System and method for controlling operation of boiling water reactor

Claim 1

A system for controlling the operation of a boiling water reactor, comprising first detector means for detecting the pressure in the reactor vessel, second detector means for detecting the flow rate of the cooling water flowing in the core in the reactor vessel, third detector means for detecting the flow rate of the steam supplied to a turbine from said reactor vessel, means for setting the enthalpy of said cooling water at the inlet of said core at a value in dependence on the reactor power, said set value rendering the void fraction in the lower part of the core when the reactor power is less than a predetermined maximum value to be greater than the void fraction in the lower part of the core when the reactor power is at the predetermined maximum value so as to flatten the power distribution in the axial direction of the core when the reactor power is less than the predetermined maximum value, means for adjusting the enthalpy of the feed water supplied to said reactor vessel, and means for controlling said feed water enthalpy adjusting means on the basis of said pressure, said cooling water flow rate and said steam flow rate detected by said first, second and third detector means respectively and said cooling water enthalpy set by said setting means, thereby effecting a start-up of the reactor.

Claim 2

A system for controlling the operation of a boiling water reactor, comprising first detector means for detecting the pressure in the reactor vessel, second detector means for detecting the flow rate of the cooling water flowing in the core in the reactor vessel, third detector means for detecting the flow rate of the steam supplied to a turbine from said reactor vessel, means for setting the enthalpy of said cooling water at the inlet of said core at a value in dependence on the reactor power, said set value rendering the void fraction in the lower part of the core when the reactor power is less than a predetermined maximum value to be greater than the void fraction in the lower part of the core when the reactor power is at the predetermined maximum value so as to flatten the power distribution in the axial direction of the core when the reactor power is less than the predetermined maximum value, means for adjusting the enthalpy of the feed water supplied to said reactor vessel, and means for controlling said feed water enthalpy adjusting means on the basis of said pressure, said cooling water flow rate and said steam flow rate detected by said first, second and third detector means respectively and said cooling water enthalpy set by said setting means, thereby effecting a start-up of the reactor.

Claim 14

A system for controlling the operation of the boiling water reactor, comprising a reactor vessel, a turbine supplied with the steam produced by said reactor vessel, means for supplying the feed water to said reactor vessel, means for heating said feed water to control the void fraction in the lower part of the core so as to flatten the power distribution in the axial direction of the core, and means for controlling the amount of heat supplied from said feed water heating means to said feed water, said heat amount control means reducing the amount of heat applied to said feed water according as the reactor power increases from a first level up to a second predetermined maximum level to flatten the power distribution in the axial direction of the core.

Claim 15

A system for controlling the operation of the boiling water reactor, comprising a reactor vessel, a turbine supplied with the steam produced by said reactor vessel, means for supplying the feed water to said reactor vessel, means for heating said feed water to control the void fraction in the lower part of the core so as to flatten the power distribution in the axial direction of the core, and means for controlling the amount of heat supplied from said feed water heating means to said feed water, said heat amount control means reducing the amount of heat applied to said feed water according as the reactor power increases from a first level up to a second predetermined maximum level to flatten the power distribution in the axial direction of the core.

Claim 18

A method of controlling the operation of the boiling water reactor, comprising: detecting the pressure in the reactor pressure vessel; detecting the flow rate of cooling water in the reactor core within said reactor pressure vessel; detecting the flow rate of steam supplied from said reactor pressure vessel to a turbine generator; setting the enthalpy of said cooling water at the core inlet at a value in dependence on the reactor power, said set value rendering the void fraction in the lower part of the core when the reactor power is less than a predetermined maximum value to be greater than the void fraction in the lower part of the core when the reactor power is at the predetermined maximum value so as to flatten the power distribution in the axial direction of the core when the reactor power is less than the predetermined maximum value, and controlling the enthalpy of feed water to be supplied to said reactor pressure vessel in accordance with values of said detected vessel pressure, cooling water flow rate and steam flow rate and said set enthalpy of said cooling water.

