TENNESSEE VALLEY AUTHORITY CHATTANOOGA. TENNESSEE 37401

51 1573 Lookout Place

FEB 27 1987

WbRD-50-390/84-17 10 CrV 50.55(e) WMRD-50-391/84-17

U.S. Nuclear Regulatory Comaission / Attn: Document Control Desk V Office of Nuclear Reactor Regulation Washington, D.C. 20555

Attention Dr. J. Nelson Grace

MATTS BAR NUCLEAR PLANT UNITS 1 AND 2 - DEFICIENT WULDS FOR HANGER LUGS O

ASMN CODE PIPING - WUBD-50-390/84-17, USD-50-391/84-17 - ITwIT RPOR

The subject deficiency was initially reported to IRC-Region II Inspector Steve Elrod on January 27, 1987, in accordance with 10 CFR 50.55(e) as ICR W-S18-P-8 for unit 1. 8CR WN 7192-S Mas initiated to document the potential for this deficiency for unit 2. A similar deficiency was reported previously (W•BD-50-390/84-17, UBRD-50-391/84-17) but was downgraded to nonreportable in our May 18, 1984 report to NC. Because of the similarity to the previous deficiency, we are reopening that itm rather than reporting this as a new construction deficiency. Enclosed is our interia report. We expect to submit our final report on or about January 15, 1988.

If there are any questions, please get in touch with R. D. Schuls at (615) 365-8527.

Very truly yours,

TENNESSE VALLEY AUTHOIITY

R. ridley, Director Nuclear Saf ty and Licensing

Enclosure cc: See page 2

B '

An Equat Opportunity E imployei

U.S. Muclear Regulatory Comission FEB 27 1987

ec (Enclosure): U.S. Nuclear Regulatory Comission legion II Attn: Mr. Gary G. Zech, Director, TVA Projects 101 Narietta Street, NW, Suite 2900 Atlanta, Georgia 30323

Reeccrds Center Institute of Nuclear Power Operations 1100 Circle 75 Parkway, Suite 1500 Atlantas, Georgia 30339

U.S. Nuclear Regulatory Conmission Watts Bar Resident Inspector P.O. Box 700 Spring City, Tennessee 37381

ENCLOSURE

WATTS BAR NUCLEAR PLANT UNITS 1 AND 2

DEFICIENT WELDS FOR HANGER LUGS ON ASKE CODE PIPING

SCR W-518-PS, SCR WRI 7192, SCR WBN 5559

WBRD-50-390/84-17, WBRD-50-391/84-17 10 CFR 50.55(e) INTERIM REPORT

DESCRIPTION OF CONDITION

During rework activities on unit 1 supports on the Essential Raw Cooling Water

(ERCW) system, it was discovered that welds joining the piping shear lugs to

the pipe did not achieve complete penetration in conformance with the design

drawings which specify full penetration welds. In addition, the welds on some

of the shear lugs did not extend the entire length of the lug. Discrepancies

were also found with the specified root gap on a small number of the known

discrepant welds. On unit 1, weld deviation reports have been written which

identify other full penetration shear lug welds in various other systems that

have a lack of the specified full penetration. This nonconformance was

reported under SCR W-518-P for unit 1. SCR WBN 7192 was written for unit 2 to

facilitate evaluation for generic nonconformances. A photograph of a section

of a discrepant unit 1 shear lug which has been polished and etched is

attached.

In March of 1984, NCR WBE 5559 was initiated to address a generic problem of a

lack of full penetration on shear lug welds due to the welds not being

backgouged after the initial weld pass. The May 18, 1984 final report

dispositioned the nonconformance as use-as-is. TVA has since discovered

errors in this disposition for Class 2 and 3 pipe and thus the use-as-is

disposition was not adequately justified and will be reevaluated.

The most likely cause of the lack of full penetration in the welds is the same

as that identified in NCR WBN 5559, i.e., the welder did not backgouge before

welding the second side of the lug as required by General Construction

Specification G-29M, drawing l.M.1.2-12, although improper fitup between the

lug and pipe could have also contributed to the condition. The lack of weld

along the entire lug length and the lack of the specified gap apparently

resulted from poor craftsmanship and inadequate inspections.

This deficiency was discovered and reported by a welder who was performing

unrelated rework activities for the purpose of resolving zero period

acceleration (ZPA) concerns. His action was indicative of his alertness and

comuitment to quality.

SAFEUY IMPLIrATIONS

The lack of a lull penetration weld results in an increased stress in the weld

and the pipe w-l1. Experience shows that the stress ratio (applied

stress/allowatle stress) will normally be more critical in the pipe wall. The

increased striss could, in some instances, result in some shear lugs inducing

stress in th,' pipe wall that would exceed the allowable stress. The

overstressed condition in the pipe wall could potentially result in some local

yielding at ýhat point. However, the stress intensity would not likely be

sufficient to cause a loss in the pressure boundary, thereford, the pipe and

system would continue to fulfill its design function. However, a complete

analysis has not been performed on all discrepant welds to determine the

likelihood of a t•ilure under all design loading conditions.

INTERIM PROGRESS

Five supports have been identified on unit 1 with ~repartial penetration

shear lug welds. An analysis was performed to determine the acceptability of

the induced stresses in the weld and pipe wall. Of these, four supprts were

found to be within the acceptable limits of the ASHE code. However, the

calculations for the fifth support show that the stress in the pipe exceeds

the allowable stress by 46 percent. These calculations were based on very

conservative assumptions and it is highly unlikely that the overstress would

result in a loss of pressure boundary. These five supports have already bad

their shear lugs removed due to other rework activities and new shear lugs

will be installed using the proper procedures. This action will be sufficient

to correct the deficiencies for these supports.

TVA is currently evaluating the existing welds on shear lugs by ultrasonic

examination. For this ultrasonic examination. acceptance criteria will be

established for ful'1 penetration welds. On unit 1. 100 percent of the shear

lugs on the safety-related systems will be examined ultrasonically. Welds

which do not meet the acceptance criteria will be reanalyzed, using

conservative design assumptions, to ensure that the existing welds are within

ASKE Code requirements. For those shear lugs which do not meet the ASHE Code.

modifications or repairs will be performed.

From the unit 1 results, a trend can be identified to aid in the development

of an evaluation program for unit 2. It should be noted that 40 shear lugs oau

unit 2 have already been examined ultrasonically. All 40 shear lug welds were

found to have the specified full penetration.

A final report will be submitted to NRC on or about January 15. 1966.

WATTS BAR NUCLEAR PLANT - UNIT 1

Shear Lug Removed from ERCW System

Polished to 600 Grit and Etched