readily transportable to, the construction site. A large on-land near- 

 shore construction site, preferably with a graving basin, will be needed 

 as will a protected shallow water site. A near-shore, protected deep 

 water site with a deep passage to sea is highly desirable to 

 preclude or minimize the need for expensive flotation and to minimize 

 construction time in the open sea. The construction site will likely 

 need to be at or near an industrial area to most economically provide 

 trained manpower, construction equipment and supporting services. 



The structural requirements to provide "System Reliability" are: 



1. Design for Service and Survival Modes . The structure will probably 

 be designed to operate in a service mode during a defined environmental 

 condition or a defined accident condition. For sea and accident conditions 

 beyond the service mode, the structure will be designed for survival. 



That is, the structure will maintain its integrity and remain afloat so 

 that men and the facility are safe; however, power is not being generated 

 and repairs may be needed before the plant is again in operation. 



2. Safety . Safety depends on probability of failure and consequences of 

 failure. Thus safety requires structural characteristics that will mini- 

 mize probability of failure by good quality design and construction, durable 



materials, and so forth and that will minimize the seriousness of failure 

 by designing for an acceptable mode of failure. 



3. Noncatastriphic Failure Mode . Structural failure should be gradual 

 and partial rather than sudden and catastrophic. This requires the use 

 of structural redundance, the provision of structural resilience (to 

 absorb energy without failure) and structural ductility (to accommodate 

 deformation without failure) , and the avoidance of instability failure. 

 Accident tolerance may require sacrificial protective structures such 



