ML19319D708
| ML19319D708 | |
| Person / Time | |
|---|---|
| Site: | Crystal River, 05000303  |
| Issue date: | 08/10/1967 |
| From: | FLORIDA POWER CORP. |
| To: | |
| References | |
| NUDOCS 8003240704 | |
| Download: ML19319D708 (8) | |
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APPEIlDIX SA STRUCTURAL DESIGI; BASES
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APPENDIX 5A
(~L]J STRUCTURAL DESIGN BASES, AEC Publication TID-7024, " Nuclear Reactors and Earthquake," as ~amplifi'ed herein v4.11 be used as the basic design for seismic analysis.
Structural. design for nor=al operating conditions vill be governed by the applicable design codes. The design for the loss-of-coolant accident and maximum seismic condition vill ensure no loss of functions when related to public safety.
1 CLASSES OF STRUCTURES AND SYSTEM The plant structures, components, and systems vill be classified according to their function and the degree of integrity required to protect the public.
The classes are:
1.1 CLASS I Those structures, components, and systems, including instruments and con-trols, whose failure might cause or increase the severity of a loss-of-coolant accident or result in an uncontrolled release of excessive amounts of radioactivity and those structures and components which are vital to safe shutdown and isolation of the reactor are classified Class I.
When a system as a whole is referred to as Class I, certain less essential portions not associated with loss of function of the system may later l3
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be designated under Class II or III as appropriate. Examples of Class I structures, components, and systems are:
Reactor Building and its penetrations including plant vent.
a.
b.
Rea,ctor Building crane.
Reactor ve.tsel and its internals including control rod c.
drive assemblies.
- d.
Vital cooling water systems.
Primary system including vents and drains within Reactor e.
Building.
- f.
Spent fuel cooling system and shutdown cooling system.
- g.
Makeup and purification system.
'h.
Engineered safeguards systems including their electrical power sources and distribution systems.
- i. Fuel storage pool.
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j 5A-1 (Revised 3-1-68)
- k.
WastD dicposf. syCtem.
- 1. Post-incident air filtration system.
2
- m. Auxiliary and vaste disposal buildings.
" Totally or partially outside the reactor building.
1.2 CLASS II Those structures, components, and systems which are important to reactor operation but not essential to safe shutdown and isolation of the reactor and whose failure could not result in the release of substantial amounts of radioactivity are classified Class II.
Examples of Class II structures, components, and systems are:
a.
Secondary coolant system.
b.
Electric power system, except emergency systems.
Deleted 1.3 CLASS III Those structures, components, and systems which are not related to reactor operation or centainment are classified Class III.
2 CLASS I DESIGN BASES All structures, components, and systems classified in Class I will be designed in accordance with the following criteria:
a.
Frimary steady state stresses, when combined with the seismic stress resulting from the response to a ground acceleration of 0.05 g acting horizontally and 0.033 g acting vertically and occurring simultaneously shall be maintained within the allovable working stress limits accepted as good practice and where applicable, set forth in the appropriate design standards, e.g., AS!!E Boiler and Pressure Vessel Code, ASA B31.1 Code for Pressure Piping, Building Code Bequirements for Reinforced Concrete, ACI 318 and AISC Specifications for the Design and Erection of Structural Steel for Buildings.
b.
Primary steady state stress when combined with the seismic stress resulting from the response to a ground acceleration of 0.10 acting horizontally and 0.067 g acting vertically and occurring minultaneously, shall be limited so that the function of the component, system, or structure shall not be impaired as to prevent a safe and orderly shutdown of the plant.
In the case of Class I piping systems, no stress 2
value vill exceed 120 percent of the minimum of the allovable stress limits set forth in USASI Standard Code for Pressure
, Piping. : B31.1.0-1967.
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All major structures will be founded on essentially similar material.
1 Because structures will be founded at various elevations, an evaluation lT will be made of permanent differential settlements if any. This factor
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could result in a permanent motion of one building with respect to another which must be accomodated presumably by isolation of the buildings, at least including foundations and concrete superstructures. This presumes that the steel superstructures could be designed to accc=modate this motion.
