ML20207H178
| ML20207H178 | |
| Person / Time | |
|---|---|
| Site: | Vogtle  |
| Issue date: | 12/22/1986 |
| From: | Baily J GEORGIA POWER CO. |
| To: | Denton, Youngblood B NRC, Office of Nuclear Reactor Regulation |
| References | |
| GN-1247, NUDOCS 8701070475 | |
| Download: ML20207H178 (37) | |
Text
Georgd Power Company 3 ,
- ibst Offica Box 282 Wayrcsbora Georgia 30830 Telephone 404 554-9961 f
404 724-8114 w Southern Company Services, Inc.
Post Office Box 2625 Birmingham, Alabama 35202 g
Telephone 205 870-6011 g
December 22, 1986 Director of Nuclear Reactor Regulation File: X6BR01 Attention: Mr. B. J. Youngblood X7BC35 PWR Project Directorate #4 X7N14.2 Division of PWR Licensing A U. S. Nuclear Regulatory Commission Log: GN-1247 sWashington, D. C. 20555
. NRC DOCKET NUMBERS 50-424 AND 50-425
. CONSTRUCTION PERMIT NUMBERS CPPR-108 AND CPPR-109 VOGTLE ELECTRIC GENE 3ATING PLANT - UNITS 1&2
, VEBTICAL_ CABLE _SUPPOBIS
Dear Mr. Denton:
Subsequent to the Georgia Power Company November 17, 1986 meeting with the NRC staff regarding the use of tie wraps as vertical cable support on the Vogtle units, the NRC staff requested documentation of information in the form of nine questions.
Cle'rifications in regard to the information request were provided s in the Georgia Power Company December 18, 1986 meeting with the
,, Nhc staff. Those clarifications have been factored into the enc.losed ( ,orgia Power Company response to the requested inf orm a t c sn . The responses are numbered to correlate with the questions in the NRC staff request.
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To be-fully reponsive to the NRC staff request, Georgia Power Company initiated a two-part evaluation program regarding the use of' tid wraps as vertical cable support. The initial part provides thy response to the NRC staff questions based on one cycle of operation. This evaluation has shown that tie wraps as installed on,the Vogtle units provide adequate vertical cable support for the period' evaluated (first fuel cycle) and meet regulatory
. requirements.
~The second part will be an assessment for adequacy of the cable s u p p o r t's' for the long term. The results of the long tera l
y assessment will be provided to the NRC for review no later than June 1, 1987. At this time it is not known that any changes will b e g reqiti red. However, any corrective action identified as being required to be implemented prior to the end of the second cycle of
'? . operation will be completed prior to startup for the second cycle 0 0l
/of operation. Other required corrective actions will have k
- .( specif;ied dates by which they must be implemented.
t 8701070475'861222 di PDR ADOCK 05000424 A
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Director of Nuclear Reactor Regulation Vertical Cable Supports December 22, 1986 Page Two If your staff requires any additional information, please do not hesitate to contact me.
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J. A. Bail Project Licensi g 4anager Attachment JAB /lf xc: R. E. Conway B. W. Churchill, Esquire P. D. Rice M. A. Miller (2)
R. A. Thomas B. Jones, Esquire G. Bockhold, Jr. NRC Regional Administrator L. T. Gucwa NRC Resident Inspector C. W. Whitney D. Feig J. E. Joiner, Esquire Voglte Project File
.. . . _ = . _ .
o-gyssTIgg_1:
During the November 17, 1986 presentation by GPC, it was stated that a total of 24 static tests were performed to determine the load capacity of the Panduit Cable Ties for several cable configurations. The staff considers that the number of tests performed is not representative of the great number of ties used for various configurations of cables to the extent that the test results could be used as a basis for qualifying the ties. GPC must perform additional tests to obtain a representative data base or justify the validity of the analytical qualifications based on the 24 tests.
EgSPQNSE1 The static test program established to determine the capacity of the tie wraps was based on standard industry test practice. Static tests have been used throughout the industry to determine the design capacity of numerous pieces of hardware and support components. Examples of industry tested hardware include other cable tray support components such as strut channel sections and strut connection hardware.
The number of tests for determining the design capacity of such items has historically been three static tests.
