ML12044A356

Email from G. Cheruvenki, NRR to C. Fairbanks, NRR on North Anna ISI

ML12044A356
Person / Time
Site:	North Anna
Issue date:	09/03/2011
From:	Ganesh Cheruvenki Office of Nuclear Reactor Regulation
To:	Carolyn Fairbanks Office of Nuclear Reactor Regulation
References
FOIA/PA-2011-0357
Download: ML12044A356 (3)

Text

Fairbanks, Carolyn From: Cheruvenki, Ganesh Sent: Saturday, September 03, 2011 9:32 AM To: Fairbanks, Carolyn Cc: Poehler, Jeffrey

Subject:

North AnnalSl Attachments: North AnnalSl.docx Importance: High

Carolyn, Please review and send me your comments.

1

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North Anna-Units 1 and 2-Seismic Event ---Inspections Reactor Vessel Internal (RVI) Components--Inspection- Staff does not have any regulatory requirement that enforces inspections of the RVI components at this time.

My recommendation--- This does not reflect Matt's position on this issue.

(1) The licensee should provide a robust explanation why the inspections of the RVI components is not necessary specifically, for the following components that were originally designed using seismic loadings e.g., SSE and DBE as a part of its design basis (Reference-Westinghouse Report-WCAP-14577, 2001). These are considered "Primary" components that require routine inspections during every ISI interval.

(a) Lower Support Forging; (b) Baffle Former Assembly; (c) Upper Core Plate; (d) Guide Tube; and (e) Core Barrel Assembly.

(2) The licensee's evaluation shall be reviewed by DE's (Meena's branch) engineers and if they are not satisfied we can negotiate with the licensee regarding the extent of inspections based on the stress levels.

(3) Pressure Boundary Components-ASME Section III Class I Welds-Reactor Vessel Nozzle to Safe-end Welds At least one dissimilar weld (with highest stress-e.g., hot leg) in the population should be inspected. If the licensee does not want to inspect it, it should provide an explanation for not doing so. Since stainless steel and nickel alloys have high flaw tolerance, it is likely that no cracks will be initiated as a result of a seismic event.

Due to transient loading (only one cycle) it is unlikely that any cracks are initiated or propagated during the seismic event.

At least a surface examination of a structural weld ovelay on a dissimilar weld at least on the low alloy steel nozzle on the side should be performed. This is to ensure that the temperbead welds are adequately protecting the underlying 182 weld.---The licensee will never agree to do this.

At least the licensee should perform the aforementioned inspections during the next outage.

North Anna-Units 1 and 2-Seismic Event ---Inspections Reactor Vessel Internal (RVI) Components--Inspection- Staff does not have any regulatory requirement that enforces inspections of the RVI components at this time.

My recommendation--- This does not reflect Matt's position on this issue.

(1) The licensee should provide a robust explanation why the inspections of the RVI components is not necessary specifically, for the following components that were originally designed using seismic loadings e.g., SSE and DBE as a part of its design basis (Reference-Westinghouse Report-WCAP-14577, 2001). These are considered "Primary" components that require routine inspections during every ISI interval.

(a) Lower Support Forging; (b) Baffle Former Assembly; (c) Upper Core Plate; (d) Guide Tube; and (e) Core Barrel Assembly.

(2) The licensee's evaluation shall be reviewed by DE's (Meena's branch) engineers and if they are not satisfied we can negotiate with the licensee regarding the extent of inspections based on the stress levels.

(3) Pressure Boundary Components-ASME Section III Class 1 Welds-Reactor Vessel Nozzle to Safe-end Welds At least one dissimilar weld (with highest stress-e.g., hot leg) in the population should be inspected. If the licensee does not want to inspect it, it should provide an explanation for not doing so. Since stainless steel and nickel alloys have high flaw tolerance, it is likely that no cracks will be initiated as a result of a seismic event.

Due to transient loading (only one cycle) it is unlikely that any cracks are initiated or propagated during the seismic event.

At least a surface examination of a structural weld ovelay on a dissimilar weld at least on the low alloy steel nozzle on the side should be performed. This is to ensure that the temperbead welds are adequately protecting the underlying 182 weld.---The licensee will never agree to do this.

At least the licensee should perform the aforementioned inspections during the next outage.