Where separation is provided, a sufficient gap (rattle space) is also required to prevent physical interaction due to different seismic response.
The foregoing previcions apply to all Class I structures.
The permanent and transient motions of one strveture with respect to another must also be considered in the analysis of the piping systems. The dynamic analycis provides for the determinaticn of the fundemental periods and mode shapes of the piping system / systems. The model to be used will also include as boundary conditions displacements which may be induced at support points.
The effect of shear axial, torsional, and flexural deformations are included in this analysis. Knowing the natural frequencies and mode shapes, the displacements are determined using the response spectra for a single degree of freedom system. After the displacements are determined inertial forces are calculated to obtain internal forces and moments.
Peactor Building Cranes The polar crane is a Class I component and will be designed along with its supporting structure to satisfy the criteria for Class I structures and components contained in Appendix 5A of the Preliminary Safety Analysis Report.
f'N In order to ensure stability -during an earthquake the crane trolley will be tied down to the bridge and the bridge tied down to the runway girder at all times during plant operation.
Crane Brackets The preliminary design provides for a standard WF-section used as a bracket, velded directly to a continuous bent plate ring that is thicker than the liner.
(See Figure SA-1.) The moment introduced to the bracket will be resisted by two structural tees embedded in the vall. The shear vill be transferred frem the bracket web plate, through the liner plate, into the stiffener plates, and resisted by bearing of the structural tee web plates.
5A-2a (Revised 1-15-68) 0193 I
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3 CIfSS II_D_ESIGN BAS _Q r
All structures, ecmponents, and systems classified as Class II will be
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designed for a ground acceleration of 0.05 g in accordance with procedures of the Uniform Building Code published by the International Conference.of Building Officials.
4 CLASS III DESIGN BASES All structures, components, and systems classified as Class III will be designed in accordance with applicable building code requirements.
5 DAMPING ~' ACTORS The following gives the damping factors. used in the seismic design of ecm-por..nts and structures.
Per Cent of Component Or Structure Critical Damping 1.
Reactor Building 2.0 2.
Concrete Support structures inside the Reactor Building 2.0 3.
Assemblies and Structures a) Bolted or Riveted 2.5
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b) Welded 1.0 V
h.
Vital Piping Systems 0.5 5
Other Concrete Structures above ground 5.0 6
METHOD OF ANALYSIS The acceleration response spectra included in Appendix 2I will be used for the design of Class I and II structures, components, and systems. The vertical component of ground motion is assumed to be 2/3 of the horizontal component. The respective vertical and horizontal seismic components at 1
any point on the shell vill be added by summing linearly and directly the h
of each contributing ' 'esponse (i.e., stress, shear, moment, or deflection) absolute values of tt:
suency due to vertical motion and adding the resul-tants to the corresnonding absolute values of the response of each contri-buting frenuency due to horizontal motion.
For Class I structures, components, and systems the method of analysis vill either be a modal analysis wherein modal shapes, fl aquencies, stresses, and proportionality factors are determined or vill be perfor=ed as follows:
a.
The natural period of vibration of the structure, component, or system vill be determined.
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b.
The response acceleration of the co=ponent to the seismic motion will be taken from the response spectrum curve at the appropriate natural period.
Stresses and deflections resulting from the combined in'1uence c.
of normal loads and the additional load from the 0.05 g earth-quake vill be calculated and checked against the limits imposed by the design standard or code.
d.
Stresses and deflections resulting from the combined influence of the normal loads and the additional loads from the 0.10 g earthquake will be calculeted and checked to verify that deflec-tions do not prevent functioning and that stres,ses do not pro-duce rupture or excessive distortion.
e.
h Deleted 7
HEFERENCES Nuclear Reactors and Earthquakes, AEC Publicat.on TID-7024.
a.
b.
Wind Forces on Structures, Task Committee on vind forces, ASCE Paper No. 3269 O
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