ML20054C097
| ML20054C097 | |
| Person / Time | |
|---|---|
| Site: | Big Rock Point File:Consumers Energy icon.png |
| Issue date: | 04/13/1982 |
| From: | Ronaldo Jenkins CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.) |
| To: | NRC OFFICE OF THE EXECUTIVE LEGAL DIRECTOR (OELD) |
| Shared Package | |
| ML20054C095 | List: |
| References | |
| ISSUANCES-OLA, NUDOCS 8204200028 | |
| Download: ML20054C097 (8) | |
Text
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4/13/82 UNITED STATES OF AMERICA NUCLEAR REGULATORY COMMISSION BEFORE THE ATOMIC SAFETY AND LICENSING BOARD In the Matter of
)
) Docket No. 50-155-OLA CONSUMERS POWER COMPANY
) (Spent Fuel Pool
)
Modification)
(Big Rock Point Nuclear Power Plant)
)
CONSUMERS POWER COMPANY'S ANSWERS TO NRC STAFF INTERROGATORIES 1 THROUGH 8 Pursuant to 10 C.F.R.
S 2.740b, Consumers Power Company
(" Licensee") hereby submits answers to NRC Staff Interrogatories 1-8, which were filed on March 30, 1982.
INTERROGATORY 1:
Is the overhead crane for the spent fuel pool able to withstand a seismic event as defined by the Systematic Evaluation Program (SEP) site specific spectrum for Big Rock Point, anchored at 0.11g peak ground acceleration (PGA)?
RESPONSE TO INTERROGATORY 1:
The overhead crane is being evaluated with respect to its ability to withstand a seismic event.
The seismic event being analyzed, 0.12g peak ground acceleration, envel-opes the SEP site specific earthquake for Big Rock Point.
The results of this analysis will be furnished to the NRC Staff by April 15.
8204200028 820415 PDR ADOCK 05000155 G
. INTERROGATORY 2:
Have any analyses been performed to support your determination of whether the spent fuel pool over-head crane could withstand such a seismic event?
RESPONSE TO INTERROGATORY 2:
See answer to Interrogatory 1.
INTERROGATORY 3:
If such analyses have been com-pleted, have they been submitted to the NRC Staff for its review?
If not, when are they expected to be completed?
RESPONSE TO INTERROGATORY 3:
See answer to Interrogatory 1.
INTERROGATORY 4:
If they have been submitted to the Staff, please identify the analyses by:
a)
Name of document.
b)
Date submitted.
c)
If submitted as part of a larger document, the exact page references where the analyses in question may be found.
d)
Date of document if different from submittal date.
. RESPONSE TO INTERROGATORY 4:
See answer to Interrogatory 1.
INTERROGATORY 5:
If such analyses have not been submitted to the Staff, please describe in detail the results of such analyses and the analytical techniques and assumptions employed.
Assure that any references or responses include a de-scription of the Reactor Building structural analyses on which the crane analysis is based and a detailed dis-cussion of the differences, and their significance, between this and the June 1978 Reactor Building analy-sis on which the design of the spent fuel pool racks, and the Staff's SER regard-ing these, are based.
RESPONSE TO INTERROGATORY 5:
No response can be made to the question posed by the first sentence of the interrogatory until the analysis described in response to Interrogatory 1 has been completed.
However, a response is being provided to the question posed by the second sentence.
The design response spectra being employed in the analysis of the crane were developed from the amplified response spectra at appropriate supporting levels of the m
_4_
Reactor Building internal structure.
These amplified response spectra were developed as part of the Seismic Safety Margin Evaluation of the Reactor Building under the auspices of the Systematic Evaluation Program currently being undertaken by the U.S.
N.R.C.
and CPC for Big Rock Point.
The details of the analy-sis of the Reactor Building and the response spectra employed for the crane are presented in the report by D'Appolonia entitled " Seismic Safety Margin Evaluation, Big Rock Point Nuclear Power Plant Facilities," Revision 1, August 1981.
