ML20072H081
| ML20072H081 | |
| Person / Time | |
|---|---|
| Site: | Braidwood  |
| Issue date: | 03/23/1983 |
| From: | Swartz E COMMONWEALTH EDISON CO. |
| To: | Harold Denton Office of Nuclear Reactor Regulation |
| References | |
| 6150N, NUDOCS 8303290266 | |
| Download: ML20072H081 (7) | |
Text
[ O' 'N Commonwealth Edison..
).one First Natiornt Plua. Chicago, Ilhno!s
=
C
(
~. Addrass Riply to: Post Office Box 767
(,
Chicago, Illinois 60G90 March 23, 1983 Mr. Harold R. Denton, Director Office of, Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Washington, DC 20555
Subject:
Braidwood Station Units 1 and 2 Additional FSAR Information NRC Docket Nos. 50-456/457-Reference (a):
B.
J. Youngblood letter to L. O. DelGeorge dated January 14, 1983
Dear Mr. Denton:
The above Reference requested that the Commonwealth Edison Company provide certain additional information concerning our FSAR for Braidwood Station Units 1 and 2.
The Attachment to this letter provides our response to Questions 130.56, 362.11 and 371.17.
Our FSAR will be amended to include the information contained in the Attachment to this letter as appropriate.
Additionally, our schedule for submittal of the remaining open items is currently being discussed with Ms. Janice A.
Stevens.
Please address any questions that you or your staff may have concerning this matter to this office.
One (1) signed original and fif teen (15) copies of this letter with Attachment are provided for your use.
Very truly yours E. Douglas Sw Nuclear Licensing Administrator Attachment cc:
J. G. Keppler - RIII RIII Inspector - Braidwood g/
8303290266 830323 DR ADOCK 05000456 l
BRAIDWOOD-FSAR QUESTION 130.56
" Conflicting information is provided in Table 3.7-3 of Section 3.7 and Section 3.8.5.1.5 of the FSAR which state that the Braidwood lake screen house rests on rock and glacial till respectively.
If the information contained in Section 3.8.5.1.5 is correct, describe the method of analysis used to account for the soil-structure interaction.
"It is the staff's position that the methods implementing the soil-structure interaction analysis for structure situated on soil should include both the half space lumped spring ahd mass representation and the finite element approaches.
Category I structures, systems and components should be designed to responses obtained by the appropriate methods described in the Standard Review Plan, Section 3.7.2.II.4.
"Therefore, you are requested to compare the responses obtained by the half space (lumped parameter) method to those obtained by the finite element approach at the following locations:
" (a)
Base mat (b)
El. 588'-0" (c)
El. 602'-10" (d)
Roof.
~ "In both analyses the variation of soil properties should be considered.
"If the lake screen house is supported by bedrock, please confirm that the information provided in Section 3.8.5.1.5 on the same subject ic incorrect and make the necessary FSAR corrections."
RESPONSE
The Braidwood lake screen house foundation rests on 10 feet of glacial till underlain by rock.
Due to the shallow depth (10 feet) of the till and a high shear wave velocity of 2400
_ft/sec, the soil structure interaction effects are not significant (see the response to Question 362.11).
The original design for structures and components was based on a fixed base analysis using the deconvoluted rock time history; the comparison between the design spectra and the spectra from the deconvoluted rock time history is shown in Figures 3.7-21 through 3.7-40.
Q130.56-1 m
o
BRAIDWOOD-FSAR Furthermore, as a result of Question 130.6a, a reanalysis was performed on a fixed base analysis using the design time history.
The main slabs and walls and the major equipment are designed for the envelope of the two analyses results.
Table 3.7-3 has been revised to indicate there is 10 feet of hard glacial till between.the rock and the lake screen house foundation.
(
9 i
t Q130.56-2 S
~
[
BRAIDWOOD-FSAR TABLE 3.7-3
'~ '
~
SUPPORTING MEDIA FOR SEISMIC CATEGORY I STRUCTURES EMBEDMENT SIZE OF TOTAL DEPTH OF SOIL DEPTH OF STRUCTURAL STRUCTURAL OVER BEDROCK FOUNDATION FOUNDATION HEIGHT STRUCTURE (ft)
(ft)
(ft)
(ft)
Containment 0
38 157 225 (Diameter)
- Auxiliary-Varies Varies l
Fuel Handling Max. 36 Max. 70 167 x 462 169 Building Min.
