ML20080C262

Forwards Final Weld Insp & Repair Results.Final Disposition of Welds Found W/Crack Indications,Results of Exam of Plug Removed from Weld & Radiographs of Weld & Modified Repair Program Also Encl

ML20080C262
Person / Time
Site:	Quad Cities
Issue date:	01/27/1984
From:	Rybak B COMMONWEALTH EDISON CO.
To:	Harold Denton Office of Nuclear Reactor Regulation
Shared Package
ML20080C268	List: ML20080C262 ML20080C280 ML20080C290 ML20080C309
References
8018N, NUDOCS 8402080035
Download: ML20080C262 (4)

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c N Commonwealth Edison

) One First N1tional Plaza. Chicago. Ilknois

, "J Address Reply to: Post Office Box 767 G Chicago, Illinois 60690 January 27, 1984 Mr. Harold R. Denton, Director Of fice of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Washington, DC 20555

Subject:

Quad Cities Station Unit 2 Weld Inspection Results '

NRC Docket No. 50-265 References (a): IGSCC Inspection Order Confirming Shutdown for Dresden Station Unit 3 dated August 26, 1983.

(b): IGSCC Inspection Order Confirming Shutdown for Quad Cities Station Unit 2 dated August 26, 1983.

(c): B. Rybak letter to H. R. Denton dated December 9, 1983.

(d): B. Rybak letter to H. R. Denton dated December 13, 1983.

Dear Mr. Denton:

Ultrasonic inspection and repair on stainless steel welds covered by the referenced order is now complete. With this letter we wish to provide the final weld inspection and repair results for Quad Cities Unit 2. Final disposition of the welds where we have found crack indications is summarized in Attachment 1. In a meeting held in Bethesda on December 20, 1983, interim approval for all but five welds was received. The five welds in questions contained crack indications of a length greater than 1/3 of the circumference. Two of the welds were in the 12 inch risers; 02F-F6 and 02J-F6 with the remaining three being 28

! inch welds 02AS-F14, 02BS-F7, and 02BS-S12. These five welds remained in

! question due to a recent ACRS letter dated December 19, 1983. On the l basis of that meeting Commonwealth Edison established a program for additional second and third part advanced Ultrasonic Testing (UT)yprocedures. inspection of theparties, Both five welds ITLusing more and UTL, began their inspections using Shear Wave techniques and were in close agreement both in location and depth with the original inspections performed by LMT. Beyond the initial Shear Wave examinations UTL and ITL l

used a Crack Tip Diffraction and OD Creeping Wave to disposition the l

8402000035 840127 f PDR ADOCK 05000265 gf7f G PDR I

h H. R. Denton January 27, 1984 crack indications. Furthermore, UTL also used a newer technique-ID Creeping Wave on the crack indications. Neither ITL or UTL found any crack indications using the more advanced techniques. UTL, based on their review, determined that no cracks existed in the welds. ITL, based on their shear wave data, conservatively called the indications as cracks.

On January 5, 1984, we presented the UT results to the staff.

We had begun to overlay the two 12 inch welds due to the fact that the repair would have been relatively easy and not on the critical path.

Welds 02F-F6 and 02J-F6 were overlayed using the conservative design basis of assuming a thru wall crack for a 3600 circumferential extent.

The staff was in general agreement with our position that the cracks were sized to the latest UT techniques, that the uncertainty in measured crack depth was reduced to a point where credit for the remaining wall section could be given and that the second and third party UT results allowed for the possibility of no cracks. However, due to the aforementioned ACRS letter, the staff concluded that this data was not conclusive. Due to the fact that any weld overlays were on the critical path we had subsequently made a decision to begin overlaying 02BS-F7. Upon further discussion with the staff it was agreed that if we removed a core sample from one of the other 28 inch welds and performed both an examination of the sample and a radiograph of the weld itself, and if it was determined that no indications were found the weld overlays need not be completed.

A sample was removed from one of the welds, 02BS-S12, and both oxamination of the plug itself and the subsequent radiograph of the weld showed no indications (see Attachment 2 for further details). Based on these results, Commonwealth Edison believes that no IGSCC cracks exist in the five welds. With agreement from the staff we proceeded to repair 02BS-S12 in accordance with ASME Section X1 and left 02AS-F14 as is (IHSled). At that time however we could not reach agreement with the Staff on the final disposition of 02BS-F7 which we had already began overlaying. Finally, it was agreed that for 028S-F7 the overlay process could be terminated when the resultant overlay met the structural requirements two times the original crack depth estimate, a conservative assumption since it is believed that no crack presently exists.

Attachment 3 contains a modified version of the repair program es previously submitted in Reference (c). The changes in the program ossentially contain a minor change in the crack growth law, inclusion of the regulatory requirement for repair of welds where the crack indications are greater than 1/3 of circumference and deletion of references to Dresden Unit 3. The requested susceptibility matrix pursuant to Section III.C.5 of the shutdown order of August 26, 1983, is included in Attachment 4. Please note specific carbon contents were not available for this Unit 2 as Certified Material Test Reports (CMTR) were not required at the time of construction. Without those specific contents a traditional susceptiblility matrix could not be constructed.

In its place we provided a summary of all available materials.

H. R. Denton January 27, 1984 On January 120, 1984 in a telephone conversation with Mr. Bill Koo of-your staff we reviewed the list of Class 1 Stainless Steel welds inspected 1and provided the following breakdown:

Reactor Recirculation - 120 Core Spray -

25 CRD Return -

12 RHR - LPCI - 29 RHR - Head Spray - 19 Head Vent -

1 RHR - Shutdown Cooling - 16 Cleanup -

3 We told him that there are two nonconforming welds that cannot be isolated. One on the 4 inch Head Spray located in a water barrier between the Drywell and Reactor Cavity. The temperature being that of the Drywell or ambient, and there is a reinforced branch weld with a saddle around it, located on a 6 inch line in the reactor water cleanup piping. .The flow rate in the line is 150 gpm and the temperature is

~

540 0F, Attachment 5 is a copy of a letter dated September 30, 1983 from B. Rybak to ti.R. Denton, which delineates which welds were not inspected.

Per Mr. Koo's request we have included with this letter the

'following attachments:

Attachment 6: Quad Cities Unit 2 - Steady State Stresses for IHSI Treated Welds With Flaw Indications.

Attachment 7: Quad Cities Unit 2 - Weld Overlay Induced Shrinkage Stresses.

Attachment 8: Quad Cities Unit 2 - Weld Overlay As-Built Information.

As requasted in our December 20th meeting, the NRC requested us to clarify the differences between Commonwealth Edison and LMT inspection techniques. Basically, the inspection techniques are identical. 45 degree shear wave is used for detection of crack indications, and 60 degree shear wave is used for sizing. The only difference between the Commonwealth Edison _and LMT is that the Commonwealth Edison procedure stipulates that sizing is based on 50% of max amplitude whereas the LMT corporate procedure uses 25% of max amplitude. Nevertheless, at Quad Cities Unit 2-LMT sized all crack indications to at least 25% of max amplitude.

c.

H. R. Denton - 4- January 27, 1984 With this. submittal we believe we've met all requirements of the IGSCC order. We've inspected all welds required by.the order, presented the results of,our inspection and the repair remedies to the Staff and have received verbal approval to allow startup for at least one more fuel cycle.

If you have any questions regarding this matter, please contact this office.

One signed original and forty (40) copies of this transmittal are pro <ided for your use.

Very truly yours,

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B. Rybak Nuclear Licensipg L_ )' Administrator 1m Attachments 8018N P

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