ML20150C951
| ML20150C951 | |
| Person / Time | |
|---|---|
| Site: | Sequoyah  |
| Issue date: | 03/11/1988 |
| From: | NRC OFFICE OF SPECIAL PROJECTS |
| To: | |
| Shared Package | |
| ML20127A683 | List:
|
| References | |
| NUDOCS 8803220459 | |
| Download: ML20150C951 (2) | |
Text
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SAFETY EVALUATION REPORT BY OFFICE OF SPECIAL PROJECTS EMPLOYEE CONCERN ELEMENT REPORT 24101
"!NADE0UATE SPLICING AND TERMINATION PRACTICES AND PROCEDURES" TENNESSEE VALLEY AUTHORITY
_SE0UOYAH NUCLEAR POWER PLANT, UNITS 1 AND 2 DOCKET NOS. 50-327/328 I.
SUBJECT Category:
Engineering (20,000)
Subcategory:
Cable Terminations and Splices (24,100)
Element:
Inadequate Splicino a'd Terminations Practices and Procedures (24101)
Employee Concern:
IN-85-392-01 Elenent Report 24101, Revision 2 prepared April 6, 1987, involves an employee concern which asked "What would happen w1th the large number of electrical i
splices located underground if the system became flooded?
(1) Would the splice hold up under long exposure to moisture?
(2) If the splice failed, wou'fd a safety related problem occur?
(3) Wou'd a back up system be activated?" The employee concern was raised for the Watts Bar facility, but is considered to be generic to Sequoyah since cable splice requirements are similar for all plants.
II.
SUt&ARY OF ISSUE TVA Design Criteria SON-DC-V-12.4 specifies that cables required to maintain the plant in safe shutdown or flooded cerdition be suitable for submersible operation.
The design criterie further states that these cables shall be continuous (not spliced), unless qualified waterproof splices are used based en manufacturers testing to TVA standard specifications which demonstrate proper performance.
As part of TVA's program to qualify cable splices that may be subject to design basis ficed levels, TVA proviced cable sanplcs to Raychem for test purposes.
The samples included low voltage (600 V) power and control cables, signal cables, and medium voltage (8 kV) cables.
Raychen prepared several test ccnfigurations of splices on low voltage power, control, and signal cables, using the Raychen Heat Shrink N bing WCSF-N.
The 880322045'9 880311 DR ADOCK 050 L'
. spliced cables were subjected to 100-day fr=ersion in a pressurized cylinder and tested to pressure and temperature pararreters supplied by TVA.
Raychen reported test results shnwing that the samples performed satisfactorily.
Raychem also performed the successful test on tredium voltage cable splices.
Upon cerrpletion of the Raychem tests, the TVA EEG issued the "Criteria and Procedures for Msing Splices of Insulated Cables in Manholes and Handholes,"
for interim use by Construction and for incorporation in standard drawings and Construction Specification G-38.
Additicrally, TVA issued three electrical standard drawings to delineate cable splicing procecures and materials.
TVA also issued TVA Modifications and Additicns Instruction M!AI-7 in 1979 which discusses splicing guidelines and refarences th tiectrical standard drawings.
Nevertheless, the adequacy of splices before issuance of the above guidance and all splices prior to 1977 coulo not be determined.
As a result, TVA has initiated ccrrective action to address and to resolve, if necessary, the ratter of underground cable splices.
The corrective action includes:
(1) a determin-ation of the number cria location of all IE cable splices; (2) a special inspecticn of all tranholes and handholes; and (3) a resolution / repair of any inadecuate splices identified above.
Ill. EVALUATION NRC anc its consultant, SAIC, reviewed the employee concern and the TVA response.
A request for additional information (RAI) was sent to TVA in order to obtain a better understanding of the RaycheL tc3 ting, an adequacy assessment of the 100-day test, a clarificaticn of voltages tested and actual voltage levels at TVA Sequoyah, and additional information on the manhole and handhole walkdown.
TVA provided its responses to these cuestions in their August 13, 1987, letter from TVA to NRC.
Basically, TVA clarified the Raychem testing of cable splices, but more vportantly, TVA comitted to 1C0% megger and hi-pot testing of all ERCW pumps and MCC cables, and all fire pump cables are being teggered.
In addition, TVA will treggar test 50% of the diesel auxiliary boards while 50% of the diesel supply cables are being reggered and hi-potted.
Moreover, TVA has committed to perfccming anrual manhole in.pcctions.
IV.
CONCLUSION The NRC staff concludes that the employee ccncerns were valid and thac,ws investigation, evaluation and corrective acticn plan for the concerns, as described in element report EN-24101 SON, Rev. 2, and in their letter of August 13, 1987 are acequate.
We further believe that implementation of these actions will close the issue of cable splices in marJ. oles /handholes.
Verification of corrective actions which TVA has identified es a restart item, should be verified by NRC inspectors in a future inspection.
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