ML20077G962

Forwards Info Re Planned Weld Overlays,Including Info on Piping Stresses & Predicted Crack Growths.Position Re 10 Recirculation Welds for Which No Weld Overlay Planned Will Be Submitted in Near Future

ML20077G962
Person / Time
Site:	Browns Ferry
Issue date:	08/05/1983
From:	Mills L TENNESSEE VALLEY AUTHORITY
To:	Harold Denton Office of Nuclear Reactor Regulation
References
NUDOCS 8308090507
Download: ML20077G962 (20)

Text

_

TENNESSEE VALLEY AUTHORITY.

CHATTANOOGA. TENNESSEE 374ot 400 Chestnut Street Tower II August 5, 1983 Mr. Harold R.'Denton, Director Office'of Nuclear Reactor Regulation U.S. Nuclear Regulatory Comaission Washington, D.C. 20555

Dear Mr. Denton:

In the Matter of'the

)

Docket No. 50-259 Tennessee Valley Authority

)

As discussed with your staff and comaitted to in my letter to you dated August 4, 1983, we are submitting information regarding planned weld overlays for the Browns Ferry Nuclear Plant unit 1.

Included is information regarding piping stresses and predicted crack growths. We i

are currently applying overlays with the dimensions given in the enclosure.

In a meeting with your staff on July 6, 1983 there was discussion of ten recirculation welds for which no weld overlay was planned. Our position with regard to those ten welds will be submitted in the near future.

--Very truly yours, TENNESSEE VALLEY AUTHORITY a

L.M. Mills,) Manager Nuclear Licensing fore Subscribed and sworn to p///A, me this, 8 day of /

1983 A m A 6 71. A m i v NotaffPublic

/ 4

-My Commission Expires- /////K_d

//

Enclosure

.cc: See page 2 s \\

9309090507 830805 183-TVA SOTH ANNIVERSARY OR ADOCK 05000 An Equal Opportunity Employer

FJ

)

l 1

0 I

. Mr. Harold R. Denton August 5, 1983 cc (Enclosure):

U.S. Nuclear Regulatory Commission Region II ATTN: James P. O'Reilly, Regional Administrator 101 Marietta Street, NW, Suite 2900 Atlanta,. Georgia 30303 Mr. R. J. Clark Browns Ferry Project Manager U.S. Nuclear Regulatory Commission 7920 Norfolk Avenue Bethesda, Maryland 20814 Nuclear Regulatory Commission Document Control Desk Washington, D.C.

20555 W

ENCLOSURE.

DETAILS REGARDING PLANNED WELD OVERLAYS BROWNS FERRY NUCLEAR PLANT UNIT 1 Basis of Overlav Sizina ne weld overlay sizes were developed using the following bases:

1.

The welds to be overlaid were identified by IVA.

2.

He ultrasonically determined crack depths were doubled.

3.

All cracks were 3600 at maximum depth.

4.

The design minimum overlay thicknesses were used.

5.

The 1e'sser of measured or nominal pipe thicknesses was used.

6.

He pipe stresses provided by IVA were used.

7.

Paragraph IWB-3640, ' Acceptance Criteria f or Austenitic Steel Piping,'

was used. When the applied stress ratio was below that required, the methods inherent in IWB 3640 were used to extend the table.

Crack Growth Methodoloav The residual stress distribution for each overlay design was determined by grouping the 26 weld overlays into 7 enveloping categories. The categorization precedure considered pipe diameter, crack depth, overlay thickness, overlay length, and steady-state-applied stress. The seven categories are:

1.

End caps.

2.

Twenty-eight-inch pipe with deep cracks and large overlay.

3.

Twenty-eight-inch pipe with standard overlay.

4.

Twelve-inch pipe with mini overlay.

5.

Twelve-inch pipe with high applied stress and standard overlay.

6.

Twenty-and twenty-four-inch pipe with standard overlay.

7.

Twenty-four inch pipe with large overlay.

The details of the categorization are presented in Tables 1 and 2.

1 For each category, a post weld overlay res'idual stress distribution was obtaine d.

For categories 1, 4, and 5, the distributions were obtained f rom previous NUTEG analyses. For categories 2, 3, 6, and 7, new residual stress profiles were calculated.

4 e

=

b

4 wtA s

M'N'--

' W A 4 %s q4m Mw.e4wn,,

v

_g,

,g,,,

4

Both a straight pipe-to pipe joint and a pipe-to-fitting joint with a 300 taper were considered. He taper was found to have a negligible eff ect on the residual stress profile. He residual stress profiles were then combined with the enveloping applied stress profiles and the stress intensity f actor as a function of crack depth. Figures 1, 3, 5, 7, 9, 11, and 13 are plots of the stress intensity f actor f or categories 1 through 7.

respectively. The predicted crack growth was then calculated assuming:

1.

The initial crack size was 3600 with a depth equal to two times the ultrasonically determined crack depth.

2.

Two crack growth laws were used:

(a) M1 TECH-reccamended crack growth law:

r, i

da dT = 4.116 x 10-12 K4.615

= crack depth (inches) a T = time (hours)

= stress intensity f actor (KSI k inches)

K A

j (b) EPRI bounding crack growth law:

1

.4.1 dT = 1.2 x 106.0.11X Results He results are plotted in figures 2, 4, 6, 8,10,12, and 14 for categories 1 through 7, respectively. These figures show that f or all cases the predicted crack size will remain below the allowable crack size for several fuel cycles.

