.298 Sar~ce Level B L, in 0.315 0.807* 0.361 Sdnice Level C L*, In 0.350 0.563 0.401 Senecae Level 0 L,In 0.201 0.283 0.202 The required overlay length is c:alcUlated at Locations IA, IB, and 2 along the* nozle and safe end configuration (see Figure 1). N*ote that these locations are evaluated twice; wite WOL metal and nozzle and safe end base metal (see Table 7). The design drawing implements'a configuration that meets all the designed FSWOL thickness and length requirements.

The lengths shown in Table 7 ensure adequate shear stress transfer along the length of the weld overlay.

Service Level C is the most limiting of all cases. This length is sufficient to trasf'er the imposed loads and maintain stresses (sheary'within the appropriate ASME Code allowable limits.

In addition)to the necessary shear transfer length, the overlay must be inspectable by PDI qualified UT methods. Any additional length determined to be necessary by the UT personnel for proper PDI' qualified inspection will be noted on a design drawing.

Preservice Examination Weld overlay access for preservice examination requires that the overlay length and profile be such that the overlaid weld and any adjacent welds can be inspected using the required NDE techniques. This requirement could cause the overlay length to be longer than required for structural reinforcement. The specific overlay length required for preservice examination is determined based on the examination techniques and proximity of adjacent welds to be inspected.

9~F ii

.. Area Limitation on Nozzle The total weld overlay surface area is limited to 500 in2 [1, Section 1-1] (this value will be specified in the relief request) on the nozzle (ferritic base material) when using amhiei~t temperature temper bead welding to apply the 0Verlay. Using an outside diameter of 6.0625", the maximum length is limited to 500/ (nD0) --26.25" on the ferritic steel nozzle material. The required overlay length on the nozzle is less than this limit (see Table 7).

SMaximum Overlay Sizing This calculation documents the minimum overlay thickness and length necessary fbr structural requirements. Additional thickness and length may be added to addr~ess Inspectability and crack growth concerns. [n addition, a maximum overlay thickness (typically an additional 0.25") and a maximum overlay iength Will be determ.ined. The determination of the maximum length is based on implementation factors and is intended to be large enough so as to not unnecessarily constrain the o*verlay process. These dimensions Will be indic~ated on a, subsequent design drawing to create a "box" within *which the *overlay is analyzed. In the subsequent analy~es, the finite element models use the geometry (minimum or maximum) that will produce conservative results.

DI,SCUSSIONS AND CONCLUSIONS Table 8 antd Figure 2 summarize the m!inium requird overlay dime nsions. This calculation documents the development of a weld overlay design for the*pressurizer safety/relief valve nozzle-to-safe end*

DMWs at the Calvert CliffsNuclea Power Plant, Units ! and 2. The design meets the requirements of the ASME Code, Section *XI, C*ode Case N-740-2 [1] and AsME Code,Section XI, Appendix C [3] for a full structural Weld overlay.

The weld overlay sizing presented in Table 8 is based upon the primary loadings documented in Section 4.0 and using the criteria from the ASME Code, Section Xl, Appendix C. The Overlay thicknesses and lengths listed in Table 8 meet ASME Code stress criteria.

Table 8: Minimum Required Overlay Dimensions I Location Thickness(in Lnt l)

INozzle Side of DMW (IAIIB) I 0.438 I 0.401 Safe End Side of DMW (2 0.438 0.564 Figure 2: Full Structural Weld Overlay Geometry, Minimum Dimension. (Schematic Representation)

/0 or Ii

REFERENCEs ***'* .. ,:;:. , *'"*.:!. ;

1 .. ASME Boiler and Pressure Vessel Coda, Code Case N-740-2, "Full Structural Dissimilar

.:*:Metal Weld Overlay for Repair"or Mitigaition of Class, 1, 2, and .3Item's, Section* XI, "'

2. Calvert Cliffs Design C~alculaition No. CA05999, "Unit 2 Pressurizer Reiief Va'lve Class I

Analysis,"! Rev.~ 0, S][ File No.0801014.216..

Nuclear Power Plant C o6nents *2004 Edition .... " .... ': ..

