ML20126F455

Discusses Review of 920729 Request for Removal of 24 Condensate & Feedwater Sys Welds from Inservice Insp, Nondestructive Exam Program

ML20126F455
Person / Time
Site:	Fermi
Issue date:	12/18/1992
From:	Colburn T Office of Nuclear Reactor Regulation
To:	Orser W DETROIT EDISON CO.
References
TAC-M84177, NUDOCS 9212300318
Download: ML20126F455 (4)

Text

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• k UNITED STATES -

NUCLEAR REGULATORY COMMISSION c*E$ 1 f- WAM WOTON, D. C. 20655 do December 18.11992

' Docket No. 50-341 Mr. William S.l0rser Senior Vice President - Nuclear Operations Detroit Edison Company 6400 North. Dixie Highway Newport,' Michigan 48166

SUBJECT:

FERMI-2 REMOVAL OF 24 CONDENSATE AND FEEDWATER SYSTEM WELDS-FROM THE-INSERVICE INSPECTION NONDESTRUCTIVE EXAMINATION (ISI-NDE) PROGRAM' (TAC NO. M84177) 4

Dear Mr. Orser:

The staff has completed its review of your submittal dated July 29, 1992, raquesting removal of 24 condensate and feedwater-system welds from the Fermi-2 Inservice Inspection, Nondestructive Examination (ISI-NDE) program.

These are nozzle-to-safe-end or safe-end-to-piping welds located on.the Numbers 3, 4, 5, and 6 feedwater heaters which were previously identified.as: s Generic Letter (GL) 88-01 welds and which were inspected during the first refueling outage and, subsequently, recategorized from " Category:G" to j

" Category 0" welds. Your justification ior removing the welds from the ISI-NDE program is summarized as follows:

u (1) GL 88-01 applies to welds that are located in auste'nitic stainless steel- I piping that contains reactor coolant or are located.on reactor vessel 1 attachments or appurtenances. The subject welds'are' located-in a  !

portion of the condensate and feedwater system piping outboard-of the containment isolation valves; and'the subject piping does not contain 1 reactor coolant.

q (2) The subject welds are non-safety-related, non-seismically qualified ANSI . J B31.1 welds and are not a part of the reactor pressure boundary. The 1

-subject condensate and feedwater systems are not required'for the safe .

shutdown of the reactor or for operation of-the nuclear steam supply. '

system safety features.

(3) Intergranual stress corrosion cracking (IGSCC) would be insignificant for those welds because under normal. conditions, dissolved oxygen levels  !

are approximately 20 ppb and the conductivity is less than 0.06 uS/cm. -

We do not agree with your contention'that the condensate and:feedwater piping system outboard:of the containment isolation valves does not contain. reactor -

coo.lant. The water in the subject piping is the same water that:will enter

.the reactor vessel to serve as reactor coolant. As stated in GL 88-01,-the-staff positions in GL 88-01 apply to all:BWR austenitic stainless steel-piping that is 4 inches-or larger in nominal diameter and that contains reactorc coolant-at a temperature above 200*F g

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during power operation, regardless of American Society for Mechanical Engineers (ASME) Code classification. The intent of the language of "regardless of ASME Code classification" is to indicate that GL 88-01 applies to all piping classifications including piping with non-ASME Code classifications such as the subject piping. The staff concludes that the subject welds are within the scope of GL 88-01 because the piping contains reactor coolant and has a nominal diameter of 20 inches to 24 inches with a service temperature above 200*F. These welds may be susceptible to IGSCC.

Therefore, the 24 welds should not be removed from the fermi-2 ISI-NDE program.

