IAEA activities on passive safety systems and overview of international development

Analyzing the Role of Values and Ideals in the Development of Energy Systems: How Values, Their Idealizations, and Technologies Shape Political Decision-Making

This study examines an important aspect of energy history and policy: the intertwinement of energy technologies with ideals. Ideals play an important role in energy visions and innovation pathways. Aspirations to realize technical, social, and political ideals indicate a long-term commitment in the design of energy systems, distinguishable from commitment to other abstract goals, such as values. This study offers an analytical scheme that could help to conceptualize these differences and their impact on energy policy. In the proposed model, two spheres of interaction are highlighted: a material sphere in which values and technologies co-evolve, and an imaginary sphere in which ideals interact with idealized technologies. Furthermore, the relation between these two spheres can be understood in different ways. This study examines three cases that are illustrative of the different roles of ideals in the development of energy technologies and visions: (1) the evolution of safety in nuclear reactor design; (2) visions of atomic power in France; (3) the political idealization of a tidal power scheme in the Severn Estuary. Finally, the developed model implies more general insights for the development of sociotechnical systems. Amongst others, it shows why certain projects and technologies remain a political, but not a techno-economic option.

Analysis of operating characteristics of IPWR under natural circulation

Many integrated pressurized water reactor (IPWR) designs using natural circulation operation mainly to enhance their inherent safety. The operating characteristics of primary coolant are completely different without mechanical pumps. The designs and safety analysis of forced circulation reactors are widely researched, but the natural circulation characteristics of IPWR have not been well studied by literatures. The present work discussed the thermal-hydraulic characteristics of IPWR under natural circulation conditions by using the best estimate codes RELAP5. And the effect of system parameters on natural circulation characteristics of IPWR is also studied. The results show that, the primary coolant average temperature and steam pressure are two key parameters that affect the natural circulation stable operating load. The set value of primary coolant average temperature effects the core outlet temperature and the steam temperature, but the primary coolant flow is basically the same under different primary coolant average temperature but same load conditions. The smaller steam pressure is more conducive to produce superheated steam, but there is risk of two phase flow instability in OTSG secondary side. The rapid load change process under natural circulation indicating that the reactor has a good load tracking characteristics under natural circulation, but the rapid change of primary coolant temperature will cause oscillations in system parameters.