Claim 19

A method of controlling the operation of the boiling water reactor, comprising: detecting the pressure in the reactor pressure vessel; detecting the flow rate of cooling water in the reactor core within said reactor pressure vessel; detecting the flow rate of steam supplied from said reactor pressure vessel to a turbine generator; setting the enthalpy of said cooling water at the core inlet at a value in dependence on the reactor power, said set value rendering the void fraction in the lower part of the core when the reactor power is less than a predetermined maximum value to be greater than the void fraction in the lower part of the core when the reactor power is at the predetermined maximum value so as to flatten the power distribution in the axial direction of the core when the reactor power is less than the predetermined maximum value, and controlling the enthalpy of feed water to be supplied to said reactor pressure vessel in accordance with values of said detected vessel pressure, cooling water flow rate and steam flow rate and said set enthalpy of said cooling water.

Claim 20

A method of controlling the operation of a boiling water reactor for effecting a rapid start-up of the reactor, comprising the steps of: (1) extracting a control rod to raise the power of the reactor; (2) increasing the flow rate of a coolant in the core of the reactor to raise the power of the reactor with the said extraction of the control rod being stopped; (3) decreasing the flow rate of the coolant in the reactor core to lower the reactor power; (4) repeating the steps (1), (2) and (3) in the described order to raise the reactor power; and (5) decreasing the enthalpy of the coolant at the core inlet of the reactor as the reactor power is increased so as to control the void fraction in the lower part of the core and flatten the power distribution in the axial direction of the core.

Claim 21

A method of controlling the operation of a boiling water reactor for effecting a rapid start-up of the reactor, comprising the steps of: (1) extracting a control rod to raise the power of the reactor; (2) increasing the flow rate of a coolant in the core of the reactor to raise the power of the reactor with the said extraction of the control rod being stopped; (3) decreasing the flow rate of the coolant in the reactor core to lower the reactor power; (4) repeating the steps (1), (2) and (3) in the described order to raise the reactor power; and (5) decreasing the enthalpy of the coolant at the core inlet of the reactor as the reactor power is increased so as to control the void fraction in the lower part of the core and flatten the power distribution in the axial direction of the core.

Claim 22

A system for controlling the operation of a nuclear reactor having a reactor vessel and a core, comprising first detector means for detecting the pressure in the reactor vessel and for providing a first output signal indicative thereof, second detector means for detecting the flow rate of cooling water flowing in the core of the reactor vessel and for providing a second output signal indicative thereof, third detector means for detecting the flow rate of steam supplied from the reactor vessel to a turbine and for providing a third output signal indicative thereof, means for setting a value of the enthalpy of the cooling water at the inlet of said core in dependence on reactor power and for providing a set output signal indicative thereof, said set value rendering the void fraction in the lower part of the core when the reactor power is less than a predetermined maximum value to be greater than the void fraction in the lower part of the core when the reactor power is at the predetermined maximum value so as to flatten the power distribution in the axial direction of the core when the reactor power is less than the predetermined maximum value, means for adjusting the enthalpy of the feed water supplied to the reactor vessel, and means for controlling the feed water enthalpy adjusting means in response to the set output signal and said first, second and third output signals.

Claim 23

A system for controlling the operation of a nuclear reactor having a reactor vessel and a core, comprising first detector means for detecting the pressure in the reactor vessel and for providing a first output signal indicative thereof, second detector means for detecting the flow rate of cooling water flowing in the core of the reactor vessel and for providing a second output signal indicative thereof, third detector means for detecting the flow rate of steam supplied from the reactor vessel to a turbine and for providing a third output signal indicative thereof, means for setting a value of the enthalpy of the cooling water at the inlet of said core in dependence on reactor power and for providing a set output signal indicative thereof, said set value rendering the void fraction in the lower part of the core when the reactor power is less than a predetermined maximum value to be greater than the void fraction in the lower part of the core when the reactor power is at the predetermined maximum value so as to flatten the power distribution in the axial direction of the core when the reactor power is less than the predetermined maximum value, means for adjusting the enthalpy of the feed water supplied to the reactor vessel, and means for controlling the feed water enthalpy adjusting means in response to the set output signal and said first, second and third output signals.