ML20235Z583

Forwards Response to Request for Addl Info Re Augmented IGSCC Piping Insp 84-11 During Fall 1986,per Dr Mueller

ML20235Z583
Person / Time
Site:	Dresden
Issue date:	07/22/1987
From:	Johnson I COMMONWEALTH EDISON CO.
To:	Murley T Office of Nuclear Reactor Regulation
References
3364K, NUDOCS 8707270336
Download: ML20235Z583 (10)

Text

,-

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N Commonwealth Edison

_. (t. fl. ) _. One Fir:t Nuional Plaz2, Chicago, Illinois v

Address Rrply to: Post Offce Box 767 E

Chicago, Illinois 60690 0767 July 22, 1987 Mr. Thomas E. Murley, Director Office of Nuclear Reactor' Regulation U.S. Nuclear Regulatory Commission Washington, DC 20555-

Subject:

Dresden Station Unit 2 Response to Request for Additional Information Pertaining to Dresden 2 Fall 1986 IGSCCC Inspection NRC Docket No. 50-237

Reference:

Letter from D. R. Mueller to.D. L. Farrar dated May 27, 1987

Dear Mr. Murley:

In the above referenced letter, members of your staff requested additional information pertaining to the Dresden Unit 2 84-11 Augmented Piping Inspection program.

~ Attached please find the additional information which had been.

requested in your above referenced letter.

Please direct ony questions you may have regarding this matter to

~

this office.

Very truly youra, Y' '

I. M. Johnson Nuclear Licensing Admi.

rator 1m Attachment cc:

M. Grotenhuis - w/Att.

Dresden Resident Inspector Regional Administrator - RIII B707270336 8707E2 gDR ADOCK 0 % y 7 3364K

.1 l-ATTACHMENT The following is a restatement.of the requested information from the subject document and our response.

1.

Please provide the stress information and UT. measured pipe wall thickness for weld PDIA-D14, so that the staff can calculate the crack growth and'the allowable flaw depth for the subject weld.

The' requested information as well as a Flaw Evaluation has been attached entitled Dresden 2 Wold PDIA-D14 (28" P-E) Flaw Evaluation.

2.

Weld PDIA-D14 was not listed in Attachment 2 to the submittal dated March 23, 1987. Please explain.

Weld PDIA-D14 is a 28" elbow to pipe weld. This weld's flaw history is summarized in Attachment 3 of the submittal dated March 23, 1987. This weld was inadvertently left off the listing of flawed welds in.

This attachment is being resubmitted.

3.

Two additional RWCU welds were added to the list of welds susceptible to IGSCC. Please describe these two welds including weld identifications and locations. ' Explain why there were not listed in previous counts of IGSCC welds.

In 1984 the RWCU line was replaced from the first isolation valve to the second isolation valves with IGSCC resistant material.

The two welds in question are-8-6-A and 8-1-A, These welds are pipe to Valve welds where the piping is resistant material and the valves are nonresistant forged material. These welds were left off the 84-11 submittal dated August 27, 1986 because at the time the valves were thought to be of cast material which is resistant to IGSCC. As a conservatism, these welds were scheduled to be inspected in addition to the generic letter 84-11 stainless steel welds-scheduled. No indications of IGSCC were found in the two welds in question. These welds will be treated as IGSCC susceptible on the valve side.

As per your request, a drawing of the RWCU line is enclosed.

4.

There are 14 furnace sensitized safe ends in Dresden Unit 2.

How many

.were inspected in this outage? Please identify each of those welds.

Four (4) furnace sensitized safe ends were inspected this outage. They are:

N1B - 28" Recirc Outlet N2F - 12" Recirc Inlet N2C - 12" Recirc Inlet JPIA - 4" Jet Pump Instrument

l

. 5.

Weld pS2/201-l'was described as a elbow-pipe weld in page 2 of Attachment 3 to the submittal dated March 23, 1987.

Is it possible that this weld is a safe end-slbow weld?

W6.d PS2/201-1 is a safe end to c1 bow weld.

It is identified as such on page 4 of 4 in Attachment 3.

The reference to this weld as a pipe-elbow configuration was a typo in Attachment 2.

6.

Referring to page 2.3 of NUTECH report transmitted by letter dated March 23, 1987, please explain why the downstream as-built overlay thickness of weld 8-12 could not be taken. Please provide a sketch of the weld overlay including the dimensions and its surrounding components.

