JP3053905B2 - Control rod removal monitoring device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control rod pullout monitoring device used in a nuclear power plant.

[0002]

2. Description of the Related Art In a conventional nuclear reactor, when a control rod is withdrawn, an output level around the control rod is monitored by monitoring output levels of a plurality of local output area monitors (LPRM) arranged around the control rod. When the output level around the rod abnormally rises, a control rod pull-out prevention signal is output to inhibit the control rod from being pulled out and to suppress the rise in output. A control rod pull-out monitoring device (RB)
M).

FIG. 3 shows a configuration example of a conventional RBM.

As shown in FIG. 1, detection signals from the LPRM groups around the control rods, which are separated into the A-system and the B-system and are controlled to be pulled out, are input to the RBM output operation units 1a and 1b. In the RBM output operation units 1a and 1b, the LPR
The RBM output of one control rod is obtained from the detection signals of the M group and output to the RBM output state monitoring units 2a and 2b. Then, the final power level is calculated by correlation with the core flow rate. The RBM output level of the predetermined control rod determined in this way is used as the trip determination unit 3a, 3
b and is compared with the trip level set therein.

Normally, the RBM performs an operation called a setup in which a trip level serving as a reference for determining the output of a control rod pull-out prevention signal is gradually switched from low to intermediate to high in order to avoid a transient change.

For example, when the control rod is pulled out, the RBM output corresponding to the output level around the control rod changes from point A to point C as shown in FIG. When the output level of the RBM is at point A, the trip level is set low. Then, when the output level of the RBM falls within the setup permission range, the RBM is switched to an intermediate trip level. When the trip level is set to low, R
When the BM output reaches the point C, a control rod pull-out prevention signal is output.

The switching of the trip level, that is, the setup, is performed by the operator while monitoring the output of the RBM output state monitoring units 2a and 2b, and when the output level falls within the set-up permission range, the trip determination units 3a and 3b. The setup signal has been input.

Conventionally, as shown in FIG. 4, the signal input configuration of the LPRM signal is divided into two systems, an A system and a B system, and control rods are shared and monitored in each system. In the conventional reactor, control rods are pulled out one by one. Typically, as the RBM output increases, two setups are required, low to medium and medium to high. In addition,
If the RBM system A and system B are redundant, 1
A total of four setup operations are required for pulling out the control rod. This setup is performed by the operator for each control rod.

On the other hand, in the improved boiling water reactor, gang extraction is performed in which a plurality of control rods are simultaneously extracted, and the signal input configuration is completely different between the A system and the B system as shown in FIG. It is heavy. Therefore, it is necessary to set up 4 times × 2 (A system, B system) = 8 times by pulling out one control rod. For example, when gang pulling out eight control rods, 64 setup operations are required.

[0010]

As described above, in the conventional control rod pullout monitoring device, when the control rod is pulled out by a gang, the number of setups increases, and the operation and operation are complicated, and the burden on the operator is increased. Had become.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to provide a control rod pull-out monitoring device capable of greatly reducing the number of setups and reducing the burden on the operator. I do.

[0012]

According to the present invention, in order to achieve the above object, a trip level serving as a criterion for outputting a control rod withdrawal prevention signal is determined according to an output level around a control rod to be controlled to be withdrawn. If each output level corresponding to a plurality of control rods falls within a preset setup permission range in a control rod pullout monitoring device that sets up step by step, each trip level of the control rods is set up at once. It is provided with a setup permission determining means.

[0013]

According to the present invention constructed as described above, the setup permission range is set in advance in the setup permission determination means. When the control rods are gang-pulled out, the output levels around those control rods increase simultaneously, and if the output levels around these multiple control rods are within the setup permitted range, each trip level of those control rods Are set up at once.

[0014]

An embodiment of the present invention will be described below.

