Dynamics of Expanding Plutonium-Fuelled Systems of Nuclear Power Plants

As a rule the analysis of the long-term dynamics of large expanding systems of plutonium-fuelled nuclear power plants involves three characteristic parameters: specific investment of plutonium, breeding gain and energy content of the fuel. Unlike the case of a specified fast core, in an expanding system these parameters as a rule never reach equilibrium values and cannot be taken as constant. The problem of dynamics of such systems can be solved by using the 'age of plutonium' concept as presented in the paper. Physically the age concept reduces the complex problem of change of isotopes in the system to a much easier one. Instead of dealing with all plutonium isotopes and investigating the influence of their changing proportions in the system as a whole on the values of characteristic parameters, we have to do solely with plutonium, whose features do depend on its age. On this basis the sets of equations, allowing any 'single-reactor type' or 'two-reactor type' systems to be analysed, were found. The equations are non-linear integro-differential equations which cannot be solved analytically and had been solved using an analogue computer. (author)