ML20135A951
| ML20135A951 | |
| Person / Time | |
|---|---|
| Site: | Oyster Creek |
| Issue date: | 11/25/1996 |
| From: | Roche M GENERAL PUBLIC UTILITIES CORP. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| 6730-96-2336, NUDOCS 9612040105 | |
| Download: ML20135A951 (11) | |
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GPU Nuclear, Inc.
(
U.S. Route #9 South NUCLEAR Post Office Box 388 Forked River, NJ 08731-0388 Tel 609 9714000 I
November 25, 1996 6730-96-2336 U. S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555 Gentlemen:
Subject:
Oyster Creek Nuclear Generating Station (OCNGS)
Docket No. 50-219 Facility Operating License No. DPR-16 Response to Request for Additional Information Regarding Thermo-Lag Related Ampacity Derating Issues NRC letter dated August 26, 1996 (6730-96-3276) requested additional information regarding Thermo-Lag related ampacity issues.
1 The attachment provides an itemized response to each of the NRC questions. If any additional information is required, please contact Mr. David J. Distel, GPU Nuclear Regulatory Affairs at J
(201) 316-7955.
Very truly yours, h
b O4nna-Michael B. Roche 6y20jo y $6g 2 M Vice President & Director, p
PDR Oyster Creek Nuclear Generating Station DJD/ pip Enclosures I
b)o 71 I
cc: Administrator, Region I OCNGS NRC Resident Inspector OCNGS NRC Project Manager
..- - -.- - - -- - - - -.-. - ~. -.-.... -
6730-96-2336 Page1of3 i
Attachment -
i NRC Ouestion:
I
- 1. The licensee stated that Thermo-Lag was installed on conduits using preformed sections and concludes that this would leave no air gaps. However, the staff agrees with its contractor that i
j an air gap between the outer surface of the conduit and the inner surface of the barrier would i
be expected unless specific steps are taken to eliminate this gap. This may invalidate the licensee's comparison to the Tennessee Valley Authority (TVA) test results because TVA installation procedures for conduits specifically called for eliminating this air gap by "prebuttering" the entire inner surface of the barrier sections. The licensee must funher assess -
j the applicability of the TVA test results to its own installations recognizing this potential i'
difference in installation procedures.
Response
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OCNGS has utilized only the 3-hour test results from the TVA ampacity test program.
OCNGS ampacity derating values for 1-hour barriers are derived from Texas Utilities (TU) test results for 1-hour barriers.
It is noted that the TVA 3-hour barrier test configurations were not prebuttered on the entire surface of the barrier sections. The Omega Point Laboratory Repons No. I1960-97337 and l
97338, " Electrical Test to Determine _ the Ampacity Derating of an Electrical Raceway Fire Barrier System for Class IE Electrical Circuits," dated August 21, 1995, describe the test barrier. material installation highlights and state that the enclosure for the conduit was constructed from nominal 1-1/4 inch thick preformed conduit sections which were dry fit to the conduit and secured with stainless steel bands. Therefore, the presence or lack of an air gap can be considered not applicable since both OCNGS and TVA 3-hour barrier base Thermo-Lag test barrier construction are comparable as both were dry fit around the conduit.
Additionally, it is noted that TVA's 3-hour test barriers employ additional mats and trowel grade material providing an additional insulating effect as indicated in our previous response letter (C321-95-2350) dated December 8,1995. Based on the above, the TVA 3-hour test results are considered to be representative of OCNGS 3-hour installations for the purpose of bounding ampacity derating values applied to the OCNGS 3-hour barrier configurations.
NRC Ouestion:
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- 2. The licensee needs to provide complete calculations in order to evaluate the appropriateness ofits ampacity assessment approach and implementation. Otherwise, specific and complete examples of the ampacity derating calculations illustrating all aspects of those calculations in detail (baseline ampacity with source, cable characteristics, conduit size and type, percent fill, number of conductors, fire barrier rating, etc.) should be provided for typical 1-hour conduits, typical 3-hour conduits, and typical air drops. See attached SNL Report for details.
