ML19242B990
| ML19242B990 | |
| Person / Time | |
|---|---|
| Site: | Midland |
| Issue date: | 07/03/1979 |
| From: | Howell S CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.) |
| To: | James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| Shared Package | |
| ML19242B991 | List: |
| References | |
| 7234, HOWE-195-79, IEB-79-02, NUDOCS 7908090632 | |
| Download: ML19242B990 (8) | |
Text
e-g N
- D Consumers tj POWBf
(
.j g Stephen H. Howell Senior Vice PressJent General of ficas: 1945 West Pernali Road, Jackson, Michigan 49201 * (517) 788-0453 July 3, 1979 Hove 195-79 Mr James G Keppler, Regional Director Nuclear Regulatory Commission Region III 799 Roosevelt Road Glen Ellyn, IL 60137 ICDLAND PROJECT DOCKET No 50-329, 50-330 IE BULLETIN 79-02 FILE: 0505.12 SERI AL:
7234 We have reviewed IE Bulletin 79-02 on the subject of " Pipe Support Base Plate Designs Using Concrete Expansion Anchor Bolts" against the Midland Plant Unit 1 and 2 design. Attached are three (3) copies of the results of that review.
The attachment was prepared prior to the receipt of 79-02, Revision No 1.
We are not aware of any piping supports for which leveling nuts are in use in conjunction with expansion anchors.
The reinspections necessary to accomplish the requirements of Item h of the bulletin vill not be completed until the end of July.
There is a preliminary indice. tion that there is some problem with meeting the required embedment depths. Acquisition of additional UT instruments, review of design require-ments for individual hanger installations and further inspections are required to quantify the extent that the embedment depth characteristic has not been met.
A further response vill be provided to the NRC on this matter by August 15, 1979.
\\
g
,p
),
N SRH/jm CC: Director, NRC Office of Inspection & Enforcement Director, Nuclear Reactor Regulation
- ;; n 1s *.
) (.' u.
JUL 6 1979 790809063 9
NRC IE BULLETIN 79
- DATED W.RCll is in response to the requirements of NRC IE Bulletin 79-02, This document Investigation includes pipe supports using concrete dated March 8, 1979.
expansion anchors for Seismic Category I systems as defined by Regulatory 1973.
The Guide 1.29, Seismic Design Clacsification, Rev 1 dated August FSAR response in Appendix 3A clarifies Regulatory Guide 1.29, Seismic Design Classification.
Question 1 Verify that pipe support base plate flexibility was accounted for in the
~
calculation of anchor bolt loads.
In lieu of supporting analysis i
justifying the assumption of rigidity, the base plates should be considered flexible if the unstiffened distance between the member velded to the plate and the edge of the base plate is greater than twice If the base plate is determined to be the thickness of the plate.
flexible, then recalculate the bolt loads using an appropriate analysis which will account for the effects of shear-tension interaction, minimum This is to be done prior to edge distance, and proper bolt spacing.
testing of anchor bolts. These calculated bolt loads are referred to hereaf ter as the bolt design loads.
Response
Prying action in the base plate-to-concrete connection using expansion anchor bolts is considerably less than the same phenomenon in steel-to-steel connections, mainly because of the much lower expansion anchor If the bending stresses in the base plate are within the stiffness.
AISC allowables, the base plate is rigid enough for prying action to be For this negligible (ref er to ITT Crinnell report, Attachment 1).
project, the bending stresses in the base plate were kept within the AISC allowables.
the moment arm (C) to When the base plate is subject to a moment, determine the tension (T = M acnt) in the expansion anchors was taken to be equal to C1 as shown in Figure 1.
In reality, the moment arm is greater than Cy, and will approach C2 as the plate becomes infinitely rigid. For this project, the base plate and bolts were designed conservatively for bending loads.
Question 2 Verify that the concrete expansion anchor bolts have the following minimum factor of safety between the bolt design load and the bolt 9
A y
'uJ
(i.e., type of concre c bolts
.Four - For wedge and sleeve type anchor
' a, Five - For shell type anchor bolts b.
P
Response
l A minimum safety factor between the bolt design load and the bo t i
the ultimate capacity, determined f rom static load tests simulat ng four for actual conditions of installation, was taken to be equal to These minimum stud type anchor bolts, and five for the shell type.
i loads were safety f actors were increased by a f actor of two when seismic considered.
design for all pipe supports and hangers.
