ML19352A142
| ML19352A142 | |
| Person / Time | |
|---|---|
| Site: | Zimmer |
| Issue date: | 03/06/1981 |
| From: | Borgmann E CINCINNATI GAS & ELECTRIC CO. |
| To: | Harold Denton Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 8103110456 | |
| Download: ML19352A142 (11) | |
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,m TIIE CISCINNATI GAS & ELECTRIC COMPANY C
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E. A 80RGM ANN st a ca v< C F*t s C r a' Docket No. 50-358 March 6, 1981 Mr. Harold Denton, Director Office of Nuclear Reactor Regulation U.S.
Nuclear Regulatory Comission Washington, D.C.
20555 RE:
WM. H.
ZI.'O!ER NUCLEAR POWER STATION -
UNIT 1 - LEAK CHASE CHANNEL ATTACHMENTS
Dear I;r. Denton:
This is in reply to an NRC letter dated November 20, 1980 from R.
L. Tedesco to E. A. Borgnann.
The supplemental
.nformation requested by that letter is attached.
Very truly yours, THE CINCINNATI GAS & ELECTRIC COMPANY k
fe e -
E.A.
BORG'! ANN EAB: dew Enclosure cc:
Charles Bechhoefer State of Ohio
)
Glenn O.
Bright County of Hamilton)ss Frank F.
Hooper Troy B. Conner, Jr.
Sworn to and subscribed before James P. Fenstermaker me this 94 day of March, 1981.
Steven G.
Smith William J. Moran J. Robert Newlin William G.
Porter, Jr.
MM.m h. /hdCIMc-%
James D. Flynn
- 1) Notary Public F.
T.
Daniels W.
Peter Heile WO E I# U James H. Feldman, Jr.
' * '.',.' n^.9,$,v.>-
John D. Woliver q,
Mary Reder David K. Martin Robert A.
Jones Andrew B. Dennison 8108110 W Pt
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ZPS-1 QUESTION 1 1.
From the results of analysis as presented in the report, the staff is not certain if the stresses resulting from attachments to leak chase channel are superimposed to those for which the liner and the liner-anchor system were originally designed. Staff's main concern is the stresses in the anchor and the weld connecting the anchor and the liner plate. Provide a description of the detailed analysis of the liner and the liner-anchor system, noting that anchors could f ail under the high tr. ear loads imposed on them if one panel buckled while adjoining pane!L retained their original shape or if any of and a combination of the following conditions exist:
1.
Variation in anchor spacings.
2.
Variation in anchor stiff nesses.
3.
Variation in liner plate material yield stresses.
4.
Var,iation in liner plate thickness.
5.
Variation in the Poisson's ratio of the liner plate material.
6.
Misalignment of liner plate seams.
7.
Cracking of concrete in anchor zone.
8.
Initial inward curvature of the liner plate between anchors as a result of f abrication and erection inaccuracies.
9.
Creep and shrinkage of concrete.
Indicate which of the above f actors were considered in the original design, and sumnarize the stress or strain values resulting from each of the load or eff ect consi dered.
RESPONSE
The method used' to analyze the containment liner and liner-anchorage system is described in Reference 1.1 and Section 3.8.1.4.5 of the FSAR. The computer pro-gram LAFD, which uses the method of Refere' ce 1.1,.was used to analyze liner-anchor force-displacanent.. A description of LAFD is given in Section 3.14 of
.the.FSAR.
e 1
e In Reference 1.1, the total strain in the liner due to creep and shrinkage of concrete, post-tensioning of concrete, and temperature rise is assumed to exceed the yield strain of the l'ner material while the stress stays constant and equal to the yield stress of tSe liner material.
This assumption implicitly accounts for the effect of shringage and creep of concrete, post-tensioning, and temper-ature rise.
Their strains are added to other strains in the buckled panel to calculate the total strain in the liner.
I.
Description of Conditions Considered in Analysis Table Ql.1 summarizes anchor displacements and liner strains in the buckled panel for the nine conditions listed in the NRC q sestion.
These are tabu-lated in the same sequential order specified in the NRC question.
As explained earlier, Conditions 1 through 8 contain the effect of creep and shrinkage.of concrete, post-tensioning, and accidental temperature rise, as well 'as ~ the specific variation requested in the NRC question.
In Condi-tion 9, no variation is considered.
A description of these conditions is given in this section, and the case assumed for the design is described in Section II.
1.
Variation in Anchor Spacing 1 Buckled panel span is considered to be twice the regular anchor spacing.
This covers spacing variation as well as a hypothetical case of a miss-ing or f ailed anchor.
