ML12038A240

Email from A. Istar, NRR to G. Bjorkman, NMSS North Anna Fatigue Analyses Question?

ML12038A240
Person / Time
Site:	North Anna
Issue date:	09/14/2011
From:	Ata Istar Office of Nuclear Reactor Regulation
To:	Gordon Bjorkman Office of Nuclear Material Safety and Safeguards
References
FOIA/PA-2011-0357
Download: ML12038A240 (1)

Text

Craver, Patti From: Istar, Ata \ *\ .

Sent: Wednesday, September 14, 2011 8:47 AM To: Bjorkman, Gordon

Subject:

RE: North Anna Fatigue Analyses Question?

Gordon:

Could you please point out the ASME code requirement for this.

In the original fatigue analyses at the nuclear power plant, I do not believe that occasional loading conditions are/were considered! The fatigue analyses are/were performed under operating loading conditions only! They could be cyclic conditions due to temperature and pressure as well as cycle counting.

THANKS From: Bjorkman, Gordon \ f\

Sent: Wednesday, September 14, 2011 8:38 AM To: Istar, Ata

Subject:

Re: North Anna Fatigue Analyses Question?

The earthquake exceeded the SSE over a broad range of frequencies, which would have produced high stresses in some SSCs. A few cycles at high stress can make an important contribution to fatigue damage (Miner's Law). I would say it needs to be considered.

Sent from my NRC BlackBerry

~Ph.,D."P,PE.

=1 From: Istar, Ata To: Bjorkman, Gond, nCV--

Sent: Wed Sep 14 07:44:24 2011

Subject:

North Anna Fatigue Analyses Question?

Gordon:

Should the occasional loading conditions (OBE and SSE) be considered for the SSCs subjected to the fatigue analyses?

Ata ISTAR (301) 415-4049 ata. istaranrc..ov Reduce waste - print when necessary!

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