Turbine follow boiler operation of Nuclear plants

Nuclear plants operate as a base load plants. Once the plant starts producing electricity it continue to deliver same power in both peak load and off-peak load conditions. Some of the reasons why nuclear plants are operated ass base load plants are:

• Power levels in the nuclear plant cannot be varied depends on the load demand. This affect the reactivity variation in the reactor which can endanger the reactor safety. Also reactor components are affected due to thermal stresses and life of the reactor will come down. Therefore the reactor power variations with respect to the demand power is as minimized as possible
• The operating cost of nuclear plants is comparatively lesser than thermal, gas and other peak load plants.Hence it is economical to operate nuclear plants as base load plants.

Turbine follow reactor:

In thermal power plants boiler follows the reactor. Depends on the demand governor valve opens and to cater the demand more or less coal is burned in the boiler and sufficient amount of heat is generator. On the other hand nuclear power plants operate in turbine follow reactor mode. Irrespective of the grid power demand nuclear plant generates constant amount of power depends on the reactor power level. In nuclear power plants safety of the plant is primary concern rather than production of electricity. Therefore if the plant is operated in boiler (reactor) follow turbine mode for different power levels reactivity in the reactor should be changed by control rods. This can significantly trip the reactor and may endanger the reactor if operated beyond the flexible margins. Therefore nuclear plants always turbine follow reactor mode of operation is employed.

In order to achieve this turbine governor system should always maintain constant turbine inlet pressure during all the duration. This is done by pressure controller in governor control system