ML20028G594
| ML20028G594 | |
| Person / Time | |
|---|---|
| Site: | Fermi  |
| Issue date: | 02/04/1983 |
| From: | Lehnert R, Steinert L, Teramoto C NUTECH ENGINEERS, INC. |
| To: | |
| Shared Package | |
| ML20028G592 | List: |
| References | |
| DET-15-038, DET-15-038-R00, DET-15-38, DET-15-38-R, NUDOCS 8302170056 | |
| Download: ML20028G594 (20) | |
Text
I DET-15-038 Revision O
(
ENRICO FERMI ATOMIC POWER PLANT
[
UNIT 2 SINGLE DOWNCOMER CHUGGING LATERAL LOAD
[
[
Prepared for:
Detroit Edison Company
{
E L
Prepared by:
NUTECH Engineers L
Prepared by:
Issued by:
c W
'H.fr 1
~
C.
S.
- Teramoto, P.E.
L.
D.
Steinert
~
Consultant I Project Manager E
L p
Approved by:
L fasl'rg,M.y 4,f993 Date:
L R.
A.
- Lehnert, P.E.
Engineering Manager 8302170056 830204 OU PDR ADOCK 05000341 A
I
[
REVISION CONTROL SHEET TITLE: Enrico Fermi Atomic Power REPORT NUMBEft: DET-15-038 I
Plant, Unit 2, Single Downcomer L
Chug ing Lateral Load
(
R. A. Lehnert/Eng. Manager INmALS W
[
J. D. Lowe/ Specialist INmALs
)
on S. P. Quin'/ Senior Technician n
C. S. %4 csr _
INmALS
{
C. S. Teramoto/ Consultant I INmALS PA EO ANAW WMRLA PAGE(51 REV REMAR KS SY / OATE CHECK BY / OATE CHECA BY / OATE
@E es-/rzw.c 4+
g4g:
i-iv 0
-+G 1-4 0
g/.+p, cWr4 n 5
0 2
6-10 0
Cyf2453 hd'0I ggf/[z45 JR{n.n 11 0
4FI 240
%g483, a 4 r3 12 0
q C.vT
-6)
+93 13-14 0
f
(
(
m
[
nutgqh
TABLE OF CONTENTS Page
(
LIST OF TABLES iii LIST OF FIGURES iv
(
l.0 INTRODUCTION 1
2.0 SINGLE DOWNCOMER LATERAL IDAD CAPACITIES 3
l 3.0 METHODS TO INCREASE DESIGN MARGINS 6
4.0 CONCLUSION
13 LIST OF REFERENCES 14
[
[
1 DET-15-038 ii Revision O l
nutggh
k I
s r
LIST OF TABLES L
Table Title Page I
(
2.1 Single Downcomer Chugging Lateral Load Capacities 5
3.1 Summary of Design Margins in the Out-of-Plane Direction 11
(
l
\\
DET-15-038 iii Revision 0 nutagh
LIST O? FIGURES Figure Title Page 3.' l Proposed Distributions for Maximum Single Downcomer Lateral Load 12 c
DET-15-038 iv Revision 0 nutgg;b
1.0 INTRODUCTION
As part of the Nuclear Regulatory Commission (NRC) review of the Fermi 2 Plant Unique Analysis Report (PUAR) (Reference 1), the basis for the generic chugging downcomer lateral loads for Mark I plants defined in NUREG-0661 (Reference 2) was reviewed.
The review included comparisons with chugging loads for Mark II e
plants, which arc defined in NUREG-0808 (Reference 3).
4 The NRC concluded that the single downcomer chugging lateral loads defined for Mark I plants may not be the bounding condition, because of the limited size of the Full Scale Test Facility (FSTF) data base when compared with conditions postulated for an actual plant.
The current loads defined by NUREG-0661 for multiple chugg-ing downcomer lateral loads or fatigue are unaffected.
The NRC has agreed that their concern would be resolved if individual plants demonstrate that adequate design margins exist for an increased single downcomer lateral load.
Accordingly, several methods which demonstrate increased design margins for load combinations contain-ing a single downcomer lateral load for Fermi 2 are presented in this report.
The critical Fermi 2 location af fected by the single downcomer chugging lateral load DET-15-038 1
Revision 0 nutggh
(
is the vent header /downcomer intersection.
This report documents the existence of sufficient design margins for the Fermi 2 vent header /downcomer intersection to accomodate a substantial increase in the single downcomer chugging lateral loads.
DET-15-038 2
Revision 0 nutggb A
2.0 SINGLE DOWNCOMER LATERAL LOAD CAPACITIES A description of the vent header /downcomer intersection is contained in the Fermi PUAR (Reference 1).
A crotch plate and two stiffener plates transfer in-plane loads from the downcomer to'the vent header, as shown in Figure 3-2.1-12 of Volume III of the PUAR.
A bracing system transfers out-of plane
- oads from the downcomer to the vent header as shown in Figure 3-2.1-11 of Volume.
III of the PUAR.
The overall effect of the reinforced vent header /downcomer intersection is a substantial increase in capacity for downcomer lateral loads.
The design is such that the stiffness of the in-plane direction is greater than that of the out-of-plane direction.
As a result, the in-plane downcomer frequency is larger than that of the out-of-plane downcomer frequency.
The maximum chugging downcomer lateral load acting on a single downcomer in the in plane and estt-of-plane directions is calculated using the method defined in NUREG-0661, as described in the Fermi 2 PUAR.
The FSTF data used to calculate these loads include the maximum measured Resultant Static Equivalent Load (RSEL) of 3046 lb and the untied downcomer frequency of 2.9 Hz.
The DET-15-038 3
Revision 0 nutggb
Fermi 2 data used in this calculation include the in-plane downcomer frequency of 12.4 Hz and the out-of-plane frequency of 7.6 Hz, obtained using the methods discussed in the Fermi 2 PUAR.
The resulting in-plane and out-of-plane single downcomer lateral loads are shown in Table 2.1.
As reported in the Fermi 2 PUAR, the controlling load combination for Fermi 2 which includes chugging downcomer lateral loads is the SBA II combination.
The allowable stresses for the SBA II load combination correspond to the ASME Code Service Level B condition.
The capacities for an increased single downcomer lateral load are obtained by increasing the stresses due to the chugging downcomer lateral load, within the SBA II combination, until the Service Level B allowables are reached.
The ratio of the increased stresses due to chugging to the stresses for the original chugging load, represents the amount by which the downcomer lateral load may be increased.
The resulting capacities and percent of increase in generic load for the in-plane and out-of-plane directions are summarized in Table 2.1.
As shown in Table 2.1, the capacity of the vent header /
downcomer intersection is controlled by the out-of-plane load, in which the generic RSEL of 3046 lb may be increased by 38.4 percent to 4216 lb.
DET-15-038 4
Revision O nutggh
Table 2.1 SINGLE DOWNCOMER CHUGGING LATERAL LOAD CAPACITIES LOAD
% OF
% INCREASE DIRECTION FREQUENCY MAGNITUDE CAPACITY CAPACITY IN GENERIC (Hz)
(kips)
(kips)
(1)
LOAD (2)
In-plane 12.4 13 24.5 53 88 Oute f-Plane 7.6 8
11.07 72 38 NOTES:
L ad Magnitude 1.
% of Capacity =
Capacity Capacity - Load Magnitude 2.
% Increase in Generic Load =
Load Magnitude DET-15-038 5
Revision 0 nutggh
3.0 '
METHODS TO INCREASE DESIGN MARGINS Three. methods are. presented in this section to increase the existing downcomer lateral load design margins discussed in Section 2.0 and summarized in Table 2.1.
These methods include the use of the Square Root of the Sum of the Squares (SRSS) method as a means of combining responses of the dynamic loads; the use of a more realistic chugging load distribution over the lower portion of the downcomer; and the use of a revised acceptance criterion for load combinations containing the single chugging downcomer lateral load.
The appli-cation of these methods to Fermi 2 are discussed in the paragraphs which follot.
3.1 SRSS The results of load combinations contained in the Fermi 2 PUAR are obtained by combining stresses from dynamic loads absolutely.
This method conservatively implies that the maximum stresses due to chugging downcomer lateral loads, Safety Relief Valve (SRV) discharge loads and seismic loads occur simultaneously.
NUREG-0808 suggests that the probability of this event occurring is negligible.
Therefore, the use of a more realistic method, such as SRSS, to combine stresses for this DET-15-038 6
Revision 0 nutggh
(
condition is appropriate.
The use of SRSS has been previously approved for piping analysis in NUREG-0484.
The downcomer lateral load capacity for Fermi 2 is increased by 35 percent using SRSS to combine the stresses in the SBA II load combination.
As a result, Fermi 2 is able to accommodate a 48 percent increase in the generic RSEL of 3046 lb, as shown in Table 3.1.
3.2 Load Distribution The chugging downcomer lateral loads evaluated in the Fermi 2 PUAR are applied as concentrated loads at the ends of the downcomers.
Application of the load in this manner is conservative, since an assymetric bubble collapse during chugging would result in a pressure load distributed over a finite length of the downcomer.
A more realistic method of applying the load would be to assume a uniform or hydrostatic distribution over the lower 2 feet of the downcomer, as shown ir. Figure 4.1.
Use of a distributed downcomer lateral load results in a reduction in the bending moment applied to the vent header /downcomer intersection.
Applying chugging lateral loads in a uniform distribution is consistent with the Mark II chugging load definition contained in NUREG-0808.
DET-15-038 7
Revision 0 nutggb
The downcomer lateral load capacity for Fermi 2 is increased by 14 percent using a more realistic distribution of the downcomer lateral load to evaluate the SBA II load combination.