FIG. 1 shows functional blocks of a control rod pull-out monitoring device according to one embodiment. In this embodiment, an LPRM signal, which is a detection signal of each LPRM arranged around each control rod, is input to the LPRM selection unit 11. The LPRM selection unit 11 separates the LPRM signal into two different LPRM groups, and converts the LPRM signals of the A-system and B-system two channels into an RBM output operation unit 12.
a and 12b. RBM output operation unit 1
Reference numerals 2a and 12b denote RBM outputs of a plurality of LPRMs (LPRM groups) around a control rod to be controlled to be pulled out, for A system and B system.
Each channel is calculated and output to the RBM output state monitoring units 13a and 13b. The RBM output state monitoring units 13a and 13b calculate the output level of the RBM from the RBM output and the core flow rate. The output level around each control rod is determined by the setup permission determination units 14a and 14b.
Are input to the trip determination units 15a and 15b, respectively.

Setup permission determination unit 14a, 1
4b, a setup permission range, for example, as indicated by hatching in FIG.
Determines whether there are M outputs, outputs a simultaneous setup signal to set up the trip levels simultaneously if there are multiple RBM outputs, and outputs the setup signal if there is only one RBM output I do.

The trip determination units 15a and 15b are:
The trip level is set by the simultaneous setup signal and the setup signal from the setup permission determination units 14a and 14b.

The operation of the embodiment constructed as described above will be described with reference to FIG. Since the RBM shown in FIG. 1 is completely duplicated, only one system will be described.

When the control rods are gang-pulled, the RBM output of the LPRM group of each control rod is calculated by the RBM output operation unit 12a, and the calculated RBM outputs are further calculated by the RBM output state monitoring unit 13a. , The respective output levels of the RBM outputs of the plurality of LPRM groups are calculated.

Now, it is assumed that the respective RBM outputs of the plurality of gang-pulled control rods are in the state shown in FIG. That is, the RBM outputs of P1 to P4 are in the monitoring state, P1 to P3 are within the setup permission range, and RB
Only the M output P4 has not yet entered the set-up permission range.

In such a state, when setting up the trip level from "intermediate" to "high", the setup permission determination unit 14a determines whether a plurality of RBM outputs are within the setup permission range, and outputs the RBM output P.
Set up the trip levels 1 to P3 simultaneously.
Further, since the RBM output P4 does not fall within the setup permission range, it is not set up and remains at “middle”.

As described above, according to this embodiment, the setup permission range is determined, and if a plurality of RBM outputs exist within the setup permission range at the time of setup, they are set up at the same time. The number of setup operations when the gang is pulled out can be greatly reduced, the driving operation is simplified, and the burden on the operator is greatly reduced. In addition, it is possible to improve the control rod withdrawal monitoring function.

[0023]

As described in detail above, according to the present invention, it is possible to provide a control rod pull-out monitoring device capable of greatly reducing the number of setups and reducing the burden on the operator.

[Brief description of the drawings]

FIG. 1 is a functional block diagram of a control rod pull-out monitoring device according to one embodiment of the present invention.

FIG. 2 is an explanatory diagram of the operation of the control rod pullout monitoring device according to one embodiment.

FIG. 3 is a functional block diagram of a conventional control rod pullout monitoring device.

FIG. 4 is a diagram showing a signal input configuration of a non-redundant RBM.

FIG. 5 is a diagram showing a signal input configuration of a redundant RBM.

FIG. 6 is a diagram for explaining a setup operation.

[Explanation of symbols]

11: LPRM selection unit, 12: RBM output operation unit, 13: RBM output state monitoring unit, 14: setup permission judgment unit, 15: trip judgment unit

Claims (1)

(57) [Claims] 1. A control rod withdrawal monitoring device that sets up a trip level, which is a criterion for outputting a control rod withdrawal prevention signal, stepwise according to an output level around a control rod to be withdrawn. If the output levels corresponding to the plurality of control rods are included in the set-up permission range, the control rod pull-out is provided with setup permission determination means for setting up each trip level of the control rods at one time. Monitoring device.