2
2.
Variation in Anchor Stiffness 1
The normal load-deflection behavior of the anchor used in '.he analysis is obtained from Reference 1.1.
A variation of 115% in the anchor stiffness is considered.
i i
3.
Variation in Liner Plate Material Yield Stresses A~ variation of 115% in the liner plate yield stress is considered. The critical variation here is a higher yield of the unbuckled plate com-bined with a regular yield in the buckled panel.
4.
. Variation in Liner Plate Thickness
~ A. variation of 115%.in ! the liner plate thickness is considered.
The critical. variation is an increased thickness for the unbuckled panels combined with a normal thickness for the buckled panel.
- 5. - Variation. inlthe Poisson's Ratio of the Liner Plate Material The Poisson's ratio has been ' conservatively - assumed to be.zero.
Any value grener than' zero results-in an increase in the post buckling capacity of the buckled panel, 'thus reducing the forces and disp 1 ace-
.ments of the ~ anchors.. This tis illustrated by. the-results of this case Treport6d in Table Q1.1.
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i 6.
Misalignment of Liner Plate Seams The effect of the misalignment of the liner plate seam is to redu.e the post buckling capacity of the panel. However, all liner plate seams are j
-covered with leak chase channels of Size C 3x4.1 which are cont'.nbously L
welded to the liner.
The addition of the channel (3" wide,1.41" deep; 2
area a 1.21 in ) provides a cross section whose area and stiffness exceed any reduction in the panel capacity due to misaligment.
This condition is not considered, since buckling of this type of panel is not likely.
7.
Cracking of Concrete in Anchor Zone l
The coricrete contairnent wall of the Zimmer Contaiment is under hoop and meridional'prestressing; therefore, the concrete is not. expected to
^
crack.
. 8.- Initial Inward Curvature' of the Liner Plate This condition is considered by assuming the buckled panel. has an initial irward curvature corresponding to dn irward deflection of 1/16".-
g 9.
Creep 'and Shrinkage of Concrete
- This is' the normal condition under which anchor displacements and liner
. strains ' are determined.
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II. Conditions Considered in the Desien The design conditions are described in FSAR Section 3.8.1.4.5 and are detailed here for completeness.
It is again noted that for each ccndition cited belaw, the effects of creep, shrinkage, post-tensioning, and temper-ature rise are included in the response calcula' ions for each case:
I a.
An initial inward deflection of 1/16 inch; b.
Lower yield stress of 15% combined with a 15% decrease in plate thick-ness of buckled panel; c.
Higher yield stress of 15% combined with a 15% increase in the plate thickness of the stable liner panels; and d.
Anchor spacing doubled to simulate failed or missing anchors Izipper effect). This case considers conservatively the post buckling strength to'be zero.
l Tabl'e Q.1.2 shows.results for the cases enumerated. above.
It is noted that h
Case (a) of Table Q1.2 correspo'nds to -Item 8 of Table Q1.1; Cases (b) l it and (c) are a' combination of Items.3 and 4'and finally, Case '(d) considers a more ' conservative condition than that of Item 1 of Table Q1.1.
~
Al comparison of, anchor displacements and liner strains given in the two tables shows that the worst condition for the -anchor -displacements is Case (c) 1 of Table Q.1.2.
The. worst condition ;for the~ liner strain is
Case (a) of Table Q.1.2.
These ccnditions ar 6 used fcr design eva19ation.
Specifically, the maximum anchor displacement from Combination (c) is 0.0144 inch.
The ultimate value of displ acement in the anchor is 8 u
O.18 inch, based on tests reported in Reference 1.2.
This would result in a f actor of safety of 12.5 as against a f actor of 2.0 required by the ASE code. In addition, to be consarvative, a value of $, = 0.0838 inch, corres-pcnding to the average valae of displacement at the maximum anchor load, was useo to evaluate the anchor. On these b.ses, the factor would be 6.17.
Because of this high f acter of safety in the design conditions, the liner-anchorage system will not f ail under the various conditions specified in the NRC question.
Liner strains in the buckled panel are calculated and compared to the a'.?cw-ables specified in Section CC-3720.of the ASE F4PV Code. They are found to satisfy the code.,
References 1.1. Doyle,.J. M., ' and Chu,. S.
L., " Liner Plate Buckling. Behavior of Stud &nd Rib Type Anchors," Proceedings of the First International Conference on Structural Mechanics in Reactor Technology, Berlin, September 22-24, 1972.
1.2 Burdette,. E. G., and Rogers, L. W., " Liner Anchorage Tests," Jcurnal ~of the -
- Structural Division, ASCE, ; Vol. 101,. : No. ST7, Proceedings : Paper 11432,
. July 1975, pp.1455-1468.
