ML20087B898

Ro:Clad Failure Occurred on Primary Side of 12 of 3 Steam Generators.Cause Not Found.Cladding Being Replaced

ML20087B898
Person / Time
Site:	Robinson
Issue date:	06/28/1971
From:	Utley E CAROLINA POWER & LIGHT CO.
To:	Morris P US ATOMIC ENERGY COMMISSION (AEC)
Shared Package
ML20087B746	List: ML20087B773 ML20087B846 ML20087B898
References
NUDOCS 8403090392
Download: ML20087B898 (1)

Text

_ - _ -

. .o ,

C 50 ~2 h1 Carolina ~ Power & Light Company , g Raleigh, North Carolina 27602 q N June 28, 1971 67 fi$ I Y

~

JUL 2 =

197ta a

~~

bS N h&UGr o.1,

%sy syr g Dr. Peter A. Morris, Director o> & /

Division of Reactor Licensing U. S. Atomic Energy Com:nission Washington, D. C.

H. B. ROBINSON PLANT LICENSE DPR-23

Dear Dr. Morris:

In accordance with Paragraph 6.6.3, Technical Specifications, License DPR-23, it is reported that some clad failure has occurred on the primary side of two of the three steam generators installed at the H. B.

Robinson Plant. .

/

The unbonded clad appears to be localized on the tube sheet di /

rectly under the partition platot and extends out to the first row of tubes on each side. Ultrasonic mapping indicates that this condition exists on the "A" and "C" steam generators. The "B" steam generator is apparently flaw free; however, a more extensive inspection is underway.

Repairs are being effected under warranty by the Tampa Division, Westinghouse Electric Corporation. The unbonded clad is being removed out to sound material and will be replaced by welding clad overlay. The first row of tubes on each side of the partition plate,. some 94 tubes, will be plugged and covered with the new clad overlay. It is planned to stress relieve the new clad in place.

The precise mechanism that caused the unbonding is not completely understood. A complete review of the design and the manufacturing processes is being conducted by the Tampa Division. Samples of the failed material are being examined in the laboratory. A detailed report outlining the ex-tent of the damage and, more importantly, the adequacy of the anticipated repairs, will be prepared by the Tampa Division when the investigation is complete. A copy of this report will be forwarded when it is approved by Carolina Power & Light Company.

_< > i 3 >

MI 7d1//7/ Yours very truly, 8403090392 710820 *

- 9 - - - -

PDR ADOCK 05000261 s' S PDR E. E. Uticy

((NBB:HH Manager Generation & System Operations

~

COPY SENT-REGION Y -, 1 4 3037.

- - - . . . . . . .. .