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As a result, the Vogtle test program originally specified that a total of 24 data points be obtained, i.e. three data points for each of the four cable specimens (large cable, large bundle, small cable and small bundle) for two tributary spans. The results of the tests were monitored as the testing progressed and, based on the knowledge gained, the test program was modified as described below.
It was determined that t' e capacity of the cable tie was insensitive to tributary weight (span and type of bundles) and that the results were repeatable. Therefore, only two tests were performed for each tributary span for 'the small bundle. The cable tie had such a large capacity when compared to the weight of the small cable (A27) that these tests were concluded after the first test. In this case, the cable, being very small (0.487" diameter, 0.144 lb/ft.),
slipped at a load of 50 lbs. This corresponds to a load of 86g on the cable tie under 4 ft, spacing, i.e. a safety factor of 24 under SSE condition. Based on the favorable results obtained from this test, no further testing was performed for this specimen size. As a result of the above modifications, a program total of seventeen data points were collected. Table 1-1 summarizes the final test matrix.
r Eleven data points were collected from testing on the PLT 4H cable tie and six data points were collected from the PLT 6H cable tie testing. Table 1-2 provides the test results. It can be seen that regardless of the size of the cable / bundle, the failure of the cable tie depends on the total pull-out load. Therefore, the test results are applicable to all cable / bundle configurations.
For the PLT 4H cable tie, utilizing the eleven data values, the mean axial load at tie failure is determined to be 107.7 lbs. with a corresponding standard deviation of 8.8 lbs. The coefficient of variaticn, which is the amount of variation in h
a given data set as a ratio to the mean load, is 8%. This indicates that.very little variation of the data exists and repeatability is high.
The PLT 3H and PLT 4H cable ties are equal in cross-sectional area and the length of the cable tie is the only difference between the two. Therefore, the PLT 3H and PLT 4H cable ties have the same capacity.
For the PLT 6H cable tie, utilizing the six data values, the mean failure load is determined to be 205.8 lbs. with a l
j standard deviation of 10.2 lbs. The coefficient of variation is 54.
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To obtain additional conservatism, the capacity of the cable tie was based on the minimum failure load achieved, namely 100 lbs. for PLT 4H and 200 lbs. for PLT 6H. 1 i
The above capacities adopted for the safety factor calculations have been substantiated by additional test data obtained from the manufacturer of the cable ties. The manufacturer has provided the typical test values for the PLT 4H and PLT 6H ties, and 50% relative humidity, as 204 lbs.
and 225 lbs. respectively. These values were based on the standard MIL Specification MIL - S-23100 Split Mandrel Test and were conducted for various relative humidity conditions.
The results of the 50% relative humidity condition are applicable to VEGP since the relative humidity inside the plant is approximately 50%.
Aging and temperature affect the strengths of the tie wraps.
These effects are discussed in the response to Question 2.
On the above tie wrap properties, safety factors have been calculated using methodology discussed in the response to Question 5. No credit was taken for the cable friction or tie wraps in horizontal runs of the cables leading into the vertical cable trays. The minimum safety factor at any time during the first cycle of operation will be 1.3. This safety factor is based on the as-installed diameters of cable bundles and associated tie wrap spacings. These calculations of safety factor are performed and documented in accordance with the quality assurance (Appendix B) provisions for engineering calculations.
i This safety factor assures that tie wraps will support with adequate margin the vertical-runs of cable and thus during SSE there can be no loading on terminations, the cables do not impact and damage other equipment and the cable themselves are not damaged. Thus the integrity and functionality of the e'lectrical circuits are assured. No credit was taken for the other cable tie wraps applied in the electrical equipment and for ties.of cables to bars in floor blockouts which are required in the construction specification as additional protection to the terminations.
Refer to the response to Question 5 for the methodology.used to calculate the safety factor.
Panduit, in its manual, recognized that tool application and hand' application methods can be used for installation of the cable ties. At the Vogtle plant, tools have been distributed to the craft workers for use with the setting recommended by the manufacturer. Use of this tool results in consistency of tightness.
The construction specification for cable installation requires that ties be installed with four foot spacing with construction tolerance permitting a maximum spacing of five feet. As part of the quality control inspection of cable installation, the inspection verifies that the tie wrap spacing does not exceed five feet.
