NL-10-1419, HNP-ISI-ALT-10, Version 1, Temporary Non-Code Repair Service Water System, Response to Request for Additional Information

HNP-ISI-ALT-10, Version 1, Temporary Non-Code Repair Service Water System, Response to Request for Additional Information

ML102010574
Person / Time
Site:	Hatch
Issue date:	07/20/2010
From:	Ajluni M Southern Nuclear Operating Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
NL-10-1419 SMSH-10-007
Download: ML102010574 (16)

Text

Southern Nuclear Operating Company. Inc.

SOUTHERN'\\'

COMPANY July 20,2010 Docket Nos.: 50-321 NL-10-1419 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D. C. 20555-0001 Edwin I. Hatch Nuclear Plant - Unit 1 HNP-ISI-ALT-10, Version 1, Temporary Non-Code Repair Service Water System Response to Request for Additional Information Ladies and Gentlemen:

On July 16, 2010, Southern Nuclear Operating Company, Inc. (SNC) submitted letter NL-10-1377, HNP-ISI-ALT-10, Version 1, Temporary Non-Code Repair Service Water System, to the Nuclear Regulatory Commission (NRC). During a telephone conversation on July 19, 2010, the NRC staff requested SNC to submit the enclosed flaw evaluation, SMSH-10-007, Version 2.0, 30" Plant Service Water Header Pinhole Leak Evaluation. The requested flaw evaluation is included as an enclosure to this letter.

This letter contains no NRC commitments. If you have any questions, please contact Jack Stringfellow at (205)992-7037.

Respectfully submitted, iYLvJ~ r-M. J. Ajluni Nuclear Licensing Director MJA/EGAllac

Enclosure:

Flaw Evaluation SMSH-10-007, Version 2.0

U. S. Nuclear Regulatory Commission NL-10-1419 Page 2 cc:

Southern Nuclear Operating Company Mr. J. T. Gasser, Executive Vice President Mr. D. R. Madison, Vice President - Hatch Ms. P. M. Marino, Vice President - Engineering RTYPE: CHA02.004 U. S. Nuclear Regulatory Commission Mr. L. A. Reyes, Regional Administrator Mr. R. E. Martin, NRR Project Manager - Hatch Mr. E.D. Morris, Senior Resident Inspector - Hatch Mr. P.G. Boyle, NRR Project Manager

Enclosure Edwin I. Hatch Nuclear Plant - Unit 1 SMSH-10-007, Version 2.0 30" Plant Service Water Header Pinhole Leak Evaluation

SOUTHERNA Southern Nuclear Design Calculation COMPANY E"uv,.Snw Y"..,.WOrU' Calculation Number:

SMSH*I0-007 Plant:

Unit:

Discipline:

Hatch

[&]1 02 01&2 Stress

Subject:

Pipe Stress 30" Plant Service Water Header Pinhole Leak Evaluation Analysis SW Pipe Purpose I Objective:

Pipe Stress Analysis System or Equipment Tag Numbers:

P41 Contents Topic Page Attachments

1. of (Computer Printouts, Technical Papers, Sketches, Pages Correspondence)

See Purpose of Calculation A. Minimum Pipe Thickness calculation 1

pg. 1 Design inputs B. Field Inspection Data 2

References C. Evaluation per GL 90-05 4

Assumptions Evaluation Conclusion Total # of Pages including 13 cover sheet & Attachments :

Nuclear Quali Level OIl Safet -Related o

Safet Si niflcant o

Version Record Originator Reviewer Approval!

Approva12 Version PrlntedN.....

PrlRtedN.....

PrlRted_

PrlntedNamo No.

Description lnIdall Date lnIdall DIote lnIda1l Date lnIda1l Date Pipe Stress Evaluation of Pinhole Leak:

Scott Pellet An Nguyen Mike Burgess Mike Burgess 1.0 on Service Water Piping Header 07/0712010 07/07/2010 07/07/2010 07/07/2010 Added assessment of additional mass of Scott Pellet An Nguyen Mike Burgess Mike Burgess 2.0 proposed mod and eval per GL 9(}"05 07/14/2010 07/14/2010 07/14/2010 07/14/2010 Revised sht. 1 & 3.

Scott pelle~t VA Patel/.d,,!, MikeBUrg~

3.0 Mike~t1 07/20/2010 07/20/2010 07/20/201

~ 07/20/201 Notes:

Southem NI D' cu atlons uc ear eSlgn Call' Plant:

Unit:

Calculation Number:

Hatch 001 02 01&2 SMSH-10-007

Title:

Sheet:

i 30" Plant Service Water Header Pinhole Leak Evaluation R.*

eVlSlon L o~.

