ML20150C155
| ML20150C155 | |
| Person / Time | |
|---|---|
| Site: | Sequoyah  |
| Issue date: | 07/06/1988 |
| From: | Gridley R TENNESSEE VALLEY AUTHORITY |
| To: | NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM) |
| References | |
| TAC-R00386, TAC-R00387, TAC-R386, TAC-R387, NUDOCS 8807120330 | |
| Download: ML20150C155 (8) | |
Text
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-M.. j TENNESSEE VALLEY AUTHORITY
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' CHATTANOOGA, TENfJESSEE 374ol SN 157B Lookout Place y
JUL 061988 U.S. Nuclear Regulatory Commission.
ATTN: Document Control Desk Washington,JD.C.
20555 Gentlemen:
'In-the Matter of
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Docket Nos. 50-327 Tennessee Valley Authority
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50-328 SEQUOYAH NUCLEAR PLANT (SQN) UNITS 1 AND 2 YEAR QUALIFICATION TESTING OF SILICONE RUBBER-INSULATED CABLES
References:
- 1.. NRC letter to TVA dated May 25, 1988, "Qualification Testing of Installed Silicone Rubber Insulated In Containment (TAC Nos. R00332, R00333)"
2.
TVA letter to NRC dated March 17, 1988, "Sequoyah Nuclear Plant (SQN) - Silicone Rubber Cable Environma tal Qualification" 3.
TVA letter to NRC dated December 28, 1987, "Sequoyah Nuclear Plant (SQN) - Silicone Rubber Ii.2ulated Cable Issue Resolution" 4.
TVA letter to NRC dated November 24, 1987, "Sequoyah Nuclear Plant (SQN) Units 1 and 2 - Wyle Laboratories
' test Report for Silicone Rubber-Insulated Cables" This letter provides Nuc with TVA'e program to extend the qualified life of silicono rubber insulated cables installed at'SQN from 10 to 40 years.
The program provided herein is pursuant to TVA commitments made in reference 2 and responds to tSose views presented by the staff in reference 1. provideu both the details and background it. formation associated with TVA's 40-year environmental qualification testing program. This program will supplement the successful results of the 10-year qualification program provided to NRC in references 3 and 4.
The program will involve obtaining silicons rubbar-insulated cable samples (i.e., five for ecch man uheturer) selected f rom the worst-case conduit configurations located in containment at Watts Bar Nuclear Plar.t (WBN).
Details of the 4mmple selection, serple size, and removal proceso are 1Pv3o j
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, U.S. Nuclear Regulatory Commission provided within enclosure 2.
These cable samples will then be sent to Wyle Laboratories located in Huntsville, Alabama, where thcy will undergo environmental qualification testing. To remain consistent with the existing qualification of these cables, the acceptance criteria will be the same as that used in the previous 10-year Wyle test program provided
!n reference 4.
This acceptance criteria has been iound acceptable by NRC as stated in reference 1.
In conjunction with the 40-year samples. TVA also intends to prepare 15-year samples of Anaconda and Rockbestos cables using the criteria outlined in the enclosures to this letter. This alternato qualification test is detailed in enclosure 3 and will only be used in the event of test failure in the 40-year samples. also provides the procedure TVA will follow to disposition a test unomaly or test failure in the event one occurs during the environmental qualification test program at Wyle Laboratories.
TVA is proceeding with the implementatloa of this test program. The int'.nt of TVA'u 40-year qualification program envelopes those views expressed by the staff in reference 1.
The complellon of this program is scheduled to be before the restart of unit 2 following the unit 2 cycle 3 refueling outage.
This is in accordance with the commitment made by TVA in reference 2.
As mutually agreed, the succe9sful completion of this 40-year qualification program on Rockbestos and Anaconda silicone rubber insulated cable resolves the one remaining issue relative to the acceptability of the cable it.9ta11ation practices at TVA.
Summary statements of cor.itments contained in this letter are provided in enclosure 4.
please direct questions you may have concerning this issue to Barry A. Kimse, at (615) 870-6847.
Very truly yours, TENNESSEE VALLEY AUTHORITY
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1 rector Nuclear Licensing and Regulatory Affairs Enclosures cc: See page 3 m
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U.S. Nuclear Regulatory Comission
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Mr. F. McCoy, Asslatant Director =
for Inspection Programs TVA Projects Division U.S. Nuclear Regulatory Comission Region.11 101 H ciet'.a Street, ilW, Suite 2900 Atlaut.a. fiaorgia 30323' Ms. S. C. Black, Assistant Director for Projects TVA Projects Division U.S. Nuclear Regulatory Cotnmission Ono White Flint, North 11555 Rockvillo Pike Rockvil10. Maryland 20852 Sequoyah Resident Inspoetcr Suquoyah Nuclear Plant 2600 Igou Ferry Road Soddy Daisy, Tennesseo 37379
ENCLO5URE 1 40-Year Qualification Test Program Information and Background TVA resolved concerns detailed in the 10 CFR 21 final report on silicone rubber-insulated cables (dated January 25, 1988) by performing environmental qualification testing of silicone rubber-insulated cables at Wyle Laboratories. The cables included in the program were manufactured by American Insulated Wire (AIW), Anaconda, and Rocxbestos.
The test specimens from all three vendors were artificially damaged to simulate reduced insulation wall thickness and impact damage before receiving pretest aging equivaler.t to 10 years inside containment service and subsequent accident exposure.