IVA is currently applying overlays with di.nensions as presented in Table 1.

We believe these overlay designs are adequ' ate for startup and operation of unit 1 because they:

1.

Provide more than an adequate margin for flaw sizing error; 2.

Provide j oints that can be reasonably baseline examined; 3.

Will have minimum impact on the system stresses; and 4.

Provide the required safety margin for a minimum of 80 months.

[

O'l

%kN V>3 g- - '

a _-

T, TABLE 1 i

OVERLAY DESIGNS Steady Pipe Crack Ove rl ay Overl ay State Weld No.

Diameter Depth Thickness Length Stress Category KR-1-37 22in.-

35%

.200in.

4.51n.

6,099* psi 1

KR-1-15 22 27

.200 4.5 6,099*

1 KR-1-3 28 43

.35 7.0 8,411 2

GR-1-3 28 35

.25 7.0 8,145 3

GR-1-58 28 45-

. 35 7.0 7,845 2

GR-1-54 28 45

.35 7.0 8,38a 2

GR-1-60 28 36

.25 7.0 7,725 3

.KR-1-18 12 35

.125 2.5 15,110 4

KR-1-21 12 35

.125 2.5 12,461 4

KR-1-22 12 35

.125 2.5 11,754 4

KR-1-16 12 35

.125 2.5 13,283 4

GR-1-41 12 12

.200 4.5 35,244 5

GR-1-46 12 20

.125 2.5 12,593 4

D-RHR-1-17 24 31

.200 4.5 13,224 6

D-RHR-1-18 24 20

.200 4.5 15,058 6'

D-RHR-1-15 24 30

.200 4.5 9,461 6

DS-RH R-1-9 20 29

.200 4.5 13,829 6

DS-RHR-1-8B 24 41

.200 '

4.5 13,427 6

DS-RHR-1-11 20 24

.200 4.5 12,633 6

DS-RHR-1-10' 20 30

.200 4.5 12,057 6

DS-RHR-1-5 24 31

.200 4.5 11,879 6

D-RHR-1-5 24 36

.25 7.0 11,599 7

DS-RHR-1-4 24 30

.200 4.5 14,071 6

D-RHR-1-20 20 43

.200 4.5 12,450 6

D-RHR-1-8 24 25

.200 4.5 11,396 6

(

DS-RHRl-4A-24 44

.25 7.0 13,617 7

Pressure stress only - assumed equal to that for weld number KR-1-34

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TABLE 2 g

a

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OVERLAY CATEGORI2ATION f

f Initial i

}.

Source of Weld Applied Crack Pipe Pipe Overlay Overlay I

,l.., -

Category Residual Stress Stress Size

• Diameter Thickness Thickness Length u

1 Reference 3 6,099 psi 70%

22" 1.031

.2" 4.5" l-2 Compu ter Run 8,411 90 28.51 1.322

.35

'7.0 f

3 Compu ter Ru n 8,145 72 28.15 1.138

.25

-7.0

,I 4

Reference 4 15,110 70 12.75

.789

.125 2.5 5

Reference 5 35,344**

24 12.75

.579

.20 4.5 i

6 Compu ter Run 15, 0 5 8 * * *,.-

86 20.

1.031

.20 4.5 I

7 Computer Run 13,617 88 20 1.031

.25 7.0 1

i

'i The measured U.T. depth was multiplied by 2.0 for usn in the crack growth analysis.

The tabulated crack sizes are in percent of unrepaired pipe thickness.

Crack growth evaluation performed using 26,270 psi = 3 5,344

.579

.200 Crack growth evaluation performed using 12,612 psi = 15,058 1.031 l

1.031 +.200 i

TVA-01-031 f

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40 -

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(% OF OVERLAID THICKNESS)

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Figure 1

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Figure G CRACK GROWTH FOR CATEGORY 3

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Figure 7 STRESS INTENSITY FACTOR FOR CATEGORY 4 4

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TIME (MONTHS) t Figure 8 CRACK GROWTH FOR CATEGORY 4 I

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c.

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==: = = = _ = g

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100 30 M

wzx9=

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62 ALLOWABLE DEPTH x

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m O

x 0<

ec 20 -

I8 K.615 da

-12 4

g = 4.116 X 10 O

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20 40 60 80 100 TIME (MONTHS)

Figure 10 CRACK GROWTH FOR CATEGORY C

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20 40 60 80 100 8

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(% OF OVERI. AID THICKNESS) a-1 RESIDUAL l 4_

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5,

'm.446' A,

4 e

e a

0 100 ALLOWABLE DEPTH 80 -

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so -

=

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40 -

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20 -

0-3 0

20 40 60 80 100 TIME (MONTHS)

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-.... -, ~..... -... - _ - -

a 9

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APPLIED -

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u.

>=b U.

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0 3

20-40 60 80 100 h

CRACK DEPTH E

(% OF OVERLAID THICKNESS)

U.

?

RESIDUAL.

J Figure 13 STRESS INTENSITY FACTOR FOR CATEGORY 7 9

p =

w

...m

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a p,

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71 NO CRACK GROWTH AS K IS APPROXIMATELY 0.0 Q

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e uJ>0 u.

t O

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Figure 14 CRACK GROWTH FOR CATEGORY 7 p#

W FS 4

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