ML20238A213
| ML20238A213 | |
| Person / Time | |
|---|---|
| Site: | Sequoyah  |
| Issue date: | 09/01/1987 |
| From: | Gridley R TENNESSEE VALLEY AUTHORITY |
| To: | NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM) |
| References | |
| NUDOCS 8709090193 | |
| Download: ML20238A213 (14) | |
Text
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TENNESSEE VALLEY AUTHORITY CHATTANOOGA, TENNESSEE 374o1 5N 157B Lookout Place SEP 011987 U.S. Nuclear Regulatory Commission ATTN:
Document Control Desk Washington, D.C.
20555 Centlemen:
In the Matter of.
)
Docket Nos. 50-327 Tennessee Valley Authority
)
50-328 SEQUOYAH NUCLEAR PLANT (SQN) UNITS 1 AND 2 - ADDITIONAL INFORMATION FOR ELECTRICAL PENETRATION SPLICE ENCLOSURES AND SPLICES
References:
1.
Letter from TVA to NRC dated April 30, 1987, "Sequoyah Nuclear Plant - Justification of Splices in Annulus Trays" 2.
Letter from J. A. Zwolinski to S. A. White dated August 3, 1987, " Splices in Annulus Trays" This letter provides NRC the additional information requested by reference 2 to clarify various details concerning the justification of splices in annulus trays as provided in reference 1.
The information provided in enclosures 1, 2, 3, and 4 addresses the location of the splices involved, the number of splices, the affected equipment, and the justification for the splice box configuration. Also included is information associated with the method used to qualify these splice enclosures as fire barriars and their approval for use at SQN.
Reference 1 contained an error regarding the number of splices involved with the penetration splice boxes.
(Reference 1 incorrectly indicated that a small number of splices were involved.) The configuration discussed in this letter and reference 1 is typical for a majority of containment electrical penetrations for low-voltage circuits.
Very truly yours, TENNESSEE VALLE AUTHORITY l
J R. Cridley, Direc or Nuclear Safety a d Licensing Enclosures l
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8709090193 870901 PDR ADOCK 05000327 p
PDR An Equal Opportunity Employer i
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, U.S.' Nuclear. Regulatory Commiesion L
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.Mr. G. C. Zech, Assistant Director for Inspection Programs Office of Special Projects U.S. Nuclear Regulatory Commission 101 Marietta Street NW, Suite 2900 Atlanta, Georgia 30323 I
Mr. J. A. Zwolinski, Assistant Director for Projects Division of. TVA Projects Office of Special Projects U.S. Nuclear Regulatory Commission 4350 East West Highway EWW 322 Bethesda, Maryland 20814
,Sequoyah Resident Inspector Sequoyah Nuclear Plant.
2600 Igou Ferry Road.
Soddy Daisy, Tennessee. 37379
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ENCLOSURE 1 NRC QUESTIONS /TVA RESP 0NSE 1.
How many splices exist in the annulus trays?
2.
Describe the actual circuits involved in the splicing program so that the effect on the plant rystems can be assessed.
Reference 1 contained an error regarding the number of splices involved with the penetration splice boxes.
(Reference 1 incorrectly indicated that a small number of splices were involved.) The configuration discussed in this letter and reference 1 is typical for a majority of containment electrical penetrations for low-voltage circuits.
The splices in question are located within the last 5-foot section of the tray where it ends at each penetration assembly. This is to allow splicing of the vendor penetration pigtails to the field cables on the outboard side of the steel containment liner.
please refer to the detail D5 taken from TVA drawing 45N860-5 included in enclosure 2 in order to see the splice configuration in question.
Therefore, the number of splices will vary from penetration to penetration depending upon the devices that are associated with each particular penetration and the number of vendor pigtails available. This configuration is typical for a majority of SQN penetrations.
The actual circuits involved are depende.- upon the voltage level of the penetration.
These circuits include the low-voltage power cables, control cables, and instrumentation cables, which feed a variety of equipment.
The cables and splices in question affect all circuits entering containment by way of these penetrations. The routing of the cables to their respective penetrations
'7 part of the design process to ensure that the physical separation requit sments of SQN Design Criteria SQN-DC-V-12.2 are fully satisfied and to ensure that the total installed system will satisfy the single failure criterion as stated in paragraph 4.2 of Institute of Electrical & Electronic Engineers (IEEE) 279-1971.
3.
Describe the frequency and extent of the periodic test program for the two circuit projections.
The frequency and extent of the periodic test program for the circuit protection are outlined in SQN technical specification 3.8.3.1.
All devices used to protect containment penetrations from overcurrent conditions are included in the scope of this requirement. The testing is specified in the surveillance requirements. A representative sample of circuit breakers is tested every refueling outage.
Each circuit breaker is inspected and subjected to preventive maintenance every five years.
Fuses are inspected as a part of a periodic fuse inspection program.
Currently, a 10-percent sample is selected every refueling outage.
- 4.
'The cover letter in reference 1 refers to the use of qualified fire barriers.
