ML19329E160
| 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 represen i
s and consensus of the individual judgments of a group of Bechtel eng neer plant consultants who are experienced in both structural and nuclear thm degree of conservativeness inherent in the basic loads, an d; sign.
t
- ind, 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 identified and its effect can be accurately determined at ea (a) t or wind loads, a load factor representing a tolerance of 5 per cen in the vessel.
The ACI Code allows was chosen to account for dead load inaccuracies.
itten 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 accident, t
seismic and wind loads wculd produce a very small portion of the s ress (b)
Also, it is extremely unlikely that the full live loade.
would be present over a large area at the time of an unusual occurenc at any point.
For these reasons, a low load factor is felt to be just d
Seismic -- The design eart'hquake that has been selected is considere during the to be the strongest probable earthquake which could occurIn additio (c) h could earthquake which defines the maximum credible earthquake whic life of the plant.
Class 1 structures are occur at the site, is considered in design.
designed so that no loss of function would result from the For this reason, the two earthquake.
the maximum credible accident is very small.
h events, seismic and accident, are considered together, but at muc The lower load factors than those applied to the events separately.
h design earthquake load factors of 1.25 and 1.0 are conservat l t accident.
With Wind -- Loads are determined from the design tornado wind speed.
is incon-the contairment structure designed for this extreme wind, itTherefore, wind loads (d) 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 1
prsssL e. 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 OO!N 4
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