However, as stated in your request, under normal conditions of operation the oxygen level and conductivity in the subject piping are very low and the likelihood of IGSCC is reduced. The subject welds are not immune to IGSSC; however, since a crevice condition may be present in those welds which have backing rings. The crevice condition is known to accelerate IGSCC, particularly in Inconel material. The staff notes that some of those welds were buttered or clad with Inconel materials. In view of the above, the staff has determined that the same staff position delineated in GL 88-01, Supplement 1 addressing the inspection of reactor water cleanup (RWCU) piping outboard of the containment isolation valves should be applied to those 24 welds. An inspection of the subject piping welds on a sampling basis of at least 10 percent of the weld population should be performed during each refueling outage, if you have any questions, please contact me at (301)504-1341.

/S/

Sincerely, Timothy G. Colburn, Sr. Project Manager Project Directorate III-l Division of Reactor Projects - III/IV/V Office of Nuclear Reactor Projects

Enclosure:

As stated cc: See next page SEE PREVIOUS CONCURRENCE

• 3 0FFICE LA:PDIII-l* PM:PDIII-1 E PD:PDIII-lj NAME- MShuttleworth TColburn:vsb LMarsh DATE 12/16/92 /2.//Y/92 W l(/92 FILENAME: G:\WPDOCS\ FERMI \ FERMI-2.REV

-4 Mr. William Orser FERMI-2 Detroit Edison Company Cc: _,

John Flynn, Esquire Senior Attorney--

Detroit Edison Company 2000 Second Avenue Detroit, Michigan -48226 Nuclear Facilities and Environmental Monitoring Section Office Division of Radiological Health Department of Public Health 3423 H. Logan Street P. O. Box 30195 Lansing, Michigan 48909 Mr. Stan Stasek U.S. Nuclear Regulatory Commission .

Resident Inspector.0ffice 6450 W. Dixie Highway Newport, Michigan 48166 Monroe County Office' of Civil Preparedness 963 South Raisinvile Monroe, Michigan 48161 Regional Administrator, Region III U.S. Nuclear Regulatory Commission 799 Roosevelt Road Glen Ellyn, Illinois 60137 Mr. A. Cecil Settles Director - Nuclear Licensing Detroit Edison Company Fermi 2 6400 North Dixie liighway Newport, Michigan 48166

4 during power operation, regardless of American Society: for Mechanical Engineers (ASME) Code classification. The intent of the language of "regardless of ASME Code classification" is to indicate that GL 88-01 applies to all piping classifications including piping with non-ASME Code l classifications such as the subject piping. The. staff concludes that the i

subject welds are within the scope of GL 88-01 because the piping contains reactor coolant and has a nominal diameter of 20 inches to 24 inches with a service temperature above 200*F. These welds may be susceptible to IGSCC, Therefore, the 24 welds should not be removed from the Fermi-2 ISI-NDE program.

However, as stated in your request, under normal conditions of operation the oxygen level and conductivity in the subject piping are very low and the likelihood of IGSCC is reduced. The subject welds are not immune to IGSSC; however, since a crevice condition may be present in those welds which have backing rings. The crevice condition is known to accelerate IGSCC, particularly in Inconel material. The staff notes that some of those welds were buttered or clad with Inconel materials. In view of the above, the staff has determined that the same staff position delineated in GL 88-01, Supplement I addressing the inspection of reactor water cleanup (RWCU) piping outboard of the containment isolation valves should be applied to those 24 welds. An inspection of the subject piping welds on a sampling basis of at least 10 percent of the weld population should be performed during each refueling outage.

If you have any questions, please contact me at (301)504-1341.

/S/

Sincerely, Timothy G. Colburn, Sr. Project Manager Project Directorate III-l Division of Reactor Projects - III/IV/V Office of Nuclear Reactor Projects-

Enclosure:

As stated cc: See next page SEE PREVIOUS CONCURRENCE

• 3 0FFICE LA:PDIII-l* PM:PDIII-1 E PD:PDIII-li k NAME MShuttleworth TColburn:vsb LMarsh-DATE 12/16/92 /1//lf/92 11/ l([/92 FILENAME: G:\WP00CS\ FERMI \ FERMI-2.REV

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