ML20116C758
| ML20116C758 | |
| Person / Time | |
|---|---|
| Site: | Comanche Peak  |
| Issue date: | 10/27/1992 |
| From: | William Cahill, Woodlan D TEXAS UTILITIES ELECTRIC CO. (TU ELECTRIC) |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| TXX-92502, NUDOCS 9211050022 | |
| Download: ML20116C758 (7) | |
Text
_
m l
Em Ta=
- r. og iln TXX-92502 P%
F i 'l e # 10010 628
~~
821 (clo)-
7t/ ELECTRIC
$FM4(b)
Ref.
M lll(am J. Cahill, Jr.
men., r,n *'"
October 27, 1992 U. S. Nuclear Regulatory Commission Attn:
Document Co.itrol Dest Washington, DC 20555
SUBJECT:
COMANCHE PEAK STEAM ELECTRIC STATION (CPSES)
DOCKET N05, 50-445 AND 50-446 RESPONSE TO REQUEST FOR ADDITIONAL INF0rdSTION (RAI)
CONCERNING FINAL SAFETY ANALYSIS REPORT (FSAki CHAPTER 8, AMENDHENTS 79 THROUGH 84 REF:
1)
Supplement No. 25 to NUREG-0797 dated September 17, 1992, related to operation of the Comanche Peak Steam Electric Station Unit 2 2)
Nuclear Reactor Regulation (NRR) letter from Mr. Brian Holian to Mr. William J. Cahill, Jr. dated September 28, 1992 Gentlemen:
In Reference 1, Nucleer Regulatory Commission (NRC) stated that the staff completed the review of-FSAR amendments through Amendment 84 and that a number of outstanding issues (01) have been identified that remain under review as a result of the stoff's continuing review of the CPSES Unit 2 application.
Reference 1 also stated that the staff will complete its review of these items prior to making a decision regarding issuing an operating license for Unit 2 and that the review will be documented in one or more future supplements.
The outstanding issues in Reference 1 included 01 (1) on Cabie Separation Criteria. 01 (2) on Metal Clad and Rockbestos cables, 01 (7) on Cable Tray Loading Criteria and 01 (8) on Non-class 1E Transformers in Cable Spreading Rooms (CSR).
T0:103 n
/*[] I'{
9211050022 921027 gos oom mowas PDR
- 4N. Olive Street LB. El Dalla, Tem 75201 p
k
~
. ~ - -.-. ~..---- -.- - - - -..
~ -. -. -.
~
I TXX-92502-
.Page 2 of 2 Reference 2 requested additional i nformation on the outstanding issues 1,~1, 7 and 8 in Reference 1, for staff's further review o clarification in order to make a determination as to their acceptability.
TV Electric provides the response to Reference 2 as stated in the attachment to this letter.
If you have any questions or need further information, please contact Jacob H. Kulangara at (214) 812-8818.
t Sincerely, William J. Cahill, Jr.
1 By:
b D. R. Woodlan Docket Licensing Manager JHK/tg Attachment c-Mr. J. L. Hilhoan, Region IV Mr. B. E. Holian, NRR Hr.
T.. A. Bergman, NRR Resident inspectors CPSES (2)
E
=
m',
.r.
.-r.,
r r-
-3
-~
~
-. ~.
w w
~~
~. - - - -
'i 3
-Attachment to TXX-92502 Page 1..of:S HEL_QLLELUML1 Provide detailed descriptions of how the Comanche Peak cable installation configurations compare'to the cable configurations used in Wyle taboratory Test Report No. 47906 01.
(It is noted that this test report was provided for Nine Mile Point' Unit 2 Nuclear Power Generating Station.): The response should include addressing cable materials and construction, cable sizes, protective
~
wraps and positioning of cables.
State if the CPSES cable installation configurations are more or less conservative than those used in the test report and provide the basis for the stated selection (SSER 25 Outstanding issue-1).
