JPH0245160B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a reactor power adjustment device for a nuclear power plant, and particularly to a reactor power adjustment device that can realize load fluctuation requests that fluctuate in a short period of time.

Conventionally, at nuclear power plants, the share of nuclear power generation in the power supply equipment for power generation is not so large, the cost of power generation is lower than that of thermal power, and there is a track record of operation that meets load fluctuation requirements. Base load operation has been adopted for a variety of reasons, including the lack of fuel efficiency and the difficulty of reliably maintaining the integrity of the nuclear fuel as the core thermal output increases and decreases.

For this reason, conventionally, by changing the output of thermal power plants and hydroelectric power plants, changes in load, such as daily load or weekly load, have been responded to.

However, in recent years in Japan, due to the increase in the number of nuclear power plants and the increase in single unit capacity,
The proportion of nuclear power generation in the total amount of power generated has been increasing significantly, and there is a need for nuclear power plants that can respond to output fluctuation demands that change over a short period of time, for example, within a few minutes.

However, in general, in nuclear reactors, such as boiling water reactors, it is necessary to realize load fluctuations while maintaining the integrity of the reactor, such as the fuel and reactor core. Responding to fluctuating demands has been difficult because it is not possible to quickly monitor whether the reactor's health is maintained in response to the required power fluctuations.

The present invention has been made in response to such conventional circumstances, and includes a power fluctuation range determination device that calculates an allowable range of power fluctuation that can maintain the health of the core state.
It is determined whether the required output fluctuation value is within the permissible range, and if it is within the permissible range, the required output fluctuation value is output as is as an output fluctuation value, and the permissible range is determined. If it is outside the range, a limiter outputs the limit value of the allowable range as an output fluctuation value, and an output change device inputs the output fluctuation value and changes the output of the reactor based on this output fluctuation value. It is an object of the present invention to provide a nuclear reactor power adjustment device characterized by the following features.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of the present invention will be described below with reference to an embodiment shown in the drawings.

The reactor power adjustment device shown in the figure is composed of a reactor state quantity input device 1, a process computer 2, an output fluctuation range determination device 3, a limiter 4, and an automatic output change device 5.

The reactor state quantity input device 1 inputs various state quantities indicating the state of the reactor, such as core flow rate, neutron flux, and control rod pattern, from a boiling water reactor 6, for example.

The process computer 2 is a reactor state quantity input device 1
Input various state quantities indicating the state of the reactor from
The three-dimensional power distribution within the core is calculated, and the core status is monitored based on the calculated three-dimensional power distribution within the core.

In this example, the calculation cycle of the three-dimensional power distribution within the core is one hour.

The power fluctuation width determining device 3 calculates the upper limit and lower limit of the power fluctuation accompanied by the core flow rate fluctuation required to maintain the health of the core state.

In general, in a boiling water reactor 6, in order to maintain the health of the reactor core, the linear power density of the fuel pins called the PC envelope is limited, and the output of the fuel assembly is set as a ratio to the critical output at which film boiling occurs. There are various restrictions such as a certain limit power ratio restriction, upper and lower limits of the core flow rate, and restrictions on the core flow rate and output regulated by the so-called rod block line. It is necessary to operate within a range that does not exceed the limit value.

That is, the power fluctuation range determining device 3 determines whether the core flow rate is the limit value due to the PC envelope, based on the three-dimensional power distribution calculated by the process computer 2.
In addition to determining the amount of change in flow rate that reaches the limit value based on the critical power ratio, the core flow rate and power are determined by considering the upper and lower limits of the core flow rate and the limit value between the core flow rate and power regulated by the rod block line. Find the tolerance range.

Note that in order to obtain the limit value due to the PC envelope and the limit value due to the limit power ratio, it is necessary to determine the power distribution fluctuation due to the core flow rate fluctuation based on the three-dimensional power distribution. , the three-dimensional output distribution calculated by the process computer 2 is input, and based on this input three-dimensional output distribution, for example, by the method shown in Japanese Patent Application No. 52-142209 previously filed by the present applicant. , and the output level is required in a short period of time.

The limiter 4 determines that the value of the output fluctuation request signal A, which is input as the output setting value of the automatic output change device 5 that automatically changes the output level of the reactor 6, is determined by the output fluctuation range determination device 3. It is determined whether the fluctuation is within the permissible range, and if it is within the permissible range, the value of the output fluctuation request signal A is changed as is.
It is output to the automatic output changing device 5 as an output fluctuation signal.

On the other hand, if it is not within the allowable range, the output automatic change device 5 uses the limit value of the allowable range as an output fluctuation signal.
Output to.

The automatic output change device 5 controls the output of the nuclear reactor based on the output fluctuation signal output from the limiter 4.

In the reactor power adjustment device configured as described above, the allowable range of power determined by the power fluctuation range determining device 3 is set as the limiter 4, and power fluctuation requests that impair the integrity of the reactor core condition are avoided. When signal A is input to limiter 4, limiter 4
Among the values of this output fluctuation request signal A, the values within the allowable range are output to the automatic output change device 5 as output fluctuation signals, so the output fluctuation request can be implemented to the maximum extent within the range that maintains the reactor health. can be limited.

As described above, according to the power adjustment device of the present invention, it is possible to limit the output fluctuation request to the maximum extent within the range that maintains the health of the reactor, and also to reduce the power fluctuation request within a short period of time, for example, within a few minutes. It is also possible to respond to changing output fluctuation demands.

In the example, the axial one-dimensional model shown in Japanese Patent Application No. 142209/1986 was used for the prediction calculation of power distribution fluctuations due to core flow fluctuations, but the model is not necessarily limited to this, and the accuracy may be improved to some extent. Alternatively, a point model or three-dimensional calculation model can be used.

When using a three-dimensional calculation model, it is no longer necessary to use the three-dimensional power distribution calculated by a process computer, so the present invention can be applied even during control rod operation, and the limiter settings can be adjusted to the core state. You can make it change only when there is a change.

[Brief explanation of the drawing]

The figure is a block diagram of an embodiment of the reactor power adjustment device of the present invention. DESCRIPTION OF SYMBOLS 1...Reactor state quantity input device, 2...Process computer, 3...Output fluctuation range determination device, 4...Limiter, 5...Output automatic change device, 6...Reactor.

Claims (1)

[Claims] 1. A power fluctuation range determination device that calculates the permissible range of power fluctuation that can maintain the integrity of the core state, and a device that determines whether the required power fluctuation value is within the permissible range, and determines whether the required power fluctuation value is within the permissible range. In some cases, a limiter outputs the requested output fluctuation value as it is as an output fluctuation value, and if it is outside the tolerance range, outputs a limit value of the tolerance range as the output fluctuation value; 1. A nuclear reactor output adjustment device comprising: an output changing device for inputting a value and changing the output of the reactor based on the output fluctuation value.