ML20058D661
| ML20058D661 | |
| Person / Time | |
|---|---|
| Site: | Catawba  |
| Issue date: | 07/16/1982 |
| From: | Parker W DUKE POWER CO. |
| To: | James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| References | |
| 10CFR-050.55E, 10CFR-50.55E, NUDOCS 8207270260 | |
| Download: ML20058D661 (3) | |
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DUKE POWER COMPm Powru Ut:st.nixo 423 SouTn Cnuncu StarzT, CrunwrTE, N. C. 28242 w1LLIAM Q. PA R M E R, J R.
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July 16> 1982 o
373-.o.3 Mr. James P. O'Reilly, Regional Administrator U. S. Nuclear Regulatory Commission Region 11 101 Marietta Street, Suite 3100 m
Atlanta, Georgia 30303 N
Re:
Catawba Nuclear Station
.5 Units 1 and 2 m
ao N
Docket Nos. 50-413 and -414 p
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Dear Mr. O'Reilly:
cu Pursuant to 10 CFR 50.55e, please find attached Significant Deficiency Rhrt ro SD 413-414/82-12.
O Ver truly yours, JQCG William 0. Parker, Jr.
RWO/php Attachment cc:
Director Mr. Robert Guild, Esq.
Office of Inspection & Enforcement Attorney-at-Law U. S. Nuclear Regulatory Conmission 314 Pall Mall Washington, D. C. 20555 Columbia, South Carolina 29201 Mr. P. K. Van Doorn Palmetto Alliance NRC Resident Inspector 2135b Devine Street Catawba Nuclear Station Columbia, South Carolina 29205 8207270260 020716 r'^ J' g
gDRADOCK05000 m
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REPORT NUMBER: SD 413-414/82-12 REPORT DATE:
July 16, 1982 FACILITY: Catawba Nuclear Station - Units 1 and 2 IDENTIFICATION OF DEFICIENCY:
Possible incorrect end distances for Type 1 and 2 embedded plates with Nelson headed anchors INITIAL REPORT:
On May 6,1982, A. Ignatonis, NRC Region II, Atlanta, Georgia was notified of the deficiency by W. 0. Henry and M. C. Green of Duke Power Company, Charlotte, North Carolina.
COMPONENT AND/0R SUPPLIER:
The components which are of concern are Type 1 and 2 embedded plates with Nelson headed anchors.
DESCRIPTION OF DEFICIENCY:
Type 1 and Type 2 standard plates are embedded in concrete walls, columns, beams, and slabs at locations where it is anticipated that a need may arise for subsequent structural attachments to support pipe hangers, cable trays, etc., and transfer the loads from the attachments to the concrete structures. These standard embedment plates are low carbon steel, with Nelson headed anchors welded to the backface of the plate. The capacity of the embedded plate is dependent on the spacing of these Nelson studs. The plate length varies according to the specific support needs. Both plates are similar in geometry, with the Type 2 embedded plate being twice the width (12" wide) of the Type 1 embedded plate (6" wide),
the purpose of which is' to give the designer a choice of standard embedment plates to suit various attachment sizes and load magnitude requirements.
The Nelson headed anchors are welded to the plates in the construction fab shop.
The plates are fabricated in standard 20 and 25 foot lengths. These plates are then taken to the construction concrete pour where they are to be installed, cut to the needed length, and placed in the forms.
Type 1 and 2 embedded plates were found to exist in the Catawba Auxiliary Building which did not adhere to the edge distance criteria for the first row of Nelson studs. Specifically, the design drawings and specifications require the first row of Nelson studs to be located no more than 1" from the end of the plate.
Preliminary indications were that the existing plates had "end" distances of up to 6" to the first row of Nelson studs. The embedded plate will have less capacity in this "end" region as the distance from the end to the first row of studs increases. NCI 13632 was initiated and Duke Power reported the potential deficiency to the NRC, Region II, on May 6, 1982.
ANALYSIS OF SAFETY IMPLICATIONS:
Too great an end distance could result in reduced capacity of an embedded plate.
.s CORRECTIVE ACTION:
Fourteen areas in the Reactor Buildings, Auxiliary Building, and Diesel Generator Buildings at Catawba were selected to be representative areas where attachments are made to Type 1 and 2 embedded plates.
Each "end" of Type 1 and 2 embedded plates in the sample areas was subjected to an ultrasonic test program to determine the actual location of the first row of Nelson studs. A total of 630 embedded plates in these fourteen areas were investigated and it was found that 437 (69%) of these plates had the "end" or "first" row of studs located incorrectly.
It was verified, however, that only the first row of studs were mislocated. The other rows of studs are spaced correctly.
After it was established that the first row of studs was not located in conformance with the design documents, a survey to identify attachments made to the "end" of the embedded plates was initiated. Utilizing the same fourteen sample areas, 37 attachments were identified in this end region. Loadings for these specific
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attachments were determined and the resultant stresses on the embedded plates were calculated.
Of the 37 attachments identified, none resulted in plate stress that would exceed allowables. The highest stressed plate of the 37 attachments identified, approached 45% of allowable stresses, with the remaining attachments resulting in plate stress of under 20% of allowables.
If this deficiency had gone undetected, public safety would not have been jeopardized.
The possibility of misplaced studs in the end region of Type 1 and 2 plates will be incorporated into all future attachment designs. No action to modify existing attachments is necessary since the survey indicated that existing attachments do not exceed the capacity of the plates.
For future attachments to the "end" zone of Type 1 and 2 embedded plates, appropriate Design Engineering Department, Construction Department, and Steam Production Department procedures have been initiated to account for the possibility of misplaced studs in the end region of the plates.
Specifically, whenever an attachment is tc be placed within 6" of the "end" of a Type 1 and 2 embedded plate, an ultrasonic test will be required to determine the actual location of the first row of studs. This actual stud location will then be incorporated into the design of the attachments, and the actual plate capacity versus the attachment load compared and verified to be acceptable. Procedures will be in place by August 1, 1982.
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