ML101050521

Email, Request for Additional Information Re License Amendment Request, Revise FSAR Update Critical Damping Value for Structural Dynamic Qualification of Control Rod Drive Mechanism Pressure Housings (TAC ME2995-ME2996)

ML101050521
Person / Time
Site:	Diablo Canyon
Issue date:	04/15/2010
From:	Wang A Plant Licensing Branch IV
To:	Baldwin T, Parker L Pacific Gas & Electric Co
Wang, A B, NRR/DORL/LPLIV, 415-1445
References
TAC ME2995, TAC ME2996
Download: ML101050521 (2)

Text

From: Wang, Alan Sent: Thursday, April 15, 2010 1:52 PM To: Baldwin, Thomas (DCPP); Larry Parker Cc: Lent, Susan; Burkhardt, Janet

Subject:

Request for Additional Information Regarding CRDM Damping Factors (ME2995 and ME2996)

Tom and Larry, By letter dated December 14, 2009 (Agencywide Documents Access & Management System (ADAMS) Accession No. ML093580092), Pacific Gas and Electric Company (PG&E), the licensee for Diablo Canyon Power Plant, Unit Nos 1 and 2 (DCPP), requested a change to revise the licensing basis and the Final Safety Analysis Report Update (FSARU) to allow use of a damping value of 5 percent of critical damping for the structural dynamic qualification of the control rod drive mechanism (CRDM) pressure housings on the replacement reactor vessel head for the design earthquake (DE), double design earthquake (DDE), Hosgri earthquake (HE), and loss-of-coolant accident (LOCA) loading conditions.

The US Nuclear Regulatory Commission (NRC) staff has determined that the following additional information is needed to complete its review of the subject license amendment request for DCPP. This request was discussed with Larry Parker of your staff on April 15, 2010, and it was agreed that a response would be provided by April 23, 2010. If circumstances result in the need to revise the requested response date, please contact me at (301) 415-1445 or via e-mail at Alan.Wang@nrc.gov.

REQUEST FOR ADDITIONAL INFORMATION

1) Please provide the following information:

(a) Provide a summary of the recent analysis results for the new CRDM pressure housing based on a 5% critical damping value for all load combinations that contain DE, DDE, HE, and LOCA loadings, showing the respective margins.

(b) Provide a brief description of the structural dynamic analysis methodology used in the qualification of the CRDM pressure housings on the replacement reactor vessel head.

(c) Provide, for comparison, a summary of lower damping values used in the original CRDM analysis and a summary of the design basis analysis results, with the respective margins.

(d) Clarify that the higher 5% critical damping value will only be applied to the CRDMs, and will not be applied to the reactor coolant piping or reactor internals analyses.

2) Pages 3 and 4 along with Figure 1 of the enclosure to PG& Es letter dated December 14, 2010 (DCL-09-086) provide the basis for similarity between the original equipment manufacturer (OEM) CRDM and the new AREVA supplied replacement CRDM from considerations such as the seismic support plate gap, CRDM length, latch housing and rod travel housing materials, CRDM geometrical section properties, operating parameters, appurtenances, and design differences. Provide a similar comparison of the AREVA-supplied replacement CRDMs and the CRDMs tested by Westinghouse, as described in the topical report, WCAP-7921-AR.

E-mail Properties Mail Envelope Properties (C0A338EE37A11447B136119705BF9A3F6165789ABE)

Subject:

Request for Additional Information Regarding CRDM Damping Factors (ME2995 and ME2996)

Sent Date: 4/15/2010 1:52:19 PM Received Date: 4/15/2010 1:52:19 PM From: Wang, Alan Created By: Alan.Wang@nrc.gov Recipients:

TRB1@pge.com (Baldwin, Thomas (DCPP))

Tracking Status: None LMP1@pge.com (Larry Parker)

Tracking Status: None Susan.Lent@nrc.gov (Lent, Susan)

Tracking Status: None Janet.Burkhardt@nrc.gov (Burkhardt, Janet)

Tracking Status: None Post Office:

HQCLSTR02.nrc.gov Files Size Date & Time MESSAGE 11744 4/15/2010 Options Expiration Date:

Priority: olImportanceNormal ReplyRequested: False Return Notification: False Sensitivity: olNormal Recipients received: