ML20073R206
| ML20073R206 | |
| Person / Time | |
|---|---|
| Site: | Cooper  |
| Issue date: | 04/30/1983 |
| From: | EDS NUCLEAR, INC. |
| To: | |
| Shared Package | |
| ML20073R189 | List: |
| References | |
| 04-0640-0062, 04-0640-0062-R01, 4-640-62, 4-640-62-R1, TAC-57149, NUDOCS 8305030564 | |
| Download: ML20073R206 (12) | |
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l COOPER NUCLEAR STATION WETWELL-DRYWELL VACUUM BREAKER VALVES LONG-TERM PROGRAM STRUCTURAL EVALUATION Prepared for:
Kaiser Engineers, Inc.
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i Prepared by:
EDS Nuclear Inc.
350 Lennon Lane Walnut Creek, California 94598 April 1983 EDS Report No. 04-0640-0062 Revision 1
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8305030564 030429 PDR ADOCK 05000298 P
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KAISER ENGINEERS, INC.
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TABLE OF CONTENTS
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Section Page f
Table of Contents i
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1.0 INTRODUCTION
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2.0 SCOPE OF WORK 2
i 3.0 APPLICABLE CODES 2
4.0 DESIGN LOADS 2
5.0 VACUUM BREAKER EVALUATION 3
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6.0 CONCLUSION
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7.0 REFERENCES
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l TABLES AND FIGURES 5.
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1.0 INTRODUCTION
i This report, prepared by EDS Nuclear Inc. (EDS) for Kaiser Engineers, describes l
the piant-unique structural evaluation of the Cooper Nuclear Station GPE 18" i
Wetwell-to-Drywell Vacuum Breaker Valves for hydrodynamic loads associated with a postulated Loss-of-Coolant Accident (LOCA). In addition, seismic and normal operating loads are also considered. The evaluation is performed for the j
existing vacuum breakers which have already been modified once. These modifications include replacement of the hinge shaft and hinge arms with higher strength materials and the securement of all fasteners. The vacuum breaker-vent header intersection has been previously qualified in the vent header evaluation.
j As a result of this plant-unique final evaluation, the vacuum breaker valves are shown to meet the design requirements.
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04-0640-0062 Revision 1 Page 2 2.0 SCOPE OF WORK The objective of this work is to assist Nebraska Public Power District in comply-ing with the Mark I Containment Program requirements by qualifying the GPE vacuum breaker valves installed at Cooper Nuclear Station. In Cooper Nuclear Station, the GPE wetwell-to-drywell vacuum breakers are located in the wetwell, cantilevered from the main vent header. Figure 1 illustrates their relative position inside the Mark I Containment. A schematic of the GPE vacuum breaker is shown in Figure 2.
The vacuum breaker is basically a check valve permitting gas to flow into the drywell only. During a postulated Loss-of-Coolant Accident (LOCA), the vacuum breaker will be exposed to a drywell/wetwell pressure differential as shown in Figure 3.
This pressure transient is comprised of a number of different 4
l phenomenon which result in different loadings to the vacuum breakers valves and their components. This report describes the structural evaluation of the vacuum i
breaker valves, j
i 3.0 APPLICABLE CODES The Code of Record as per Reference 1 is the ASME Code,Section III, Subsection NC-3500, for Class 2 components up to and incl.uding the Summer 1977 Addenda.
In addition, Code Case N-62-2 (1621-2), " Internal and External Valve ItemsSection III, Division 1, Class 1, 2, and 3 Line Valves", approved May 15, 1980, was used i
in the evaluation.
4.0 DESIGN LOADS The loads acting on the vent system and on~ the vacuum breaker valves are exten-I sively described in Reference 2, which is based upon the Mark I Program Load Definition Report (Reference 3) and the NRC Acceptance Criteria (Reference 4).
The loads acting on the vacuum breakers include gravity, seismic, and hydrodynamic loads. The hydrodynamic loads consist of direct fluid loads acting on the vacuum breakers and hydrodynamically-induced vent header accelerations at the vacuum I
breaker penetrations. The hydrodynamically-induced pallet impact loads were also
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considered. These loads were based on the pallet impact velocities provided in
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l Reference 5.
A table of the load cases and load combinations considered is provided in Reference 6.
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S.0 VACUUM BREAKER EVALUATION The evaluation is performed for the following valve components:
1.
Pallet 2.
Hinge Arm 3.
Hinge Shaft 4.
Hinge Arm Studs 5.
Valve Seat Bolts These components are considered critical from the point of view of responding at a significant level to at least one of the design loads.
The loads are combined in the structural evaluation as per Reference 6, and the resulting stress values obtained are compared to the stress limits as per References 7 and 8.