O Min.
O Complex Lake Screen 10 37 193 x 116 77 l
House i
3
[
i
- See Figures 2.5-16,2$5-26,and3.8-45.
~
i 4
t i
f 3.7-38 9
ZRAIDWOOD-FSAR QUESTION 362.11 "The safe shutdown earthquake foi the Braidwood Station
~
site is based on the postulated occurrence of a maximum Modified Mercalli intensity VIII (body wave magnitude about 5.8) earthquake near the site (see Byron Station
~
Safety Evaluation Report (SER), NUREG-0876).
The staff's position, as stated in the Byron Station SER, is that a Regulatory Guide 1.60 spectrum with a high frequency anchor of 0.20g at the foundation level of structures founded on rock is an adequately conservative representation of the vibratory ground motion from this size earthquake.
Soils can amplify vibratory ground motion.
The amplitude and frequency of the amplified motion is a function of the physical properties of the material and its thickness.
For all Category 1 structures not founded on rock, demonstrate the adequacy of the design basis by directly calculating a site-specific response spectrum and/or by calculating the amplification of an appropriate rock spectrum resulting from the presence of the soil.
"We recommend that the details of the study planned in response to this question be discussed with the staff prior to work' initiation."
RESPONSE
For the Braidwood site, the design response spectra, which is defined at the ground, is a 0.26g Regulatory Guide 1.60 spectra as shown in Figure 2.5-47.
Foundation level response spectra and time histories were generated by deconvolution as described in Subsection 3.7.1.
The maximum horizontal and vertical ground accelerations at the foundation level is 0.2g for SSE..
l In response to Question 130.6a, all structures and equipment
. required for cold shutdown were reevaluated for a 0.2g Regulatory Guide 1.60 spectra specified at the foundation elevation of all Category I structures.
The founding conditions of the various Category I structures and justification for the use
~
of 0.2g Regulatory Guide 1.60 spectra at the foundation elevation is as follows.
Lake Screen House The Lake Screen House rests on 10 feet of hard glacial till.
The shear wave velocity of the till material is 2,400 f t/sec.
The shear wave velocity of the underlying rock is 3,200 f t/sec.
Because of the high soil column frequency the low velocity contrast (3,200/2,400=1.33) s/4H=60 Hz)
(v and between the rock and the soil medium, there will be no appreciable amplification of motion between the rock and the top of the till in the Q362.11-1 e
-s
4 BRAIDWOOD-FSAR critical frequency range of 1 to 20 Hz.
Thus the use of the 0.2g Regulatory Guide 1.60 spectrum at the foundation elevation of the Lake Screen House for reevaluation in response to Question 130.6a is justified.
Containment Structure The containment structure is founded on rock.
Auxiliary Building Fuel Handling Building Comolex The auxiliary-fuel handling building complex is founded on rock with only a small percentage of the foundation at the periphery overlying soil (see Figures 2.5-16 and 3.8-45).
The major slabs of the structure are continuous diaphragms and monolithically connect the portions on soil to the portions on the rock foundation.
Thus, the structure is essentially founded on rock and was analyzed as such.
%)'
=
J
~.. _
's e
1
- Q362.11-2
l
- ?'
BRAIDWOOD-FSAR QUESTION 371.17 "Are there any governmental agency controls on the river that could preclude withdrawal for the Braidwood Plant for any river flow conditions?
If so, provide a discussion of such controls and effects on plant operability."
RESPONSE
The applicant has agreed to the following conditions set by the Illinois Department of Conservation on water withdrawal from the Kankakee River:
1.
To limit withdrawal of Kankakee River water to a maximum of 160 cfs.
2.
To stop withdrawing water from the Kankakee river when the flow in the river is 442 cfs (7-day 10-year low flow) or less, and not to withdraw water such that the flow of the river is diminished below 442 cfs.
The average makeup withdrawal from the Kankakee River at 100%
load factor is 90.8 cfs, out of which 43.2 cfs is returned to the river as blowdown.
Therefore, the net makeup withdrawal
. from the river is 47.6 cfs.
The low flow frequency and duration information for the Kankakee River at the river screenhouse is shown in Table 2.4-16.
During short periods of time when the net makeup water of 47.6 cfs is not available from the river, the cooling pond water levels will drawdown temporarily.
This drawdown will not affect the normal plant operability.
e i
i 9
e 6
Q371.17-1 6
v-op r
m--
ew-e