Fast reactor design features

This appendix provides a brief description of the Fast Flux Test Facility (FFTF) fuel handling system and its operation as described by Cabell (1980) and in the Fast Flux Test Facility System Design Description (FFTF, 1983). The description is limited to those system features that are potentially relevant to the refueling of a liquid-salt very high-temperature reactor (LS-VHTR). Because the FFTF was designed as a reactor to test fuel, it has additional capabilities and equipment compared with a sodium-cooled fast reactor designed only to produce electricity. 

As an effort to enhance the key LMR technologies, KAERI decided to join the I-NERI, a three-year collaboration program between Argonne National Laboratory (ANL) and KAERI. The objective of this collaboration is to identify and quantify the performance of innovative design features in metallic-fuelled, sodium cooled fast reactor designs. Korea also expects to... 

Chapter 7 covers the design and analysis of fast reactors. The features of the Super LWR and Super FR are that the plant system configuration does not need to be changed from the thermal reactor to the fast reactor. The analysis of plant control, stability, and safety of the Super FR as well as core design are provided. 

One of its attractive features of rhenium is that it is a spectral shift absorber (SSA), which means that it has a low relative absorption cross section for fast neutrons while in the thermal spectrum its absorption cross section increases dramatically. This has safety applications for the reactor design in accident scenarios. Rhenium has an absorption cross section of in the fast spectrum, however the magnitude of the difference between the absorption cross section and the fast fission cross section of is low compared to the difference at a thermal spectrum. It also provides a barrier that protects Niobium 1% Zirconium from nitrogen attack and damage caused by other fission products that outgas from the fuel. Most of the other SSA materials have a relatively low melting point, making them less attractive. 

However, the choice of liquid sodium as a coolant and principal design features of fast reactors were mainly determined in the 1960s, as already mentioned, by the requirement of high power densities in the reactor core (about 500 kW(th)/l for MOX fuel), and the need of a weakly moderating material with good heat transfer properties. The important fact was also that sodium is practically non-corrosive to stainless steal. 

One of the attractive features of the fast reactor is its hard neutron spectrum. To expand this feature, a metallic fuel core is employed in the 4S. However, it is more difficult to reduce void reactivity for a core with a harder spectrum. It is very important to design the void reactivity to be negative in order to prevent a severe nuclear accident in the event of sudden loss of coolant, sudden loss of coolant flow or a large gas bubble entrainment in the core. 

The purpose of this section is to compare the features of the RBMK reactor operated at Chernobyl with reactor types pertinent to the UK. It will be recollected that the RBMK covers a large number of reactors and the comparisons made are indeed with Chernobyl No. 4. The UK reactors covered are in three classes the commercial reactors now built and operated or in commission (Magnox and Advanced Gas-cooled Reactor (AGR)) the prototype Steam Generating Heavy Water Reactor (SGHWR) and Prototype Fast Reactor (PFR) that have comparable performance to commercial reactors and the proposed Pressurised Water Reactor (PWR) or Sizewell B design which, it... 

The high temperatures will require special considerations in the design of the refueling machines and will likely require that the fresh fuel be preheated before refueling. These features exist in refueling machines for sodium-cooled fast reactors such as the Fast Flux Test Facility (Sect. 5 and Appendix A) and in refueling machines for the British Advanced Gas-Cooled Reactors (Sect. 4.3). 

Sodium fast reactor. Sodium-cooled fast reactors are low-pressure, high-temperature reactors. Because these characteristics are similar to the AHTR, the AHTR plant design shares many features with this class of reactors, and specifically the General Electric S-PRISM, for which a considerable R D investment has already been expended. These features inelude overall facility design and decay heat removal systems. 

The BN-350 nuclear power plant has been used for seawater desalination and electricity production for 23 years, the longest of any commercial liquid metal fast reactor (LMFR). During that time much has been learned about successful LMFR operation and design. The present paper describes some important design features of the BN-350 NPP and presents some performance results from the whole operational period. 

It is worth-while to note that there are some features of fast reactor economics in Russia. On one hand, in Russia the BN-800 design development has been completed, its construction has been already started, and studies have been made on the improved (with respect to technical and economic parameters) BN-600M reactor. On the other hand, intensive works are under way on designing of thermal reactors of improved safety (NP-500 and VPBER-600 designs). 

In Japan, the self-actuated shutdown system (SASS) has been developed as a passive safety feature (Takamatsu et al. 2007 Nakanishi et al. 2008) using the phenomena that electromagnetic force of the control rod latch will be lost when alloy temperature exceeds the Curie point. Several kinds of in-sodium transient testing have been carried out together with in-pile experiments in the experimental fast reactor Joyo. This mechanism is effective to the robust restraint core, which is designed for seisnuc requirements. 

This concept is essentially different from the concepts of the reactors currently in operation and under development in its radically new approach to safety. Instead of addition of expensive engineered features and systems, safety rehes mostly on fundamental natural behavior patterns and processes, feedbacks, physical and chemical properties inherent in a fast reactor, its fuel, coolant, and other components. Also important in this respect are the design solutions that allow using to the utmost the natmal safety properties. 

The natural properties of lead coolant and mononitride fuel and the neutronic characteristics of the fast reactor combined with the design of the core and cooling circuits raise the BREST reactor to a radically different level of safety and provide for its stable behavior without involving active safety features in the severe accidents unmanageable in any one of the existing reactors, such as ... 

In the future, electricity production at large NPPs is likely to remain the main application of nuclear energy. This factor and the reduction of unit costs with increase in the power and number of nuclear units were the reasons for conceptual study of a 1,200 MWe lead-cooled fast reactor as a candidate basic component of a large-scale nuclear power mix. The BREST-OD-300 being developed as a prototype of the BREST-1200 reactor, their design and engineering features are largely similar, as may be seen from the data of Table 58.6 (ISTC 2001 Adamov et al. 1997). 

The fast reactor database (FRDB) summarized in this report is very detailed. It includes operational parameters, physical, hydraulic and thermomechanical characteristics, technological requirements, methods and criteria to ensure safe operation design data like dimensions, materials information and main design features and performance parameters of reactor cores, components, and various systems, along with sketches and drawings. 

The FRDB is arranged in units records of parameters, characteristics and design features are arranged in columns on paired pages as follows data on experimental, demonstration or prototype reactors (two units for 24 reactors) and on commercial size fast reactors (one unit for 13 reactors) on the first and the second page, respectively. This database setup makes it possible not only to easily find the required parameter of a certain reactor, but also to compare it with that of the other reactors. 

INTERNATIONAL ATOMIC ENERGY AGENCY, Comparative analysis of the arrangement and design features of the BN-350 and BN-600 reactors, Int. Symp. on Design, Constmction and operating Experience of Demonstration Liquid Metal Fast Breeder Reactors, IAEA SM-225/64. 

The 4S-LMR incorporates neutron reflectors to control the core reactivity without neutron absorber rods. The reflectors are driven from outside the reactor vessel and move very slowly the movement speed is below 1 mm/day. Electromagnetic pumps are used for primary coolant circulation. Incorporation of these design features eliminates fast moving or rotating components, contributing to a decreased component failure and reduced maintenance. 

Waltar, A. E. and A. B. Reynolds. 1981. Fast Breeder Reactors. New York Pergamon Press. This book discusses the basic principles and methods as well as design features of fast breeder reactors. Each chapter ends with references and problems to be solved. Appendices include fast reactor data, comparison of homogeneous and heterogeneous core designs, and a list of symbols. 

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