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i 6730-96-2336 Page 2 of 3 Attachment
Response
Attachment A provides specific circuit examples of the OCNGS derating calculation approach for typical 1-hour conduits, typical 3-hour conduits, and typical air drops. Baseline ampacity 1
(rated amps) and derating values for ambient temperatures and the number of conductors in the raceway are based on National Electric Code specifications, as shown in Attachment A.
Cable and conduit characteristics are also identified in the Attachment A.
Additional calculation assumptions and conservatisms were previously described in GPU Nuclear letter C321-95-2350, dated December 8,1995.
NRC Ouestion:
- 3. It appears that the licensee has assumed an ambient temperature of 30 C for items 15,16,17, and 31. Ambient temperature of 30 C would not be expected to bound the environmental conditions in most typical plant areas. The licensee should review the assumed ambient temperatures used in the calculation and provide adequatejustification for the assumptions.
Response
The OCNGS ambient temperature cable deratings based on 30*C, as previously submitted, have been revised to incorporate more conservative deratings based on an ambient temperature of 40 C. The revised derated amperage values are shown on the attached revised Table 1. This Table indicates that the existing OCNGS Thermo-Lag protected Appendix R circuits are adequate for the revised design ampacity derating factors.
NRC Ouestion:
- 4. It appears that the licensee has assumed an 11% " bounding" ampacity derating factor (ADF) for 1-hour fire wraps including air drops. This value fails to bound the Texas Utilities (TU) results in which air drop ADF values in the range of 21.2% to 31.8% were reported. Ampacity assessments for cables involving air drop configurations should be performed using realistic estimate of the fire barrier ADF impact.
Response
OCNGS Circuits 62-93 and 62-100 contain 1-hour fire wraps for an air drop configuration.
These two circuit air drop configurations are each approximately 2 to 3 feet in length. The total length of each respective circuit is over 500 feet. National Electric Code 310-15(c) specifies that no additional derating factor need be applied for circuits which are less than 10%
of the total length of circuit or a maximum of 10 feet. Based on the above, OCNGS has determined that the 11% bounding ADF is applicable for the air drops associated with these j~
two (2) circuits.
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6730-96-2336 Page 3 of 3 Attachment However, it should be noted that the maximum available ADF for Circuit 62-93 is 48.7%, and the maximum available ADF for Circuit 62-100 is 19% using an actual maximum circuit loading based on the existing breaker rating. However for Circuit 62100, the ADF is 97%
based on calculated circuit load. These values are shown on the attached Table 1.
NRC Ouestion:
- 5. The calculated load current for battery chargers (items 5 and 6) is shown as 12.5 amps (actual). ' This current could be much higher if the battery is discharged. Provide a technical basis for the acceptability of the cable during charging the fully discharged battery for the required duration.
Response
During normal plant operation the station battery chargers carry the load for the normal DC load on Bus "C" and the float current for battery "C". The load is approximately 10 amps.
The OCNGS station batteries are discharged and charged only during the performance and i
service tests which are performed during each refueling outage (2 year interval). Under normal plant operating conditions the battery is on float. Battery current is monitored once per shift in accordance with Plant Procedure 106, and corrective action is taken if required.
l Therefore, no credible scenario exists within the existing design basis which would require these circuits to be derated due to current flow to a fully direharged battery.
Additionally, it is noted that a maximum current of 153 emps, based on the battey charger nameplate rating plus a 10% overload current (battery chargers are current limited), would be expected if the battery is discharged. This conservative value remains bounded by the calculated derated value of 158 amps shown on Table 1.
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Attachment A Page1 of3 Example item 19 (one hour fire wrap, air drop length 2 to 3 feet)
Circuit designation:
62-100 Circuit description:
125 VDC control power to 4160V SWGR ID 2-lC #4 AWG, conduit 1%" steel, portion of this cable is run in conduit with cable 62-93 (1%" conduit).
Conduit fill = 16%.
Maximum cable load =
56 Amps. (This is based on 70 Amps breaker and l
80 % of the breaker rating. Calculated continuous Icad is about 2 Amps).