Ver.

No.

Description By:

Date Chk:

Date 1

Pipe Stress Evaluation of Pinhole Leak on Service Water Scott Pellet 07/07/10 An Ngyuen 07/07/10 Piping Header 2

Added assessment for impact of additional mass of proposed Scott Pellet 07114110 An Ngyuen 07114/10 modification and eval per GL 90-05 3

Made editorial corrections (sht. 1 & 3)

Scott Pellet 07/20/10 VR Patel 07120110

South Plant:

Unit:

Hatch l&J1 02 01&2

Title:

30" Plant Service Water Header Pinhole Leak Evaluation Table of Contents Description Purpose.........................................................................................

Background.....................................................................

Design Inputs...............................................................

References..............................

Assumptions.....................................................................

Evaluation.....................................................................

Conclusion.....................................................................

ern Nucear DeSlgn C I I.

a cu atlons Calculation Number:

SMSH-10-007 Sheet:

ii Page Last Page 1

1 2

2 2

2 2

2 3

3

Southern Nucear oeSlgn C I I.

a cu atlons Plant:

Unit:

Calculation Number:

Hatch 001 02 01&2 SMSH-10-007 TItle:

Sheet:

30" Plant Service Water Header Pinhole Leak Evaluation I

Purpose:

This calculation performs a piping stress analysis for a pipe flaw and checks compliance with the applicable code requirements. The initial version of this calculation was prepared to support the determination of operability.

Subsequent to version I of this calculation, it was decided to perform a non-Code repair on the pipe in order to stop the leakage as a housekeeping measure. Version 2 provides supplemental assessment of the flaw using Generic Letter 90-05 techniques. Version 2 also added analysis to evaluate the affect on pipe stress represented by the weight of the modification proposed by Temporary Modification TM 1-10-023.

Background

CR 2010108598 identifies a pin-hole leak in the Plant Hatch, Unit 1, Service Water Header Pipe located in the Service Water PumplIntake Structure. The pipe flaw is located near node point 215 on piping isometric Drawing S-00779.

Subsequent to version I of this calculation, the applicability of Code Case N-513-2 for this condition was drawn into question. Particularly, section I(c) states that, "The flaw evaluation criteria are permitted for adjoining fittings and flanges to a distance of (Ra t)1I2 from the weld centerline." However, the flaw in this case is on an elbow fitting and is not within the specified distance from the weld. Therefore, it is not clear whether the intent of Code Case N-5l3-2 is met. Therefore, it was decided to re-evaluate the flaw condition using GL 90-05.

The repair being considered by TM 1-10-023 will encapsulate the area of the flaw and associated leak by welding a stub pipe with an isolation valve. This would be considered to be a "Code repair" except for the fact that the flaw is not being removed. The repair is considered to be a non-Code repair, as defined in GL 90-05. The reason for this designation and the requirement to seek NRC exemption is necessitated by the fact that leaving the flaw in place produces the possibility that the flaw will grow and cause catastrophic damage. Usually flaws are characterized as crack and propogation of cracks along pipe walls subject to pressure and vibration is a common concern. However, in this case the flaw is suspected to be caused from microbiological (MIC) damage. Therefore, flaw enlargement through crack growth is not an expected occurrence.

Design Inputs:

See discussion below and attached spreadsheets.

Southern Nucear oeSlgn C I a cuIafIons Plant:

Unit:

Calculation Number:

Hatch

[&)1 02 01&2 SMSH-10-007

Title:

Sheet:

30" Plant Service Water Header Pinhole Leak Evaluation 2

References:

1. Piping Isometric S-00779, v3

2. CR 2010108598

3. Pipe Stress Calculation BH1-PD-5119, v4

4. Code Case N-513-2, Evaluation Criteria for Temporary Acceptance of Flaws in Moderate Energy Class 2 or 3 Piping...

5. Pipe Specification A-IlO00

6. Generic Letter GL 90-05, "Guidance for Performing Temporary non-Code Repair of AS ME Code Class 1,2, and 3 Piping", dated June 15, 1990.

7. Temporary Modification TM 1-10-023.

8. NCIG-05, "EPRI Guideline for Piping Reconciliation", Rev 1 Assumptions:

1. For the Code Case N513-2 evaluation, the operating pressure is 180 psi. This is conservative, since this is the design pressure. The 90-05 evaluation is based on a conservative operating pressure of 140 psi. This lower pressure was extracted from the piping specification A-I 1000 for this section of piping with HEE designation.

