ML12019A409

Lr - DB Teleconference Draft RAI

ML12019A409
Person / Time
Site:	Davis Besse
Issue date:	08/02/2011
From:	Office of Nuclear Reactor Regulation
To:
References
Download: ML12019A409 (3)

Text

Davis-BesseNPEm Resource From: CuadradoDeJesus, Samuel Sent: Tuesday, August 02, 2011 12:34 PM To: 'custerc@firstenergycorp.com'; dorts@firstenergycorp.com

Subject:

DB Teleconference Draft RAI Attachments: DRAFT Follow-up RAIs Reactor Head Closure Studs.docx Importance: High Cliff Attached is the Draft RAI well be discussing in todays teleconference (I just received it). Please forward it to your team.

Regards Samuel Cuadrado de Jesús Project Manager Projects Branch1 Division of License Renewal U.S. Nuclear Regulatory Commission Phone: 301-415-2946 Samuel.CuadradoDeJesus@nrc.gov 1

Hearing Identifier: Davis_BesseLicenseRenewal_Saf_NonPublic Email Number: 3096 Mail Envelope Properties (Samuel.CuadradoDeJesus@nrc.gov20110802123300)

Subject:

DB Teleconference Draft RAI Sent Date: 8/2/2011 12:33:58 PM Received Date: 8/2/2011 12:33:00 PM From: CuadradoDeJesus, Samuel Created By: Samuel.CuadradoDeJesus@nrc.gov Recipients:

"'custerc@firstenergycorp.com'" <custerc@firstenergycorp.com>

Tracking Status: None "dorts@firstenergycorp.com" <dorts@firstenergycorp.com>

Tracking Status: None Post Office:

Files Size Date & Time MESSAGE 414 8/2/2011 12:33:00 PM DRAFT Follow-up RAIs Reactor Head Closure Studs.docx 24325 Options Priority: High Return Notification: No Reply Requested: No Sensitivity: Normal Expiration Date:

Recipients Received:

Draft follow-up RAI B.2.34-2

Background

In its response to RAI B.2.34-1, the applicant stated that according to the certificate of material test report (CMTR) for the reactor head closure studs, the actual measured yield strength varied from 151 to 159 ksi, and the tensile strength varied from 166 to 171 ksi. The applicant also stated that its reactor head stud material is SA-540, Grade B-23 and that as provided in Regulatory Guide (RG) 1.65, Materials and Inspections for Reactor Vessel Closure Studs, this material when tempered to a maximum tensile strength of 170 ksi, is relatively immune to stress corrosion cracking (SCC). The Reactor Head Closure Studs Program was amended to include an enhancement to preclude the future use of replacement closure stud bolting fabricated from material with actual measured yield strength greater than or equal to 150 ksi, except for use of the existing spare reactor head closure stud bolting.

The preventive actions program element of GALL AMP XI.M3, Reactor Head Closure Stud Bolting, references the guidance in RG 1.65and NUREG-1339, Resolution of Generic Safety Issue 29: Bolting Degradation or Failure in Nuclear Power Plants. GALL AMP XI.M3 states that one of the preventive measures that can reduce the potential for SCC includes using bolting material for closure studs that has an actual measured yield strength less than 150 ksi.

Issue LRA Section B.2.34 states that the Reactor Head Closure Program is an existing program that with enhancements will be consistent with the 10 elements of an effective aging management program as described in GALL AMP XI.M3. All of the applicants reactor head closure studs were fabricated from material with measured yield strength above 150 ksi and some of the furnished materials have a measured tensile strength above 170 ksi. The staff noted that this is an exception to the preventive actions program element of GALL AMP XI.M3.

Request

1) Revise the appropriate sections of the LRA to reflect the use of reactor head closure studs with measured yield strength above 150 ksi as an exception to GALL AMP XI.M3.

2) In view of the greater susceptibility to SCC of the studs, justify the adequacy of the Reactor Head Closure Program to manage cracking due to SCC of high-strength bolting material. As part of the justification, describe how the program manages the potential exposure of closure bolting to borated water and other potential contaminants that may initiate SCC of the reactor head closure bolting studs and components.