ML19351D834
| ML19351D834 | |
| Person / Time | |
|---|---|
| Site: | Trojan File:Portland General Electric icon.png |
| Issue date: | 07/31/1980 |
| From: | Coleville J, Colville J AFFILIATION NOT ASSIGNED, COLVILLE, J. |
| To: | |
| Shared Package | |
| ML19351D832 | List: |
| References | |
| TAC-11299, TAC-12369, TAC-13152, NUDOCS 8011200095 | |
| Download: ML19351D834 (8) | |
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ATTACHMENT 1 TO SER SUPPLEMENT RE: TROJAN NUCLEAR PLANT CONCRETE MASONRY DESIGN CRITERIA O
REPORT ON CRITERI A AND ME1110r TGY FOR Tile EVALUA7 OUT-OF-PLANE ON MASONRY WAL,3 AT THE TROJAN POWER PLANT l
i Subnitted to:
l Brookhaven National Laboratory Upton, N.Y.
l I
1 by I
Dr. James Colville, P.E.
j Consultant i
.'lulf,1980 l
l 8 01 1 u 0 0095'
l l
I Introduction Since submitting the Report on " Design Criteria for Masonry Walls in the Trojan Power Plant" in March, 1980 and the subsequent three reports in April, 1980 a considerable amount of discussion has centered on the anpropriate criteria and methodology for the evaluation of out-of-plane loading on all masonry walls at the Trojan Power Plant.
A number of different types of walls exist at the Plant.
These may be categori:ed as follows:
a) Single wythe walls b) double wythe heavy weight block walls c) double wythe light weight block walls d) composite masonry walls On June 10, 1980, Portland General Electric Company submitted Supplement 4 to Licencee Event Report (LER) 79-15 which presented a proposed criteria and methodology for the evaluation of out-of-plane loads on double wythe heavy weight block walls.
Subsequently, and after meetings held on June 19-20 and June 25-28, 1980 with NRC Staff, Supplement 4 was revised and extended in scope to ccver all masonry wall types listed above.
This report summarizes my comments on these revisions and ray observations concerning the overall interim criteria to be used to evaluate the adquacy of all masonry walls.
).
2 II Review of Developed Criteria The criteria developed on June 28, 1980 for evaluation of all masonry walls is, in my opinion, adequate to ensure the integrity of 2 of all walls having safety significance, as defined in Attachment the June 28, 1980 submittal.
Although there are a considerable number of items relating to the masonry wall problem, the more significant of these are listed below:
(1)
Identification of walls having safety significance (2) Magnitudes of interstory displacements throughout the complex.
(3) Material properties for stiffness evaluation (4) Material properties for capacity evaluation (5)
Allowable stresses for walls, including:
a) heavy weight double wvthe walls b) standard weight double wythe walls c) single wythe walls d) composite wa]Is (6)
Calculation methodology for determining collar joint shear bond stresses. in double wythe walls.
Stiffness considerations for energy balance technique for walls (7) failing to meet the accepted criteria (8)
Impact of wall response on attached safety related systems (9) Method of modifying walls that fail to meet the accepted criteria to state Before briefly reviewing the above, it is important the philosophy of the criteria.
In essence, the criteria addresses the masonry wall problem in two stages:
(1) walls which must be modified prior to start-up of 'the plant, and (2) walls which can be modified by October 31, 1980 during plant operation,
3 In my opinion, considering the relatively minor variations in the criteria for identifying walls which must be modified prior to start-up and the deadline for modifying all walls having safety significance, this approach is rational and reasonable.
(1)
Identification of Walls having Safety Significance The criteria stated in Attachment 2 for identifying walls having safety significance is considered appropriate.
(2)
Amplification Factors for Interstory Displacements The procedures followed in Attachments 3 ad 4 for determining the displacement amplification factors an3 displacement profiles through-out the Complex seem complete and adequate.
However, the detailed pro-cedure and associated numerical values developed have not been reviewed since this is beyond the scope of my past involvement with NRC Staff.
It should, however, be noted that the information contained in these attachaents are for interim use only and will be replaced by information currently being developed by Bechtel using a finite element computer algorithm which has some capability of modeling nonlinear effects caused by degradation of the shear walls under in-plane loadings.
(3) Material Properties for Stiffness Evaluation (Table 3-2)
The values for modulus of elasticity of the various materials are acceptable as given. The major revision to this Table concerns the development of modulus of rupture ranges for the various materials listed.
Although the use of a range of modulus of rupture values is awkward and it would be preferable to have single values available for use, I concur that, because of the complex nature of the analytical problems
4 associated with the masonry walls, upper and lower bounds values are needed.
In the absence of sufficient test data to bette. quantify the modulus of ruptures and tensile bond strengths of the materia:
used, I e
believe that the ranges listed in Table 3-2 represent reasonable estimates of the variability of these properties.
Also the use of 80 psi as de-scribed in Note 2 is acceptable.
(4) Material Properties for Capacity Evaluation (Table 3-3)
The values given in Table 3-3 are satisfactory.
(5) Allowable Stresses for Walls The allowable stresses given in Tables 5-la, 5-lb, 5-Ic, and 5-Id, are in my opinion, satisfactory for use at present.
However, it should be pointed out that the collar joint shear stress values of 10 psi for heavy weight double wythe walls, and 20 psi for standard weight double wythe walls are based on a limited number of tests performed on in-situ walls at the Complex.
Also the test procedure from which these values have been developed is subject to question.
