ML20237J899
| ML20237J899 | |
| Person / Time | |
|---|---|
| Site: | Comanche Peak  |
| Issue date: | 02/12/1987 |
| From: | Williams N CYGNA ENERGY SERVICES |
| To: | CYGNA ENERGY SERVICES |
| References | |
| CON-84056 NUDOCS 8709040113 | |
| Download: ML20237J899 (12) | |
Text
S'O -L)c.lf LjU -( W i
)
y Communications 3
4L 6 i Report summmmmme CES company: , % 3,,,,,,,,
Pro, ct. TV Electric Jo6 No. 84056 CPSES IAP Phase 4 m 2/12/o7 su es,ect Cable Tray Support Design Review Audit T6me: 10:00 a.m.
vraca aauc ParticipaAk R 3 4 8 4 8Hids R* "W 363"G"s i'* 'W " W e 'd
- I"' d d * '* I""""'"* b J W'u D
a l a v s n A r.o R .1 rhon P. Ma r r i c.n n . F. Hattinapr g Fhaten C athloy, R Dameny w Imoell 5 , u ~ -. t y, __ My A t1 g af T tt V1orte4r item Comments Reg'd Action B This documents the meeting of Thursday, Fsruary 12, betwee l Cygna, Ebasco, Impell and TV Electric. The primary items o '
discussion consisted of those which were touched upon in th > l ptblic meeting. l Compression Menbers Cygna asked Ebasco how AISC Equation 1.5.7 is checked, with .
respect to choosing a menber length for the code checks. )
Ebasco replied that the menber length is taken from node-to - i node, that is, between the physical connections of the menb er.
Twist Buckling of Angles Cygna asked Ebasco whether the torsion of angle brace menbe s due to the attachment of the opposite legs at the ends was considered. Ebasco deferred their response.
l Compression A110wables Cygna explained their concern regarding the application of the load factor to the compressive allowable, Fa . Cygna stated that allowing tensi?e and bending stresses to reach 0.9Fy was acceptable, since there is additional margin due :o ductility of the material under these loads. However, for buckling, allowing the menber stresses to reach 0.9Fydoes not provide adequate margin for uncontrolled failure.
8709040113 870212 PDR ADOCK 05000445 A PDR
- , _14 , i -
- " V W I/ 1 ) }{ R A /
gng . g - ---
'm ,
e ,,
- - - n___n . ~ ,~~n ~n n ..
1 i
Communications 4Dt i Report 14llll11111!Il11111lll11111111 item Comments ace y Cygna stated that the only body which addresses compressive allowables for factored load conditions is the ASME Code. 1 1 Section III, Stbsection NF, F, is limited to 2/3 F cr.
Impell stated that ASME W is not the code of record and tha t the CPSES FSAR provides that, for the SSE load case, the AIS : 4 allowables be increased by 1.6, not to exceed 0.9Fy .
Further, Impell believes that the AISC allowables provide a 1.67 - 1.92 buckling margin, as shown below:
gh 6h l
NA
' ,)
aWy ,,
N l
c, 'Vr Cygna sthmitted that the 23/12 value is not a factor of safety but reflects a level of uncertainty in determining the critical buckling stress for menbers. As noted in the above graph, the longer the menber, the greater the uncertainty.
This is in part due to the initial imperfections in the i menb er. Tests have shown that the theoretical curve is not I
achieved for actual menbers.
Impell stated that work by the Structural Stability Research Council (SSRC) substantiated their position on increased i buckling allowables. Impe11 also stated that transient buckling allowables are higher than static buckling allowab les. l l
Cygna stated that the SSRC does suggest that transient compressive loading may show higher buckling limits, but in practice, the actual value may be higher or lower.
Impe11 further explained that the ANC0 tests substantiate thc use of higher allowables. In the test, there were menbers with kt/r in excess of 300. The input motion was five (5) times the SSE level, and the system frequency was tuned to the peak response. There was no failure in the system.
Page of
I Communications 4L i i Report :
11111llll111ll11111ll111111111 nem comments Ic7o$$
Cygna noted that, because there was no failure, it was not 1 possible to determine the margin to failure. Impell stated i that loads could be calculated based on the system q configuration and input motion; however, the strain data obtained for the menber was determined to be unreliable. '
Cygna stated that they would discuss the matter' internally and explained that they need a technical basis for the criteria. 'It is not adequate to invoke the SAR as basis for j a technical problem, and further justification would be necessary.
Detail 5 - CTH-1-3136 Cygna requested clarification that the Category II steel had been decoupled from the Category I steel and whether the practice is standard for all Category 1/II interfaces.
Ebasco confirmed that the above had been done for CTH-1-3136 in that the structural support provided by the Category II steel was omitted, but the mass of the Category II structure was included in the model. Ebasco stated that this support was the only Category I/II interface in their scope.
