ML19319C275

App 5B to Davis-Besse PSAR, Descriptions of Load Factors for Shield Bldg & Containment Internal Structure Design.

ML19319C275
Person / Time
Site:	Davis Besse
Issue date:	08/01/1969
From:	TOLEDO EDISON CO.
To:
References
NUDOCS 8002110750
Download: ML19319C275 (4)

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D-B APPENDIX 5B DESCRIPTIONS OF LOAD FACTORS FOR SHIELD BUILDING AND CONTAINMENT INTERNAL STRUCTURE DESIGN The following are descriptions for load factors used in the design equations in Section 5.2.2 5, and in Section 5.2.3 1 Dead Load:

The dead load factor for the shield building design will be 1.0 in combination with the other factored loads. The reason for using this load facter instead of those suggested by ACI-318-63 code is that the code is written for general types of construction. Since the dead weight of the shield building can be accurately determined because of its simple geometric configuration, a load factor of 1.0 is justified.

A factor ef 1.0 is also justified for the internal structure 3 since the most unpredictable dead loads such as the major equipment loads are excluded from the dead load, and considered separately. During operating and shutdown conditions the centainment internal structure will be investigated according to ACI-318-63 code, and the dead load factor vill be 7

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2 Live Load:

The live load that would be present along with accident, seismic and wind loads would produce a very small portion of the stress at any point. Also, it is extremely unlikely that the full live load would be pr ssent over a large area at the time of an unusual occurrence. For these reasons a low load factor is felt to be justified and live load will be considered together with dead load at a load factor 1.0.

3 Earthouake Loads:

For the maximum probable (smaller) earthquake of 0.08 g ground

, acceleration, a factor of 1.25 is used in combination with the other factored loads in designing both the shield building and the containment internal structure. The selection of this load factor is in agreement with past and current practice of concrete containment design for nuclear power plants and also the ACI-318-63 code. Under the condition of maxi =um possible (larger) earthquake of 0.15g ground acceleration a factor of 1.0 vill be used both for the shield building and the containment internal structure.

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5B-1 Amendment No. 3

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The fat e of unity is consistent with the loading condition '^

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which i to demonstrate no loss of function under a maximum possible (larger) loading condition.

k Wind Load:

The shield building vill be designed to withstand the vind load and the associated pressures. The design load factor vill be 1.25 in combination with the other factored loads in accordance with the ACI-318-63 code.

5 Tornado Load:

The shield building vill be designed to withstand the tornado load and the associated pressure differential vi,sout loss of function. A load factor of 1.0 vill be used and is consistent with the loading condition and vill demonstrate no loss of func-tion under a maximum hypothetical condition.

6 Temnerature Load:

The shield building and the containment internal structure vill be designed for ther=al loads (temperature gradients) in combina-tion with the other factored loads. Accurate extremes can be determined in establishing the temperature gradient through walls, do=e, and slabs. Therefore a thermal load factor of unity with variations of + 5 percent and + 10 percent may be used for the shield building and containment internal structure respectively.

The variations in load factors are consistent with the degree of structural complexities in the relative structures, and are considered in the same category as dead loads.

7 Loss of Coolant Accident Lead:

The steel containnent vessel practically isolates the shield building from the reactor coolant systems and therefore eliminutes significant pressura and temperature loads on the shield building during an accident. However, small pressure buildups and tempera-ture changes do occur in the annulus during the accident. These vill be taken into account in design. The load factor for LOCA vill be 1.0 in co=bination with the other factored loads. The shield building vill also be analyzed for one and one-half times the LOCA load for no loss of function. (

8 Equipment Load:

The equipment loads in the containment internal structure are separated from the dead load so that more reasonable load factors can be assigned to the equipment dt a weight. A factor of 1.5 is used for equipment load during operating and shutdown condi-tions in accordance with the ACI-318-63 code. Otherwise, a factor of 1.25 is assigned to allow for inaccuracy resulting 3 from weight calculations and load distributions. For the case of ,

I:.aximum possible (larger) earthquake, a factor of unity is assigned to the equipment load.

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D-B p 9 Miscellaneous Loads: -

During a loss of coolant accident, the containment internal structure will be subjected to such accident loads as pressure, thermal, missile, jet force, and piping anchor loads. Load factors are assigned to different load sources in loading combi-nations as shown in Section 5.2.2.3. The losd factors are assigned recognizing the degree of accuracy available in determining the loading and also the unlikely combination of simultaneous load occurrences.

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