A sketch of the Veld overlay Repair Detail shows that the valve body increases in thickness immediately past the weld end prep. Nutech Drawing No. CEC-79-105 is attached.

7.

Referring to page 4.4 of the same NUTECH Report, please provide the minimum specified pipe wall thickness for each weld listed in Table 4.1-1.

The attached Flawed Pipe Thickness table shows the wall thicknesses used in the Applied Stress calculations and overlay Designs.

8.

Referring to page 4.5 of the same NUTECH Report, please provide the overlay shrinkage data for welds 8K-13 and 8-12.

Axial shrinkage measurements were not included in the report because they do not affect the stress analysis of the Recirculation system. A table entitled, " Total As-Built Weld overlay Shrinkage of Welds 8K-14 and 8-12" are attached here.

9.

Referring to page 5.10 of the same NUTECH Report, please provide the as-measured UT thickness data for each overlay repaired weld and unrepaired welds.

The attached table entitled Flawed Pipe Thickness shows the Actual Upstream / Downstream pipe wall thickness as measured by UT.

3364K

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DRESDEN 2 l

WELD PDIA-D14 (28" P-E)

FLAW EVALUATION ASME SECTION XI IWB-3514 EVALUATION o

Measured Flaw = 1" x 8% (pipe side) o Measured Wall >rhickness (pipe side / elbow side) = 1.18"/1.34" Aspect Ratio =.08 x 1.18/l = 0.094 o

o Allowable Flaw Depth =-10.24 (Table IWB-3514-2)

ASME SLC,ON XI IWB-3640 EVALUATION o

Measut, claw = 1" x 84

-o Measured Wall Thickness = 1.18" Stress Ratio = (P,+ P )/8

= 8105/16950 = 0.48 o

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Flaw Length Ratio = 1"/zD = 1"/(s x 28") = 0.11 o

Allowable End-of-Evaluation Flaw Depth Ratio = 0.75 o

o 2/3 x 0.75 = 0.50 (per Generic Letter 84-11)

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DRESDEN 2 WELD PDIA-D14 FLAW EVALUATION (Concluded)

FLAW GROWTH ANALYSIS o

CRACK GROWTH CORRELATION

-8

= 3.58 x 10 K*

(from NUREG-1061 Vol. 1) where:

da = differential crack size (inches) dt = differential time (hours)

K -=' applied stress intensity factor (ksi / lit.)

o RESIDUAL STRESS PATTERN (from Draft NUREG-0313, Rev. 2)

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2.

Maximum reported flaw depth by 360*.

3.

Allowsble end-of-evaluation flaw depth ratio per Generic Letter 84-11.

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PIPE VALVE

( WELD 1

WELD OVERLAY REPAIR DETAILS p,,,nt,,,,;w,,,

NOTES:

1. BLEND WELD OVERLAY REPAlR SMOOTHLY INTO VALVE BODY.

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DESIGN DIMENSIONS WELD NUMBER FLAW CHARACTERIZATION COMMENTS A

t 6-12 100% x 360' l.5" 0.21" Full-Structural Weld Overlay Design 3

A 2-81

'/A L/87

//21,/g7 l/12/r; CM~ //zg37 9 54 vic "iC CWI Modified Weld overlav Length MC

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P.E. APPR./

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DESCRIPTION REV.

DATE DATE DAYE DATE DATE JOB NO:

PLANT:

REV.

CEC-/9 Dresden finit 2 SHT.

BC 1

.1 FILE NO:

DWG. NO:

op CEC 079.0105 CEC-79-109

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DRESDEN UNIT 2 TOTAL AS-BUILT WELD OVERLAY SHRINKAGE A. sial Shrinkage Weld No.

(in.)

8-12 0.160 8-K13 0.076

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• DRESDEN 2 FLAWED PIPE THICKNESS (INCHES)

Applied Crack

Actual, Stress Overlay Growth Weld No._

Upstream / Downstream Calculation Design Analysis 8-12 0.50/NA 0.50 0.50 NA 8-K13 0.54/0.55 0.50 0.50 NA PD2-D5 0.60/0.66 0.687 NA 0.687' PDS-D23 0.60/0.64 0.58 0.687 NA PD5-D20 0.68/0.71 0.587 NA 0.687 PD7-D11 0.66/0.60 0.58 0.687 NA PD9-D6 0.59/0.65 0.58 0.687 NA PD19-D14 0.60/0.66 0.S8 0.687 NA PDIA-Die 1.34/1.18 1.113 NA 1.113 l

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