A sinmary of the governing stresses for the five valve components is provided in Table 1 for the significant design loads. Table 2 provides the critical stresses together with the stress allowables for the governing load combinations. Stresses induced to the pallet, hinge shaft, and hinge arm by impact loading from chugging were evaluated by finite element analyses using the ANSYS computer program. A detailed finite element model of the pallet, hinge ann, and hinge shaft was developed using plate and beam elements. A transient analysis was perfomed to compute the stresses in these components due to the impact load. Stresses associated with the remaining load cases were evaluated by a static or equivalent static analysis. Stresses in the hinge arm studs and valve seat bolts were evaluated based on the corresponding response of the hinge ann and pallet to the static and dynamic induced loadings. A summary of the evaluations for each of the components is provided next.
Pallet i
The pallet was evaluated for the impact loading due to chugging and for the pressure differential following a postulated LOCA. The pallet was found to qualify.
Hinge Shaft The hinge shaft was analyzed for seismic, gravity, and hydrodynamically-induced loads. The shaft was found to qualify.
Hinge Am The hinge anns were evaluated for gravity, seismic, and hydrodynamically-induced
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loads. The hinge arms were found to qualify.
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KAISER ENGINEERS, INC.
04-0640-0062 Revision 1 Page 4 Hinge Arm Studs The studs for the hinge ann were evaluated for gravity, seismic, and hydrodynamically-induced loads. The studs were found to qualify.
Valve Seat Bolts The twenty valve seat bolts were evaluated for loads due to seismic, to pressure differential across the vacuum breaker pallet, and to pallet impact on the pallet seat. The bolts were found to qualify.
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6.0 CONCLUSION
S The existing 18" GPE Wetwell-to-Drywell Vacuum Breaker Valves at Cooper Nuclear Station have been found to meet the design requirements; no modifications,are required.
7.0 REFERENCES
1.
" Mark I Containment Program Structural Acceptance Criteria, Containment System Design Rules and Classification, Task Number 3.1.3", General Electric Report NED0-24522, April 1978.
2.
" Cooper Nuclear Station, Thermal Hydraulic Load Definition for Vent System, Torus Shell, and Structures within the Torus (Worker Order No.14)", EDS l'
Nuclear Report No. 01-0640-1071, Revision 1, November 1981, i
3.
" Mark I Containment Program, Load Definition Report", NEDO-21888, Class. I, Rev.1, March 1980.
4.
"Saf,ety Evaluation Report, Mark I Containment Long-Term Program", U.S. Nuclear Regulatory Commission, NUREG-0661, July 1980 5.
" Improved Dynamic Vacuum Breaker Valve Response for Cooper", Rev. O, Continuum Dynamics, Inc., Tech Note 82-31, October 1982.
6.
" Mark I Containment Program Structural Acceptance Criteria Plant-Unique Analysis Applications Guide, Task Number 3.1.3", General Electric Report NEDO-24583-1, October 1979.
7.
ASME Code Case N-62-2 (1621-2), " Internal and External Valve Items,Section III, Division I, Class 1, 2, and 3 Line Valves," approved May 15, 1980.
8.
ASME Code,Section III, Subsection NC-3500, up to and including the Summer i
1977 Addenda.
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KAISER ENGINEERS, INC.
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04-0640-0062 Revision 1 Page 6 TABLE 1 STRESSES (psi)
Hinge Hinge Hinge Arm Pallet Seat Load Pallet Arm Shaft Studs Bolts 79 9 1,959 7 29
- 1. Gravity
- 2. Earthquake (SSE) 1 65 392 302
- 3. S/RV 6,6 41 17,991 12,115
- 4. Pool Swell
- 5. Condensation 106 1,475 10,299 7,896 169 Oscillation
- 6. Chugging 20,984 14,750 25,000 13,491 13,371 2,032
- 7. Pressure 1,276 (LOCA-induced following DBA)
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j TABLE 2 1
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STRESSES (psi) 1 Hinge Hinge Hinge Arm Pallet Seat Pallet Arm Shaft Studs Bolts l
Material SA-516 SA-516 SA-479 SA-516 SA-320 Gr 70 Gr 70 MX19 Gr 70 B8 f
Allowable Sh 17,500 17,500 25,000 17,500 15,000 i
Service Level A
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Load Combination 22,260 15,549 26,959 14,220 15,403 (1 + 6 + 7)
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Allowable (1.5 x S )
26,250 26,250 37,500 26,250 22,500 h
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Stress Ratio 0.85 0.59 0.72 0.54 0.68 i
service Level B l
Load Combination 22,260 15,632 27,155 14,371 15,403 (1 + 0.5
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l Allowable (1.65 x S )
28,875 28,875 41,250 28,875 24,750 h
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Stress Ratio 0.77 0.54 0.66 0.50 0.62-
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l Service Level C l
Load Combination 22,260 15,714 27,351 14,522 15,403 l
(1 + 2 + 6 + 7)
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Allowable (1.8 x S )
31,500 31,500 45,000 31,500 27,000 h
l Stress Ratio 0.71 0.50 0.61 0.46 0.57 i
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i FIGURE 3 Typical Pressure Differential Across Vacuum Breaker During LOCA z
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