TV EtL(IRLC RESPONSE 1 CPSES utilizes Wyle Laboratory Test Report No.'47906-02 for Nine Mile Point Unit 2 (NMP2) to establish separation requirements for cable in air to rigid or flex conduit.
Cables tested at NMP2 in this test report were manufactured-by Okonite (power cables) and Rockbestos (control cables). The cables used at -
Comanche Peak Steam Electric Station (CPSES) are of the same manufacturers, materials, and construction as those tested at NMP2 Cable size ranges for both CPSES and NMP2 are from #12 AWG to 750 MCM.
~
In this test configuration. the target cables or conduits were positioned closer than one-quarter inch to the f ault cable or conduit containing the-
-fault cable.
CPSES requires a minimum of 1 inch separation between condult L
and cable in air.
l l
Based on the acceptable test results for NMP2 per Wyle Laboratory Test Report 47906-02 with a separation distance of less than 1/4 inch, the separation distance of 1 inch required at CPSES is very conservative.
l NRC OUESTION 2 The ' evaluation perf ormed by 10 Electric.for use of copper sheathed (CS). cable in lighting circuits inside the Comanche Peak' containment buildings indicates that technical justification for_ use of this type cable is provided in Wyle Laboratory Test Report Number 53575.
This report contains information relating to testing of CS cable _for use at-the-South Texas Project..
As indicated, the intent of the testing performed was to~ establish that a physical separation distance of 1 inch is adequate to protect Class 1E cables from a fault in a 3/C No. 8 AWG CS cable.
In view of thie _ background information, provide responses which address the items requested below (SSER-25 Outstanding issue 2).
-ta)
Information contained in the TU Electric evaluation and the Wyle Test Report indicates that' during-testing a fault current level of 325 amperes was applied to a 3/C:No. 8 AWG CS cable.
Further. it is indicated that this f ault current level was used during testing because i
it is_ equivalent to the secondary (upstream) protective _ device long time
Attachment' to TXX-92502 Page 2 of B trip setting.
However, if the.f ault current quickly open-circuited the cable without '~nition, it' appears that a more demanding test for demonstrating the adequacy / acceptability of CS cable for the proposed physical separation application would be to apply a sustained current value greater than the primary protective device setting and substantially less than the secondary protective device setting.
This being the case, provide a detailed discussion including technical bases which explains why the CS cable need not be tested in this manner, (b)
The testing as documented in the Wyle Test P3 port applied a f ault level current to a 3/C No. 8 AWG CS cable.
However, at the Comanche Peak Ste* ion, maximum CS cable size is documented as 4/C No. 10 AWG.
Since tr is the case, provide a discussion containing technical details which clearly supports how testing results obtained by testing a 3/C cable of one physical size and length are also applicable to a 4/C cable of a smaller physical size and any length.
TV ELECTRIC RESPONSE 2 The copper sheathed (CS) cable used at CPSES is enclosed in a 16 mil thick corrugated copper tube which provides mechanical integrity (crush resistance) greater than aluminum sheathed (ALS) cable per correspondence with Rockbestos and is comparable to the 6 mil thick 3/4 inch B0A flex conduit tested per Wyle-Laboratory Test Report No. 48037-02.
'The CS cable insulation is flame retardant, and the seamless copper tube containing the CS cable conductors will contain any cable ignition due to a fault.
A maximum of four #10 AWG conductors make up the cable assembly.
The annulus between the conductors and the tube is tightly packed with flame retardant filler mat 9 rial, which will inhibit flame propagation due to the absence of free-air surrounding the conductors.
The 4/C #10 AWG CS cable is used in the containment building for lighting circuits. Per Wyle_ Laboratory Test Report No, 48037-02 test 2E for CPSES,_a 1/C #12 AWG conductor fault cable contained in-3/4 inch B0A flex conduit _was subjected to a 135A f ault current for approximately 27 minutes until it open circuited. The maximum upstream protective device for rcntainment lighting is-a ISOA panel main circuit _ breaker; theref ore, the. fault currentiin the LCS cable can be assumed to be l'mited to ISOA for a worst case fault with primary protective device failure.
