Nuclear reactor safety fast reactors

Bezhunov, G.M., et al. (1989) Experimental and analytical study of prompt neutron lifetime in fast reactors with moderation zones in the reflector, in Neutronic problems of nuclear power system safety paper theses VI AU-Union Workshop on Reactor Physics, Tsniiatominform Publishers, Moscow, pp.48-50 (in Russian). 

A. Netchaev, et al., Safety Characteristics of the Multipurpose Fast Reactor (MPFR) , Annals of Nuclear Energy, 28, 1717-1732 (2001). 

Nuclear reactors are designed for production of heat, mechanical and electric power, radioactive nuclides, weapons material, research in nuclear physics and chemistry, etc. The design depends on the purposes, e.g. in the case of electric power production the design is chosen to provide the cheapest electricity taking long term reliability in consideration. This may be modified by the availability and economy of national resources such as raw material, manpower and skill, safety reasons, etc. Also the risk for proliferation of reactor materials for weapons use may influence the choice of reactor type. Many dozois of varying reactor concepts have been formulated, so we must limit the discussion in this chapter to a summary of the main variables, and the most common research and power reactors. Fast reactors and some other designs are discussed in Chapter 20. 

The paramount fundamental problem to resolve is that of the central worth discrepancy. It is important not only for its academic interest or for reassuring the reactor physicist in the adequacy of the calculational methods and nuclear data he u.ses, but also for practical reasons. Safety factors that account for the CWD must be included in the design of fast reactors an economic penalty is associated with these safety factors. Related to the question of the CWD is the more general problem of the multigroup calculation of bilinear functionals. The questions arising here are (I) for which applications, and under what conditions, are spectral fine structure effects non-negligible (2) how can these fine structure effects be taken into account in the multigroup formulation. 

Prevention, detection and mitigation of sodium leaks, improved resistance of nuclear systems to fires and choice of concrete for minimisation of interactions remain important directions for safety research. In France a new aluminous concrete which does not interact with sodium has been proposed. The EFR (European fast reactor) anchored safety vessel option was tested with this concrete. There is a need to continue the R D on sodium-resistant concrete to minimise damage to structures in the event of sodium leaks. 

Analyze the nuclear and radiation safety of MOX fuel fabrication for existing light water and fast reactors ... 

Key words 2 -Random Liquid metal fast reactor, LMFR, knowledge preservation, CEA, safety, working thermohydraulics, nuclear fuel ... 

The European Commission has nuclear organisations that have never appeared to achieve the regulatory significance or influence of their coal and steel activities. Euratom issues directives on radiation protection, and an independent committee coordinate codes and standards. In addition, there are safety working groups on fast reactor technology. 

Holmes J.A.G. -"The role of structural integrity in liquid metal fast breeder reactor safety." pp 1-475 to 1-491, Proceedings of the L. M.F.B.R safety topical meeting, Lyon, France. European Nuclear Society. July 1982. 

Kazakhstan has a nuclear scientific-industrial complex which was set up as a part of a nuclear infrastructure of the former USSR. More than 50% of the uranium resources of the former Soviet Union are in Kazakhstan, with seven uranium mines. Two UO2 plants produced up to 35% of the total uranium in the USSR in 1990. There are extensive facilities for producing UO2 pellets for VVER fuel elements from Russian enriched uranium. Kazakhstan has several research reactors and one operating nuclear power plant, the BN-350 fast reactor, which started operation in 1973 with a design life of 20 years. Work on its lifetime extension has the intention of bringing it into compliance with current safety standards. 1995 and 1996 were devoted to this work. In October 1996. experimental investigation on accident-proofdecay heat removal by natural circulation was carried out. The reactor BN-350 was restarted in February 4, 1997 at a power level of 420 MW(th). 

The investigation of safety and more particularly of severe accident conditions is important for accelerator driven systems (ADS). Subcritical ADS could be of particular interest for the actinide transmutation from the safety point of view, because fast reactors with Neptunium, Americium and Curium have a much smaller fraction of delayed neutron emitters (compared to the common fuels and U), a small Doppler effect and possibly a positive coolant void coefficient. This poses a particular problem of control since the fraction of delayed neutrons is essential for the operation of a nuclear reactor in the critical state. In addition, the IRC presented in the past a review of accelerator-driven sub-critical systems with emphasis on safety related power transients followed by a survey of thorium specific problems of chemistry, metallurgy, fuel fabrication and proliferation resistance. 

W. J. McCarthy, Jr., and D. Okrent, Fast Reactor Kinetics, Technology of Nuclear Reactor Safety, Chapt. 10. M.I.T. Press, Cambridge, Massachusetts, 1964. 

The fast reactor activities of FZK are part of the Nuclear Safety Research Project. The R D program of this project has been restructured in accordance with the demands of the Federal Government. The key issues and tasks of the program concern LWR and FBR safety and transmutation of minor actinides. 

Fast reactor construction in the nearest decades will be justified if they will be used reasonably as NPPs the safety level of which meets up-to-date requirements, and also for solving environmental problems, concerning spent nuclear fuel and released weapons grade plutonium. 

Within the next 2 decades, when mostly thermal reactors will be built in the world, it is necessary to develop and bring in new fast reactors of natural safety with a closed fuel cycle, which can pave the way for large-scale nuclear power in the twenty-first century. 

Admittedly, the experience of using the advanced fuels in fast reactors is by far less substantial than that obtained in operation of oxide fuel. Nevertheless, for all the importance of the previous experience and the maturity of the technology, choice of fuel for the innovative fast reactor of the future large nuclear power will be dictated by the requirements of high safety and economic efficiency. 

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