Information Notice No. 81-04: Cracking in Main Steam Lines

                                                            SSINS No.: 6835 
                                                            Accession No.: 
                                                            IN 81-04       

                                UNITED STATES
                           WASHINGTON, D.C. 20555
                              February 27,1981

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 which 
connects the vertical run of 30-inch piping to the safety relief valve 
header and 30-inch main 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.D. surface of the 
weldment nearest the containment penetration established that the cracking 
extended about 120F around the fitting counterbore between the 4 
o'clock to 8 o'clock position. Cracking was also observed in the weld 
counterbore at the opposite end of the T-fitting during visual examination 
of the piping interior. Radiographic 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 
measurements of the crack at its mid-length indicated 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 cold shutdown for refueling. 

Recommendation to Licensees: 

This information 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 similar main steam line configurations 
which are currently in a refueling or extended repair outage, it is 
recommended that a ultrasonic and/or radiographic examination of the three 
welds and counterbore areas of the T-fittings be performed before resumption 
of operations, unless some current basis for assurance of piping integrity 
is available. 

                                                         IN 81-04         
                                                         February 27, 1981 
                                                         Page 2 of 2      

No response to this notice is requested at this time. If you have any 
questions regarding this matter, please contact the Director of the 
appropriate NRC Regional Office. 

1.   Sketch
2.   Recently issued IE Information


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