TABLE 1 - 1 TEST MATRIX NO. OF TESTS CABLE PLT 4H TIE PLT 6H TIE 81L Large 7 Cable 1.34 lbs/ft 34 cables 4
Large 6 Bundle 5.1 lbs/ft 4 Cables ,
Small 4 Bundle 1.02 lbs/ft Total 11 6 l
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s TABLE l -- 2L TEST RESULTS Cable Cable Failure Load Failure Mode Tie (LBS)
PLT 4H 81L 100, 100, 120, 100 Latching Mechanism Large 110, 110, 100 Failed Cable 4-Cable 100, 120, Latching Mechanism Bundle 105, 120 Failed PLT 6H 34-Cable 200, 200, 210, Latching Mechanism Bundle 225, 200, 200 Failed l
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9VISIlog_2:
GPC must provide an assessment that the long term load capacity and behavior of the Panduit Ties (in terms of aging, relaxation, plastic creep, flammability, embrittlement, etc.)
, will not deteriorate over the life of the plant for all appropriate environmental conditions. The assessment should be based, in part, on applicable material test data and prior application experience for nuclear plants.
g!SPONSE:
The following response has been developed to describe consideration of the environmental affects on cable tie i
performance during the first fuel cycle.
Strgngth_Bgdugligg_Dyg_Tg_Tgangggiurg To determine the applicable reduction in material strength, plant operating conditions have been assessed. It has been determined for random fill power cables that the maximum
! temperature at the surface of the cable jacket (hot spot temperature in cable mass) is 55 C. Based on Dupont tensile strength reduction criteria (Figure 2-1) and a cable Jacket temperature of 55 C, a strength reduction of approximately 24% is required.
! 1/Panduit Letter Dated: October 23, 1986,
Subject:
Panduit
- Cable Ties and Cable Tray Usage.
I
Additionally, control, instrument and maintained-space power cable have been assumed to be operating at essentially the maximum ambient temperature of 38 C. Control and instrument cable are low energy circuits that effectively have no internal temperature rise. For maintained-space power cable in-tray ampacity calculations were reviewed. Due to the large size of the conductors for short circuit considerations, it was calculated that the surface temperature of the armor would essentially be at ambient. Therefore, for these cables a strength reduction of approximately 134 is applied based on the above referenced Dupont data. For those cases which run above ambient temperature the resultant safety factor is significantly above the minimum safety factor of 1.3 and sufficient margin exists to account for the slight increase in temperature above ambient.
Agigg_ Effects The Dupont tensi]e impact life data for Zytel 101/105 has been obtained, and regression polynomials were determined for the effects of age based upon temperature . For the random fill power cables that have been found to be operating at a maximum of 55 C , an additional derating of approximately 64 is required. This, added to the 24% discussed above, brings 2/ Panduit letter dated: October 23, 1986,
Subject:
Panduit Cable Tiea and Cable Tray Usage.
3/ Value determined per IEEE Std. 242-1986, pg 343.
l
the total derating to 304. This 30% derating and the 13%
derating for the other cable types has been factored into the safety factor calculations. The resultant safety factor is a minimum of 1.3.
For instrument, control and maintained space power cable, it was calculated that aging effects during the first fuel cycle are negligible and therefore no additional derating is required.
flgggability While a seismic event and a fire are not concurrent design bases, (please refer to BTP CMEB 9.5-1 critieria), Panduit cable ties have been tested to the UL94 Flame Test criteria for materials classed 94V-0 (Tefzel) and 94-2 (nylon) .
Fammability is of no consequence with regard to cable support since the sama fire event which may reduce the effectiveness of the ties will also affect the cables they are supporting.
The effects of fire damage have been addressed in the project Fire Hazards analysis in accordance with the requirements of BTP CMBB 9.5-1.
I 4/ Panduit Technical / Application data sheet TADS-CT-15.
gghlg_Ilg_Eghritilgggni Panduit has advised us that their aging tests show brittleness as a mode of failure under both wet and dry conditions. However, at the "50 percent retention of tensile strength line", embrittlement is present but only in rare instances. As the tensile strength retention decreases below the 50 percent level, this type of failure mode may become more commun. Lucing the first tuel cycle, the strength reduction will not approach 50%. Therefore, failure due to embrittlement will not occur.
Eslexstigg_{Plggtic_grggpl In correspondence dated December 4, 1986, Panduit addresses the effect of relaxation and recommended maximum values for cable hanging weights. The weight limits are as follows:
PLT-4H TIE 30 lbs.