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s-TABLE Q1.1 LIflER-AfiCHOR AflALYSIS RESULTS i
FOR C0fiDITIONS Ifi THE TAC CUESTION Anchor Lirer Strains - Ccabined I
Condition Displacement Membrane & Bendina (1) i (Inches)
Comoressive Tensil e 1
0.0106 0.00343 0.00308 2
0.0060 0.00679 0.00596 3
0.0104 0.00727 0.00657 4
0.0084 0.00706 0.00626 5
0.0050 0.00668 0.00587 6
7-r 8
0.0127 0.00744 0.00727 9
0.0056-0.00675 0.00592 Note:
(
Allowable' liner plate strains for cor:bined membrane plus bending (per ASME B&PV Code Table CC-3720-1) are:
6, sc = 0.014 i n/ in.
(est = 0.010 in/in.
Allowable :: anchor displ acement for the. abnormal. ' loading -category,(per 'ASME
.B&PV code,. Table CC3730-1) is:
~
$ a. = 0. 5' where f = 0.18 inch i- -
u u
= 0.09 inch
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TABLE Q1.2 LINER-ANCHOR ANALYSIS RESULTS FOR DESIGN CONDITIONS Anchor liner Strains - Combined Displ acement 4;mbrane & Bending (1)
(Inches)
Compressive Tensile a.
Initial inward deflection of 1/16 inch.
.0127
.00744
.00727
- b. - Lower yield bound and 15%
decrease in plate thickness of buckled panel.
.0096
.00613
.00561 c.
Upper yield bound and 15%
increase in plate thickness of stable panel.
.0144
.00766
.00708 d.
Anchor spacing doubled to simulate f ailed or missing anchor (zipper effect).
This case conservatively considers the post-buckling strength :of this panel to be zero.
.0143
.00343
.00343 Note:
Allowable liner plate strains for combined membrane plus bending (per ASME BLPV Code Table CC-3720-1) are:
6
=.0.014 in/in sc (Est = 0.010 in/in Allowable --anchor displacement for the abnormal loading category (per ASFE
. B&PV code,. Table CC3730-1) is:
h,_=0.5 where[u=0.18 inch u
=:0.09 inch I
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b QUESTI0'l 2 2.
flote 2 to Table 3 states that mechanical stresses due to the attachments are not combined with the self-limiting themal stresses in the liner.
In staff's opinion, the effect of temperature on the liner is the same as that of rrestressing and is therefore not self-limiting. Provide a discussion to support your statement that the thermal stresses in the liner are self-limiting, specifically how the themal stresses in the weld connecting the anchor and the lirer plate are considered to be self-liciting, taking into consideration the effects of the various conditions indicated in the pre-ceeding question.
RESPONSE
Stresses or strains induced in a structure due to constraint from diff erential volume changes (creep, shrinkage, themal, etc.) or support movement are all self-limiting or self-relieving in nature.
This is because such stresses are limited by the yield strength of the material and stiffness of the constraints and will redistribute as the structure is loaded with additienal mechanical loadings.
This f act is supported by the definition given in AS!E !ZPV code Section III, Divisien 2, Section CC-3730, which defines displacement-limitec loads as "...those resulting from constraint of a structure or constraint of a-adjacent maturial and are self-limiting or self-relieving."
Therefore, the strains or stresses induced into the liner due to creep, shrinkage, elastic shortening and thermal loads are self-limiting.
The self-limiting loads en a structure do net reduce the mechanical load carrying capacity of the structure. They do, however, have an impact on the dispiacement characteristics of the structure and therefore need to be checked to assure that the displacement allowables'are not exceeded. The criteria used in ASME code for ciecking the mechanical loads against the allowable stress limits and the self-limiting loads against the allowable displacement limits are consistent with this approach. Although the comparison of the mechanical loads and self-limiting loads is done independently against their respective allowables, this procedure 9
4 e
inherently results in a structure which is capable of carrying the combinaticn of the two loads. Therefore, the liner and its anchor systcn are capable of taking the loads resulting from various conditions outlin-d in the preceeding questien, in addition to the mechanical loads contained in '.eference 2.1.
As an additional measure of conservatism, anchor displacements were calculated due to the combined affect of displacccent limited loads and the mechanical loads and were found to be within the acceptable limits of the ASME B&PV code.
Refcrence 2.1
" Investigation of the Effects of Liner Leak-Chase Channel Attachment,"
Sargent & Lundy Report No. SAD-348.
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