D'Appolonia also performed the analyses related to the derivation of amplified responses at the spent fuel pool location.
Tha report on these analyses (D'Appolonia, 1978) is referred to as the "1978 Reactor Building Analysis."
The analytical model for this study consisted of three-dimensional stick model representing the internal structure and a single mass model of the containment shell. The analytical model of the reactor building was supported by three translational and three rotational springs representing the Soil Structure Interaction (SSI) effects.
The dissipation of energy into the subgrade was similarly represented by six dampers (three t
translational and three rotational).
These SSI parameters used in the 1978 Reactor Building analysis were initially developed on the basis of baring log data, literature survey i
4 and D'Appolonia in-house experience with similar subsurface materials.
The analytical model so developed was exercised using a linear time-history integration technique to generate time histories at appropriate locations in the analytical model.
These generated time histories and their associated response spectra were used as input to the spent fuel pool analysis.
Subsequent to the performance of the spent fuel pool analysis, data on the compressional and shear wave velocities of the site subsurface material became available through testing.
The SSI parameters were then revised in light of these additional data, and the effects of the revised SSI parameters on the response of the Reactor Building analysis were evaluated.
Because the revised SSI parameters were found to be within the bounds of parameter variation considered in the 1978 Reactor Building analysis, no additional derivation of amplified responses was performed with the new set of SSI parameters.
Following the completion of the 1978 Reactor Building analysis, D'Appolonia participated in the Seismic Safety Margin Evaluation of the Big Rock Point safety-related plant structures which was documented in a 1981 report.
As part of this program, the Reactor Building and the Primary Coolant Loop (PCL) were analyzed simultaneously for evaluation
. of the safety margin under the same postulated earthquake as employed in the 1978 analysis.
Thus, identical forcing functions were input into slightly different analytical models.
The differences between the model used in the 1978 report as compared to the model used in the 1981 report are considered relatively minor and result from the following changes:
1.
The PCL was represented as part of the Reactor Building analytical model.
The PCL, to include the reactor vessel and steam drum, is a very flexible system and its effect on the Reactor Building itself is considered negligible.
2.
The revised SSI parameters determined on the basis of cross-hole data were used in the analysis.
3.
To accommodate the detailed representation of the PCL, an additional node point was introduced into the SEP Reactor Building analytical model.
This revision necessitated a minor redistribution of the calculated masses lumped at various node levels.
The effects of parameter variations in the two Reactor Building analyses have been studied by D'Appolonia and are presented in a report entitled, " Parametric Study, Soil
. Structure Interaction."
This report will be made available to the NRC Staff on April 15, 1982.
The studies consider best estimate and plus and minus 50 per cent variations in soil spring constants es well as varying amounts of structural damping.
Analysis compared the amplified response spectra of the three common structural locations in the 1978 and 1981 analyses as a function of soil spring stiffness and structural damping variations.
The conclusions reached as a result of these studies is that the differences between the two analyti-i cal models do not lead to any significant deviations from the results or conclusions of the 1978 Reactor Building analyses.
The studies also reflect no significant variation in response spectra at damping values of interest as a result of parameter variation.
INTERROGATORY 6:
If it has been determined that the overhead crane will not withstand a seismic event as defined by the SEP site specific spectrum anchored at 0.11g PGA, please describe the problem which might occur if such a seismic event were to happen.
RESPONSE TO INTERROGATORY 6:
See answer to Interrogatory 1.
. INTERROGATORY 7:
Please describe the modifications, if any, proposed to account for this potential problem.
RESPONSE TO INTERROGATORY 7:
See answer to Interrogatory 1..
INTERROGATORY 8:
If no detailed description of the proposed modification or modifica-tions exists, please provide a schedule within which such a description could be provided.
RESPONSE TO INTERROGATORY 8:
See answer to Interrogatory 1.
.s