PLT-6H TIE 43.75 lbs l The as-installed condition has been verified to not exceed i
these vendor provided values. Accordingly, it has been concluded that the relaxation during the first fuel cycle will be insignificant.
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Erler_6eelisatigg_Exegrlgggg_Qg_Qthgr_Huclegr_Egwgr_Elggtg Cable ties have been selectively used in other operating nuclear power plants. Ten Bechtel designed Projects (eleven including Vogtle), utilize ties for cable support in some vertical trays. As with the Vogtle Project, other support means are employed for special applications.
- f. our knowledge, there have been no reported failures of Panduit ties for operating plants through the Bechtel Problem Investigation Report system. There has been no reports of relaxation or breakage of ties when utilized on similar applications to Vogtle.
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9988II9N_3:
GPC must provide the basis for using equivalent static test' data for demonstrating the acceptability of the cables and cable ties in vertical cable trays subject to loads, including the SSE.
ggSPQMSg:
The equivalent static load method is routinely used in the evaluation of the adequacy of structures under seismic conditions (reference response to question 1 and VEGP FSAR Section 3.7.B.3.5). For example, on the Vogtle Project, the standard method used to design the cable tray-support system is the equivalent static load method. In this method, the maximum forces under-the dynamic seismic environment are calculated and are compared against the capacity of the member which may be based on the static analysis or static test data or a combination thereof.
In the case of the cable ties, the potential failure modes are cable slippage or strength inadequacy. For very small cables, failure mode can be slippage. However the slippage occurs at loads - that correspond to significantly high safety factors (see response to question 1), and therefore is not a concern. For other cables, cable slippage is not a credible failure mode because of the binding of the cable tie on the
. - - _ _ . - .~
cable. (Refer to Figure 3-1.) This binding increases under seismic conditions due to the lateral deformation of the cable, which is laterally very flexible. This hypothesis that the cable slippage is not a credible failure mode for the cable ties is amply supported (as seen in the video tape shown at the November 17, 1986 and December 18, 1986 presentations) by the Bechtel dynamic tests done on vertical cable trays, in which the cable trays were subjected to significantly higher acceleration values than those applicable to VEGP. The details of this test program performed by ANCO Engineers for Bechtel are provided in the response to Question 7. Since the cables are flexible, the applied load on a cable tie can be calculated based on the tributary length concept, i.e. load on tie = (cable weight /ft.) x (tie spacing) x (acceleration value). In the equivalent static load method, distributing the seismic inertia loads by tributary area of flexible elements is a standard design practice.
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-GPC indicated during the November 17, 1986 presentation that the Panduit Ties are used to secure " bundles" of cable us well as individual cables to the cable trays. In bundles of three or more cables there may be one or more cables that are not in direct contact with the ties. In cases where bundles have one or more cables not in direct contact with the ties, the applicant must provide justification that the interior cable (s) will not slip relative to the bundle.
RESP 9ESE:
It is recognized that there are cables within a bundle under the same tie which are not in direct contact with the tie.
By the principle of equilibrium of forces, the pressure exerted by the tie on the exterior cable in the bundle is directly transmitted to the inner cable in a squeezing manner. The inner cables are therefore held in their relative positions. Furthermore, the intertwining of the -
cables caused by the pulling techniques and the cable pulling devices, prevents any slippage due to frictional resistance developed by the intertwining. This friction is adequate to hold the cable in place under the forces exerted for plant conditions as evidenced by the following:
/
- 1. During cable pulling operations when multiple cables are pulled in together, a basket grip is used which holds groups of cables by grasping the outer cables only.
This pulling operation requires forces in the 100 to 200 lbs. range on the cable to overcome various forces such as friction with conduit sidewalls, bending around fittings and sheaves (pulleys) and weight of the cable bundle in vertical "up" pulls. This type pulling operation is carried out successfully without any displacement (slippage). of the inner cables.
