Medium-sized Reactor Research Articles

06/02129 Recursively coupled thermal and mechanical FEM–analysis of lower plenum creep failure experiments: Willschütz, H. -G. et al. Annals of Nuclear Energy, 2006, 33, (2), 126–148.

A conceptual design study for a small-pressurized water reactor (PWR) core has been presented in this research paper that utilizes carbon coated fuel particles with a novel composition. The utilization of novel tristructural-isotropic (TRISO) fuel particles can completely eliminate the use of soluble boron system and requirement of burnable poison if adequate number of control rods is used. Apart from the simplification of the design by excluding such as complex systems from the design, the utilization of TRISO fuel particles in PWR technology can enhance the design integrity by confining the radioactive fission products within fuel itself during reactor operation. Reactor simulation computer codes WIMS-D/4 and CITATION were used for neutronics design and RELAP5 was used for thermal hydraulic analysis. The designed core is small which has only 25 MWth power out put with more than 2 EFPY operating life. The values of Doppler, moderator and void reactivity coefficients were found negative. The Soluble Boron Free (SBF) and Burnable Poison Free (BPF) concepts are more viable in small and medium size reactors (SMRs) because it makes the plant simpler and uniform burnup can also be achieved throughout the core life.

低減速自然循環沸騰水型炉における起動時の流動安定性に関する基礎研究(NP3 新型炉技術)

Reduced-moderation natural circulation BWR has been promoted by JAERI in Japan as one of advanced small and medium-sized reactors from the aspect of more effective utilization of uranium and introduction of passive safety systems in conformity with the natural law. However, various thermo-hydraulic instabilities might be induced in low pressure and power conditions due to an elimination of re-circulation pumps. Therefore, the purpose of this study is to experimentally investigate the characteristics of thermo-hydraulic instabilities with natural circulation loop consists of twin parallel boiling channels. Resulting characteristics has been compared with Aritomi and Chiang's to clarify the effect of length of non-heated length in particular, and then the rational reactor configuration has been proposed.

Advances in nuclear desalination

The Nuclear Desalination Demonstration Project (NDDP) at Kalpakkam aims to demonstrate the safe and economic production of good quality water by desalination of seawater comprising 4,500 m³/d Multi-Stage Flash (MSF) and 1,800 m³/d Reverse Osmosis (RO) plant. The design of the hybrid MSF–RO plant to be set up at an existing nuclear power station is presented. The MSF plant based on long tube design requires less energy. The effect on performance of the MSF plant due to higher seawater intake temperature is marginal. The preheat RO system part of the hybrid plant uses reject cooling seawater from the MSF plant. This allows lower pressure operation, resulting in energy saving. The two qualities of water produced are usable for the power station as well as for drinking purposes with appropriate blending. The post treatment is also simplified due to blending of the products from MSF and RO plants. The hybrid plant has a number of advantages: part of high purity desalted water produced from the MSF plant will be used for the makeup demineralised water requirement (after necessary polishing) for the power station; blending of the product water from RO and MSF plants would provide requisite quality drinking water; and the RO plant will continue to be operated to provide water for drinking purposes during the shut down of the power station. Commissioning of the RO section is expected in 2002 and that of the MSF section in 2003. Useful design data are expected from the plant on the coupling of small and medium size reactors (SMR) based on PHWR. This will enable us to design a large size commercial plant up to 50,000 m³/d capacity. India will share the O&M experience of NDDP to member states of the International Atomic Energy Agency (IAEA) when the plant is commissioned. The development work for producing good quality water for power station from high salinity water utilizing low grade waste heat is presented. About 40 and 100 MWth low temperature waste heat is available in the moderator systems of the 220 and 500 MWe PHWR respectively. A significant part of this waste heat can be utilized for seawater desalination for in-house consumption. The Low Temperature Evaporation (LTE) technology for producing low conductivity water from seawater has been demonstrated at BARC on 30 m³/d scale by using waste heat. This plant is being connected to the CIRUS reactor for demonstration of coupling to a nuclear research reactor. The product water from this plant after minor polishing will meet the make up water requirement of the research reactor.

