ML17179A615

Forwards Review of Planned Intergranular stress-corrosion Cracking Related Activities for Winter 1993 Refueling Outage

ML17179A615
Person / Time
Site:	Dresden
Issue date:	12/05/1992
From:	Siegel B Office of Nuclear Reactor Regulation
To:	Kovach T COMMONWEALTH EDISON CO.
References
NUDOCS 9212110182
Download: ML17179A615 (5)

Text

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e, December 5, 1992 e D©~ket No. 50-237 OFC NAME DATE Mr. Thomas J. Kovach Nuclear Licensing Manager Commonwealth Edison Company-Suite 300 OPUS West III 1400 OPUS Place Downers Grove, Illinois 60515

SUBJECT:

REVIEW OF PLANNED INTERGRANULAR STRESS-CORROSION CRACKING RELATED ACTIVITIES FOR THE WINTER 1993 REFUELING OUTAGE (D2Rl3)

By letter dated September 17, 1992, Commonwealth* Edison Company (CECo) described its planned activities related to intergranular stress-corrosion cracking (IGSCC) for the winter 1993 refueling outage (D2Rl3).

The staff had requested this plan for review in its letter of December 20, 1990, because of concerns related to the long-term behavior of the piping.

The staff's review of CECo's planned activities during the upcoming refueling outage is enclosed.

The staff has also concluded it will not be necessary to submit future plans.

Enclosure:

IGSCC Review cc w/enclosure:

See next page DISTRIBUTION:

NRC & Local PDRs POI II-2 p/f T. King C. Moore OGC ACRS (10)

Docket Fil.e POI II-2 r /f J. Roe J. Dyer B. Siegel M. Banic B. Clayton Riil

PM: POI II-2 "ii Sincerely, Original Signed By:

Byron L. Siegel, Project Manager Project Directorate III-2 Division of Reactor Projects - III/IV/V Office of Nuclear Reactor Regulation

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December 5, 1992 ~

Dgcket No. 50-237 OFC NAME DATE Mr. Thomas J. Kovach Nuclear Licensing Manager Commonwealth Edison Company-Suite 300 OPUS West I II 1400 OPUS Place Downers Grove, Illinois 60515

SUBJECT:

REVIEW OF PLANNED INTERGRANULAR STRESS-CORROSION CRACKING RELATED ACTIVITIES FOR THE WINTER 1993 REFUELING OUTAGE (D2Rl3)

By letter dated September 17, 1992, Commonwealth Edison Company (CECo) described its planned activities related to intergranular stress-corrosion cracking (IGSCC) for the winter 1993 refueling outage (D2Rl3).

The staff had requested this plan for review in its letter of December 20, 1990, because of concerns related to the long-term behavior of the piping.

The staff's review of CECo's planned activities during the upcoming refueling outage is enclosed.

The staff has also concluded it will not be necessary to submit future plans.

Sincerely, Original Signed By:

Byron L. Siegel, Project Manager Project Directorate 111-2 Division of Reactor Projects - 111/IV/V Office of Nuclear Reactor Regulation

Enclosure:

IGSCC Review cc w/enclosure:

See next page DI STR IBUT ION:

NRC & Local PDRs PDIII-2 p/f T. King C. Moore OGC ACRS (10)

Docket File PDIII-2 r/f J. Roe J. Dyer B. Siegel M. Banic B. Clayton RII I

PM:PDill-2

D:PDIIl-2

)L 15 /92

Mr. Thomas J. Kovach

• Commonweal th Edi son Company cc:

Michael I. Miller, Esquire Sidley and Austin One First National Plaza Chicago, Illinois 60690 Mr. C. Schroeder Plant Manager Dresden Nuclear Power Station 6500 North Dresden Road Morris, Illinois 60450-9765 U. S. Nuclear Regulatory Commission Resident Inspectors Office Dresden Station 6500 North Dresden Road Morris, Illinois 60450-9766 Chairman Board of Supervisors of Grundy County Grundy County Courthouse Morris, Illinois 60450 Regional Administrator Nuclear Regulatory Commission, Region III 799 Roosevelt Road, Bldg. #4 Glen Ellyn, Illinois 60137 Illinois Department of Nuclear Safety Office of Nuclear Facility Safety 1035 Outer Park Drive Springfield, Illinois 62704 Robert Neumann Office of Public Counsel State of Illinois Center 100 W. Randolph Suite 11-300 Chicago, Illinois 60601 Dresden Nuclear Power Station Unit Nos. 2 and 3

