ML19329E160

App 5D of AR Nuclear 1 PSAR, Load Factors & Load Combinations. Includes Revisions 1-18

ML19329E160
Person / Time
Site:	Arkansas Nuclear
Issue date:	11/24/1967
From:	ARKANSAS POWER & LIGHT CO.
To:
References
NUDOCS 8005300772
Download: ML19329E160 (3)

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APPENDIX 5-D JUSTIFICATION FOR LOAD FACTORS Ag .

LOAD COMBINATIONS USED IN DESIGN EQUATIONS _

FOR CONTAIMCIT STRUCTURE t the Tha load factors and load ccubinations in the design criteria srepresen i and consensus of the individual judgments of a group of Bechtel eng neer plant consultants d; sign.

who are experienced in both structural and nuclear ind, thm degree of conservativeness inherent in the basic loads, an t by the probabilities of coincident occurrences in the case of acciden , w and seismic loads. individual The following discussions will explain the justification for the factors, particularly as they apply to containment structures.

Dead Load -- Dead load in a large structure such as this is easily (a) _

identified and its effect can be accurately determined t at ea in the vessel.

or wind loads, a load factor representing a tolerance The ACIof Code 5 perallows cen itten was chosen to account for dead load inaccuracies.

a tolerance of +25 per cent and -10 per cent, but the code was wr f to cover a variety of conditions where weights and configurations o materials in and on the structure may not be clearly defined and are subject to change during the life of the structure.

Live Load -- The live load that would be present along with t accident, (b) seismic and wind loads wculd produce a very small portion of the s ress at any point. Also, it is extremely unlikely that the full live load e.

would be present over a large area at the time of an unusual occurenc For these reasons, a low load factor is felt to be just d

Seismic -- The design eart'hquake that has been selected during theis considere (c) to be the strongest probable earthquake which could h couldoccurIn addition life of the plant.

earthquake which defines the maximum credible earthquake Class 1 structures are whic occur at the site, is considered in design.

designed earthquake .

so that no loss of function wouldtheresult For this reason, two from the the maximum credible accident is very small. h events, seismic and accident, are considered together, but at Themuc lower load factors than those applied to the events separately. h design l t earthquake load factors of 1.25 and 1.0 are conservat accident.

With Wind -- Loads are determined from the design tornado wind speed.

is incon-(d) the contairment structure designed for this extreme wind, itTherefore, wind loads ceivable that the wind would cause an accident.However, a load factor of will not be considered with accident loads.

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1.25 will be applied to the tornado load to provide assurance of the structure performing satisfactorily at design wind. ,

(e) Accident -- The design pressure and temperature are based on the operation of partial safeguards equipment using emergency diesel power.

European practice has been to use a load factor of 15 on the design prsssL e1 . This factor is reasonable and has been adopted for this design. "~ae probabilities of a maximum accident occurring sinaltaneous-ly with a maximum vind or seismic disturbance are very small, therefore, a reduced load factor of 1.25 is used for the combination of events.

In c.11 cases the design tercerature is defined as that corresponding to the factored pressure. At 1.;iP the temperature will be somewhat higher than the temperature at P. It would be unrealistic to apply a corres-ponding temperature factor of 1 5, since this could only occur with a pressure rach greater than a pressure of 15P.

1. Refer T. C. Waters and N. T. Barrett, " Prestressed Concrete Pressure Vessels for Nuclear Reactors," J. Brit. Nucl. Soc. 2,1963 -

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