In summary, these values are in my opinion appropriate as interim criteria, although it is recom-mended that further testing be conducted as soon as possible to validate these values.
In the meantime the immediate use of 12 psi and 24 psi for heavy weight and standard weight doubic wythe walls, respectively,that will be accessible for modification during plant operation is acceptable, in my opinion.
(6) Calculation Methodology for determining Collar Joint Shear Stresses The general methodology outlined in Supplement 4, Section 6.1.1
S for calculation of the collar joint shear stress in double wythe walls is valid and proper.
(7)
Stiffness Considerations for Energy Balance Technique The procedure described in Attachment 6 outlining the method of determining the stiffnesses used to obtain wall deflections is reasonable and consistent.
(8)
Impact of Wall Response on Attached Safety Related Systems The use of the energy balance technique on walls in which the mid-span reinforcement strains exceed three times the yield strain and the requirement that an evaluation of the impact of wall flexibility on attached safety related systems of walls having a structural frequency of less than 20 H are, in my opinion, necessary elements of the criteria.
(9) Method of Modifying Walls The use of modifications based only on alternatives 3 and 4 of Sup-pleme.it 4 to LER 79-15 is acceptable.
In other words, Alternatives 1 and 2 of Supplement 4 to CER 79-15 should not be used to modify walls failing to meet the criteria,
6 III Margin of Safety Since I have not reviewed the estimated in-plane capacity to load ratios of the numerous shear walls in the Complex, the overall margin of of safety existing in the Compicx is impossible for me to assess.
How-ever, I believe that the procedure outlined previously in my initial report on " Design Criteria for Masonry Walls in the Trojan Power Plant" for determining in-plane capacities of shear walls provides a reasonable basis for establishing an upper bound estimate of the margin of safety when compared to the results of an appropriate analysis of the structural system.
The estimated margin of safety based on such a comparison should, in m) opinion, be considerably larger than unity since factors such as, but not limited to, quality of original workmanship, variability of material properties, current structural condition of the walls, and the difficulty of accurately modeling the complex response of the struc-ture in a post cracked condition may combine to significantly reduce the theoretical safety margin.
With respect to out-of-plane margins of safety of masonry walls the following cor.:ments are presented:
(1) All safety related walls conforming to the allowable stress
- riteria set forth in Supplement 4, as modified, will have a safety margin estimated, in my opinion, to be approximately 2.0.
(2) All multiple wythe walls in which the interface stress criteria are violated run a considerable risk of serious structural damage.
(3) Other walls having stresses in excess of the allowable values given in the criteria will have margins of safety which may be less than 2.0, ana depending on the nagnitude and type of over-stress may also experience structural damag.
In particular, walls having strains in excess of the yield strain due to out-of-plane inertia loadings, will be permenently damaged and will, 4
I in my opinion, need to be subsequently strengthened or re-placed. 'Ihe extent of this damage will depend on the magnitude of the wall deformations.
i (4) Since the criteria requires the modification of walls in which i
f safety related systems would be adversely affected by over-stress or deiamination of multiple wythe walls, damage to in-l f
dividual walls should not adversely affect the safety of the Plant.
However, I do not feel competent at present, to corrent with assurance on the validity of the procedures established in the criten a for assessing whether or not safety related l
systems would be impacted.
But the use of the energy balance technique with a factor of two applied to the computation of j
wall displacements would appear to give a conservative basis for evaluating the impact of wall deformations on safety re-lated systems.
j IV Summary In sumary, in my opinion, the criteria and methodology outlined in Supplement 4, as modified, represent a rational application of structural engineering principles tempered with reasonable estimates of material properties existing in the Complex. However, it is recommended that collar joint shearing bond stress values be verified by additional testing.
The overall margin of safety of the Complex cannot be assessed at present, although it is believed that wall damage can result from an SSE carthquake.
Proper implementation of the criteria, however, should l
limit and control this damage such that safety related systems will not i
be adversely impacted.
I i
l l
i Jurie 28, 1980 PorUand GexxralElecticM Trojan Nuclear Plant
./
License NPF-1 I
Dras.iB e Ass stam vce Pescem Docket 50-344 lfI I
I H. Engelken, Director Mr.
R. Nuclear Regulatory Commission U.
S.
j Region V Creek Plaza Suite 202, Walnut 1990 h. California Blvd.
i Walnut Creek, CA 94596
Dear Mr. Engelken:
4 to LER 79-15, which contained the pro-posed criteria to be used in the analysis of the out-of-Supplement No.
10, was submitted to you by my letter dated June 25-28 with In meetings held on June 19-20 and June
- walls, i
i the NRC Staff agreement was reached on revised cr ter a, 1980.
d ll masonry which have been expanded in scope to inclu e aThe enclosed attachments walls having safety significance. reflect the agreed-upon revisions to the criteria and tables all masonry walls in the meetings, he revised As also agreed to at the Plant will be evaluated in accordance with t that the allowable collar joint shear stress for standard weight and heavyweight double wythe criteria, except operation walls in areas which are accessible during Plant respectively.
Based on the shall be 24 psi and 12 psi, the following actions will results of these evaluations be taken prior to resumption of power operation for walls i
having safety significance which do not satisfy the criter a:
interface For multiple wythe, walls for which thewall delam.ination 1) stress criteria are exceeded, will be assumed and a determination will be made as to whether the assumed delamination would adversely impact the function of safety-related e wall or in its area of r
i attache
- systems, influence (2 fee If fhe safety-re DUPLICATE DCCUMENT impacted the wal Entire document previcusly entered into system under:
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