Please describe the method used to qualify the barriers and the
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results.
As stated in enclosure 1 of reference 1, the special penetration splice I
enclosures were provided to act as a qualified fire stop or barrier.
The
)
questions raised in the past by NRC inspectors most often addressed j
whether or not this fire stop was qualified.
Please refer to the detail I
D5 taken from TVA drawing 45N860-5 included in enclosure 2 to review the l
fire barrier details.
Photographs of typical electrical penetration
-l splice boxes are included as enclosure 4.
This fire barrier or electrical j
penetration splice box design is based upon TVA test and tests performed i
by Factory Mutual of full scale mockups. TVA has included in enclosure 3 I
a memorandum that includes a discussion of the test results.
In particular, the mockup C test sample addressed on page 3 of enclosure 3 l
and the results addressed in the last two paragraphs of that same page should be noted. These results support the design configuration as shown in enclosure 2.
TVA would also like to indicate that these test results have been previously reviewed and approved by NRC as addressed in the Safety Evaluation Report Supplement No,1, Section 9, dated February 1980.
ENCLOSURE 2 ELECTRICAL PENETRATION SPLICE BOX DETAIL (TAKEN FROM 45N860-5) i
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CERT. BLANKET ARQUND CASLE5 AS THEY ENTER ELEVATEON VIEW THE.=?LIC.'NG BOX. CCaT DMzuSURFACES OF CABLE 5 WITH A 3/16
. INCH t 1/I6 INCH (WET DEPTH) THf CKNESS OF DETAIL D5 FLAMEMASDC 77 ELECTRICAL PENETRADON SPLlCE BGX,5EE NOTE B NOTE:
(45N860-3 & B70-3)
A.CONDU/7" DESIGNAT/CNS 1 AME FCR UN/7 2 EXCCP7 AS NOT[D.(UW/7 PREF /X 2)
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$*-O' SECTION 0F CABLE TRAY EXTENDING TO THE ELECTRICAL PENETRATION WILL BE USED AS A CABLE SPLICE BOX THESE SPLICE BOXES SHALL W PHYSICALLY IDENTIFIED FOR THEIR PARTICUL AR DIVISION OF SEPARATION IN A SIMILAR MANNER AS THE CABLE TRAYS,SEE SECTION 4.5.5 OF SON.DC-12.2. :DENTIFi-CATION MARKINGS SHALL BE PLACED ON AT LEAST ONE SIDE AND ON THE TOP COVERS OF THE SPLICE BOX. THE SPLICES SHALL BE A 5 N 8 6 0 - b, STAGGERED TO AVOID PHYSICAL BUILDUP IN THE SPLICE BOX. PLACE A HEAT SHRINKABLE CAP OVER THE ENDS OF ALL SPARE CABLES.
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e ENCLOSURE 3 TEST RESULTS - ELECTRICAL ENGINEERING BRANCH (EEB) MExoggypyy l
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Memoyandam Trunnsste vAuEY AUTHORITY
?:t 84 TO Electrical Engineering Files I.
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- C. H. Striduth, Prin:1 pal Electrical Engineer,133I65 C-E
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- February 10, 1977 sunJccT: SEQtKTIAH NICLEAR Fum IMI2S 1 AED 2 EVALUATION OF TEST REStE"S OF CAELE AhPACITY TESTS FOR CCMPLE'IED FIRE STOP FEETRATIONS
Reference:
' Hemoranium f: rec: J. C. E1111an,to F. W. ChnM' er dated-Novenber 9,1976, subject: "We.tts Bar Nuclear Plc.n Sequoyah Nuclear Plant thits 1 an.12 - Cable Sleeve I
Penetration Tests" (WEN 771111 033).
I l
The current design practices for sizing cables do not address any additional derating requirements of cables installed throtsh cable tray penetration fire stops. The ampacities established in
,- l Electrical Design Staniard DS-E12.1.2 (fornerly Electrical Stanaard Drawing 30A1021Rl) are based on Insulated Power Cable Engineers Association (IICEA) Publication P-46 k26 and IEEE Transaction Paper TO TP 557 PWR, "Ampacities for Cables in PsNy Filled
,J Trays," by J. Stolpe. From the latter it was abovn that the smaller M amater power cables instaned in cable trays were the ones most likely to overheat.
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To ensure that the ampacity (current-ca: Tying capacity) of the cables iratalled t.% cot pleted fire stops is accepte.ble, tests i
vere emdu:ted an differect designs unier s1=ulated service con-ditions. The smallest size insulated power cable used by TVA in the desit;n of generating stationa vas. selected for mechup of the ampacity tests. This mockup is considered to proinee more cable beating than the actual installation, which has various cable sizes and cable ratings of 125 percent of full loao. current actor ratings. A single continuous power cable (one 3-conducter, No.12 XC, type CPJJ cable, Vatts Bar Nuclear Pla=t mart WIC) vna loo;ed t.% ea:1 penetrati=n the required numler cf ti:nes te s'* ' ate the mm-de allevable design fil.1 cf the respective cable tray. 'lbe deeign " cri-4m fc-Icy-vcitage power cable trays I
is a wtr'm--= c' 30 ;erce:: cf the cross-see-d-e area c' a 3-1:ch lonit:s depth trzy, excm vbere a single layer cf cable is used. Tbe tests were for an 6-hour dtn-ation with the test cable in ca.ch penetration being contd-a"y energized with 15 a= peres Ier ccxxin:tcr. h requi:ed current flov was adjusted to compensate
!ce changes from a ho C (104 ?) ambd.er: m::::e.