The helium-cooled high-temperature reactor in the Federal Republic of Germany: safety features, integrity concept, outlook for design codes and licensing procedures

In the Federal Republic of Germany, the helium-cooled high-temperature reactor (HTR) and the fast breeder reactor are being promoted as advanced nuclear reactor systems. The HTR development based on spherical fuel elements has led to the construction of a 300 MW el prototype reactor, the THTR 300, following favourable experience with the operation of a small experimental reactor, the AVR. The THTR 300 became operational in the mid-eighties. It has exhibited good service behaviour and has confirmed the favourable safety characteristics of the system. At the present time, two HTR concepts are being followed up by German companies, a small HTR (approx. 200 MW th) with a steel pressure vessel and a medium-sized reactor (approx. 550 MW el) with a prestressed concrete pressure vessel for electricity generation. The special safety features of the HTR originate in the core construction of ceramic materials resistant to high temperatures and the low power density of the core. An analysis of the technical safety features shows that the general activity containment concepts developed for light-water reactors (LWR) are not transferable to the HTR. It was necessary to develop technical safety concepts especially for the HTR, and the result is the HTR integrity concept. Technical guidelines and design codes for nuclear plants in the Federal Republic of Germany are tailored to the LWR systems, so that a design code for the HTR had to be formulated. In an extensive research project, the underlying principles for such a design code have been worked out. Licensing procedures have been established for the design, construction and commissioning of the prototype THTR 300 and invaluable experience has been gained. A concept for licensing approval of the HTR module plants, independent of the siting of the modules, is now being investigated.

中小型原子炉をめぐる各国の対応

Concerning small and medium sized reactors, the countries concerned have been increasingly interested in their safety, public acceptance and economy etc. In this review, the development and its strategy of the concerned countries on these reactors are described depending upon the papers of the First International Seminar on Small and Medium-Sized Reactors held last summer in Laussanne, informations obtained with discussions including industrial people who are designing small and medium sized reactors and already published papers. Reactor safety is classified into four safety items for pointing out the reactor safety characteristics.

Nuclear Energy for Coal and Steel

Besides the production of electricity, the high-temperature reactor (HTR) offers the potential for producing secondary energy carriers for the fuel and heat market. Therefore, the HTR can make a considerable contribution to solving future problems in the energy supply of the Federal Republic of Germany, as well as of the whole world. On the basis of experience with the power plants Arbeitsgemeinschaft Versuchsreaktor, Fort St. Vrain, and THTR-300, new concepts of reactors have been proposed: the medium-sized reactor HTR 500 and the modular HTR concept. The high-temperature heat application is directed toward the refinement of fossil fuels, the long-distance energy system, and other applications, such as process steam for the chemical industry, enhanced oil recovery, and energy for steel production. The research and development program in the Prototype Plant Nuclear Process Heat and Nuclear Long-Distance Energy projects has shown very promising results. These results show that nuclear process heat is technically feasible and that it is possible to reach a commercial application in the next few decades.

The HTR and nuclear process heat applications

The High Temperature Reactor HTR offers beside the production of electricity the potential of the production of secondary energy carriers for the fuel and heat market. Therefore the HTR can considerably contribute to solutions of future problems in the energy supply of the Federal Republic of Germany as well as of the world. On the basis of the experiences with the power plants AVR, Fort St. Vrain and THTR-300 new concepts of reactors have been proposed: the medium size reactor HTR 500 and the Modular HTR concept. The high temperature heat application is directed towards the refinement of fossil fuels, the long distance energy system and other applications as e.g. process steam for chemical industry, enhanced oil recovery and water splitting. The research and development program in the projects Prototype Plant Nuclear Process Heat (PNP) and Nuclear Long Distance Energy (NFE) has shown very promising results. These results show that nuclear process heat is technically feasibly and that it is possible to reach a commercial application in the next decades.