| Abstract: | The hypothesis laid down in this paper offers an alternative to the current interpretation of the processes: hideout (hideout-return), crud deposition and change of the coolants activity level in the nuclear power reactors under different operating conditions. This alternative is based on the supposition that the heat flux has not a direct effect on the processes mentioned above, but acts through the heat transfer mechanism in the boundary, caused by itself. The boundary influenced by heat flow is in non-equilibrium state and in such system states (at adequate heat flux) non-equilibrium structures called dissipative structures arise which ale closely connected with heat transfer mechanism. The transport and the location of the colloidal corrosion products dispersed in steam generators-or reactor water during the units operation are strongly influenced by the existence of dissipative structures. The transport and location of the main part of ion species depend also on the existence of these structures because the colloidal particles act like collectors of the ions dissolved in the water (The ions are inserted in the colloidal particles double layer). The hideout and hideout-return phenomena are interpreted as closely connected with the existence of the above mentioned dissipative structures. It was attempted to consider the changes in nuclide concentrations in the LWR coolant upon start-up and shutdown as hideout respectively hideout-return processes. The recent shutdown chemistry aspects are discussed also. |