2. Calculation BH1-PD-5119 reports a worst case Occassional Load condition (ANSI B3 1.1, Equation 12) stress of 14,464 psi. This stress does not occur at node point 215, which is expected to have much lower computed stress due to the adjacent support H-30 located directly below this pipe elbow, as shown on Drawing S-00779. Therefore, using this stress value to evaluate this piping node point is considered conservative.

Evaluation:

Code case N-5l3-2 Code case N-513-2 is used as the basis for this evaluation in Attachment A. The specific paragraph is 3(e),

which allows the branch reinforcement approach. Minimum pipe wall thickness is determined by using equation 4 of the code case, which is shown in attachment A. The minimum thickness is determined to be 0.179". The maximum operating pressure is conservatively assumed to be the same as design pressure at 180 psi. The allowable stress for A-lS5 KC55 is listed in the pipe stress calc (BHl-PD-5l19) as 12.4 ksi based on a weld joint efficiency of 0.9. In this case, we can use an allowable of 15.7 ksi based on a safety factor of 3.5 on the ultimate strength. An allowable of only 15,000 psi is conservatively used.

Based on this approach, a tadj of 2 times the minimum thickness would be required to meet the requirement of paragraph 3(e). This thickness will conservatively be taken to be 0.360".

The inspection data shows that the actual measured thickness of the pipe exceeds 0.360" in all areas surrounding the pipe circumference, except for areas directly adjacent to the pinhole flaw. The area that falls below the 0.360" criteria is approximately circular and about 5" in diameter. The total area is then given by (PI*D"2)/4 = 19.6 in2* This area is smaller than the acceptance criterion of 20 in2 given in Code Case N-5l3-2, paragraph 3(e). Therefore, the acceptance criteria of the Code Case are met.

Southern Nucear DeSlgn C I I f a cu a Ions Plant:

Unit:

Calculation Number:

Hatch 1:&11 02 01&2 SMSH-10-007

Title:

Sheet:

30" Plant Service Water Header Pinhole Leak: Evaluation 3

GL90-05 Guideline 90-05 is used as the basis for the evaluation in Attachment C. Based on a conservatively characterized flaw length of 3", the evaluation shows that the flaw satisfies the criteria for temporary non Code repair.

The affect of the additional mass represented by the modification proposed by Temporary Modification TM 1-10-023 on the pipe stress model and pipe stresses must be addressed. The repair plan drawing indicates that the additional weight of the components being added is approximately 661bs. The weight of the 30" short radius elbow, including contained water is about 440 lbs. Therefore, the weight of the added pipe stub, flange and valve represents about 15% of the mass ofthe elbow. The elbow has a pipe support (H-30) located almost directly beneath it. Based on the small percentage of additional weight and the proximity of the adjacent support, the modification will not have significant affect on the piping stress.

Attachment A shows that the branch connection created by the temporary modification met the requirements of 104.3 of the B31.1 Code, since the thickness in the reinforcement area is greater than 2 x 0.179 or 0.36 inches.

==

Conclusion:==

The piping has been evaluated to consider the flaw, as measured and reported by field personnel, and it has been determined to meet the Code Case requirements. Therefore, the pipe configuration and associated stresses meet the evaluation criteria of Code Case N-513-2. Augmented examination per this Section 5 of the Code Case is required. Based on a conservatively characterized flaw length of 3", the GL 90-05 evaluation shows that the flaw satisfies the criteria for temporary non-Code repair.

DESlGI\\

."fnoNS..L........ ptI........................ F...........

IIIWIOI HOtoeW.tIII owa__

Dr!

Or, HIlIoeW. WAI.L ACI\\IjOl 01_ ~

'n

't,

_RC.

AUOWIIiILl_

~

nN fII'OIHCY

~

En

'FIICICII Vh Vb At,

'MIIIIIiQIJN MIIIiU_ _ '"

~1ItC::IMa I

L-_

• AItf;IIt 10 bit 4lt 10 quo i'lcUIIIa (Me 131.1 Para. I(W.3.I(A>>

REQUIREO MNMUM 1tIC>>IESS:

PO I '80 3 0

o. 17.'1 th =

oh

+At,=

........ x........

+.....=.....

~Eh + ZoihP 2x.'.~~ J. +2 X.'?'. i.. X.I.'$'9 tb '"

POw

+..A."t) '"

.*.,.*** X.,,.,. !

+ *.... *.. :II *..,....

2St,~ + 2'ft;/'

2x......x.. +2X...... X....

UMitS OF REINFORCEMENt:

Dob *2Tb "' **.*, ** 2 x.........,=......

d 1 = lin 8

• • t......

02 = dlOf '" 1b+lll+o.tidl=......... +..... +O.5lc...., '"'.....