4. ASME Boiler and Pressure Vessel Code, Code Case.N-504-3, "Alternative Rules for Repair of Cliasse's 1:2, anid -3 ,usfenitlii Stainle~ss Steel Piping,'Section Xi, Division 1."

5. Calvert Cli ffs Drawiing N'o. 1i209-12, R*:V. 2, "Nozle Details for 6750-M-485-15-4, 96" i.D. Pressurizer," SI File Nqo. 001014.215. ":

6. ASME Boiler and Pr-essure Vessel Code, Section 11, part D, Material Properties, 2004 Edition.

7. Combustion Engineering Book No. 72367, "Instnuction Manual, Pressurizer, Calvert Cliffs Station" Si File No. 0'801014.213. .. .. .. :...

8. ASM'E Boiler aid Pr~essur Vessel Code', Code Case N-638-1, "iSimil~ar ad Dissimilar Section XI, Division I." - , * . - .:.. :. * :**,.

9. ASME Boiler and Pressure Vessel Code, Section 111, Rules for Construction of Nuclear Facility Component~s, 2004 Edition. . ... ... *.... ... . ... ... . ..

10. CCNPP Table 21-4, "Unit I Alloy 82/182 Full Penetration Welds," SI File No.

0801014.205. *, -o .. .***.:: " :'. : *: ,.* . '.*

11. Attachment (1) to Constellation Eniergy Letter to USNRC, December 29, 2008, "Fourth Interval Inservice Inspection Program Plan for Calvert Cliff's Nuclear Power Plant Units 1 and 2," Rev. 0, SI File No. 0801014.211.

12. CCNPP Design Specification No. 8067-31-4, "Project Specification for a Pressurizer Assembly for Calvert Clifis 1 & 2," Rev. 12, Feb 2006, SI File No. 0801014.212.

)13r 2/

ATTACH MENT 2 DRAWING 12024-0051 SH0001 Calvert Cliffs Nuclear Power Plant March 5, 2016

George Gellrich Site Vice President

~Exe!.on Generation Calvert Cliffs Nuclear Power Plant 1650 Calvert Cliffs Parkway Lusby, MD 20657 410 495 5200 Office 717 497 3463 Mobile www. exeloncorp .com george.gellrich~exeloncorp.com March 5, 2016 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555 Calvert Cliffs Nuclear Power Plant, Unit No. 1 Renewed Facility Operating License No. DPR-53 NRC Docket No. 50-317

Subject:

Information Concerning Dissimilar Metal Weld in Pressurizer Safety Relief Nozzle-to-Safe-End Weld

References:

1. Letter from N. L. Salgado (NRC) to G. H. GelrInch (CCNPP), dated February 24, 2011, Relief from the Requirements of the ASME Code

2. Letter from D. T. Gudger (Exelon) to Document Control Desk (NRC), dated February 25, 2016, Report Concerning Dissimilar Metal Weld Flaw in Pressurizer Safety Relief Nozzle-to-Safe-End Weld In Reference 1, Calvert Cliffs Nuclear Power Plant, LLC was granted a relief from certain requirements of the American Society of Mechanical Engineers Code for dissimilar metal weld repairs. Reference 1 required that certain information related to a repair performed using this Code relief be provided to the Nuclear Regulatory Commission prior to entry into Mode 4 following the weld repair. A dissimilar metal weld on the Unit 1 pressurizer safety valve line was repaired during the current refueling outage using techniques approved by the subject Code relief. Attachments (1) and (2) contain the required weld overlay sizing analysis and the weld overlay material and size dimension drawing. The attached information, when combined with information previously submitted in Reference 2, meets the requirement to submit the required information prior to Unit 1 entry into Mode 4 conditions.

Document Control Desk March 5, 2016 Page 2 Should you have questions regarding this matter, please contact Mr. Larry D. Smith at (410) 495-5219.