- 2. During pulling operations of multiple cables, the cables generally twist around each other due to. bends in the raceway and pulling sheaves (pulleys). This intertwining increases the friction due to increased length of contact with other cables in the bundle and would require a greater force to cause the cable to slip within the bundle. Thus intertwining of bundled cables tend to bind individual cables together.
i l 3. The dynamic testing performed by ANCO supports the conclusion that the ties provided adequate clamping i
force to hold the cables in place in vertical cable runs. With regard to the configuration of cable bundles used in the ANCO test, the documented data includes a total weight of 40 lbs./f t. of cable in the tray, and a maximum of 4" diameter bundle. Based on the test
engineer's recollection, the cables in the bundles were approximately 3/4" to 1" in diameter.
Reflecting this information into the cable types being used at Vogtle, cable code A7B - 7/C #8 at .839 lbs./ft.
with a diameter of 1.03" is an approximate fit.
Applying this cable to the information above, results in approximately 47 cables in the tray and about 12 cables in a bundle. Naturally, cables of lesser diameter would result in more cables per bundle. The above analysis indicates that there were enough cables in a bundle such that some of the cables were not in contact with the cable tie.
Based on information from the Bechtel Project Engineer for the cable tray test program, there was no indication of slippage either of the bundle or within the bundle.
9HISTI95_s:
GPC indicated during the November 17, 1986 presentation that the Panduit Ties are spaced 4 feet on vertical trays with a tolerance of plus I foot or minus 6 inches. GPC must provide justification for the tolerances used.
BESPQMSE1 It is normal practice for engineering to allow dimensional tolerance in construction specification to facilitate construction. The tolerance of plus 1 foot, minus 6 inches is considered satisfactory for this purpose. Additionally, the project has determined that the "as-built" spacing of the ties does not exceed the maximum spacing commensurate with a safety factor of 1.3 In addition, the "as-built" spacing of the cable ties does not exceed 5'-0",provided in the i construction specification. The relationship of tie spacing, I bundle size and safety factor is described in Attachment 5-1.
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ATTACHMENT 5-1 Methgdglggy_Uggd_Tg_Cglgulate_ Safety _fagigre From the Vogtle test program, the mean failure axial loads (refer to Question 1 response for basis) of PLT 4H and PLT 6H cable ties were determined to be 107.7 lbs. and 205.8 lbs.
respsectively. Conservatively, the failure axial load is taken as the minimum test load, i.e. 100 lbs. for PLT 4H cable tie and 200 lbs. for PLT 6H cable tie.
Considering the lateral load acting on the tie from the tributary cable / bundle weight, the test resultant load is 100.3 lbs for PLT 4H, and 202.3 lbs. for PLT 6H. These values are used as the capacity of the cable ties.
To calculate the maximum design loads on the cable ties, conservatively, the peak acceleration values from the Vogtle SSR 15% damping response spectra curves are used.
Considering the self weight of the cable / bundle and the three-component earthquake effects, the design resultant load on the cable tie is calculated. Therefore, the safety factor is calculated using the following equations:
Test Resultant Load TRL Safety Factor (SF) = ---------------------- = ---
Design Resultant Load DRL
where, TRL = 100.3 lbs. for PLT 4H cable tie and 202.3 lbs. for PLT 6H cable tie DRL = the tributary weight on the cable tie multiplied by the seismic factor Tributary weightl, = (cable bundle weight /ft.) x tie spacing i
on cable tie y TRL gy = -------------------------------------------------------
(cable bundle Ibs/ft) x (Tie spacing)-x (seismic factor)
The maximum seismic factor for VEGP is 3.6.
99HEII95_f:
GPC indicated during the November 17, 1986 presentation that a walkdown of vertical cable trays was performed to determine
! the extent of vertical trays using cable' ties.- GPC must j
provide verification that the walkdown of vertical cable trays complies fully with the requirements of 10 CFR 50, Appendix B.
EggPQHgg:
Evaluation of Class 1E vertical raceway and associated cables was performed by senior engineering personnel experienced in the design of raceway and cable systems and who are familiar with the application of project design criteria and construction specifications. Initial assessments addressed vertical cable tray lengths. The as-built data gathered in subsequent inspection assessment activities were with regard to cable bundle sizes and cable tie spacings. Comparison of these data to the allowable bundle size and cable tie spacing provided by engineering either confirmed acceptability or ,
identified required corrective actions for a minimum safety i factor of 1.3. The results of these assessments have been documented, checked by supervisory personnel and are retained 4
in project files. Calculations for establishing the allowable cable bundle sizes and cable tie spacing were performed in accordance with Appendix B requirements.
gyssTIgN_2:
GPC should provide the test objectives, criteria and instrumentation details used for the dynamic tests performed on a vertical cable tray st ANCO Engineers. Also provide-detail discussion of the test criteria, loads, instrumentation and basis of test data reduction used in the static tests performed on the Panduit Cable Ties.