I Question 3 t.
Describe the design requirements if applicable for anchor bolts to ting withstand cyclic loads (e.g., seismic loads and high cycle opera loads).
Response _
to high Expansion anchors are not used on the supports of pip d
machinery or flow-induced vibrations).
l be verified by field the proj ect specification (Attachment 2), and it udlinspectio Question 4_
Verify from existing QC documentation that design requirenents have been in the following areas.
met for each anchor bolt Cyclic loada have been considered (e.g., anchor bolt preload is In the case of the equal to or greater than bolt design load).it is not in contact with the back of the a.
shell type, ensure that support plate prior to preload testing.
Specified design size and type is correctly installed (e.g., proper b.
embedment depth).
then initiate a testing If sufficient documentation does not exist, been met program that will ensure that minimum design requirements have A sampling technique is with respect to Items a and b above.One acceptable technique is to randomly sele in cach base plate (i.e., soinc supports may have more than acceptable.
The test should provide verification of Items a and b anchor bolt one banc plate).
. - = = -.
W ?= - _
7
.)Gt
Response
Installation of Expansion Anchors a.
Torque testing was performed at the jobsite (Attachment 3) to determine torque values and correlate these value.= with tension These tests are the basis for the project specification loads.
(Attachment 2).
b.
Testinc Expansion Anchors for Pullout Capacity Installed stud type expansion anchors were tested using a calibrated, Minimum torque salves as given in manually operated torque wrench.
In the specification (Attachment 2) were obtained during testing.
lieu of torque testing, shell type expansion anchors were tested Test lood values equal to approximately 200% of with a tensioner.
the allowable tension load for 3,000-psi concrete were used.
u, Inspection of Expansion Anchors c.
The following procedure for stud and shell type bolts are cpplicabic for inspection and testing during installation and 3,.
reinspection of samples.
1.
STUD TYPE Bolt capacity will be checked by testing as specified in a)
Item b, Testing of Anchors for Pullout Capacity.
b)
Bolts are stamped with their length. For the bolts which stamped, a sample will be checked by using were not The person performing the ultrasonic ultrasonic means.
test will be required to sign the data sheet, c)
Bolt diameter will be verified.
Verification that the nut is not bottomed out on the bolt d) will be accomplished by backing the nut of f and visusily for threads below the surface of the inspecting the bolt In lieu of this, a comparison of the manufacturer's plate.
thread length with measured length will be an acceptable alternative, Concrete surrounding the plate will be checked for signs c) of failure.
,l
Item b. Testing of Anchors for Pullout Capacity.
b)
The bolt thread engagement will be checked for a minimum of one bolt diameter.
c)
The shell will be checked for contact with the support plcee by making certain that the setting depth of the shell varies from flush with the concrete surface to approximately 1/8 inch below the surface.
d)
Bolt diameter will be verified.
e)
Concrete surrounding the plate will be checked for signs of failure.
m.
d.
Restore Original Torque Values After Testing e
If the nut is loosened during inspection or reinspection, bolts will be tightened using the installation torque specified in the project specification (Attachment 2).
e.
Test Sample Size and Acceptance Criterion In order to improve and substantiate the degree of acceptability of the quality control documentation, random samples of 60 stud anchors and 60 shell anchors will be selected and tested.
These tests will demonstrate, with a confidence level of 95%, that not.
more than 5% of the installed anchors are defective.
The sequential sampling program shown in Table 1 will be followed if some bolts are found defective in the sample.
The randem selection of the anchors will be performed by numbering the anchors and using random number tables.
Stud and shell type anchor samples vill be identified separately and tested as two different lots, e.
ee-*
e 6 e ese e ese e e e*me see e' % w *Wan w ge p e a eene em Ogdes e
- er m ease e seu* w _
-*-=***eme==
_v
~
TABLE 1 SEQUENTIAL SAMPLING PROGPRI Acceptable Number of Defects in the Sample Sample Size 0
- y...
60 1
92 2
124 3
152 4
182 5
216
- -i 0
6/21/1 t
- i.. i i l
T EllSION I
C
'M C
i 2
/
CCI.tF l;Esil:N y
i 3
FIGURE 1-s e
v l
9 e e.
n