As a result, Fermi 2 is I
able to accommodate a 19 percent increase in the generic RSEL of 3046 lb, as shown in Table 3.1.
3.3 Acceptance Criteria The alternate methods discussed in the preceding paragraphs increase the design margins by decreasing the calculated stresses for a given downcomer lateral load.
The design margins can also be increased by using less restrictive acceptance criteria or allowable stresses.
This method is appropriate for load combinations which include maximum chugging downcomer lateral loads since this load is not a sustained load and has a low probability of occurring.
This condition is similar to that of pool swell impact and the acceptance criteria for the associated load combination.
The proposed acceptance criteria for load combinations containing the maximum single downcomer chugging lateral load is the same as the criterion for load combinations containing pool swell as defined in NUREG-0661.
The DET-15-038 8
Revision 0 nutg.gh
criterion with and without SRV discharge loads are as follows:
l 1.
Without SRV discharge loads, modified Service Level B allowables are used:
a.
Primary membrane allowables remain unchanged b.
Local primary membrane allowables are increased by a factor of 1.3 c.
Primary-plus-secondary stress range evaluation is not required d.
Evaluation of fatigue is not required e.
Component support allowables remain unchanged 2.
With SRV discharge loads, Service Level C allowables are used:
a.
Primary membrane allowables are equivalent to the material yield stress b.
Local primary membrane allowables are equal to a factor of 1.5 of the mar ~
eld stress c.
Primary-plus-secondary str
,a evaluation is not required d.
Evaluation of fatigue is not required e.
Component support allowables are increased by a factor of 1.33 1
DET-15-038 9
Revision O nutggh
As in the case of pool swell, use of this acceptance criteria ensures that the integrity of the containment i
is maintained although small deformations near discontinuities are permitted.
The application of this acceptance criteria results in a substantial increase in the vent header /downcomer intersection with or without l
SRV discharge loads as shown in Table 3.1.
The controlling case is the load combination without SRV discharge loads, which increased the downcomer lateral load capacity by 88 pertant. As a result, Fermi 2 is able to accommodate a 123 percent increase in the generic RSEL of 3046, as shown in Table 3.1.
i DET-15-038 10 Revision 0 nutggb
i Table 3.1
SUMMARY
OF DESIGN MARGINS IN THE OUT-OF-PLANE DIRECTION METHOD OF
% INCREASE IN
% INCREASE CAPACITY CALCULATING EXISTING ALLOWED IN (kips)
CAPACITY GENERIC LOAD DESIGN MARGIN (1)
(2)
Existing 11.07 0
38 SRSS 14.87 35 48 Distributed 12.62 14 19 Load w/out 20.90 88 123 Modified SRV Acceptance Criteria w/SRV 26.57 140 193 NOTES:
Capacity - Existing Capacity 1.
% Increase in Existing Capacity =
Existing Capacity Capacity - Load Magnitude 2.
% Increase Allowed in Generic Load =
Load Magnitude Load Magnitude = 8 kips DET-15-038 11 Revision 0 nutp_qh
(
E VENT HEADER I
I
/
\\
/
\\
,/
\\
s g
I l
I
_ ~ - _ -- _-
__ ___ ? --
Y il h
2'-0" 2'-0"
\\
U :
\\
a t_
Hydrostatic Uniform Distribution Distribution Figure 3.1 PROPOSED DISTRIBUTIONS FOR MAXIMUM SINGLE DOWNCOMER LATERAL LOAD DET-15-038 12 Revision 0 py{
4.0 CONCLUSION
As can be seen from the results presented in Sections 2.0 and 3.0, adequate design margins exist for an increased single downcomer lateral load for Fermi 2.
Combining the effects of applying SRSS for load combination formulation (48%) and a more realistic chugging load distribution (19%), with the existing increase allowed in the generic load (38%), results in the ability to accommodate a single downcomer lateral load 105 percent larger than the load presently defined in NUREG-0661.
Furthermore, applying less restrictive acceptance criteria for load combinations involving the maximum single downcomer load results in the ability to accommodate an additional 123 percent increase in the present NUREG-0661 load.
Therefore, with the use of more realistic considerations, this report demonstrates that the Fermi 2 vent header /downcomer intersection design is capable of accomodating a substantial increase in single downcomer chugging lateral loads.
DET-15-038 13 Revision 0 nutggh
LIST OF REFERENCES I
1.
Enrico Fermi Atomic Power Plant, Unit 2, Plant Unique Analysis Report, Volumes 1-5, NUTECH documents DET-04-028-1, DET-04-028-2, DET-04-028-3, DET-04-028-4 and DET-05-015-5, all Revision 0, April 1982.
2.
Safety Evaluation Report Mark I Containment Long-Term
- Program, U.S.
NRC NUREG-0661, July 1980.
3.
Mark II Containment Program Load Evaluation and Acceptance
/
- Criteria, U.S.
NRC NUREG-0808, August 1981.
DET-15-038 14 Revision 0 nutp_qh