ML19350B254
| ML19350B254 | |
| Person / Time | |
|---|---|
| Site: | Maine Yankee |
| Issue date: | 02/27/1981 |
| From: | Grier B NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| To: | Groce R Maine Yankee |
| References | |
| NUDOCS 8103200176 | |
| Download: ML19350B254 (1) | |
Text
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UNITED STATES
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NUCLEAR REGULATORY COMMISSION g,t a
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KING OF PRU'JtA. PENNSYLVANIA 19406 o
FEB 2 71981 yQ Docket No. 50-309 g[
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Maine Yankee Atomic Power Company G
ATTN:
ir, Robert H. droce 5
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renior Engineer - Licensing I
es. g% *Jg g, f 1671 Worcester Road Framingham, Massachusetts 01701
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Gentlemen:
The enclosed IE Information Notice No. 81-04, " Cracking in Main Steam Lines" is forwarded to you information.
No written response is required.
If you desire additional information regarding this matter, please contact this office.
Sincerely, Oc~ve-WI.
ELfaw e H. Grier J1 rector
Enclosures:
1.
IE Information Notice No. 81-04, with 2 attachments CCNTACT:
L. E. Tripp (215-3::7-5282) cc w/encls:
E. Wood, Plant Superintendent E. W. Thurlow, President B108200 g%
SSINS No.: 6835 Accession No.:
8011040265 IN 81-04 UNITED STATES NUCLEAR REGULATORY COMMISSION OFFICE OF INSPECTION AND ENFORCEMENT WASHINGTON, D.C. 20555 February 27,1981 IE Information Notice No. 81-04:
CRACKING IN MAIN STEAM LINES Description of Circumstances:
The Virginia Electric Power Company promptly notified the NRC on February 23, 1981 that a radiography examination, during the ongoing steam generator replacement outage at Surry Unit 1, had revealed a lengthy crack indication in the I.D. counterbore area of a weldment on the in-line "T" fitting whi'ch connects the vertical run of 30-inch piping to the safety relief valve header and 30-inch maia steam line of Steam Generator "A".
This piping connection is located outside the containment penetration immediately upstream of the main steam isolation valve as shown in the attached sketch.
A visual and dye penetrant examination on the pipe I.O. surface of the weldment nearest the containment penetration established that the cracking extended about 120 F around the fitting counterbore between the 4 o' clock to 8 o' clock 0
position.
Cracking was also observed in the weid counterbore at the opposite end of the T-fitting during visual examination of the piping interior.
Radio-graphic examination of "B" and "C" main steam line T-fitting welds disclosed crack indications at similar locations.
Metallurgical specimens of the cracking were trepanned from the T-fitting of the "A" main steam line for analysis.
Controlled excavation and depth measu ements of the crack at its mid-length indict.ted a crack depth of about 0.090" in this location.
The cause of cracking has not yet been established.
VEPCO has planned an ultrasonic examination. of similar weldments in Surry Unit 2 main steam lines utilizing " Hot Piping" ultrasonic techniques.
Preparations are also being made to ultrasonic examine similar weldments at North Anna Unit 1, currently in col i shutdown for refueling.
Recommendation to Licensees:
This,nformation is provided as an early notification of a significant safety matter that is still under review by the NRC staff.
It is expected that recipients will review the information for possible applicability to their plants.
For those plants having
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are currently in a refueling or
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DUPLICATE DOCUMENT that a ultrasonic and/or radiogr counterbore areas of the T-fitti operations, unless some current Entire cLO;mnent previously is available.
entered into system under:
EO/IQ40245 m
No. of pages:
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