Respectfully, George H. Gellinch Site Vice President G HG/KLG/psf Attachments: (1) Full Structural Weld Overlay Sizing for the Four-Inch Pressurizer Safety/Relief Valve Nozzles (2) Drawing 12024-0051 SH0001 cc: NRC Project Manager, Calvert Cliffs NRC Resident Inspector, Calvert Cliffs NRC Regional Administrator, Region I S. Gray, MD-DNR

ATTACHMENT (1)

FULL STRUCTURAL WELD OVERLAY SIZING FOR THE FOUR-INCH PRESSURIZER SAFETY/RELIEF VALVE NOZZLES Calvert Cliffs Nuclear Power Plant March 5, 2016

" DESCRIPTION¶ OF CONFIGURATION AND REPAIR PRocEss ""

The safety and relief ~alve nozles a're lociated in *the ulppe head of th~e pre~surzer and are fabricated with SA-50S Class 2 [7, Sectionhs 2-2-4 and 2-2-51 an~d are fitted with a SA-1 82 F3 16 Safe end [7, Sections 2-2-4 and 2-2-5]. The dissimilar metal weld (DMW) which joins the pressurizer safety/relief nozzles to the saf'e ends are fabricated using Alloy 821182 [10] nickel batsed weld metal.

The full structural overlay repair wiillbe performed using primary watet stress c:orrosion cracking (PWSCC) resistant Alloy 52M material depos~ited aro.und the circumference of dhe configuration. The overlay material will be deposited using the machine gas tungsten arc welding (GTAW) process. For the Alloy 52M weld overlay filler metal, the sele~cted material is. SB-166, Rod & Bar, Alloy 690 (S8Ni-29Cr-gFe) [6]. * ,. .. . .

ASME CODIE CRITER.A "

The applicable ASME Code,Section XI edition for Calvert Cli~ffs Nuc~lear Power Plant, Units. Iand 2 is the 2004 Edition [3] per Section 1.4 of Reference 11. The basis for FSWOL sizing is the ASME Code, Section Xl, Code Case N-740-2 [ I] and the ASME Code,Section XI, Division 1, Class 1 [31 rules for allowable flaw sizes in austenitic .andferritic piping (IWB-364.0). The ASME Code, Section.X11 Code Case N-740-2 [1] incorporates the weld repair by overlay approach documented in Code Case N-504-3

[4], and the temper bead welding app~roach documecnted in Code Case N-638-1 [8], and applies these to similar and dissimilar metal welds. To determine the overlay thickness, Code Case N-740-2 refers to the requirements of ASME Code, Section XlIWB-3640. IWB-3640 at' the applicable Code refers to Appendix C, which contains the specific methodology for meeting the allowable flaw sizes. The overlays are to be applied using the OTAW process, which is a nonflux process. Therefore, for cirumferential flaws, the source equations in Appendix C, Section C-5320 (limit load c:riteria) are the controlling allowable flaw size equations for *combinedloading (membrane plus bending) and membrane-only loading. These equations are valid for flaw depth-to-thickness ratios for flaw lengths ranging from 0 to 100% of the circumference as defined in Section C-5320 of Appendix C. For purposes of designing the overlay, a circumferential flaw is assumed to be 100% through the original wall thickness for the entire circumference of the item being overlaid.

!o/

The overlay is sized by iusing the souirce equations iii Siection C-5320 [3]. :, .'

The allowable bending strs's unider combined membrane plus bending loads is given by the equation:

..i ... *.: . .. . S F--~.-o l LS J-- IJ ... . C-5321.

where..3 . . . . *=2>(2:)iP In e,f or(+/3) ,,

The allowable rm..brahe stress is given, by. thie equation ........ .

o' C-5322.

-°. (a

G' 2qzl. : . . ..

where,:

9' = arcsin{0.5(.*)sin 0],

and S,

aeb = allowable b ending strss for a circumfer'entially

= bending "stressatincipient pl ti.tcolla"pse.c flawed

?" .:.::pip~e"i". .....