A review of the SQN unit 1 inside containment 10 CFR 50.49 cable listing of Category A and B circuits revealed that only a very small population of AIW silicone rubber-insulated cable existed (i.e., 14 cables consisting of 44 Individual conductors). TVA performed the same review at WBN units 1 and 2 and found no AIW silicone rubber cable in 10 CFR 50.49 Category A or B circuits. Therefore, TVx has elected to replace all AIW silicone rubber-insulated cable in 10 CFR 50.49 Category A and B circuits inside containment at SQN unit 1.
AIW silicone rubber-insulated cables are not installed in 10 CFR 50.49 Category A or B circuits inside containment of SQN unit 2.
Consequently, AIW silicone rubber-insulated cable will be excluded from further testing.
To supplemert the successful 10-year qualification, a new program will be performed utilizing currently installed cable from WBN.
The selection and removal process will be as defined in enclosure 2.
After removal, the cables will be shipped to Wyle Laboratories in Huntsville, Alabama, where they will receive protest thermal and radiation aging to simulate 40 years in containment service.
The cables will then be exposed to steam / chemical spray while energized to rated voltage and current to simulate the SQN and WBN accident environment. To remain consistent with the existing qualification or these cables, the acceptance criterin will be the same as that used in the previous Wyle test of silicone rubber cables, which has been accepted by NRC.
However, the post-loss-of-coolant-accident, high-potential-withs ind-test voltage for margin assessment will be equal to twice the cable's rated voltage plus 1,000 vcits (e.g., 2 x rated voltage + 1,000).
In the event of an actual test failure (one that is not attributed to a testing anomaly). NRC will be promptly notified; and a Condition Adverse to Quality Report (CAQR) will immediately be issued. The CAQR will be evaluated and dispositioned in accordance with established procedures that require that an operability determination with respect to technical specifications be performed. An additional discussion of this issue can be found in enclosure 3.
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ENCLOSURE 2 Sample Selection, Sizo, and Removal process The total population of conduits containing safety-related circuits located
~inside containnent at WBN will be screened to find those in 10 CFR 50.49 Category A and B circuito contair. lng silicono rubber-insulated cables that have been subjected to "worst-caso pulls." The screening process to be used is outlined below. Given the large population of cables manufactured by Rockbestos in unit 1 (~400 cables), that unit will be considered as representative of both units at WBN and SQN. Worst-caso installations containing Anaconda cables will be determined using both units at WBu as the initial family.
The following steps outline the cable test specimen selection and removal process.
1.
The first step of the process will be to identify all circuits insido containment that contain 10 CFR 50.49 silicono tmbber cables manufactured by Anaconda (units 1 and 2) and Rockbestos (unit 1 only).
2.
Concrat construction Specification (C-38), "Installing Insulated Cables Rated up to 15,000 Volts," Appendix F Tablo F1 for power and Table F2 for control cables C-38, will be used to dotormino worst-caso cable pulls.
These tables show the umximue cable longth allowed for a given conduit size > hat can be pullod w?thout performing a sidewall pressure calculation. Using thcso tables as a guido, all cables with a circuit length less than those det'ined in Appendix F will be eliminated from the selection process.
3.
Additional eliminctions umy be mado for circuit lengths that are less than those defined in C-38, Appendix F, as coquiring sidewall pressure calculations based on condult size.
If en adequate cample is not found, the scopo of the selection procesJ Will be expanded by reducing the Appendlx F values by 25 percent.
4.
The next step in the process will be to ollminate the cables installed in conduits that havo less than two 90-degroo cor.dulots in the run.
This number of conduits will be as determined by field walkdowns.
5.
Five cables will be selected from each manufacturer for the test specimens.
Each of the samplos for a given manufacturer will be selected i
l from different conduits. The selection allt be based on tho actual longth I
between pull points rotativo to the len*,th allowed by C-38.
For the purpose of this evaluation, "C" condulots are not er.nsidered as pull points.
Cables that excoed or como closest to exceeding tho values given j
I in Appendix F of C-38 by the greatest percent will be selected.
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After identifying the worst-case section of the conduit rua, the cable
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test sample will be carefully removed from this section of conduit by.the field.
Each sample will be approximately 15 feet in length and tagged with a unique cable identifier number.
7.
Finally, the cable semples will be placed in a shipping' crate for transportation to Wyle Laboratccles located in Huntaville Alabama.
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ENCLOSURE 3 Resolution of-Test Anamolles and Test Failures TVA will follow the procedure outlined below in the event of a test anomaly or test f ailure in any of the 40-year samples of Anaconda or Rockbestos cables.
The scope of work documented for this test requireo the test laboratory to notify TVA of all anomalies within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> of the occurrence. Upon receipt of the notice, TVA will promptly notify NRC and proceed to work with the test lab to evaluate the anomaly. The evaluation will be based on compliance with
'the criteria established in the scope of work document. The results of the anomaly evaluation will be reported to NRC immediately after a determination has been made.
In the event that the anomaly is determined to be an actual test failure, a CAQR will be issued. As previously stated, the CAQR will be evaluated in accordance with existing procedures.
The procedures require that the anomaly be evaluated against technical specifications in regard to unit operability.
NRC will be notified immediately of the results of this evaluation.
If a failure occurs in one of the 40-year samples. TVA intends to proceed with the qualification process using the 15-year samples.
It should be noted that TVA only intends to proceed with this process using cable from the vendor that failed (i.e., if Rockbestos passes, only Anaconda will be retested).
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ENCLOSURE 4 Cotamitments 1.
TVA will replace all-AIW silicone rubber-insulated cables installed in SQN unit 1 containment that are in either 10 CFR 50.49 Category A or B circuits before unit I restart.
2.
TVA will provide the results of the Wyle Laboratories environmental qualification tests and TVA's evaluation of these results, associated with the 40-year qualification program of Rockbestos and Anaconda silicone rubber-insulated cables, upon completion of TVA's test program.
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