Impell stated that they had seven (7) examples in their scope. They are all baseplates welded to Category II baseplates. The analysis of the cases are still open, pending consideration of the Category II steel by SWEC. Either the Category 11 steel will be upgraded to Category I specifications, or it will be detached from the Category I structure.
Cygna then asked specific questions regarding CTH-1-3136.
Cygna asked Ebasco to justify removing the Category 11 steel from the analysis model. Ebasco replied that the primary response was that of the Category I steel. It is thought that the Category I steel supports the Category 11 steel.
Cygna stated that they thought that there were additional i trays supported on the top wide flange; however, there were only three (3) trays modeled in the analysis. Ebasco stated that most of the support was inaccessible and that the drawing had not been checked by QC yet. Thus, the analysis that Cygna reviewed was still preliminary.
Cygna asked Ebasco how the thermolagged trays are verifit;d and how the walkdown information is used by the analyst.
Page of
.$ m. k
. l Communications 4(nx. Report l 11fi11111111111111ll1111111111 .
1 I
Item Comments c$o$ y Ebasco said that they would get Mike Strethlow to explain the j walkdown procedure.
1 Two-Bolt Base Plates l
Cygna noted that neither Impell nor Ebasco have procedures to l consider two-bolt base plates. Impe11 stated that they l I
consider two-bolt base plates in the same manner that they consider two-bolt base angles. Ebasco stated that they l performed detailed base plate analyses for all two bolt base ;
plates. Cygna asked why detailed analyses were performed, since there are so many two-bolt base plates in the plant.
Ebasco stated that they chose to do it that way.
Multi-Mode Response Multiplier Cygna first outlined the Ebasco procedure used to determine the W M to ensure that the process was clearly understood:
(1) Three (3) models were used to generate MM. Two of the i three consisted of multi-tiered four-span systems of equal spans, four (4) identical transverse supports, and l one (1) longitudinal support. The third model was choser from the population of actual tray runs.
(2) ems were determined by calculating.an average or weighted acceleration over all modes in the system and calculating a ratio with the design acceleration used in the ESM/ESML analysis.
(3) Ebasco determined that, because of the equal spans in models 1 and 2, the EC Regulatory Guide 1.92 modal combination led to unnecessarily conservative results.
Time history analyses were then performed with sinusoidal input motions, since the time histories which i corresponded to the design spectra were not available.
Later, Gibbs & Hill supplied time histories matching the design spectra. The analyses were rerun to confirm the results of the analyses with the sinusoidal input.
(4) Ebasco slso explored ems using support force and menber interaction ratios. Some of the stress interactions yielded m Ms in excess of 1.25. A statistical study was performed using 240 stress interaction values. To cbtair the 240 values,12 menbers, with two (2) ends per menber, l
Page of A.__ E
Communications 4L i i Report 11ll1llll11lllll1111I111I1ll11 .
item comments IcYoNy l
five (5) building response spectrum sets and two (2) earthquake levels were used. The statistical study showed that an mM of 1.25 resulted in a 99-99 confidence le vel.
Ebasco agreed witii Cygna's sunrnary of the EM study. Cygna !
then proceeded to ask specific questions regarding the l approach. Cygna first asked Ebasco to justify using only 4 three sytem models for the study, with respect to how they could envelop all systems in the plant. Ebasco replied that they felt that an equalspanned system would produce a higher m M due to closely spaced modes. Cygna noted that the use of l the tine history analyses instead of response spectra analy- I ses would reduce the perceived effect of the closely spaced modes. Ebasco stated that they had performed an additional set of analyses using a larger system model with 16 supports in response to a third party review comment.
1.ater in the day, Ebasco reiterated the position in Reference 37, Book 9 regarding the applicability of the three models as the representative set for the plant. The items cited were-l Trapeze and cantilever supports were used, which are the most frequently used in the plant.
- 12" and 24" trays were used, which are the most fre-quently used tray sized. 4
- Models 1 and 2 used the maximum span length of 9'-0". j
- Multiple layers of trays were used.
- Maximum tray loads were used for Models 1 and 2, and the actual tray weight, including thermolag, was used for I Model 3.
- Both hinged and fixed anchorages were used to envelop all cases.
- Fundamental frequencies of the system fell to the left ,
and right of the peak of the spectra. l
- Six sets of response spectra were used. Five were at the maximum building elevations, and the sixth w6s at the actual elevation of Model 3.
Ebasco stated that Model 3 and the new model were used to explore the effect of the equal spans used in Models 1 and
- 2. Results from Models 1, 2, and 3 showed that Models 1 and 2 give higher results. Ebasco claimed that this is due to Page of 6 _ _ ___ UL
l
=pe Communications l MG lillllllilllitilllllllilllllll Report ;
l l
l item comments [c7oUy the fact that Model 3 has a wide frequency band with no closely rpaced modes.
