ML20064K223

Forwards 800505 Memo Re Underclad Cracking in Reactor Vessel Nozzles.Review Re Safety Aspects & Compliance W/Section IX of ASME Code Concludes That Problem Should Not Be Included on Generic Issues List

ML20064K223
Person / Time
Site:	Sequoyah, North Anna, 05000000
Issue date:	07/17/1980
From:	Baer R Office of Nuclear Reactor Regulation
To:	Kintner L Office of Nuclear Reactor Regulation
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References
FOIA-82-261 NUDOCS 8010210037
Download: ML20064K223 (1)

Text

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July 17,1980 SPEB File NRR. Reading 917 i

NOTE TO:

L. L. Kintner

'9 97 FROM:

Robert L. Baer

SUBJECT:

" ADD ON" GENERIC ISSUE'. UNDERCLAD CRACKS A memorandum (Attachment 1) that you referenced in a note' to me* requested information from a neber of license applicants concerning the cracking fou'nd in Westinghouse reactor vessel nozzles. In your note you requested SPEB to determine if this cracking phenomenon was an " add on" candidate for the Generic Issues _ Program.

E'-

While 'the cracks that have been found are numerous, their size, lacation and potential growth rate during service do not indicate any safety concern (see the staff evaluations in Attachments 2 and 3). In fact, the cracks that have.,

been found, if compamd to the requirements of Section XI of the ASME Code,

'?

' are both smaller than the maxim a size allowed and can only be detected reliably using equipment nure sensitive than required. Compliance with Section II is recognized by the staff as providing adequate assurance that the reactor vessel has sufficient margin against flaw induced failure. However, to gain a better understanding of the cause of the flaws and to ensum the required margin of safety, the staff is requesting additdonal information from several plants prior to issuance of their OL (see Attachment 1) and requiring that the mactor vessel nozzles on Sequoyah 1 and North Anna 2 receive a periodic augmented inservice inspection.

Based upon the staff's conclusions regarding the safety aspects of this cracking phenomenon (detailed in Attachments 2 and 3) and compliance with Section XI of the ASME Code, we do not m=+rd that this problem be included on the generic issues list. For further guidance in handling other issues of this nature.

I an enclosing a recent memorandum (Attachant 4) that details our recommenda tions regadding requests for information and identification of Generic Safety Issues.

~

J

.ggny MJ I

Robert L. Saer e

~

Attachments:

As Stated "3go/oa/co37 ces w/ attachments:

l H. Ernst R. Baer M. Boyle r

DST:SPEB DST:SPEB l