Select 1aQ8f of the vokJea. but not to exceed ~

~.....

l

2.5 Tb + t..2.511......... +..........,... or 2.5 Th- ~='

RfQUIRED Nt) AV/II..NJlf REINfORCEM£NT AREA:

Aleo a IrntI "I (2*IInB)........ x....... )(2........ ) -....... ~I)

Al

= (20.1

• 41 ) (T", * '"",) * (2x..... *.... ) (......*,.....).........

=2l0" *,_)

• 2)(....... (................) *.......

A2

"'lIn'_"".'

D IAlnll D'** I

~j t

":fia " **

tA C

tl.-b

~

RequIred reinforcement aeo tzZZ?J Alea Al - ExceIl wallin header S

Alec A2 - beeaa ~ In brcn::h Alea A3

• A'3

• filet weld metal

""1ft..

Area A.4 *metal In ring. pad Of Integral reinforcement l\\\\\\\\\\l\\\\1 AOOmONAI.~:

CALC.

A'3 * ( t't )l * (.......... )l *..........

SMSIi - [0- 007 de.

Db

• ... ~. ~... =.....

4 ***

i"i8

~

A... ( 0.... ) '** C* ***, ' *.**.. ) **...*.. '".. '.' *..*.*

An (\\c~ Mfl'l-A

{Al+Y3)+A'~+ A...

5t-1("('(

I~ f

• . ~..*... +....,... +........*,.*...

___*y.O...o OIIDU, __

lin 8 CAlt.....

I'0Il. __

~.

DIIIf LCCAIIOH 01.....

'" ( II )'.. (.*...**...)' =.....,..

HoWe Rcinforctmml AJ OAR WOIbheel WSI*B ASMBlill.l (ii AI*A2i'A3 *................. +.

O~O Dt.lI

~.,

• ....... --~.... y..

Re~1sc:d I99S

~

Nuclear

. i IOU'IHIIN..\\

Management COM.MHY I........................,.

• - I Instruction r

Ultrasonic Thickne.. Report Plant I Unit:

Hatch lOne Component:

IISO I Drawing No.:

1P41*Fl437B System 1P41 Examination Area and Location:

30" Dilution Una Description of Item Examined:

00 of 90° Elbow We.t side at thru wall pinhole Material Type:

at CIS

[JSJS other:

Calibration Standard Serial Number:

QC112 Sound Path Screen Distance:

1.00" SmaJlest Screen DivisIon:

NJA Procedure:

NMP*MA-025-511 Vir 1.0 Remarka:

,.~

..... 1.1

,id)

• * 'u,r:;

'T

.Oth

,1."-'

~r#1

.0CfW "'",'.._ r...,holG I

i--.lQl Examiner:t1))~ ILeve':

'I

.......c-TIL Reviewed By:

Southern Nuclear Operatinsa. Company NMP*ES-024-511 Ultrasonic Thickness Examination Version 1.0 Procedure Page 1S of 17 Southam Nuclear Operattng Company Date:

ISheet Number:

7f7fl0 NJA 1<.'4fP

1. .+10

, ~75

>I

~01

?;.,hb\\e lo

~.,.e lootrv-; t~

Instrument Manufacturer:

Panametrlc Model Number: 36DL Serial Number:

Transducer Manufacturer:

Panametrlc Serial Number 20024

[J A-Scan ar Spot Couplant:

QC212 Type:

Size:

Dual

.250 Frequency:

IMHz 7.5 -

[J Metered (Dlglta])

[J Continuous Sonotech Cable TypeI Length:

4' EXAMINATION RESULTS Let-a. \\ i'1t:d

~eel It::.

1~f U IJJ4.\\I Examiner:

j Level:

I Level Date:

Figure 1 - U'trasonic Thickness Report C/lLe.. S'MSH -fo-COI J\\-.,.tAc:'H M~ni -;- B 5'~~ £\\

\\ c..~ 2

C A t..C S'IY\\ S H.\\ 0 - 007 An-lAc.,J,iV.£A\\I\\ e S1\\ ~E::" 2 o.f.- Z.

Section A-A

.394

[j]

[2J r

2 ~*

.459 Pin hole

.371 o

Area oIlndicalion looking South 3"

SecltonB*B

}

3" 2 Y2" I

~

,354 I Thickness

=.449 "1.410 2

.433 3

.380 Section B*B 4

=357

• .441 5

=416 A

I

)

)

.1" 6

=.469 7

=.406

.458

.459

.452 Hatch JUnit One

• .425 lP41F1437B A

Thickness measurements for thru wall leakage

.445 Elbow looking East

e;lLC 9M SH - }o - or)'7 AnA (\\-\\ ME.-N\\ C

r4t-.1 I o~ ~

Calculation SMSH-I 0-007, Attachment C Flaw Evaluation per Guide1ine GL 90-05.

first, we must determine the stress (s) at this section ofpiping. as defined in GL 90-05.

section 2( a). The stress at this node point is conscrvati vely taken to be 14.5 ksi. as discussed in the Assumptions section. The equation 12 combination that produces this value is given by:

.-(_P_x_D....