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?J:ictrical' Engineering Files Phbruary 14 1977 SEQUDYAH NICLEAR PLANT INITS 1 AND 2 EVALUATION OF TEST RESIMS OF CAB 2 AMPACITY TESTS FOR COMP 2*J:D FIRE STOP PERETfUL* IONS Se acceptance criteria was that the temperature trithin the completed fin stop penetration shall not exceed a 50 C (122 F) rise from the ambient air temperature. Thus, the maxima acceptable temperature vas 90 C (194 F). - Also, the insulation resistance of the teet cable shall be a minimum 0.6 mogohns a$'ter mapeckty test.
Four different designs, mockups A, B, C, and D, were tested.
Hockup A simulated the design of a fire stop penetration not requiring a ymssure seal. Results of phase one of test, utiliziLg Carafiber packr.d around the cables the entin 1-foot depth of the cable sleeve and-a 5-foot distance coating of 1
Flamemastic 71A from each side of cable sleeve, showed a peak temperature of 96 C (205 F) in the-center of the sleeve.. For phisse two, the Oeratiber was amoved from around the cables inside i
the sleeve leaving only a 2-inch depth of cerafiber arov.ad the
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cables at each and of the sleeve and loosely packad Carafiber in the void above the cables. The peak temperature experienced E
under these coniitions was 82 C (180 F). Insulatien resistance t
of tbc cable was infinity after both phases of the test. The r%
results of the first phase of the test failed to meet the accep?ance criteria of the temperatu:e rise. The second phase of the test met the acceptance criteria. The thermocouple j
locations' and a tabulation of the maximum temperature recorded during the test are shown in attached figure 1.
h Mockup B simulated the design of a fire stop penetration requiring a pressure seal. Nockup E consisted of a~2-foot depth of 'Dow Corning foam 3-6548, A and B ccurponents, a 2-im:h depth cf J
Cerafiber arouni cables at each and of sleeve and each wall
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opening, Cerafelt at each end of sleeve, ami a'l-inch Cera Form board at each wall crening. The cables were coated with a 3/16-inch 11/16-inch (vet depth) of Flamemastic 71A for a 3
3-5-foot distance on each side of vall board. A 3-foot length of cable tray cover was installed on tbs high pressure side of the l
mockup. Results cf the 100 percent energized load test reverled a peak temperature M 90 5 C (195 F) ami an insulation resistcnee i
of 0.01 magohns which retu:.and to d **d-*ty af,er c* da - Se a
results cf this test wu:e not cwhive. Mockup D was a repeat of this das@ vith SD W'*d-stions.
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Electrical Engineering Files Pehruary 4 1977
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SEQD0YAH RICLEAR PLANT UNIE 1 AND 2 g'
- EVALUATIOR CF 3H El: SILTS OF CAE2 AMPACIlT t
FIRE STOP PNT' RATIONS Y
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bekyps Caad D vere constructed using a 1-a g
from a 2-inch depth to a 1-inch depth arouni the ekbles at each
/gg end of the chble sleeve, as compand to mockup B above.
ej g of 74 C (165 F) aM:an4nsulation resistance cf in The 1
f,g well within the limits of the acceptance criteria.
Um Two tests were conducted on mockup D.
gg was conducted with the current supply beir4 compensated far. A 100 ambiert temperature change; the other test was coalteted in a l
co24tro11ed ambient temperature of 22 5 C (72 F).
TQ7 both tests were essentially idatical, taiicating the temperatum The results of T
Uw correction factors were accurate, with a peak temperature of u
P.T 93 C (200 F) ad insulation resistance of infinity.
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ku is not acceptable because the allowable ten:perature rise was This design exceeded.
ani the' maximum tasperatures reco: tied during th
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From the results of these ampacity tests together with fire test g.
Qott results, we have determined the optiman depth of sealant; (silicone
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depth requ12tc no change to the current design practice of sizinTb MMME cables that will be installed through penetratica fire stops eni g
4ffy is applicable to Sequoyah ad future plants.
tray-cable sleeve / cable slot penetrations through w t
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p' ff and ceilings designated as fire barriers.
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r, g 75a
[ 5 g silicone RTY foam (coorpone=cs A and B).
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manerials are being eval".*M for pla=ts su:xquen Lo Sequoyah.
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ENCLOSURE 4 PHOTOGRAPHS OF TYPICAL ELECTRICAL PENETRATION SPLICE BOXES
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