ML20216C264
| ML20216C264 | |
| Person / Time | |
|---|---|
| Site: | Wolf Creek  |
| Issue date: | 04/06/1998 |
| From: | NRC (Affiliation Not Assigned) |
| To: | |
| Shared Package | |
| ML20216C234 | List: |
| References | |
| GL-92-08, GL-92-8, NUDOCS 9804140376 | |
| Download: ML20216C264 (7) | |
Text
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SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION I AMPACITY DERATING ISSUES WOLF CRFFK NUCLEAt OPERATING CORPORATION i
WOLF CREEK GENERATING STATION !
DOCKET NO. 50-482 4
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1.0 BACKGROUND
By letters dated June 20 and August 23,1996, Wolf Creek Nuclear Operating Corporation (WCNOC) submitted a response to the NRC Request for Additional Information (RAI) dated July 2,1996, related to Generic Letter (GL) 92-08, "Thermo-Lag 330-1 Fire Barriers," for the Wolf Creek Generating Station (WCGS).
l The staff's RAI dated July 2,1996, had identified a number of open issues and concems j requiring clarification by the licensee. The licensee's submittal dated August 23,1996, I contained the response to staff questions regarding its ampacity methodology.
2.0 EVALUATION After reviewing the licensee's submittals and Sandia National Laboratories (SNL) Technical
)
Evaluation (see Enclosure 2), the staff agrees with the SNL analyses and conclusions. The -
ampacity derating analysis questions, the licensee's response, and the staff's evaluation of the
. responses follow.
Amoacity Deratina Analysis Revjag Question 1: Calculations F-104 and XX E-003 These calculations include very significant errors and questionable assumptions. The NRC staff agrees with the Sandia National Laboratories (SNL), that these calculations should not be credited. The staff recommends that the licensee should not use these calculations and instead rely on the available ampacity test results of Texas Utilities (TU) and Tennessee Valley Authority (TVA)/ For details about the errors and questionable assumptions refer to the SNL document pared by Steve Nowien, SNL, dated April 19,1996. .
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1 Ucansee Ras 100am in its submittal dated August 23,1996, the licensee stated that the basic thermal model used in the original calculations may have provided a misrepresentation of or
- non-conservative values for fire (material) wrapped at WCGS. Therefore, the licensee stated that the subject calculations have been " voided from the design basis of WCNOC."
Staff Response >
The information provided by the licensee fully resolves the stafs concoms.
. Question 2: Calculation XX-E-010 Based on the recommendation of abandoning the calculations F-10 and XX-E-008, the
, . licensee should reconsider the basis for its overall conclusion of acceptability. The staff recommends that the licensee should use TU and more recently WA test results in formulating its final assessment.
Licensee Response in its submittal dateo August 23,1996, the licensee stated that Darmatt KM-1 will be utilized as a replacement fire wrap material where the ampacity derating values are provided by the manufacturer, Faverdale Technology Centre, Ltd. Calculation XX-E-010 has been revised in order to use the applicable TU Electric test data.
Staff Response The information provided by the licensee fully resolves the stars concoms.
. Question 3: Calculation XX-E-010 The licensee excluded conduits 134U3033 and 114U3C4G from the analysis based on the non-continuous nature of the load currents for these cables. However, the licensee '
needs to address.the operation of these cables for extended periods when called on to
. operate.
LigeG90eResonnae
. ,a 4 in its submittal d
' ated August 23,1996, the licensee stated that the subject conduits have been analyzed as if they were contmuously energized, found acceptable and are included in Revision 1 of WCNOC Calculation XX-E-010.
Staff Response -
The information provided by the licensee fully resolves the staffs concoms. However, the revised calculation was not revowed by the staff.
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- Question 4: Calculation XX-E-010 The licensee has used ampacity from insulated Cable Engineers Association (ICEA)
P46426, Page 264 for 3/C- # 1/0, 3/C- # 2/0, and 3/C- # 500 MCM cables. The ampacities on page 264 are for triplexed cables (3-1/C-T). Ampacities for three conductor .:a' oles (3/C) are on page 313. The licensee needs to provide clarification regarding, the use of ampacity values on page 264 versus page 313.