BESPgNSE:
The tests performed at ANCO Engineers, Inc. was e <-
three-dimensional dynamic test program of vertical cable trays intended to investigate the effects of different cable tie spacings on raceway support system dynamic behavior and damping characteristics. It also was intended to establish, if possible, the fragility level and failure modes of the raceway system. ,
The vertical cable tray to be tested was erected on the shake
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table as illustrated in Figure 7-1. The changes in elevation e' between the two horizontal sections of raceway was 20' - 10"._
Although not documented in the test report black nylon 1
Panduit cable ties (similar in cross-section and material to the Panduit ties installed at Vogtle) were installed at the locations indicated. Cables were tied to the cable tray rungs individually and bundle' in sizes ranging up to 4 inches in diameter.
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Individual cable weights range from 0.2 lbs/ft to 1.57 lb/ft.
4 Total cable weight in the tray was 40 lbs/ft.
Instrumentation for the testing was installed as illustrated l in Figure 7-2. The range of cable weights and cable bundle diameters, and the tray loading are similar to installed conditions at Vogtle. The configuration of tested bundles is discussed in the Response to Question 4.
, A total of 27 individual dynamic tests were conducted on the same cable ties. Cable ties were installed at nominal 5-foot centers. Cable ties at the locations indicated in Figure 7-1 1
were intentionally removed after 16 tests to investigate the 3
4 behavior of the system with greater (i.e., 10 ft.) cable tie X
spacing. The same cable ties were subjected to an additional 11 tests for a total of 27 different tests.
During the ANCO dynamic testing, the raceway support system was subjected to various input acceleration levels. The
- vertical input test response spectrum is higher than the y Vogtle plant envelope response spectrum for two tests with 5'-0" cable tie spacing and two tests with 10'-0" spacing.
Under the highest input level, which was limited by the shake J' table capacity, maximum accelerations, i.e., zero period accelerations (ZPA) of 2.2g vertical, 1.8g normal, and 2.2g transverse to the tray were achieved. For this case, i
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comparison of the 5% damping ANCO test response spectra for
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the vertical direction with the Vogt,le SSE vertical response -
spectra'is provided in Figure-7-3. .It.can be'seen th~at +-
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! test response spectrum is significantly higher than the' '
Vogtle response spectrum, t
- According to the ANCO report, no damage to the cable tray i
ejection of cables, or failure of a cable tie.was reported. ,
No cable slippage was observed by the pdrsonriel during or
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after'the 27 tests. This was monitored:during the' test by '
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observing a few of the cables.that had been marked wilh white}h [ s, 1
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The static tests on cable ties were perforded at the Vogtle i 1 . 3 e
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-jobsite to determine the capacitysof a cable tie subjected u to 3 simultaneous axial and laterar loads (refer"to gigure 7-47 For these tests a section of cable) tray was oriented in the horizontal position and inverted so'that the cable weight would hang from the cable tie. The hariging cable weight
- I simulates the lateral seismic loads (resultant of two
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horizontal earthquake components) on vertical cables.
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Pulleys were used to vary the~ tributary lateral loading of
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the cable on the cable tie. Dynamometers were installed at
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Four VEGP cable configurations were tested: a very small '
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cable (A27 cable code, 0.144 lbs/ft., 0.487" dia.); a large w
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cab'le (81L cable code, 1.34 lbs/ft., 0.964"); a small bundle
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Q of 4' cables (1.02 lbs/ft., 1.38" dia. total) ; and a large bundle'of 34 cables (5.1 lbs/ft., 3.25" dia. total) These configurations were selected to represent a cross section of bundle sizes similar to those installe<.' at Vogtle..
Each test configuration was installed on the test set-up t (
using the appropriate cable tie, i.e., a PLT 4H for the single cables and small 4-cable bundle, and a PLT 6H for the large 34
.'able c bundle. The cable tie was installed using the Panduit Tie Tool set to the manufacturer's recommended setting for the porticular cable tie being used.
