View source for B16060, Responds to RAI Re Thermo-Lag Related Ampacity Derating Issues.Calculations Encl

{{Adams
| number = ML20138H285
| issue date = 12/27/1996
| title = Responds to RAI Re Thermo-Lag Related Ampacity Derating Issues.Calculations Encl
| author name = Mcelwain J
| author affiliation = NORTHEAST NUCLEAR ENERGY CO., NORTHEAST UTILITIES SERVICE CO.
| addressee name = 
| addressee affiliation = NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
| docket = 05000245
| license number = 
| contact person = 
| document report number = B16060, TAC-M85570, TAC-M85571, NUDOCS 9701030216
| package number = ML20138H289
| document type = CORRESPONDENCE-LETTERS, INCOMING CORRESPONDENCE
| page count = 6
| project = TAC:M85570, TAC:M85571
| stage = Other
}}

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DEC 2 7 mv l                                                                                                          Docket No. 50-245 l                                                                                                                    B16060             j l
l U.S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, DC 20555
                                                                                                                                        )
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Millstone Unit No.1 Response to Request For Additional information                                           l
;                                                          Regarding TAC No. M85570 Thermo-Lao Related Amoacity Deratina Issues                                            .
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1 The purpose of this letter is for Northeast Nuclear Energy Company (NNECO) to                                       !
!                    provide additional information concerning Thermo-Lag Related Ampacity Derating                                     i' Issues as requested by the Staff in the letter of August 12,1996.' The initial response to each of the three questions presented by the Staff in the letter of August 12,1996, as well as the response to additional information requested by the Staff in the tele-conference held between the Staff and NNECO on September 5,1996, was presented l                    in the letter of October 3,1996.2 At that time the Thermo-Lag ampacity calculations had not been completed and NNECO committed to provide the Staff with updated information after completion of the calculations. The Thermo-Lag ampacity calculation l                    for Millstone Unit No.1 has now been completed. The updated information resulting l                    from the completed calculation is aontained in Attachment 1.
1
                     '             Phillip F. McKee to Ted Feigenbaum, " Request for Additional information                             ,
Regarding Thermo-Lag Related Ampacity Derating issues For Millstone Units 1                          )
and 2 (TAC Nos. M85570 and M85571)", dated August 12,1996.
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* T. C. Feigenbaum to U. S. Nuclear Regulatory Commission, " Millstone Unit Nos.
I 1 and 2 Response to Request for Additional information Regarding TAC Nos.
M85570 and M85571, Thermo-Lag Related Ampacity Derating issues", dated                                i
:   030010                         October 3,1996.
{O'of)' ;          '
9701030216 961227 PDR          ADOCK 0500o245 P                             PDR   ,._

!h        - U.S. Nuclear Regulitory Commission 4
B16060/Page 2 i           The completed ampacity dorating calculation, '96-ENG-1559E1, Ampacity Derating of Cables due to Thermo-Lag - MP1," is contained in Attachment 2.
;           if you have any additional questions concerning this submittal, please contact Mr.
Robert W. Walpole at (860) 440-2191.
4 5
'                                                                                                                           i Very truly yours, NORTHEAST NUCLEAR ENERGY COMPANY S $A f f 4 A -
p P McElw6in ~
;                                                                   Millstone Unit No.1 Recovery Officer i
:           Attachments l
l           cc:    W.D. Travers, Director of Special Projects j                   H. J. Miller, Region I Administrator
]                   S. Dembek, NRC Project Manager, Millstone Unit No.1 j                  T. A. Eastick, Senior Resident inspector, Millstone Unit No.1 1
4

