ML103140218

Lr - FW: Notification 50341635

ML103140218
Person / Time
Site:	Diablo Canyon
Issue date:	11/10/2010
From:	Office of Nuclear Reactor Regulation
To:	Division of License Renewal
References
Download: ML103140218 (6)

Text

DiabloCanyonNPEm Resource From: Pick, Greg Sent: Wednesday, November 10, 2010 9:39 AM To: DiabloCanyonNPEm Resource

Subject:

FW: Notification 50341635 Attachments: 50341635.pdf From: Grebel, Terence [1]

Sent: Monday, November 01, 2010 8:54 AM To: Pick, Greg

Subject:

FW: Notification 50341635 From: Tan, Miranda Sent: Friday, October 29, 2010 6:43 PM To: Grebel, Terence Cc: 'Terence Grebel'

Subject:

Notification 50341635

Terry, Attached is the updated notification 50341635 on the strain gauge cover plates.

Miranda

<<50341635.pdf>>

1

Hearing Identifier: DiabloCanyon_LicenseRenewal_NonPublic Email Number: 2162 Mail Envelope Properties (CA7A6E1C5CB1204FA832458074C4571BFF1493B726)

Subject:

FW: Notification 50341635 Sent Date: 11/10/2010 9:39:13 AM Received Date: 11/10/2010 9:39:20 AM From: Pick, Greg Created By: Greg.Pick@nrc.gov Recipients:

"DiabloCanyonNPEm Resource" <DiabloCanyonNPEm.Resource@nrc.gov>

Tracking Status: None Post Office: R4CLSTR01.nrc.gov Files Size Date & Time MESSAGE 501 11/10/2010 9:39:20 AM 50341635.pdf 91546 Options Priority: Standard Return Notification: No Reply Requested: No Sensitivity: Normal Expiration Date:

Recipients Received:

Notification: 50341635 U-0 Type: DN Work Type: EVAL ENGR

Description:

Evaluate the need for strain gauge PM Order:

Funct. Loc: DC-0-80-F U0 SYS 80 FACIL Reported By: KMMH Kristin M. Zaitz Rpt By Work Ctr: EDC-008 Contact Info: Created On: 15 Sep 10 12:20 Planner Group:

Main Wrk Ctr: EDC-008 Zaitz Kristin - KMMH PROBLEM DESCRIPTION 09/15/2010 12:16:45 Kristin M. Zaitz (KMMH) Phone 805/545-6058 The purpose of this notification is to evaluate the need for preventative and/or corrective maintenance to maintain a water tight seal around the containment strain gauges. This notification does not report an equipment problem. Existing drawings and descriptions of these strain gauges are not adequate for engineering to determine if a water leak path exists that could over time expose the containment rebar to corrosive conditions and pose an aging management concern. These gauges are out-of-service (abandoned in place), and do not impact the design function of the containment structure. The results of this evaluation will be used to enhance containment inspections and the associated aging management program, if deemed necessary.

Background:

Strain gauges were installed at various locations on the containment structure to assess the performance of the structure during the Structural Integrity Test. For Unit 1, this test was conducted between August 1 and 11, 1975. For Unit 2, this test was conducted between October 26 and November 5, 1977. These strain gauges were required only for these tests #they are no longer in service.

Event Date 15 Sep 10 Notif Required By 31 Dec 11 Station Sig.: 5 Other Print Date: 29 Oct 10 18:38 PG&E Corporation DIABLO CANYON Page 1 of 4

Notification: 50341635 U-0 Type: DN Work Type: EVAL ENGR

Description:

Evaluate the need for strain gauge PM Order:

The strain gauges are mounted on the containment structure no. 18 reinforcing bars. The cable used for the strain gauges wiring to the strain indication equipment is routed through a flexible conduit that is embedded in the concrete, extending from the gauge area to junction boxes attached to the outside surface of containment. A cover plate with silicone caulking is installed at the surface of containment, but the details of this configuration are vague. Refer to the following drawings for more information:

103512 663075-654 663075-657 Containment structure inspections performed in accordance with ASME Section XI Subsection IWL have noted locations where the strain gauge cover plates have partially disengaged or fallen out of place. The IWL concrete inspections have investigated the condition of the concrete around these cover plates and found there to be no degradation or indications of corrosion of the underlying reinforcing bars. Although there is currently no evidence of corrosion on the surface, the configuration of the strain gauges may be such that there is a water leak path that could extend from the surface of containment to the rebar in the long term. If this path exists, then inspections and PM should focus on ensuring a watertight seal at these locations to preclude degradation of the rebar at these locations.

09/15/2010 13:50:37 David G. Wong (DGW1) Phone 805/545-6546 As the civil engineering supervisor, I have reviewed the above writeup and provide my approval. This notification does not report a non-conforming or degraded condition, rather it is a tracking tool that engineering will use to determine whether or not a maintenance plan is needed to provide enhanced monitoring of the strain guages and their cover plates for any degraded conditions of the guages. If a degraded condition is found, a separate notification will be written to place it into the corrective action program.

Notification assigned to the responsible engineer to determine the best Print Date: 29 Oct 10 18:38 PG&E Corporation DIABLO CANYON Page 2 of 4

Notification: 50341635 U-0 Type: DN Work Type: EVAL ENGR

Description:

Evaluate the need for strain gauge PM Order:

way to monitor the strain guages/cover plates (does the present IWL inspections suffice or does a new maintenance plan need to track it?)

09/15/2010 15:40:22 Behrooz Shakibnia (BXS5) Phone 805/545-6094 For concrete surface conduit box details, see drawing 663075-655.

09/16/2010 14:59:59 Jana M. Orlando (JMSO) Phone 805/545-3126 The issue/event documented on this notification was reviewed by the Notification Review Team (NRT) and determined to be the indicated significance level per OM7.ID1. If additional information is discovered that would affect the significance level determination, contact a member of the NRT or e-mail DCPP NRT Members.

09/16/2010 18:38:41 David G. Wong (DGW1) Phone 805/545-6546 The containment structure system engineer should also consider instituting a more permanent fix, such as sealing up of the entire strain guage wire box.

10/28/2010 23:22:04 David G. Wong (DGW1) Phone 805/545-6546 Civil Engineering will be creating a maintenance plan that will ensure enhanced monitoring of the strain gauges and their cover plates for degraded conditions. Civil Engineering will also be issuing a design change or N-Mod to provide permanent fix options (including sealing up of the entire strain guage wire box) that can be implemented depending upon the as-found condition (extent of damage) of the strain guage wire boxes.

Print Date: 29 Oct 10 18:38 PG&E Corporation DIABLO CANYON Page 3 of 4

Notification: 50341635 U-0 Type: DN Work Type: EVAL ENGR

Description:

Evaluate the need for strain gauge PM Order:

STATUS DETAILS System Status: OSNO User Status: 25 ASGN Assigned to Target Workcenter Print Date: 29 Oct 10 18:38 PG&E Corporation DIABLO CANYON Page 4 of 4