ML20207J254
| ML20207J254 | |
| Person / Time | |
|---|---|
| Site: | Vogtle  |
| Issue date: | 06/30/1986 |
| From: | Foster D GEORGIA POWER CO. |
| To: | Grace J NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| References | |
| REF-PT21-86, REF-PT21-86-254-000, REF-PT21-86-337-000 GN-972, PT21-86-254, PT21-86-254-000, PT21-86-337, PT21-86-337-000, NUDOCS 8607280195 | |
| Download: ML20207J254 (4) | |
Text
".
' Georgia Fbwer Company Pbst Office Box 282 Waynesboro, Georgia 30830 Telephone 404 554 9(J31, Ext. 3360 404 724-8114 Ext. 3360 1
m D. O. Foster Pres t
pe Soupg' 'K!rc system June 30, 1986 w
?
o United States Nuclear Regulatory Commission Region II File: X78GQ-M101 Suite 2900 Log:
GN-972 101 Marietta Street, Northwest Atlanta, Georgia 30323
Reference:
Vogtle Electric Generating Plant-Units 1 and 2; 50-424, 50-425; Raceway Support Design Details; Letter GN-889 dated May 1, 1986 Attention: Mr. J. Nelson Grace In previous correspondence on this subject, Georgia Power Company described a potentially reportable concern whereby some conduit support installations were not in conformance with the design requirements.
Georgia Power Company has completed its evaluation and concluded that a reportable condition as defined by the reporting criteria of Parts 10 CFR 50.55(e) and Part 10 CFR 21 does exist.
Based upon NRC guidance in NUREG 0302 Revision 1 and other correspondence concerning duplicate reporting, Georgia Power Company is reporting this condition pursuant to Part 10 CFR 50.55(e). A summary of the evaluation is attached.
This response contains no proprietary information and may be placed in the NRC Public Document Room.
Your truly
/
p1 a
D. O. Foste REF/00F/tdm Attachment xc:
U. S. Nuclear Regulatory Commission Document Control Desk Washington, D. C.
20555 J. H. Miller R. A. Thomas L. T. Gucwa l
J. P. O'Reilly D. R. Altman C. W. Hayes G. F. Head P. R. Bemis G. A. McCarley R. E. Conway J. A. Bailey D. S. Read J. T. Beckham O. Batum Sr. Resident (NRC)
R. H. Pinson G. Bockhold C. S. McCall (OPC)
P. D. Rice C. E. Belflower J. E. Joiner (TSLA)
B. M. Guthrie J. F. D'Amico D. C. Teper (GANE)
D. E. Dutton E. D. Groover NORMS ffl 8607280195 860630 I
l DR ADOCK 05 4
g
f EVALUTATION OF A POTENTIALLY REPORTABLE CONDITION RACEWAY SUPPORT DESIGN DETAILS Initf ah Report: On April 2', 1986, Mr. R. E. Folker, Vogtle Project Quality Assurance Engineer, informed Mr.
M.
V.
Sinkule of the USNRC-Region II of a potentially reportable condition concerning raceway support design details. This condition involved some conduit support installations which were not in conformance with the design requirements.
In letter GN-899 dated May 1, 1986, Georgia Power Company indicated the NRC would be informed of the results of the i
evaluation of this condition by June 30, 1986.
Background
Information:
During field walkdowns associated with Readiness Review Module 19, conduit runs were identified where support installation and the longitudinal bracing for the supports were not in conformance with the design requirements.
A.
Single Conduit Support (Reported in Readiness Review Observation 19-2)
A 4" diameter conduit, approximately five feet in total length, I
was installed with a single conduit support.
The support was located approximately six (6) inches from one end of the conduit.
The installation details on the various engineering drawings did not specifically preclude this installation.
B.
Missing Longitudinal Bracing (Reported in Readiness Review Observation 9-11)
A field walkdown reported the absence of a longitudinal brace for some conduit supports.
At the time the supports were installed, the detail stated " Longitudinal bracing at every 16'-0" of conduit."
l The detail was clarified by stating "When total length of conduit i
is less than 16'-0", at least one long brace shali be provided."
l Engineering Evaluation:
l A.
Single Conduit Support This condition resulted from an interpretation of the design details that an unsupported length of four (4) inch conduit was allowable as long as the maximum length did not go beyond fifty-four (54) l inches.
However, the intent of the design detail was to require a minimum of two (2) simple supports for each run.
The conduit l
clamps and supports are designed to be simple connections capable i
of transferring lateral, vertical, and longitudinal forces only.
The conduit clamps were not designed to act as a moment connection.
The supporting member to which the conduit clamps are attached i
are designed to withstand the seismic loads, i
All conduit runs having characteristics indicating that they could have been installed in a similar condition with a single support were identified.
A field walkdown identified twenty-four (24)
(
additional cases where only one support was provided for a short conduit run.
All additional cases were found in Unit 1
installations. No discrepancies were found in Unit 2.
B.
Missing Longitudinal Bracing The lack of longitudinal bracing in conduit runs shorter than sixteen (16) feet results in the conduit support connections acting as moment connections under seismic loads.
- However, the orig'nal design intent was to require a minimum of one longitudinal brace I
to preclude the need for a moment connection. A walkdown examination of the conduit runs accepted prior to the drawing clarification was performed.
This walkdown identified a total of fifteen (15) previously accepted supports that lacked the required brace.
In order to evaluate the broadness implications of these installation i
discrepancies, additional investigation was performed that included a comprehensive review by a special task force to determine whether there exists a
potential for unconservative interpretation of electrical raceway support design details during construction.
The task force reviewed 135 details from standard electrical raceway support drawings, encompassing the most commonly used design details.
The review concluded that the potential for misinterpretation was limited to the two specific design details addressed in the Readiness Review Findings.
Therefore, it is considered that all other cases of support installations per design details were properly interpreted and are structuraly adequate for performing their intended design function.
In summary, it has been concluded that the as-built conditions could have adversely affected plant safety.
These conditions result from the misintrepretation of two design details in 'a total population of approximately 135 design details that are used for electrical raceway support drawings.
Review of Quality Assurance Program: A review of the quality assurance program of GPC Construction and Sechtel Engineering has concluded that a significant program breakdown has not occurred.
==
Conclusion:==
Georgia Power Company has concluded 'that a reportable condition as defined by the reporting criteria of Part 10CFR50.55(e) and Part 10CFR21 does exist.
Part 10CFR50.55(e) requires the construction permit holder to notify the Commission of each deficiency found in design and construction, which, were it to have remained uncorrected, could have affected adversely the safety of operation of the nuclear power plant.
Part 10CFR21 requires the reporting major deficiencies in the design and construction that could affect plant safety.
Based upon NRC guidance in NUREG-0302 Revision 1 concerning the duplicate reporting of a condition, Georgia Power Company is reporting this conditios pursuant to the reporting requirements of Part 10CFR50.55(e).
Corrective Action:
Deviation reports have.'been dispositioned requiring appropriate remedial measures, including rework, to restore b
the structural adequacy of the discrepant supports, s
To prevent recurrence, the following corrective actions have been taken:
1)
Detail 3 on drawing CX3DF002, applicable to Units 1 and 2, has been further clarified.
This change will ensure that installation of conduit runs utilizing this detail will have a minimum of two supports,
- 11) Detail 6 on drawing AX2D94V051, applicable to Units 1 and 2, has been revised.
Appropriate conduit supports will require an individual longitudinal brace, per this revision.
In addition, Cleveland Electric Company has provided additional training for appropriate construction personnel on the installation requirements of electrical raceway supports.
l l
_