0 7 M

~

+.)(1)(

4 x t Z

nom The pipe design pressure is P:= 180 x psi Pipe wall nominal thickness:

t

= 0.375)( in nom Pipe Bend Radius:

R:= 30)( in One Half Pipe Diameter:

r:= 15 x in For a short radius elbow the stress intensification factor (i) is given by:

i := 0.9 x h -.66' t

x R nom where h is given by h:=--

2 h = 0.05 r

plugging this into the equation for the SIF gives 0.9x h-*667 i = 6.638

CALC S'M St\\ 001 An ACr\\M~"'T C.

S'\\t.,

2 c. f" 4 Plugging in the S[F. design pressure. and nominal wall thickness values produces the following:

(180 x 30)

MI MI

-'----..:.. + 0.75 x i x -

or 3.6 x ksi + 5':

4 x 0.375 Z

Z Setting this equation equal to the worst case computed stress (14.5 ksi) for the entire piping model and solving for M/Z gives:

M I

- =

• 2.18 x ksi Z

The computed stress "s" at the flaw location does not include SIF terms and is given by:

s:= 3.6 x ksi + 2.18 x ksi s::: 5.78 ksi This is the stress term discussed in GL 90-05, section 2(a).

This stress (s) is considered as a longitudinal stress. The circumferential stress is given by the hoop stress and may be determined as follows.

poper:= 140 x psi Pipe Operating Pressure Do:= 30 x in Pipe Outside Diameter scircum '" 5.6 x Ioj psi Therefore, the longitudinal stress controls and the stress will be conservatively taken to b equal to 6,000 psi.

CA lC S.d-t SH -10* 007 A \\T AeHMWT C S'r\\t:T 3 aF 4 Generic Letter 90-05 calculations based on the "Through-Wall" Approach Detennine the minimum code-required wall thickness P:= I 40 psi Design Pressure s:= 15ksi Allowable stress A I 06BIA I 55GrC55 D

JOin tnom :=.375in p)( D tm:=----

2 )( (S +.4 )( P) 1m = 0.139 x in Detennine the flaw length "2a" The leak in the pipe side wall is surrounded by wall thickness that is below the minimum detennined above. Ultrasonic testing (UT) of the area surrounding the leak has shown tha the leak is surrounded by a depression in the wall thickness with thickness at a minimum adjacent to the leak and increasing approximately radially from the location ofthe leak. It is apparent from the UT data that the average wall thickness away from the leak is on the order of 0.4 inches thick, which is as expected to bound the nominal thickness of 0.3 75..

The flaw length may conservatively be taken as the projected length of a straight line dra\\'

through the leak that runs along portions of the pipe where thickness faUs below the minimum. In other words, it is the diameter ofa circle that may be drawn around the leak which encompasses all of the pipe wall locations that fall below the minimum thickness.

The guideline states that the maximum length cannot exceed 3 inches. Based on the UT results. a 3" length through the leak will bring the thickness up to about 0.26. which is thicker than tmin. Therefore, the tlaw length "2a" will be considered to be 3" and the minimum thickness beyond the projected flaw length will conservatively be taken to be 0.26". This is conservative, because the actual thickness has been detennined to increase to about 0.4" in most areas.

tp := 0.26)( in a:= 1.5in Stress := 6ksi R:= D - lOom 2

C At,(. <s41 S' H... )0 - 007 A\\TAc\\,-\\ M ENT" c...

qt\\~ £:"\\

4~ 4

.3 A:= -3.:!6S43 + 1.52784 x r -.072698 x r- +.0016011 x r 3

B:= 11.363.22 - 3.91412 x r +.18619 x r- -.004099 x r 3

C:= -3.18609 + 3.84763 x r

.18304 x r- +.00403 x r a

c:=-

1txR 1.5 B

2.5 C

3.S F := I + A x C

+

x C

+

x C

.S K:= 1.4 x Stress x F x (71' x a) 5 K

32.216 x ksi x inO.

O.S Klimit :== 35kSI x In Since the computed K value is less than that required for ferritic steel (35 ksi), as required GL 90-05, the flaw satisfies the criteria for temporary non-Code repair.