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Docket No. 50-245 i B16060 lI i
Attachment 1 Millstone Unit No.1                                 )l Response to Request For Additional information Regarding TAC No. M85570 Thermo-Lag Related Ampacity Derating issues I
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i December 1996   j I
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I h   . U.S. Nucl:ar R:gul: tory Commission                                                                                  i B16060/ Attachment 1/Page 1 l
The Staff, in conjunction with its contractor, Sandia National Laboratories (SNL), has                               l completed the preliminary NNECO's submittal and the following questions require clarification by NNECO:
Question 1:
NNECO should confirm that all fire barrier construction for the subject configuration (s) i            are representative of the barrier construction used in the Comsm:he Peak Steam l            Electric Station (CPSES), Unit 2 ampacity derating tests.
l l            Answer 1:
l l            Utilizing test results (base line data) obtained from testing done by CPSES on Thermo-l            Lag protected conduits, NNECO developed an Ampacity Correction Factor (AFC) that
;            would be site specific. The methodology for determining this correction factor is i
contained in Millstone Unit No. 2 Engineering Calculation 96-ENG-01288E2, "Ampacity l            Derating of Cables Due to Thermo-Lag." The Ampacity Correction Factor (ACF) used l            in the Millstone Unit No.1 calculation (Attachment 2), is .771.
1 l            Question 2:                                                                                                          I l
NNECO should verify whether the installed Thermo-Lag fire barriers are single (one 1"                                !
thick) or double (two 1/2" thick) layer systems. The Thermo-Lag fire barrier system                                  )
tested at CPSES 2 was a single layer system. If a double layer system is used at
.            Millstone Units 1 and 2, then the scaling methodology used on the TU test results is l            invalid and may prove to be non-conservative for application. If the above case proves                               i true, NNECO should provide additional justification for the extrapolation of the single                              !
layer test results to a double layer system or provide an alternative basis for ampacity derating determination and analysis of the installed Thermo-Lag configuration.
Answer 2:
Based on the information contained in references 1, 2, and 3,' the installed Thermo-                                 I Lag fire barriers at Millstone Unit No.1 are single layer systems with a 1" nominal
: 1)         Haddam Neck Millstone, Nuclear Power Statior Ur .c Nos.
1, 2, and 3, Response to Request for Additional information Regarding Generic Letter 92-08, "Thermo-Lag 330-1 Fire Barriers Pursuant to 10 CFR 50.54(f)", dated Februuy 11,1994.
: 2)         Northeast Utilities Thermal Lag installation Specifications SP-ME-596 Rev.1 and SP-ME-641 Rev 0.
I                               Northeast Utilities Purchase Order 853690 dated August 21,1986.
3)

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5   . U.S. Nuclear Regul tory Commission                                                       l B16060/ Attachment 1/Page 2                                                              '
!       thickness. Therefore, the scaling methodology used on the CPSES test results is also
:       valid for the configurations at Millstone Unit No.1.
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Question 3:
i       For the air drop example calculation provided in the NNECO submittal dated November      l 3,1995, NNECO identified that the subject cable is nominally ovsrioaded and based its l
acceptability en emergency overload temperature ratings. The staff requests that
;       NNECO address the following points and provide specific quantitative assessments of j       ampacity dorating acceptability for the Thermo-Lag installed fire barrier:
!                                                                                                i l       .       The basis for the assumed temperature limits must be documented. That is, the i
licensee should cite the source of these overload ratings and establish the
:               applicability of those values to the cables in use at Millstone Units 1 and 2.
,               (Note that NEC does not address overload ratings but that various ICEA
!               documents do.)
i
)       e       if NNECO argues that non-continuous operation above the rated temperature of     I
:               the insulation is acceptable, then one critical aspect of this argument, which   ,
t must be addressed, is the impact of such operation on the anticipated cable      l operating life. This aspect should be addressed through Quantitative life impact assessments in a context similar to that applied to the Equipment Qualification  :
Program. Even relatively short periods of operation above the nominal rated      I temperature can Isad to significant loss of cable life. (Note that this type of analysis must consider the full range of temperature cycling behavior, including normal aging at the prevailing ambient condition of 40 C and the effects of mutual heating from other nearby cables where applicable.) At the least, an aging analysis should be provided, which conservatively bounds the worst case anticipated operating conditions.
        .       By their very nature, emergency overload ratings are intended to provide for rarely occurring and unexpected events in which a circuit might be overloaded.
For example, the IPCEA P-46-246 tables state that " Operation at the overload temperatures...shall not exceed 100 hours per year. Such 100-hour overload periods shall not exceed five." The use of emergency temperature overload ratings as the basis for acceptance of normal anticipated cable operating conditions may be inappropriate. At the least, this represents a fundamental departure from accepted ampacity assessment approaches, and therefore, furtherjustification of this treatment is required.
Answer 3:
This question is only applicable to Millstone Unit No. 2 because the configuration in question does not pertain to Millstone Unit No.1.

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U.S. Nuclear Regulatory Commission B16060/ Attachment 1/Page 3 Additional Questions:
The Request for Additional information was further clarified in the conference call of September 5,1 A96, to include the following additional items: (1) consideration of the         .
total number of sWors in dorating cables in conduit, (2) recognizing the impact of service factor of metors on cable ampacity, (3) dorating cable ampacity of cables in overfillod conduits, and (4) alloy coating of copper conductors effect on ampacity.
Answer
: 1) For conduit installations, the ampacity was dorated based on the number of conductors in the conduit and the grouping factor for the conduits.
: 2) Cable design loads were determined from the Millstone Unit No.1 OPAL Program, PMMS, and One-Lines Diagrams. See Attachment 2 for details.
: 3) There are no Thermo-Lag overfilled conduits on Millstone Unit No.1.
: 4) All initial cable ampacities was based on IEEE-IPCEA Power Cable Ampacities, IPCEA P-46-426, Copper and Aluminum Conductors, at 40 C ambient air temperature and 90*C conductor temperature. The ampacity was then corrected to account for 50*C ambient air temperature in accordance with IPCEA P-46-426, Section ll B.
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