Cygna asked for justification of the applicability of I averaged acceleration responses to the mM for support i loads. Ebasco stated that the support load and stress {
interaction mms were added because they were judged to be l l moae critical and indicative of the support load mms. This l was substantiated by the fact that a few mms exceeded the i l
1.25 limit. Ebasco also emphasized that, for those cases I where the stress interaction mms exceeded 1.25, the actual stress values were very low, which increases their confidence that 1.25 m M is appropriate. For this reason, the sample size was not expanded, and further studies in this area were not pursued.
Cygna noted that in the discussions regarding the ESM and ESML on Tuesday, Ebasco explained that the ESML was applied to those supports which did not meet the Appendix 4 longitudinal span requirements. The ESML was used to compensate for cases where the mM did not cover the system mass distribution aspects as well as the multi-mode aspects. Cygna asked how the WM study established its
. applicability to Appendix 4 longitudinal spans if only one longitudinal support was included in each model. Eb asco stated that the presence of only one longitudinal support in the models does not necessarily violate the Appendix 4 requirements.
Cygna commented that the objective of the study was to cbtair W Ms for the re.sponse of the tray on the support, since it was to be used to scale the tributary weights for application I
to ESM/ESML analyses. In Cygna's opinion, it is not necessary to include the detailed support models in the systems; neither are the stress interaction mms meaningful, since the mM is applied to the design load. The stress response of the support is taken care of in the static analyses using the applictie EM.
Cygna also commented on the independence of the 240 stress l interaction values used in the statistical study. First of all, the use of 2 ends of the 12 menbers is not independent, as certain loads at the menber ends will not change, such as axial loads. Secondly, the two levels of earthquake differed by a scale factor and were therefore not independent either.
Page of 6 1_1,
Communications
- 4Ln, Repod lll111llll11111111lllll1111111 nem comments [eYoNy With these two considerations, the sample size is reduced from 240 values to 60 values. ,
Cygna al.;o asked whether the analysts had reviewed the mass point spacing for the models. Ebasco stated that they felt that the sp '.Ing was adequate to capture the required response. C;gna pointed out that the mass point spacing for i the 24" trays was adequate to capture the responses up to 25 Hz only. Ebasco agreed to review the modeling.
Bolt Hole Study l l
Cygna asked Ebasco to provide Book 22, Volume 1 for review. :
This calculation addresses bolt holes in tier menbers. l Core-Bored loles For Hilti Anchors Additional Hilti data was discussed regarding cepacities for core bored holes. Further consideration and vendor contact is required.
Cygna also cautioned that questions regarding bolt relaxation should be considered carefully before statements are made on the record.
Geometric Vs. Principal Axes Cygna noted that Ebasco considers principal axes for angles in their models. Impell uses geometric axes in their '
SUPERPIPE models; however, Appendix F to Calculation M-12 develops a 1.2 factor to use on calculated stresses to consider the principal axes effects on stress. Cygna asked whether the use of principal axes in the systems models would result in different menber responses.
Impell ststed that most other structural programs use geometric properties in the modeling of angles. Cygna disagreed and listed a nunber of programs which consider principal axis properties.
Cygna cited a study on angle behavior by Galanbos, Yasami, and Trehare. This study involved testing of single angles under compression and concluded that single angles loaded about their geometric axes will respond about their geometric axes. Impell also has additional correspondence affirming this position. They will inect whether these may be released Of Page 7
Communications 4L t i Report lillllllilillllllillllililllll Requwed item Comments Action By to Cygna and will provide all permissible information on thit stbject, including the Galanbos study. Weld Inspection and Material Preheat Cygna noted that the Visual Weld Acceptance Criteria (VWAC), written by the Nuclear Construction Issues Group (NCIG) had been accepted by the staf f. Cygna will review the VWAC further and discuss it internally. Cygna asked if there were any plates over 3/4" thickness for which preheating of the material before welding was necessary. Impell and Ebasco replied that there were plates thicker than 3/4". Cygna noted that preheat requirements were not explicit in the original CPSES weld procedure. Ebasco stated that their weld engineer did not believe that preheat was needed and was preparing a written response to Cygna 's concern. Cygna stated that it would be more expeditious to first check whether preheat was done rather than to prepare a response which may not be necessary. Ebasco stated that since their weld engineer did not believe that preheat was necessary, they think that it was not done. TU Electric agreed to check whether preheat was done before completing the response. Modeling of Tray-to-Tier Eccentricities Cygna asked Impell and Ebasco how the tray-to-tier eccentricity for the following configuration is considered: 4 % o o i
) \
