The easiest and most efficient mode of operation for nuclear power plants is called "baseload." This means that the plant is set up to operate at one hundred percent power generating capacity. Coal power plants are also best operated in baseload mode. Gas power plants and hydro power plants can be adjusted relatively easily with respect to power output to meet current demand and this is called "load-following". A mixture of both load modes works best. The baseload provides the minimum power requirements of the grid and the load-following adjusts to momentary demands above the minimum. Alternative sustainable energy sources such as solar and wind are often criticized because they cannot provide baseload power. There is intense work being done in battery technology to allow excess power generation from alternative sources to be captured for use when the source is not generating to sustain baseload power.
Although nuclear power plants are not the best source of load-following power generation, the dependency of countries such as France on nuclear power have required the development of load-following capability in nuclear power plants. In France, less absorptive control rods have been used for the past twenty five years to allow modulation of the power output of the reactors for load-following.
Ukraine has 16 reactors in four nuclear power plants that provide about half the electricity consumed in the country. Ukraine has been studying load-following for the past ten years because it is interested in adapting its fleet of VVER reactors from baseload to load-following to provide more flexibility in power generation. Ukraine targeted this year for Ukraine's reactors to be load-following. The Ukraine nuclear company Energoatom has stated that it needs additional time and additional funding in order to make all of Ukraine's reactors capable of load-following.
Unit Two at the Khmelnitsky nuclear power plant has been used for researching load-following. The reactor has been reduced from one hundred percent to seventy five percent power generation and then returned to one hundred percent twenty one times. During these tests, Energoatom identified which items of equipment would need to be modified and upgraded in order to allow the reactor to easily and safely operate in the load-following mode. Regulations state that in order for a reactor to be certified for operation in load-following mode, the reactor has to have the output reduced and restored at least two hundred times.
In order to make the Ukraine reactor fleet load-following, additional funding will be necessary to upgrade the equipment at each plant. In addition, each plant will have to be put through the required two hundred load change cycles to insure proper operation. Energoatom says that if the necessary funding is made available, it will take two years to upgrade and test all of Ukraine's power reactors.
Some critics of the plan to adapt Ukraine's reactor fleet to load-following complain that Energoatom is moving too quickly on the planning for the changes and more time is needed to insure a safe transition. The Chairman of the Ukrainian Energy Assembly has responded that research into load-following has been going on in Ukraine for ten years and that the transition project is based on solid research and engineering and is sufficient to accomplish the load-following project properly.
Location of Ukraine nuclear power plants:
