ML19261F182

RO on 721108:during Prebaseline Ultrasonic Exams of Welds in Reactor Coolant Sys,Five Found W/Ultrasonic Reflectors Greater than American Matl Stds Inst B31.7 Code. Investigations & Destructive Sampling Under Way

ML19261F182
Person / Time
Site:	Three Mile Island
Issue date:	12/08/1972
From:	John Miller METROPOLITAN EDISON CO.
To:
References
NUDOCS 7910250603
Download: ML19261F182 (3)

Text

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M ETROPOLITAN EDISON COM PANY suasioran r cr aesenat ruatic uritirie: conponariori iT OFFICE BOX 542 RE AOlNG, PENNSYLVANI A 19603 TELEPHCNE 215 - 929-3601 rece:.ber 8,1972 Mr. R. Krucsi, Director Directorate of Regulatory Operations United States Atomic Energy Commission Washington, D. C. 20545

Dear Mr. Kruesi:

SVBJECT: THREE MILE ISL M D NUCLEAR STATION UNIT 1 DOCKET NO. 50-289 ULTRASONIC INDICATIONS IN REACTOR COOLANT PIPING This letter is to further clarify the telephone conversation with Region I DRO Office on November 8,1972, concerning anomalous conditions in seven shop welds during pre-baceline inservice irspection.

Pre-baseline ultrasonic examinations performed of welds in the reactor coolant system indicated that there were five welds that had ultrasonic reflectors greater than permitted by the ANSI B31.7 Code. All these welds are B&W shop welds.

The welds are identified as follows:

WELD NO. . LOCATION / TYPE CON-057 Pucp 1C (Northwest) Suction Leg -- Stainless Steel Girth Weld.

RC-078 Pump IC (Northwest) Suction Leg -- Stainless Steel Carbon Steel Transition Girth Weld.

RC-097 Pump 1D (huchwest) Suction Leg -- Stainless Steel Carbon Steel Transition Girth Weld.

CON-022 Hot Leg Elbow on Tcp of West Steam Generator -

Carbon Steel Girth Weld CON-019 Hot Leg in Elbow on Top of East Steam Generator --

Carben Steel Longitudinal Weld.

NOTE: Two other carbon steel velds, numbers RC-063 and RC-013 were previously identified as containing UT indications; however, the indications are acceptable per ANSI B31.7 requirements.

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m' Radiographic examinations of stainless rteel welds CON-057 and RC-078 vere performed. The RT films were evaluated indepe.adently of the UT results, and the RT evaluation essentially confirms the presence of indications at the same locations found by UT. A UT examination was performed from the insidc of weld CON-057 and this examination confirmed the original UT examination which was performed from the outside surface. The third stainless steel weld, RC-097 located in the southwest leg below the reactor coolant pump, is not accessible from the inside for radio-graphic examination since the pump internals are installed in that leg.

Early in Nove=ber 1972, B&W performed additional UT examination of weld CON-057. Concurrently, they reviewed the RT fil=s of welds CON-057 and RC-078.

The following is a su==ary of B&W's results:

1. B&W confirmed the presence of reflectors in their UT examination performed from the outside surface of weld CON-057. They were also able to locate these same type reflectors in the weld when performing UT from the inside surface. In addition, loss of back reflection of the UT signal through the weld using a longitudinal beam was observed. B&W concluded that the UT reflectors were caused by the coarse granular structure in the weld and near the line of fusion between the weld and base metal.

B&W would not classify the reflectors as unacceptable linear indications.

2. B&W stated that none of the indications shown on the fil=s of both CON-057 and RC-078 exceeded code limits of acceptability. In the case of CON-057, B&W concluded that the film indications which appeared to be pockets of slag were not interconnected. In the case of RC-078, B&W concluded that the linear indications are granular phenomena occurring at the line of fusion as a result of a scalloping effect induced during welding. B&W requested that an additional RT examination of CON-057 be made to obtain films for composite viewing, rather than for single film reviewing.

3. B&W has agreed with the UT examination of the two carbon steel welds CON-022 and CON-019. They are attempting to either justify the acceptance of the indications or the carbon steel welds will haie to be repaired.

Since the parties cannot agree cencerning the acceptability of the indica-tions in the stainless steel welds, we are preparing to perform exploratory sampling of one of these velds. The results of this destructive sampling will determine if the indications are grain anomalous conditions or actual defects.

Once the question to the existence of the indication in a stainless steel weld is settled, this will resolve the questions in the two remaining welds.

The indications in the carbon steel welds are being analyzed by B&W. If in their analysis they cannot justify the UT indications, i.e. , code case or fracture cechanics, then the indications will be removed and the welds repaired.

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Any further technical information you require will be available at the :

Wree Mile Island site for your revietr. .

Very truly yours, -

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. G. Miller v, ice President '

cc: Mr. J . P . O ' Reilly

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