15.8. During the years that have elapsed following the design and con­struction of present nuclear plants, much effort has been devoted to plan­ning the features of new plants. In fact, a major Electric Power Research Institute (EPRI) program was devoted to the development of a compre­hensive set of design requirements for advanced plants. Although there are several different advanced plant concepts, they all share features in­tended to simplify design, with an accompanying reduction in construction time and costs. Standardized design is emphasized for the entire plant, not just the nuclear portion. Also, all concepts utilize advanced instrumentation and control systems to improve safety and reduce costs.

15.9. Designers have specified standard components where possible and arranged these components into prefabricated modules. During recent years, the petroleum, shipbuilding, and power plant industries have developed successful construction practices featuring the manufacturing of very large component modules at a central location and then transporting them to the construction site. In this way, fabrication and inspection is more effi­cient and field labor costs are reduced. Clearly, cost benefits are increased if the manufacturing facility serves several plant sites. Modularization is carried an additional step with gas-cooled and liquid metal-cooled concepts in which several small steam generating units are coupled to a turbine — generator to form a power block. These may then be replicated at a given site to provide whatever station capacity needed.

15.10. The development of advanced instrumentation and control sys­tems has been coordinated by the Electric Power Research Institute. Con­trol rooms have been redesigned using human factors principles. Digital instrumentation and multiplex signal transmission have been featured. The level of automation of control tasks has been increased. Maintenance —

related instrumentation throughout the plant has received attention, par­ticularly that providing diagnostics to identify equipment that may be ap­proaching failure although still operationally functional.