Per above referenced test report for CPSES, a shielded pair #16 AWG instrumert cable was wrapped-around and in contact with the 3/4 inch BOA flex conduit _and?
remained functional.
This test data shows that 6 mil thick BOA flex conduit provides adequate protection for a substantial f ault magnitude over a long duration with target cable in contact.
J
At t a c hme nt t o 1 X X 92',02 Page 3
- t. f r.
The minimum separ at ion iequired at CPLES between CL table and any Class IE cobios/ru rways t'
1 int h.
lased on the above ardlysis, the #10 AWG CL cable should provide a barrier at least as effective as the 3/4 inch BOA flex c c ruiv i t.
(used on the abo" justification. the CS table used at CPSES con be considt ed tho 'arre as cable inside conduit for separation purposes.
Testing per Wyle laboratery Test Peport No. W 75 for Louth lexas Pr oject (STP) further demonstrate' the ability of LL cable to perform as well as cablo in conLuit for separation purposes at higher fault levels over shorter durations.
IlM_0VLkilML3 The scope of the one hour fire rated materials for Comanche Peak was expanded to include one-hour fire rated cables.
It is documented t hat t his cable is u f et y r ela t ed and ha', been quali fied por t he pi avisions of ILLE Standards L'3-1974 and 3B3-1974 f or being flame retardant, in addition, it is documented that this table meets the requirements of ASTM E-119 1971 for fire resistante and therefore is considered equivalant to conventional cable enclosed within a one hour fire barrier a.g.
Thernio lag ).
It is f urther a
concluded that the use of onc-hour f ire, at ed material s (i.e., Thermo Lag and one-hour fire rated cable) are considered acceptable barriers for electrical separation and are considered equivalent to metal enclosed raceways with respect to protection from electrica' failures.
However, the only supporting information provided for these concluding statements is that this cable meets
)
the ALTH E-119 requirements.
As such, pr ovide a description which includes technical bases and clearly explains why meeting the ASTM E-119 req :irements makes this cable equivalent to metei enclosed raceways with respect to y
pr otec t ion from electrical failures in fire safe shutdown systems power and cont rol circuit applications (55ER 25 Outstanding issue 2).
11LLLMIBb YLENd.)
One-hour fire rated cable (fire nne *R*) is constructed of a continuousi) welded cor rugated t welve mil thick stainless steel sheath with high temperatare nickel-clad copper conductors, glass braid cable jac6et and silicone rubber insulation.
The one-hour fire rated cable's resistance to fire damage as evidenced by ASTM E-Il9 testing demonstrat e' it's ability to wit hst and t he ef f ect s Caused by a severe f eult on adjacent cables f or the durations typically encount er ed dur ing Requi at ory Guide 1.76 separation testinq (i.e l e s '. than onc heur).
for the constition of a fault on tho 'ne hour f ii 9 rated rablo, the following di monst rat es t hat this condition will have a neqligible offect on adjacent a..
ni/or r u eway s
l t
i Attachment to Txx 92502 f
Page 4 of 5 l
1 1
At CPSIS, the only size firezone 'R' cable used in power and control circuits of fi safe shutdown selected equipment is #8 AWG. The #8 AWG firezone
'R' e
cable may be substituted for #10 AWG and smaller field cable sizes.
The worst case postulated f ault condition f or firezone 'R' cable is a locked rotor condition of a motor with f ailur' of the primsry protective device (Hotor
~
Control Center circuit breaker) to trip.
This is deemed worst case because in control applications, upstream protective l
devices should clear a f ault of much smaller magnitude-than a motor with locked rotor.
The worst case le:ked rotor motor current f or a fire safe shutdown selected c o,,p on en t fed by #10 AWG cable where one hour fire rated Cable could-be substituted is 59.70A (4.0HP MOV l 8701B. 2-87018).