Rated current at 30 C
= 95 Amps Rated current at 40 C
= 95 x 0.91 = 86.5 Amps Rating due to multiple conductors = 86.5 x 0.8 = 69.2 Amps
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(greater than 3)in conduit Rated current due to TSI wrap
= 69.2 x 0.89 = 61.6 Amps There is no derating required due to air drop because of very small length of air drop (2 to 3 feet) relative to the totallength (about 500 feet). Reference National Electric Code Article 310-15(c).
1 Since the maximum cable load (56 Amps, actual 2 Amps) is less than the derated current (61.6 Amps), circuit is acceptable.
Maximum available derating based on a calculated load of 2 amps is 97 8%.
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6730-96-2336
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1 Attachment A i
Page 2 of 3 Examnic Item 31 (3 hour3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br /> fire wrap)
Circuit designation:
86-71 l
Circuit description:
From 4160V SWGR EDG-2 l
6-1/C, 500 MCM; 2 conduits 3%" / 4", transite/ steel j
each conduit with 3 conductors.
Conduit fill = 38%.
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Maximum load current
= 543 Amps (Ref. B&R Calculation 3731-29-E007)
Rated current at 30 C
= 950 Amps (475 Amps x 2; because of 2 conductors / phase) l Rated current at 40 C
= 950 x 0.91 = 864.5 Amps l
Since there are 3 conductors per conduit, no derating is required per NEC.
l Rated current due to TSI wrap
= 864.5 x 0.82 (18% derating)
= 708.9
~ Since the maximum load current (543 Amps) is less than the maximum derated current
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(708.9 Amps), circuit is acceptable.
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1 0
6730-96-2336
Attachment A Page 3 of 3 Examnie item 15 (One hour fire wrap) l Circuit designation:
14-25 Circuit description:
From 4160V Emergency Switchgear ID to 460V Unit Substation IB2 3-1/C,500 MCM,3%" steel 4
conduit.
Conductor fill = 38%.
Load ct.rrent:
281 Amps (Ref. GPUN TDR 1136, Rev. 0)
Rated current at 30 C
= 475 Amps 2
Rated current at 40 C
= 475 x 0.91 = 432 Amps No. of conductors in conduit
=3 No derating required per NEC for conductors 3 or less.
Rated current due to TSI wrap
= 432 x 0.89 (11% derating)
= 384 Amps Since the maximum load current (281 Amps) is less than the maximum derated current (384 Amps), circuit is acceptable.
6730-96-2336
Trble 1 Page1 of4 CALCULATION FOR THERMO-LAG AMPACITY DERATLNG FOR OCNGS DERATED AMPS DUE TO.
CALCULATED CABLE MULTIPLE FIRE WRAP CIRCUIT :
CABLE ACTUAL LOAD RATED AMBIENT CONDUCTORS FIRE W1 TAP (USING TU/TVA ITEM CIRCUIT #
DESCRIPTION SIZE AMPS AMPS # 3fPC 4tPC IN RACEWAY (USING TSI DATA)
DATA) 1 11GPl402 Inst. PNL 4C Feed to RSP 2-1/C #8 24 55 50 40 36 35.6 2
1INPl403 Inst. PNL 4C Feeder 2-1/C #12 10 30 27.3 21 8 20 19A to Fire Det. Pnl.