I Uganara Resoonse in its submittal dated August 23,1996, the licensee stated calculation XX-E-010 has been revised to use the ampacity values on page 313 of IPCEA P-46426 for three conductor cables and page 264 of IPCEA P46-426 for triplexed cables.
Staff Response The information provided by the licensee fully resolves the staffs concems. However, the revised calculation was not reviewed by the staff.
.- ' Ouestion 5: Calculation XX-E-010 I I
The licensee needs to provide a justification for using 298 amperes for two single l conductor # 2/0 cables in a conduit (Subject Calculation, Page 16). The staff believes j that 298 amps is the value for only one single conductor # 2/0 cable. (Triplexed # 2/0 cable ampacity is 204 amperes and three conductor # 2/0 cable ampacity is 190 '
amperes per ICEA P-46-426). Furthermore, National Electrical Code (NEC) Table 310-16 provides ampacity of 195 amperes for not more than three conductors of # 2/0 cable in a raceway.
Licensee Response in its submittal dated August 23,1996, the licensee stated that Calculation XX-E-010 has been revised to use the ampacity values on Table 310-16 of the 1996 NEC for one and two conductor cables.
Staff Response The information provided by the licensee fully resolves the staffs concems. However,
' the revised calculation was not reviewed by the staff.
.- Question 6: Calculation XX-E-010 Some of the conduits exceed percentage fill criteria per NEC (i.e., conduit 135C3074 Fill is 53.3 percent). Provide justification for the overfill and impact of the overfill on cable ampacity. ,
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Licensee Response
- In its submittal dated August 23,1996, the licensee clarified that the cables in question J
- had been stripped of their outerJacketing material during installation. A review of the I subject cables indicates that the percent fill is within acceptable limits as defined in the NEC 1996, Chapter 9, Table 1. Therefore, the licensee contends that an overfili condition does not exist in conduit 135C3074.
Staff Response The information provided by the licensee fully resolves the staff's concems.
. Questior' 7: Calculation XX-E-011 l
' The licensee failed to consider the "80 percent of open air" ampacity limit which is
.specified in ICEA P-54-440 for cables in cable trays 116U5D30 and 116U5E30.
Additionally, the licensee has used ampacity values from Thermal Science incorporated (TSI) test results performed at Underwriter Laboratories (UL). These TSI test results
. were not supported by UL, and were discredited during the NRC/ Department of Justice (DOJ) investigation of TSI. Therefore, the use of these TSI test results are
' unacceptable to the NRC and are not appropriate as the basis for final assecsment of margin of acceptaoility. The staff recommends that the licensee consider more recent test results from 1VA and TU tests as the basis for its final assessment of margin of acceptability.
Licensee Response in its submittal dated August 23,1996, the licensee stated that the Thermo-Lag material on trays 116USD30 and 116U5E30 had been removed and the 80% open air ampacity for trays with a full depth of less than one inch was applied to demonstrate past acceptability for the subject trays. Since the remaining tray,111U1K01 has a fill 1 diameter greater than one inch, ICEA P-54-440 was applied to the subject tray and found acceptable.
The licensee also stated that the TSI test results that were originally used in Calculation XX-E-011, Revision 0 had been removed and replaced with more recent information from the TU and TVA test results.
Staff Response The information provided by the licensee fully resolves the staffs concems.
.. Question 8: Calculation XX-E-011 The licensee excluded the cable " schemes" (16 GLY 15LA,16 GLY 15LB,16GKG20LA,
' and 16QJG10BA) involving heaters and heat trace circuits, based on non-continuous load. However, the licensee needs to address the operation of these cables for
~ extended period when called on to operate (during extreme cold weather, the heaters might operate at near continuous levels for extended periods). The licensee must provide further justification for excluding these cables cr analyses for these cables.