1 The normal f ree air ampacit/ f or #8 AWG firezone
'k' cable is 58A.
The worst case loc 6ed rotor current noted above of 59.70A is approximately equal to the normal free-air ampacity of #8 AWG firezote
'R' cable.
Based on this, even i
under extended loc 6ed rotor conditions, the temperature rise in the #8 AWG firezone
'R' cable would be negligible.
Based on the above analysis, firezone
'R' cable can f.e considered equivalent to or better than a regular qualified cable enclosed in a metallic raceway for the purpo<et of Regulatory Guide 1.75 separation, when' considered as either a faulted or target cable.
1 HRC'OUEST10N_4 The FSAR'information does not explicitly identify any evaluation criteria and bases to be used when cables extend above the Class 1E-cable tray side rails
- but do not exceed the cable tray fill limits.
Explicitly identify'uny evaluation cliteria and bases to be used for such situations and provide a detailed. description explaining why wuch a cable installation should be considered satisfactory and technteelly adequate (SSER 25 0utstanding
- Issue 7).
TV ELEETRif RESPONSE 4 At CPSES, the tray fill limits are controlled by design, and cable sizing takes into acccunt the-cable tray fill limits.
However, due to the cable's lay in' the tray; the cables may extend above the side rails even though the fill limit is not exceeded.
In such cases when cables extend above the cable tray side railt.. the CPSES criteria requires these cables to be treated as cables in air for the purposes of sephration requirements.
I F
l l.
a r
=
--m--
m.--r,
--,--.,----,,---e-,,---,-.--.--.--.--...mm.,
..-m
~-...--- ~.., - -., +,,.
-w,
- - ~,
--~v---
- - - ~
v.. - - --
<*w-,--
i Attachment to TXX 92502 Page $ of 6 i
l l
liRLQy[5T10ft $
h IEEE 5tandard 384 1974 states that the cable spreading area shall not contain high encrgy equipment such as switchgear, transformers, rotating equipment, or potential sources of niissiles or pipe whip and shall not be used for storing flammable materials.
Provide the technical bases used to deter,tiine that t he non Class IE t ansformers located in the cable spredding room are low energy, 11 a fire should occur as a result of one of the transf ormers, describe i'1 detail how this occurrence does not preclude safe shutdown o* the station (SSER 25 Outstanding Issue 8).
i
,TlLUICTRIC RL1PffjSLi The transformers (TIC 5 1. T106+1, 1205 1 and TEC61, heated in the cable spreading rooms (CSR) supply power to the emergency respoi,se facility (ERF) computers.
Each transformer is rated 10KVA 120/208V single phase, dry type and fully contained in sheet metal enclosures.
i The associated cabling is completely contained in dedicated conduit between the trentformers and panels.
The low voltage and loading level in conjunction with total enclosure of the dry type transformers and connecting cables conforms to the intent of the requirements for Nonhazard Areas (IEEE Standard 384 1974, Section 6.1.3) as failure is limited to within the equipment or
- cables, Additionally, fire safe shutdown analysis demonstrates-that CPSES con be safely shut down in the event of a fire that damages all essential circuits in eith6r cable spreading rnom.
Due to reconfiguration of the power supply for the plant computer, which c
replaces the Ear computer, the above mentioned transformers (T2C5 1 and TEC6 1) have been de-energized and spared in CPSES Unit 2 and will be removed prior-to Unit 2 fuel load from the CSR.
A similar modification is planned to be implemented in Unit 1 during the ref ueling outage number 3 (RF03) at which time the tinit 1 transf ormers (T1CS 1 and T1061)- will also be disconnected and removed from the CSR.
1 i
-,,--,Ome,-,E,---,,_,,,-..
m.,r
,m,....m
.,-.~,,.--,m--
. -..,...., ~.
m.,
..4.
.-.-.m.
-1,,,
e