3 112P1406 IIalon Syst Protection 2-1/C #12 5.5 30 27 19 17 16.9 4'11-861 IIVAC Control PNL 2/C #10 20 40 36 25 23 22.3 5'12-600 Battery Charger C1 3-1/C #2/0 12.5 195 177.5 177.5 163 158 Actual 6*
12-601 Battery Charger C2 3-1/C #2/0 12.5 195 177.5 177.5 163 158 Actual 7'12-602 Battery Room C Ventilation 1-3/C #10 4.3 40 36.4 36.4 33.5 32.4 Fan F1
~
3*
12-603 Battery Room C Ventilation I-3/C #10 4.3 40 36.4 36.4 33.5 32A Fan F2 9
12-604 Battery Room C Vent 1-3/C #10 24 40 36.4 36 4 33.5 32.4 1Icater/ Fan 10' 12NP0825 "A" SWGR Rm liVAC Fan 3-l/C #12 17.5 30 27.3 21.8 20 19.4 1l' 12NP0826 "A" SWGR Rm iIVAC Fan 3-1/C #12 17.5 30 27.3 21.8 20 19.4 12' 12GP0816 Power to Valve 4-1/C #10 10 40 36 25 23 22.3 V-14-37 13' 12GP0817 Power to Valve 3-1/C # 12 10.25 30 27.3 19.1 17 17 i
V-14-32 14 122POS45 Refueling Platform 3-1/C #6 30 75 68 48 44 42.7 15' 14-25 460V USS 1B2 3-1/C 281 475 432 432 397 384 500 MCM 16*
14-28 460V USS IB3 3-1/C 2/0 150 205 186.5 186.5 171.6 165.9 17 14-31 400 IIP Emerg. Serv. Water 3-1/C 210 67 205 186.5 186.5 171.6 165.9 Pump 1-3 t/C #6 6730-96-2336
Trble 1 Page 2 of4 CALCULATION FOR THERMO-LAG AMPACITY DERATING FOR OCNGS DERATED AMPS DUE TO:
CALCULATED CABLE MULTIPLE FIRE WRAP -
. CIRCUIT
. CABLE ACTUAL LOAD RATED AMBIENT CONDUCTORS FIRE WRAP.
(USING TUTIVA ITEM CIRCUIT #
DESCRIPTION SIZE AMPS AMPS W 30*C 40"C IN RACEWAY (USING TSI DATA)
DATA) 18*
62-93 125V DC to 460V SWGR 2-2/C #6 56 150 136.5 109.2 100.5 97.2 1B3 19'62-100 125V DC to 4160V SWOR 2-1/C #4 56 95 86.5 69.2 63.7 61.6 ID 20'62-153 125V DC POWER to DC-2 2-1/C 2/0 85 195 177 177 163 157 PNL 21'62-158 125V DC to 460V SWGR 2-1/C #2 56 130 118.3 118.3 108 105 1A2 125V DC Power to PNL F 22'62-161 2-1/C 2/0 150 195 177 177 163 157 23 62-165 DC Power to RPS PNL 6XR l-2/C #10 15 40 36.4 25.5 23.4 22.7 24 62-168 DC Power to PNL 1IF 1-2/C #10 5
40 36.4 25.5 23.4 22.7 25 62-169 DC Power to PNL 1F/2F 1-2/C #12 14 30 27.3 19.1 17 17 26 62-170 DC Power to PNL 3F 1-2/C #10 10 40 36.4 25.5 23 22.7 27' 62GP0229 125V DC Power to 460V 4-1/C #6 56 150 136.5 109.2 100 97 SWGR 1B3 28' 62 st228 DC Power to 4160V SWGR 2-1/C #4 56 95 86.5 69.2 63 61.6 ID 29' 62GP0225 DC Power to V-16-2 Il-1/C #8 18.5 55 50 35 32 31 30' 62GIV226 DC Power to V-16-14 Il-1/C #8 I8.5 55 50 35 32 31 31' 86-71 4160V SWGR 1D 2 X 3-1/C 543 950 8R5 864.5 769.4 708.9 3-11our Wrap 500 MCC 32 21-2038 Dnwell Personnel 2/C #12 6.25 30 27 13.5 12.4 12 33 12-317 Valve NG02C 4-1/C #12 6
30 27 13.5 12.4 12 34 12-318 Valve NG02E 4-1/C #12 6
