New Method of Coolant Mixing Studies at the Operating WWER-1000 Units

Abstract

Paper [1] describes a unique method and basic results of coolant mixing experimental study, carried out on the working power unit WWER-1000 of “Bushehr” NPP. Method is characterized by the use of an emergency boron insertion system for creating the nonuniform distribution of indicator (tracer), and also by the use of all regular systems of neutron and temperature monitoring for increasing the authenticity. Method showed high reliability, effectiveness, availability and flexibility. The corresponding application for the invention of a new method is applied for a patent. Present work supports the conclusions of the paper [1] and contains the more detailed additional information and results according to the mixing indices, and also to the dissipation of temperature indicator in different sections of circulation loop. Some results of post-test modeling by calculation code KORSAR/GP are presented too. Spatial and temporal detailing relate also to the dynamics of appearance, stabilization, propagation and disappearance of boron and boron-free “spots” in the core with start-up and trip of the emergency boron insertion pumps.

Innovation in Power Maneuvering Mode for NPP Hanhikivi with WWER- 1200 reactor

“…In that paper it is declared that there is possibility to achieve CB=const during maneuvering, but this is raw result obtained on the base of very simplified calculations -onedimensional diffusion theory. Also, the big quantity of neutron and thermal sensors in the core of WWERs [4][5][6], including WWER-1200 of NPP Hanhikivi (much more than in PWRs, including the above mentioned PWRs) facilitates adequate on-line monitoring and control of power distribution by the movement of grey CRs in the core during the power maneuvering with CB=const.…”