LicenseeResponse
. In its submittal dated August 23,1996, the licensee stated that cable schemes 16 GLY 15LA,16 GLY 15LB,16GKGOLA, and 16QJG10BA have been added to Revision 1 of WCNOC Calculation XX-E-011. These cables have been analyzed and have been determined to have adequate ampacity margin using TVA test results.
Staff Response l The information provided by the licensee fully resolves the staffs concems. However, the revised calculation was not reviewed by the staff.
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. Question 9: Calculaton XX-E-011 The licensee excluded the cable " schemes" (valves ALHV09 and ALHV11) involving a unique type of MOV. It is implied that during the operation of the auxiliary foodwater system, the circuits would be continuously energized. If these circuits are required to operate for several hours or longer, then an ampacity analysis is needed to assure that these cables perform as intended.
Licensee Response
- in its submittal dated August 23,1996, the licensee stated _that Cables 11 ALO9CB and 11 AlYO9DB (for Valves ALHV09 and ALHV11) contained in tray 111U1K01, have been added iv Revision 1 of WCNOC Calculation XX-E-011. These cables have been analyzed and have been determined to have adequate ampacity margin using TVA test results. The licensee has removed the Thermo-Lag fire barrier material around the subject tray and willinstall Darmatt KM-1 as an altemate fire barrier. An ampacity dorating analysis using the manufacturer data indicates that the subject cables will be able to operate within acceptable ampacity limits.
l Staff Response The information provided by the licensee fully resoives the staff's concems. The revised calculation was not reviewed by the staff.
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. Queston 10. Calculaten XX-E-011 ;
The licensee.needs to identify the characteristics of the cable being analyzed l (i.e., diameter, Jacketing of individual conductor, overall Jacketing, single conductor, three conductor or triplexing). Also, the licensee should identify the ICEA P-54-440
- table number used for particular cable ampacity. l l
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in its submittal dated August 23,1996, the licensee clarifed which cable characteristics were used in Rev;sion 1 of WCNOC Calculation XX-E-011. These characteristics have been verified and are referenced in the body of the revised subject calculation.
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l Staff Response The information provided by the licensee fully resolves the stafs concems. However,
- the revised calculaten was not reviewed by the staff.
= Question 11: General Comment ,
The full load current (FLA) used is based on nominal voltage. The constant KVA loads
- l. will draw 11 percent more current at 90 percent of rated voltage available.' Additionally, some loads may operate at overiosd or at a service factor of 15 percent. Accordingly, j the FLA could be as high as 125 percent of FLA at nominal voltage. The licensee needs
- to address this.
Licensee Response in its submittal da'ted August 23,1996, the licensee stated that the effects of both nominal and. degraded voltage conditions have been included in revised Calculations XX-E-010 and XX-E-011.
Staff Response The information provided by the licenses fully resolves the staffs concems. However, j~ the revised calculation was not reviewed by the staff.
Apphcahon of Amoacity Derating Methodology l-The onsite review of the licensee's implementation of its methodology is outside of the scope of this evaluation. The licensee revised calculations are available for onsite review and verification l by the staff.'
l Based on a review of the licensee's response to the stafs July 2,1996,RAI SNL concluded that all of the RAI questions have been adequately resolved in terms of ampacity derating mettsick,gy. Given the fact that the licensee is now relying on industry ampacity dorating test )
data (i.e., TU Electric) which have been reviewed and accepted by the staff, there is reasonable !
. assurance based upon the significant margin as discussed in SNL's letter dated April 19,1996,
' that the ampacity loads for cables at Wolf Creek Generating Staten have acceptable ampacity margins.
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3.0 CONCLUSION
Based on the above, the staff concludes that no significant safety hazards are introduced through use of the licensee's ampacity derating methodology. Therefore, the application of Thermo-Lag fire barriers to enclose cables at Wolf Creek Generating Station does not represent l a safety concem with respect to ampacity.
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! Principal Contributor: R. Jenkins i Date: April 6,1998 l
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