ML20234D480
| ML20234D480 | |
| Person / Time | |
|---|---|
| Site: | Sequoyah  |
| Issue date: | 12/31/1987 |
| From: | Richardson S NRC OFFICE OF SPECIAL PROJECTS |
| To: | White S TENNESSEE VALLEY AUTHORITY |
| References | |
| NUDOCS 8801070053 | |
| Download: ML20234D480 (2) | |
Text
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December 31, 1987 o
Docket Nos. 50-327, 50-328 License Nos. DPR-77, DPR-79 Tennessee Valley Authority ATTN: Mr. S. A. White Manager of Nuclear Power 6N 38A Lookout Place 1101 Market Street Chattanooga, TN 37402-2801 Gentlemen:
SUBJECT:
CRITERIA FOR SEPARATION OF SAFETY-RELATED CONDUITS (NRC INSPECTION REPORT NOS. 50-327/87-18 AND 50-328/87-18)
This letter refers to Unresolved Item (URI) 87-18-01, identified during a special testing inspection conducted by an NRC team at the Sequoyah facility during March 16-17 and April 13-17, 1987, and reported in NRC Inspection Reports 50-327/87-18 and 50-328/87-18.
During the inspection of installed components, the inspection team identified several instances in which the physical separation between redundant divisional cable trays,and conduits was less than the Sequoyah Final Safety Analysis Report (FSAR) specified distances for cable trays. Although the FSAR does not provide specific criteria for physical separation of conduits which contain safety-related circuits, our technical evaluation of this issue has determined that the requirements for separation of. cable tray delineated in Section 8.3.1.4.2 should be applied to conduit. Therefore, since adequate physical separation of conduit containing safety-related circuits is essential to safe operation of the Sequoyah facility, the lack of design and installation criteria in this area raised significant questions regarding the quality of existing safety-related conduit installations.
In response to this concern you are requested to provide analyses to demonstrate that electrical faults in one raceway (conduit or cable-tray) will not cause internally generated fires that affect the functional integrity of redundant safety-related circuits in adjacent raceways. This concern needs to be resolved prior to restart of the Sequoyah units and therefore your response is requested within 30 days of receipt of this letter.
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December 31, 1987 In accordance with Section 2.790 of the NPC's " Rules of Practice" Part 2, Title 10, Code of Federal Regulations, a copy of this letter, and any reply will be placed in the NRC Public Document Room.
Should you have any questions concerning this letter please contact us.
Sincerely, Original Signed by B. D. Liaw for Steven D. Richardson, Acting Director TVA Projects Division Office of Special Projects Recently sent u an overnight package with a copy of the Regional Office Instructi No 306, Rev. 2.
In reference to the R01, IMS is requesting that your RITSJ ut be submitted to them by 12:00 noon each Monday. We will need your input by riday, so that we can meet the deadline.
cc:
H. L. Abercrombie, Site Director Sequoyah Nuclear Plant J. A. Kirkebo, Director, Nuclear Engineering R. L. Gridley, Director Nuclear Safety and Licensing M. R. Harding, Site Licensing Manager TVA Representative, Bethesda Office bcc:
S. D. Ebneter, OSP B. D. Liaw, OSP G. G. Zech, OSP K. P. Barr, OSP/RII F. McCoy, OSP/RIT R. Carroll, OSP/RII J. Brady, OSP/RTI NRC Resident Inspector DRS Technical Assistant NRC Document Control Desk
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