ML102920165

Email - Subject: Requested Information Core #54

ML102920165
Person / Time
Site:	Crystal River
Issue date:	12/04/2009
From:	Lake L NRC/RGN-II/DRS/EB3
To:	Robert Carrion, Masters A, Naus D, George Thomas NRC/RGN-II, Oak Ridge
References
FOIA/PA-2010-0116
Download: ML102920165 (14)

Text

Masters, Anthony I From: Lake, Louis Sent: Friday, December 04, 2009 12:37 PM To: Dan naus; Masters, Anthony; Carrion, Robert; Thomas, George Cc: Chou, Rich

Subject:

FW: Requested Information Attachments: Request for Information - Core #54 Attachments.pdf; Request for Information - Core #54.docx Categories: Perform Review Here is some early info on the crack below the equipment hatch. More complete engineering evaluation will be conducted.

Lou From: Souther, Martin [1]

Sent: Friday, December 04, 2009 12:25 PM To: Lake, Louis Cc: Fagan, Paul

Subject:

Requested Information The attached files reflect the current information available on core bore #54 located below the equipment hatch.

Martin E. Souther CR3 Containment Root Cause Team 240-1009 352-795-6486, ext. 1009 1

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Attachment 2 Video image of 2" diameter core

Attachment 2 Video image of 2" diameter core

Attachment 2 Video image of 4" diameter core

Attachment 2 Video image of 4" diameter core

Attachment 2 Video image of 4" diameter core

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Core Bore #54 Information The following information has been gathered based on NDT, boroscope inspections, and core bore sample inspections. Information related to the adjacent tendons is also provided.

NDT PT-407T, Enclosure 8, for bay designation RBCN-003B, documents an IR mobility range of 0.071 to 1.391. Core bore #54 was made near the scan grid point with the highest IR mobility value. Attachment 1 shows the graphical image of the IR data showing the anomaly area. The first image is the smoothed and the second shows the 0.20 increments. The outer boundary of the anomaly is shown in yellow and graduated by 0.20 increments to 1.0. PT-407T includes the following threshold values:

The recorded average mobility values shall be compared to the following threshold values, defining the existence of potential anomalies in the concrete conditions in the test area as follows:

M < 0.4: solid concrete 0.4 < M < 1.0: "gray" area, further test or coring is needed M > 1.0: potential "delaminated" concrete or other type of anomaly may exist, coring to be performed The area with an IR mobility value above 1.0 is approximately 4 sq. ft. The area within the "grey" range is approximately 48 sq. ft.

Boroscope A 2" diameter core bore was first drilled at the anomaly. The boroscope video revealed an area that appeared to be a crack or damage caused during the drilling process. A 4" diameter core bore was made over the 2" hole in an effort to better characterize the anomaly. The boroscope video clearly showed a crack that was mostly in the plane of the wall but did have ligaments that changed direction. The crack was shown to propagate through aggregate. (See Attachment 2)

Core Bore Sample Inspection The core bore sample was removed in three pieces. The piece closest to the surface,

1. 1, was broke where a metallic interference was encountered. The core location was shifted slightly and the remaining two pieces were removed. The interface between

piece #2 and #3 separated at the crack. The far end of piece #3 was broke at the back of the hole where the drilling stopped due to contact with a metallic object.

The inspection of the sample confirmed the boroscope inspection. The crack is mostly in the plane of the wall but did have ligaments that changed direction. A portion of the sample where the change in direction was seen was detached from the sample. The crack at this interface was measured to be -0.016" with smaller measurements seen near 0.009". Piece #2 and #3 interface showed aggregate that the crack passed through as well as the small portion that was detached. The difference in hardness of the paste and aggregate was investigated by performing a scratch test. This is a test used by geologists to identify minerals based on Mohs scale of hardness. A pointed metal awl was used to scratch a piece of aggregate as well as the paste in the sample.

Four similar scratches, one directly over the other, of similar force were made. The scratches in the aggregate produced a noticeable groove with powder residue. The scratches in the paste produced a barely noticeable groove with little or no residue.

This simple test would indicate that the paste is harder than the aggregate. (See )

Adiacent Tendons Core #54 is located at approximately 134.5 degrees at 104' 5 3/8". This location is between vertical tendons 34V18 (1360 15'), 34V19 (1330 45') and horizontal tendons 42H02 (103' 8 3/4"), 35H03 (105' 10 3/4"). No tendons in this general area have been detensioned in prior surveillances. (See Attachment 4)

History of tendon surveillance testing is this general area (within 5 tendons):

34V1 9 -Tested satisfactorily in Surveillance 3.

34V17 - Tested satisfactorily in Surveillance 8. (Currently removed in R16) 35H01 - Tested satisfactorily in Surveillance 5.

35H02 - Tested satisfactorily in Surveillance 6.

42H01 - Tested satisfactorily in Surveillance 5.