ML19329A515
| ML19329A515 | |
| Person / Time | |
|---|---|
| Site: | Oconee  |
| Issue date: | 08/09/1977 |
| From: | Shao L Office of Nuclear Reactor Regulation |
| To: | Goller K Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 8001060032 | |
| Download: ML19329A515 (3) | |
Text
-_
~
e s(
AUG 9 1977 i
MEM0RANDUli FOR:
K. R. Galler, Assistant Director for Operating f
Reactors, D0R f
FROM:
L C. Shao, Chief. Engineering Branch, D0R i
SUBJECT:
SEISMIC TJALIFICATION OF OCONEE EMERGENCY POWER PLANT i
Plant Name: Oconee Nuclear Station Units 1, 2 and 3 Docket Numbers: 50-269, 50-270, 50-289 Branch and Project Manager Requesting Assistance: ORB-1, J. Neighbors Review Branches Involved:
Engineering Branch, Plant System Branch Description of Request: TAC 6048 - ORB-1-250 j
Review Status: Requesting Additional Infomation The Engineering Branch, Division of Operating Reactors, has reviewed I
{
the information submitted with the letter dated October 7,1976 and April 13,1977.
We find that we need additional infomatinn, as indicated in the enclosur.e.,
i before we can complete our review.
l L. C. Shaa, Chief Engineering Branch Division of Operating Reactors
Enclosure:
DISTRIBUTION:
i As stated Central Files EB-Rdg
Contact:
G. Bagchi EB-File Number 6.48 49-28060 cc:
V. Stello D. Eisenhut W. Butler A. Schwencer R. Stuart 1
- 0. Deighbors T[
P. Atherton G. P,agchi iI 0 A
EB M [
- OR OR orrie *
,ummawa h C1 gchi:dr
_LCSha 772180333
}
I 8/2/77 8/k777 8/(l//77 l
W us o.oovanwuswr ensurine orrics sets-sas.es4 NRC PORM 313 (9 76) NROi 0240 f
8001060 O 3 ] g
OCONEE NUCLEAR STATION UNITS 1, 2, & 3 SEISMIC CAPABILITY OF EMERGENCY POWER PATH ENGINEERING BRANCH - DIVISION OF OPERATING REACTORS REQUEST FOR ADDITIONAL INFORMATION - TAC #6048 9.
In your response to Q16 it is indicated that passive earth pressure has been relied upon to resist sliding and overturning effects.
For shallow foundation embedment in backfill material, it is unconservative to rely upon the passive earth resistance.
For those of deep embedment, factors of safety against sliding should cases be calculated in such a way that slip circle failure 'iue to shear stress is prevented.
One of the acceptable methods of calculating the factor of safe y against overturning is given in BC-TOP-4A.
It should be noted that the original intent of this question was to determine to what extent the effect of the foundation interaction with the surrounding soil modifies the freefield seismic
- on.
Provide a discussion indicating in each case how soil-structure 4
interaction was accounted for. Also provide a statement indicating that the factors of safety against sliding and overturning for each foundation meet the acceptance criteria stated in Section 3.8.5.II.5 of the Standard Review Plan.
10.
In your response to Qle indicate that the effects of one horizontal and one vertical earthquake components are combined on the basis of the absolute sum method.
11.
In your response to Qlf, the reference to 5A.3 of the Appendix 5A to the FSAR is not satisfactory.
Indicate your intent to qualify each foundation to meet the load combinations and acceptance cri+ aria per Section 5A.2.2 of the Appendix SA to the FSAR.
12.
In your response to Q2 it should be noted that the National Electric Safety Code (NESC) heavy loading provides for ice and wind loading, and does not include the effects of seismic loading.
Since the load combinations referred to in section 5A.2.2 of the Appendix 5A to the FSAR are not applicable to the transmission line and the
-towers, appropriate load combinations and the corresponding acceptance criteria should be chosen from the sections 3.8.4.II.3 & 5 l
of the Stnadari Review Plan, and clearly ic'entified in your response.
l The modal analysis for the tower, in sn unloaded condition, to predict the seismic loading is not acceptable. The effect of seismic loading consists of two parts:
(.1) the effect of inertia loading on both the towers and the transmission line; for the towers the input may be the ground response spectra, but the input for the lines should be the appropriate amplified response spectra corresponding to the attachment point, (2) the effect of ground l
displacement; the ground dispiacement would cause stretching of the lines and this in turn would impose corresponding loading on the. towers..The stresses from (1) and (2) above should be combined by the absolute sum method to obtain the seismic loading which i
Ae j in turn should be ut.ed in appropriate load combinations along with Provide specific responses to the previous Q2 including other loads.
the concerns expressed in the clarifications detailed above.
In your response to Q2 failure of secondary bracing members is In combination with Q12 above it should be noted that 13.
predicted.
whenever members are predicted to fail, subsequent analyses must be performed on the model that excludes the failed members, and the resulting stresses and displacements must meet appropriate acceptance criteria.
In your response to Q3a it is stated that seismic loads wereThe referenced 14.
generated as prescribed on page SA-3 of the FSAR.
However, in order page simply provides the ground response spectra.to obtain the Therefore, analysis of its mathematical model should be performed.
provide the specific information requested in Q3a and provide a stress summary of the critical sections.
i In your response to Q3b it is stated that a seismic force of i
has been assumed to be applied to equipment supported on 15.
0.369 Floor the foundstion and the structural steel framed building.
response spectra for points of attachment provide the maximum When the equipment responses for a range of natural frequencies.
has more than one degree of freedom, the effective acceleration is usually greater than the response from the predominant mode.
Demonstrate the conservatism of the 0.369 static coefficient through a comparison of response obtained from a dynamic analysis of the multimode equipment subjected to floor response spectra.
In your response to QA, note that the Section 5A.2 of the FSAR simply states that where the analysis is difficult the highest 16.
For acceleration from the response spectrum curve is to be used. Provide justifica 2% damping this value is approximately 0.359 for ignoring contributions from higher modes (see your own discussion in note CC in response to Q7).
In your response to Q6 it should be noted that the power circuit breakers must be verified by at least prototype testing for 17.
demonstration of operability in the seismic environment.
Periodic inspection and testing of electrical power systems are required by the General Design Criterion number 18 of the Appendix A 18.
i-to 10 CFR part 50 and by the Regulatory Guide 1.118 entitled i
~
" Periodic Testing Of Electrical Power And Protection Systems".
Provide the details of a program of inservice inspection and testing
~
that would be incorporated in your technical specifications.
4' e.
f i
].-
e