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'c Rgverse loading techniques were employed in these tests, that lis, the load was applied in one direction and then in the (veverses direction. Incremental loading was applied until f[iilureofthecable tie occurred. This was accomplished by t
-43 , starting with a force of 25 lbs applied alternately in each direction, and incrementally. increasing the load by 25 lbs.
0' after each pull in each direction. The dynamometer had a
,c.i drag, device that indicated the force (e.g. 210 lbs.) being s a 4 ,
4 0 2s, applied at tie failure. As mentioned previously the g %,
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. tributary length of cable hanging from the cable tie was a ,",s
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. J. o varied to represent various resultant lateral loads of 1.2g and 1.7g (The test results, Table 1-2, show that the cable tie capacity is not sensitive to these changes in the lateral load).
The total number of tests and test data reduction used to determine the failure axial load is described in the response to Question 1. This failure load (axial load) was combined with the tributary cable weight to determine the resultant load applied to the cable tie at failure. This resultant load is therefore the capacity of the cable tie.
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- Removed to achieve 10'0" 1 20 1/2"' 27"'
nominal tie-dote spacing.
Figure 2.1: Vertically Oriented Cable Tray Raceway Task I (Test XIV)
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> Support i Solice Plates x Cable Tie Ocwns 3
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- a S-5 Figure 2.7: Accelerometer Locations and Directions Used for Task 1: Vertically Oriented Raceway P!caORE 7,2.
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DISTRIBUTION OF SEISMIC LOADS .
AND TEST SET-UP 5 .
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? yy CABLE TIE
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9H4HTIgg_a Provide justification for the appropriateness of.the way
-vectoral summations of both the static test forces and seismic response forces were combined to determine the safety factors for the Panduit Ties, gggPgggg*
In the static tests, a constant lateral force was applied to the cable tie and the axial load on the cable (bundle) was applied increasingly from zero to the failure load. Since the axial load at failure is significantly higher than the lateral load, as the axial load increases from zero to the failure load, the direction of the resultant force vector rotates from the lateral direction to close to the axial direction.
Since the cable tie is flexible and twists itself to orient in the direction of the resultant tension vector, it is appropriate to determine its adequacy based on the magnitude of the resultant vector. The direction of the resultant vector at failure load in the static test is close to the axial direction of loading. This condition is the most unfavorable position for the effectiveness of the latch locking mechanism since the twist reduces alignment of the
e o o latching mechanism. .The static test results therefore give the lowest tie capacity. This conclusion is supported by the failure loads from split mandrel tests performed by Panduit.
In a split mandrel test, the tie is pulled directly in the lateral direction. In these tests, the failure loads are higher than those obtained from VEGP tests (see response to question 1 for comparisons). Therefore, the safety factor -
computed as the ratio of the magnitude of the resultant failure load vector obtained from the VEGP static tests to the magnitude of the design resultant obtained from the appropriate combination of the three components of the earthquake forces provides a conservative assessment of the safety margin, regardless of the direction of the resultant vector of the design forces.
i n
l
O *4 W STONE 6 WassTER ENGINEERING CORPORATION 245 SUMMER STREET, Sc5 TON. MASSACHUSETTS Amonsse ALL CORRESPONDENCE TO P.O. BoK 2325. DOSTON. MAS 5. 04107 W U.?ELLA- 34 0001 w amic msteyction
- "'" * * "::51,,.m.
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Mr. U.C. Ramsey December 19, 1986 Readiness Review Program Manager J.O. No. 15224 Plant Vcgtle Nuclear Construction P.O. Box 282 River Road Waynesboro, GA 30830
Dear Mr. Ramsey:
ASSESSMENT OF OBSERVATION 22-F11 IND_EPENDENT DESICN REVIEW 3ased on SWEC's audit teau review of Georgia Power /Bechtel approach, methods and consniement, use of cable ties, if implemented accordingly, constitutes a method of " equal effectiveness" for the support of vertical cable runs through the first refueling cycle. The reviewers have concluded that the cable tie approach as identified meets the intent of NEC 300-19 and satisfactorily resolves IDR Observation 22-F11. Support of Cable in Vertical Runs Not Addressed, for the -
near term.
I Very truly yours, J)P. Allen Ptoject Manager l
_ _ _ . _ . . - _ - . - - _ . _ _ .. .. -. _ _ .. _ _ - _ _ .