Nuclear reactor power control method and device

A nuclear reactor power control device for a boiling water type nuclear reactor, comprising:

• a plurality of first pump means for feeding feed water to the nuclear reactor;
• trip detection means for outputting a trip signal when one of the first pump means for supplying feed water to the nuclear reactor is tripped, said nuclear reactor operating at a predetermined first level of nuclear reactor power when said one of the first pump means is tripped;
• first control means responsive to said trip signal;
• reduction means responsive to said first control means for reducing circulation of core flow in the core of the nuclear reactor sufficiently to reduce power;
• said first control means controlling said reduction means to first reduce the circulation of core flow in response to said trip signal;
• second reduction means including a variation means for determining and generating a mismatched amount corresponding to a difference between the flow of steam discharged from said nuclear reactor and the flow of the feed water after the trip signal is generated, and
• second control means for controlling and reducing the nuclear reactor power to a predetermined second level from said first level based upon the mismatched amount.

A nuclear reactor power control device for a boiling water type nuclear reactor, comprising:

• a plurality of first pumps for supplying feed water to the nuclear reactor;
• a second pump circulating cooling water in the core in said nuclear reactor;
• trip detection means for generating a trip signal when one of said first pumps is tripped;
• first output control means to output a first control signal for operating the nuclear reactor at a first level of power when none of said first pumps is tripped;
• second output control means to output a second control signal for operating the nuclear reactor at a second level of power, less than said first level, when one of said first pumps is tripped;
• selection control means for switching control from said first output control means to said second output control means;
• and
• reactor power reduction means for first reducing the speed of said second pump in response to generating said trip signal for reducing the nuclear power and then switching said selection control means to further reduce the nuclear reactor power to said second level from said first level.

A nuclear reactor power control device for a boiling water type nuclear reactor, comprising:

• a plurality of first pumps supplying feed water to the nuclear reactor;
• a second pump circulating cooling water in the core in said nuclear reactor;
• trip detection means for generating a trip signal when one of said first pumps is tripped;
• core flow control means for controlling the speed of said second pump;
• control rods mounted for insertion into the core;
• control rod control means for controlling operation of said control rods;
• first output control means to output a first control signal for operating the nuclear reactor at a first level of power when none of said first pumps is tripped;
• second output control means to output a second control signal for operating the nuclear reactor at a second level of power;
• said core flow control means controlling said second pump based upon the output signal from said second output control means and said first output control means;
• said control rod control means controlling selected control rods based on the output signal of said second output control means and said first output control means;
• and
• reactor power reduction means for first reducing the speed of said second pump in response to generating said trip signal and then switching operation to said second control means to further reduce the nuclear reactor power to said second level from said first level.

A method for controlling reactor power of a boiling water type nuclear reactor, comprising:

• controlling nuclear reactor power in response to a first nuclear reactor power level set at a first predetermined value corresponding to a required output of a generator driven by the nuclear reactor under normal operation of a feed water supplying system;
• detecting an abnormality in the feed water supplying system;
• reducing the nuclear reactor power by first decreasing core flow in response to said detecting of the abnormality;
• and then
• switching the nuclear reactor power level to a predetermined second level lower than said first level and corresponding to the specific abnormality detected, and continuing said controlling at the lower level.

A method for controlling reactor power of a boiling water type nuclear reactor, comprising:

• operating said nuclear reactor at a predetermined first level of power;
• detecting an abnormality of the feed water supplying system for the nuclear reactor;
• first reducing speed of a pump circulating cooling liquid in the core in the nuclear reactor when the abnormality is detected;
• thereafter, detecting a mismatched amount between flow of steam discharged from the nuclear reactor and flow of the feed water;
• and then
• reducing the nuclear reactor power to a predetermined second level of power less than said first level after said reducing speed step based upon the mismatched amount.

A method for controlling reactor power of a boiling water type nuclear reactor in response to an abnormality of a feed water supplying system, comprising:

• operating said nuclear reactor at a predetermined first level of power
• detecting an abnormality by only measuring characteristics of the feed water supplying system, which cause a flow of feed water to decrease abnormally;
• reducing the nuclear reactor power in response to said detected abnormality by first reducing a speed of a recirculation pump providing core flow to a core in the nuclear reactor to a speed corresponding to a nuclear reactor power lower than said first nuclear reactor power;
• and
• thereafter, further reducing said nuclear reactor power to a predetermined second level lower than said first level of nuclear reactor power.

A method for controlling reactor power of a boiling water type nuclear reactor in response to an abnormality of a feed water supplying system, said feed water being supplied by a plurality of pumps, comprising:

• operating said nuclear reactor at a predetermined first level of power;
• detecting an abnormality of the feed water supplying system;
• first reducing recirculation cooling flow within a core of the nuclear reactor, when the abnormality is detected, to a core flow corresponding to a nuclear reactor power lower than said first level by decreasing a speed of a pump providing recirculating cooling water in the core of the nuclear reactor;
• and
• thereafter further reducing nuclear reactor power to a predetermined second level less than said first level that prevents over speed of the others of the pumps that remain operating for supplying feed water.