30 27 13.5 12.4 12 35 12-320 Valve NG03C 4-1/C #12 6
30 27 13.5 12.4 12 36 12-321 Valve NG03E 3-1/C #12 6
30 27 13.5 12.4 12 6730-96-2336
Trble 1 Page 3 of 4 CALCIMTION FOR 11IERMO-LAG AMPACITY DERATING FOR OCNGS DERATED AMPS DUE TO:
CALCULATED CABLE MULTIPLE FIRE WRAP CIRCUIT CABLE ACTUAL LOAD RATED AMBIENT CONDUCTORS FIRE WRAP (USING TUITVA ITEM CIRCUIT #
DESCRIPTION SIZE AMPS AMPS @ 30*C 40*C IN RACEWAY (USING TSI DATA)
DATA) 37 12-323 Valvc NG08-C 4-1/C #12 0 91 30 27 13.5 12.4 12 38 12-324 Valve NG08-E 4-1/C #12 0.91 30 27 13.5 12.4 12 39 12GP0827 Valve NG03-E 4-1/C #12 10 30 27 14.0 13 12.4 40 12-328 Valve NG02-Il 4-l/C #12 6
30 27 13.5 12.4 12 41 12-330 Valve NG03-13 4-1/C #12 6
30 27 13.5 12.4 12 42 12-332 Valve NG08-B 4-1/C # 12 6
30 27 13.5 12.4 12 43 12-335 Valve V-17-54 4-1/C #12 4.9 30 27 13.5 12.4 12 44 12-341 A Valve V-1-107 4-1/C #12 0.69 30 27 13.5 12.4 12 45 12-342 Valve V-14-37 4-1/C #12 10.3 30 27 13.5 12.4 12 46 12-329 Valve NG02-D 4-l/C #12 6
30 27 13.5 12.4 12 47 12-331 Valve NG-03-D 4-1/C #12 6
30 27 13.5 12.4 12 48 12-333 Valve NG-08D 4-1/C #12 0 91 30 27 13.5 12.4 12 49 12-443 Valve V-5-166 4-l/C #12 0.91 30 27 13.5 12.4 12 50 12-446 Valve V-5-148 4-1/C #12 0.91 30 27 13.5 12.4 12 51 12-325 Valve V-16-1 4-1/C #12 4.9 30 27 13.5 12.4 12 52 11-293 SRM #I Motor Feed 3-1/C #16 0.29 18 16 8
7.3 7.1 53 11-294 SRM #2 Motor Feed 3-l/C #16 0.29 18 16 8
7.3 7.1 54 11-297 IRM #1 Motor Feed 3-1/C #16 0.29 18 16 8
7.3 7.1 55 11-298 IRM #2 Motor Feed 3-l/C #16 0.29 18 16 8
7.3 7.1 56 I l-299 IRM #3 Motor Feed 3-1/C #16 0.29 18 16 8
7.3 7.1 57 11 300 IRM #4 Motor Feed 3-1/C #16 0.29 18 16 8
7.3
- 7. I 58 11-295 SRM #3 Motor Feed 3-1/C #16 0.29 18 16 8
7.3 7.1 59 11-2 %
SRM #4 Motor Feed 3-1/C # 16 0.29 18 16 8
7.3 7.1 6730 96-2336
J Table 1 Page 4 of4
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CALCULATION FOR THERMO-LAG AMPACITY DERATING FOR OCNGS DERATED AMPS DUE TO:
CALCULATED CABLE MULTIPLE FIRE WRAP CIRCUIT CABLE ACTUAL LOAD RATED.
' AMBIENT '
CONDUCTORS FIRE WRAP.
(USING TU/TVA ITEM
' CIRCUIT #
DESCRIPTION SIZE AMPS AMPS W 30"C 48"C IN RACEWAY (USING TSI DATA)
DATA) 60 11-301 IRM #5 Motor Feed 3-1/C #16 0 29 18 16 8
7.3 7.1 61 11-302 IRM #6 Motor Feed 3-1/C #16 0.29 18 16 8
7.3 7.1 62 11-303 IRM #7 Motor Feed 3-1/C #16 0.29 18 16 8
7.3 7.1 63 11-304 IRM #8 Motor Feed 31/C #16 0.29 18 16 8
7.3 7.1 64*
86-66 EDG-2, DiiT. Protn 4-l/C 5
40 36 28.8 26.5 25.6 19/22 65' 86GC0016 FlX]-2, DitT. Protn 4-l/C #10 5
40 36 25.2 23.2 22.4 6730-96-2336
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