ML20063H468
| ML20063H468 | |
| Person / Time | |
|---|---|
| Site: | Midland |
| Issue date: | 07/23/1982 |
| From: | Jackie Cook CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.) |
| To: | Harold Denton Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML20063H470 | List: |
| References | |
| 18003, NUDOCS 8207300197 | |
| Download: ML20063H468 (7) | |
Text
-f O Consumers power James W Cook Vice President - Projects, Engineering and Construction General offices: 1945 West Parnell Road, Jackson, MI 49201 + (517) 788-0453 July 23, 1982 Harold R Denton, Director Office of Nuclear Reactor Regulation Att: Division of Licensing US Nuclear Regulatory Com:aission Washington, DC 20555 MIDLAND PROJECT MIDLAND DOCKET NO 50-329, 50-330 MASONRY WALLS AND ULTIMATE CONTAINMENT CAPACITY INFORMATION FOR SUPPLEMENTAL SER FILE:
0505.16 SERIAL:
18003
REFERENCE:
NRC (R L TEDESCO) LETTER TO CP CO (J W COOK) DATED JUNE 8, 1982 ENCLOSURE:
RESPONSES TO NRC QUESTIONS 130.29 THROUGH 130.31 The information presented in the enclosure is provided in response to Questions 130.29 through 130.31 in the reference.
It is expected that this information will satisfy the NRC staff concerns related to masonry walls and that a supplement to the Midland Safety Evaluation Report will document this conclusion. This information will be included in a future revision to the Final Safety Analysis Report (FSAR).
The response to Question 130.28 requested in the reference which concerns the ultimate capacity of containments is being discussed with your Staff. A response will be forthcoming upon conclusion of that discussion.
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PDR l
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CONSUMERS POWER COMPANY Midland Units 1 and 2 Docket No 50-329, 50-330 Letter Serial 18003 Dated July 23, 1982 At the request of the Commission and pursuant to the Atomic Energy Act of 1954, and the Energy Reorganization Act of 1974, as amended and the Commission's Rules and Regulations thereunder, Consumers Power Company submits l
a Response to a request for information from NRC concerning masonry walls and ultimate capacity of containments.
CONSUMERS POWER COMPANY By L
J W Cook, Vice'PrTsident Pro' ts, Engineering and Construction Sworn and Subscribed Before Me This,Q Day of v n h6 19h d
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ENCLO'URE S
Question 130.29 (3.8.4)
Compare the damping values used in the dynamic analysis.of masonry walls with the requirements of RG 1.61, " Damping Values for Seismic Design of Nuclear Power Plant." Explain and justify any. deviations.
Response
Masonry construction is not addressed in RG 1.61, however, the damping values
~
identified in RG 1.61 for reinforced concrete structures were considered in the design of reinforced masonry walls.
As previously stated in CP Co letter to NRC dated September 3, 1980, Serial 9406, masonry walls were designed for earthquake loadings using the following damping values:
OBE SSE Uncracked Masonry Walls 2%
2%
Cracked Masonry Walls 4%
7% ~
These damping values meet or exceed the requirements of RG 1.61 for reinforced concrete structures.
1.
i i
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2 Question 130.30 (3.8.4)
Your response by letter dated September 3,1980 to Question 4 on dynamic analysis of. masonry walls expresses the moment of inertia of partially cracked walls as:
~
M M
3-I
=
cr I +
1+
cr I
e 8
7 cr M
a In accordance with ACI 318, this expression should be:
4 M
I
=
cr I +
1-er I
e 8
cr M
M a
a-Furthermore, your expression for the cracking moment is given by:
M
= bt (0.8 ftu) er 6
This expression should be:
=7.5I,g[?T[
Mer Yt Explain and justify these discrepancies.
Response
The equation for I presented in the CP Co letter to NRC dated September 3, 1980 contains a typographical error. The equation for the moment of inertia (I ) used in the analysis of masonry walls is in accordance with the' equation.
gi,en in ACI 318.
v The equation for the cracking moment (Mer) as given in ACI 318 can be reduced by substituting the following:
I = bt and Y = t/2.
8 t
12 Where:
b = width of the wall section resisting the moment t = thickness of the wall section The substitution results in:
M
= f (bt ) = 7.5 P'
(bt )
er
- r 6
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3 1 i Comparison of this to the equation in the CP Co letter dated September 3, 1980 shows the only difference to be in the expression for f.
Since there are no published values for the modulus of rupture (f ) f r masonry, we have taken f r
as 80% of the ultimate tensile strength of masonry (ft ) which we assumed as #
threetimestheallowabletensilestrengthofmasonryYF)asgiveninACI 531-79.
In other words:
f = 0.8 f
= 0.8 (3F ) = 2.4 F r
tu t
t The establishment of f based on the tensile strength of masonry was considered to be more Eeasonable than the compressive strength of concrete as specified in ACI 318.
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b o
i Question 130.31 (3.8.4)
In regards to your revised response by letter dated April 19, 1982 to Question 5 regarding masonry walls, discuss the following:
The Safety Factors used in both the wedge and stud type expansion anchors; a.
b.
Provisions to avoid facial spalling of block walls for expansion anchors requiring a minimum embedment of 1-5/8 in.;
Interference between wall reinforcing and expansion anchors requiring an c.
embedment of 4 inches or more; d.
The consideration given to the expected loss of preload of expansion anchors in the design of attachments to masonry walls; and e.
The testing procedures used to evaluate the effectiveness of installation procedures of expansion anchors and grouted anchors.
Response
a.
The safety factor for wedge type expansion anchors (Hilti Kwik-Bolt Stud Anchor) used for "Q" attachments to masonry walls is 5.0.
The use of other types of expansion anchors is not allowed for "Q" attachments to masonry walls on the Midland Project.
b.
Facial spalling is precluded by limiting the allowable loads on the achors.
These loads were determined from tests using a minimum safety factor of 5.0 (see response "a" above).
Project specifications require that extreme care be taken in locating c.
expansion anchors in blockwalls to avoid cutting rebar.
However, if rebar is inadvertently cut, it is repaired by either lap or mechanical splicing.
The repair of portions of blockwalls removed to install rebar splices is done with drypack, concrete, mortar, or nonshrink grout following the same construction procedures as used for the repair of concrete.
d.
Midland-specific tests to determine the amount of preload remaining in the bolt indicate that an average of 37% of the original preload remains in the bolt after one year. Other tests (References A and B) have established that the amount of preload on the bolts will not affect the performance of the anchorage.
If the' initial installation torque on the bolt accomplishes the purpose of setting the wedge, then the ultimate capacity of th^ bolt is not affected by the amount of preload present in the bolt at tNe time of cyclic loading. These tests (References A and B) indicate no archor pullout failures occurred as a result of cyclic loading and that preload is not required to withstand cyclic loading.
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5
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References:
A.
Teledyne Engineering Services Technical Report 3501-2 for Utilities /TES Owners Group Summary Report Generic Response to US NRC IE Bulletin 79-02.
B.
Commonwealth Edison Company Summary Report, Static, Dynamic and Relaxation Testing of Expansion Anchors in Response to NRC IE Bulletin 79-02, 7/20/81.
The testing procedures used to evaluate expansion anchors and grouted e.
anchors in blockwalls are presented in the attached report entitled,
" Report on The Testing of Concrete Expansion Anchors and Grouted Anchors Installed in Concrete Blockwalls."
Note: This report will only be referenced in the FSAR response to this question.
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