. ' : + "

S~in = safety factor for membrane i+'Strssbased on Service Lev'el as shown in Table 1 [3, C-26211 SF,, = sf'ety factor for bendiig stress based on Service Level*as sown in Table 1 [3, C.262 I]

a =fotlwall thicns icue vra hcnsi h+* '*::+'

t, = toalowable thicknes (snclude ovrlay thicknmessn this clawed)i

=alloabl membrane stress a in foiri pastircwnfrollype flwe pipe : :': .. "+""

Ou = membrlawanlest 3,s atiniiguet plas10-i] 18°ollapse 0 l irufretalfa O = halflflaw angtea[3,xFigurefC-43d10i1] inIY o rfrad an10sfl ci.um.renia flaw:

,= angletoeneutral axismoryflawedpipe intresadihefans oai~

.+= flow stress = (s, + sa)/2 [3, C-8200(a)J +' .. .. ..

Si, *=Specifiedvalue for materiafl .yield strengt [6] at th!e. evaluation (operating) temperature s.= specified valu~e for material ultimate strength [6] at the evaluation (operating) temperature Safety factors are provided in Appendix C of Section Xl for evaluation of flaws in austenitic stainless steel piping. The safety factors used for the weld overlay sizing are shown in Table 1 and are taken from C-2621 [31.

2' II

Table 1: Safety Factors for Sizing- Circumferential Flaw Service .. Membrane Stress Safety Bending Stress

,, Level'*+!** Faictor 8P S,. Saifet Fac~tor, SFb* .

A 2.7 2.3

.....B 2.4 2.0

... C ].8 1.* . 1.6 D 1.I.3 .. 1.4 The overlay thickness must be established so that ithe flaw assu~mption herein meets the allowable.

flaw depth-to-thickness ratio requirement of te source equatons [3, C-5320], for the thickness of the weld-overlaid item, considering primary ebrane-plus-bending stresses, as well as membr'ane only stresses, per the source equations defined previously. Since the weld overlay is austenitic material and applied With a. nonflux welding process, which has hiigh fracture toughness, the limit load failure mode .isapplicable [3, Figure C-42i0-1 for nonflux welds] ad, hence, limit load e*,ijiaitioifi*'*'***

techniques are used here.

The non-overlaid piping stresses for use in the equa~tion! are, usually obtained from the applicable stress reports for the items to be overlaid. However, in this calculation, since the stresses are not provided, they are calculated based on; forces* and moimenta at the welds using equations from C-2500 of Section XI, Appendix C as described below.i Primary membrane stress (o'm) is given by:

Cm= pD/(4t), where:

p = maximum operating pressure for the.Sevicee.Level being considered ,**i D =- outside diameter of the component including the oveirlay.

t =t'hickness, consistent with the locatio*n ati whichl theo0Utside diameter is taken -

Sincluding the overlay (note that any inside diameter (ID) cladding is not counted Primary bending stress (ci)is given by:i -* -;. .:.' *: "-:

Gb=DM/(2[), where: .... :' .. * ; :'

D =outside diameter othcmpnnt includng t eo ly d = inside diameter consstent *with the point at which the outside diameter is taken

..."(note that ID cladding is not counted towar'd the inside, diameter)* i..

Mb =resultant moment for theappropriate primary load combination for each Service Level (square root of the sum of the squares (SRSS) of three moment components in X, Y, and Z diections) ,".

I =' moment of inertia, (ir/64) (D4'-d 4). " ; .. .." . -. - .

The contribution of axial .and shear forces toofpiping, stress XI, (other moments) is not included basd on C-2500 Section than force couples contributing to Appendixt C [3]; . .*,, -,, ,

The following l!oad co~mbinations are u~sed for"the full structural weld overlay. These are equivalent to the load co

m bination s defin ed in R eference ::2 (P age 13) v * *: : . . *- . "... * *. , , .; ,,. i .

",' service Level A (ormal): Pressure (P)'+Deadweight (DW)..* *... .*'*.-.....:."-

SerVice Level B (upset)*:* *' P +,OW S[kSS(Relief valve di.scharge transient (PORV) +

Operating basis..eart.hquake (ORE))

Service Level C (Emergency): P + DW + SRSS (PORV*i+ Delgignbasis earthqual~e (DBE))

Service Level D (Faulted): P,.+/- DW..+ SRSS (Safety v alv3e discharge: transient (SRV) or Once

, :7! :,*, **- 'through core cooling transient (OTCC) + DBE)*,*, :