ENCLOSURE REVIEW OF PLANNED INTERGRANULAR STRESS-CORROSION CRACKING RELATED ACTIVITIES FOR DRESDEN. UNIT 2. WINTER 1993 REFUELING OUTAGE By letter dated September 17, 1992, Commonwealth Edison Company (CECo, the licensee) described its planned activities related to int~rgranular stress-corrosion cracking (IGSCC) for the winter 1993 refueling outage (D2Rl3).

The licensee's plan addresses IGSCC concerns and conforms to the guidelines of Generic Letter (GL) 88-01, "NRC Position of IGSCC in BWR Austenitic Stainless Steel Piping."

Level II or III examiners qualified by EPRI will ultrasonical-ly examine the austenitic stainless steel piping welds and overlay repaired welds.

All IGSCC flaw indications will be resolved according to GL 88-01.

For repair, weld overlays may be used that will take into account flaw characterization and material toughness.

The licensee based the GL 88-01 examination sample on the estimated weld population after modifying the piping as planned for D2Rl3.

If the estimated weld population changes, the licensee will adjust the examination sample accordingly.

The licensee will also re-examine weld PSl-2/201-1 in the recirculation system according to its commitment to NRC Region III.

The licensee indicates the presence of four Category G welds, two of which are not accessible and will not be inspected.

One weld is in the isolation condenser return line and one in the reactor water clean up system.

Each is located at a branch connection with a reinforcement saddle.

Each has a weep hole that will leak water if a weld cracks. These will be used for visual monitoring.

Two Category C welds in each isolation condenser steam supply and return line will become Category A welds.

The change in classification is because of a replacement.

The replacement will be an IGSCC resistant spool piece of Type 304L welded with Type 308L.

Three inaccessible Category G welds will become Category A welds.

These welds will be clad with corrosion resistant cladding during this outage, making them IGSCC resistant. The NRC earlier approved the cladding procedure and weld classification in its letter of April 6, 1992.

Three Category C welds were reclassified to Category A.

These are the HPCI nozzle-to-safe end weld, HPCI safe end-to-elbow weld, and isolation condenser steam supply nozzle-to-safe end weld.

The safe ends were replaced in 1976 with IGSCC resistant Type 316L steel and welded with Types 308L and 309L.

Issues rema1n1ng from the last IGSCC examination during the fall 1990 outage were discussed with the licensee and confirmed in a letter of October 14, 1992.

The licensee has committed to perform the following actions:

1.

Reinspect weld 16-8.

The examination of this weld was incomplete.

The licensee could not inspect the entire width of the heat affected zone (HAZ).

The licensee agreed to inspect this weld to fully cover the HAZ on the elbow side with a 45 degree transducer.

2.

Measure the delta ferrite in two recirculation pump-to-cast stainless steel elbow welds.

The licensee proposed to reclassify these Category G welds to Category A.

The carbon content and delta ferrite content are such that per GL 88-01, reclassification must be considered on a case-by-case basis.

If the delta ferrite content measured is too low to allow reclassification of these welds to Category A, the licensee must inspect them during the next refueling outage.

3.

Inspect weld PS2A-202-1B.

The NRC staff disagreed with the reclassifi-cation of this weld as Category E.

Its non-standard overlay places this weld in Category F so it must be examined every refueling outage.

This weld could be reclassified as Category E if the licensee finds no cracks after four successive,examinations. Alternatively, the weld could be reclassified as Category E if the licensee provides an acceptable technical justification that the repair is sufficient.

Based on the planned activities described above, the staff has determined CECo's IGSCC program for the upcoming Dresden 2 refueling outage is acceptable.

The staff has also concluded that it is no longer necessary for CECo to submit future plans.