Impell stated that their instruction PI-02 gives modeling instructions; however, the above configuration is not addressed specifically. They suggested checking such cases in the audits of the systems models. Ebasco deferred answering the question. Pege g of
}}
b a#_ Communications BM' M ll111111!!!ll11111111111111111 Report Item Comments Ac o y Uamping f or Londuits Attached to Lab le Iray Supports Cygna asked Impell and Ebasco how they considered conduits attached to cable tray supports. Impell stated that they model conduits as lumped weights based on their tributary spans. Cygna asked how thermolagged conduits were properly l modeled, since thermolag is not noted in the as-built drawings. Impell stated that the Train A/B conduit work would have the information available. Loads would be i transmitted formally to the cable tray group. All Train C attachments would be removed. Cygna expressed concern regarding how the cable tray support analysts get the required data regarding thermolag and conduit spans. Impe11 stated that if the results of the support evaluation were close to the allowables, the analyst would send out RFIs (Requests For Information) for more specific information. Ebasco explained that, for ESM/ESML analyses, conduits are modeled as lumped forces: Force = tributary weight x peak of 2%/3% spectra x 1.5. In the Unit 2 RSM analyses, lumped masses are modeled at the conduit attachment locations. They assume that the dominant response in from the tray; thus, no consideration of the different applicable damping levels is made. Ebasco pointed to Attachment U, which contains a method to maintain conduit qualification. Cygna asked Ebasco to validate the procedure used to condense the conduit mass and stiffness to the single attachment point on the cable tray support. Ebasco explained that standard Guyan reduction was used and that they felt that it was more realistic than lunping a weight, since this method captures the first mode frequency of the conduit. Cygna expressed concern that the method of condensation was not appropriate here and that the result was not meaningful. Cygna asked Ebasco whether any studies or comparisons had been done or if this method had been used before. Ebasco stated that this was the first time the method had been used. Tray Eccentricities Cygna noted that in the Ebasco RSM analyses, the tray mass is applied at the tray centroid; whereas, for the ESM/ESML analyses, the transverse force is applied at the top of the Page 9 of 11
I Communications , 4( t i Repod 11ll11lll1ll11111ll1111111ll11 item comments [eYoNy tier menb er. Because of In1s, an additional torstonal momem". of magnitude Fh/2 is omitted. Cygna noted that, in the RSM analyses, the torsional resistance of the trays would tend to reduce the stbject moment and suggested that a vertical force couple on the tray sides may be appropriate'. Ebasco agreed j to provide quantification of the method used. Clamp Qualification Cygna asked Impell and Ebasco what procedures were used for clano qualification and what were their bases. Impell's ' procedures are documented in PI-06, which is based on the CCl. clamp tests. Ebasco's procedures are documented in SAG-CP-
- 19. Attachment T provides allowable bolt loads on clamp bolts derived from finite element analyses.
Cygna asked Impell whether comparisons were made between the i calculated stiffnesses and the test stiffnesses. Impell j explained that the clamp stiffness report was used to establish load-deflection curves to develop clamp allowables however, the calculated and test stiffnesses were not l compared. I Cygna also asked whether system damping was verified in the I ANC0 test. Impell stated that modal damping was verified. Equivalent viscous damping was determined by increasing the ; system damping in the analysis models until the results of the analysis matched those of the test. Modal damping was determined by performing random input analyses using the half power bandwidth method. Cygna stated that they would review the Impell and Ebasco clamp procedures and compare them for consistency. Thermal Loading Cygna stated that, while they agree with Impell's conclusions and approach regarding thermal loading, the approach was not quite in line with the wording in the SAR. Impell and TV Electric agreed to review the SAR and to make the justification for consideration of thermal load consistent with the S AR. Impell is also preparing a report on the effects of thermal loads on anchorages. Page ll of 11
y Communications
. A /. i i Report !!Ill111111111111111111111ll11 Item Comments Ae7oNy Refined Criteria ,
1 Impe11's document PI-11 provides refined criteria and values for qualification.~ Cygna asked Impe11 to provide references i for some of the refinements. Refined buckling factors, k, ! for post med)ers were developed in Reference 11. In Section l 3.2.1., paragraph f, geometric exes can be used instead of principal axes to determine r. Impell could not provide the reference but agreed to check on it. In Section 3.2.1, paragraph g, a reduction factor for tier moments is 1 l discussed. The development of the factor was done in I Reference 13. Clamp stiffness refinements were included as a result of the test program, l 4 1 l Page 11 of 11
e DISTRIBUTION LIST Mr. J. Redding Mr. L. Nace ; Mr. W. Counsil Mr. D. Pigott Ms. A. Vietti-Cook tMr'.-C C .O Grime's? ' , Mr. E. Siskin Mr. R. Alexandru Mr. J. Muffett Ms. N. Williams Mr. J. Russ Mr. W. Horstman Mr. K. Parikh Ms. D. Leong Project File l 1 l l}}