JPS58172580A - Reactor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the improvement of nuclear reactors, and in particular to increasing the fuel arrangement and the number of fuel rods in the nuclear F core, and increasing the operability Mt 'k Iu+l by increasing the fuel arrangement and number of fuel rods in the F core. Concerning preferred nuclear reactors.

In a boiling water reactor, IT control is used to control the operation of the reactor by adjusting the reactor core structure and power distribution. That is, at the beginning of cycle combustion, the reactivity is high, so the reactivity is adjusted to obtain the own output by pushing the suppressor deeply, but as the combustion progresses, the reactivity gradually decreases. So, pull out the control rod accordingly.

Therefore, at the end of the cycle K Id , the control rod is almost fully withdrawn. In this case, if the same control rod is used throughout the entire cycle, the combustion of the fuel in contact with it will be delayed and a local increase in output will occur at the end of the cycle. An exchange of hatans takes place.

On the other hand, specifying the operation part #lI during output operation,
Instead, a method has been proposed in which four fuel assemblies with low reactivity are arranged to form a cell (hereinafter referred to as a control cell). As the fuel assembly forming this control cell km, it is desired that the fuel assembly has a low maximum linear power density, which represents a reduction in reactivity.

The object of the present invention is to designate the operating section during power operation and arrange the linear power density Kt lowering friend reactor materials around these designated control rods, thereby reducing the power consumption of the control rods during operation. This eliminates the need for pattern exchange, reduces the number of control rod operations, and eliminates the need for control rod withdrawal.
Another object of the present invention is to provide a nuclear reactor that can simplify operation, improve efficiency, and at the same time ensure the integrity of the fuel.

The linear power density f (all/ft) of the fuel is obtained by dividing the output of the fuel assembly by the total length of the fuel rods (the product of the length of one working pipe and the number of fuel rods). Therefore, as the number of fuels in the fuel assembly increases, the linear output increases inversely. ! Ifri decreases. this thing? Used as a fuel assembly, especially in the control cell, it is a fuel holder! Control @ using fuel assemblies increased by 2
The linear power density of the fuel in the Keyaki cell is reduced.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be explained with reference to the drawings.

Figure 41 shows the arrangement a of the control rods 1, 2 and fuel assembly 3 in a 1100 MW boiling water reactor.The control rods suppress the excess reaction ft- during power operation. The control rods are classified into operation control rods l, which are designated for the purpose of operation, and stop control rods wI2, which are mainly used for starting and stopping. In the former case, the 94 fuel assemblies are called control cells. On the other hand, the four fuel assemblies around the latter stop control 112 are called non-controlled cells. Is Figure 2 a conventional technique? In the configuration row of cells based on #, the fuel assembly is loaded with 8×8 type fuel 4 consisting of 64 fuel rods.

In the present invention, in particular, the control cell is loaded with fuel having an increased number of fuel rods, such as a 9.times.9 type fuel 5, as shown in Figure 3. Since the linear power density of 9X9 type fuel 5 is approximately 22% lower than that of 8X8 type fuel 4, the restriction of PC20MR at the time of output increase is greatly relaxed, and the output at the time of full withdrawal of control at the end of the cycle is reduced. Useful for local relief. In particular, in the initial loading core, a method has been proposed to lower the output in the control cell by loading the control cell with low enrichment control fuel 1, but in this way, all low enrichment fuel is loaded from the beginning. Using too much fuel is disadvantageous in terms of fuel economy. On the other hand, when a 9x9 type fuel is used in the control cell as in the present invention, the rich am can be increased by the amount that the linear power density has decreased, so the cycle burnup of the core will increase. , the extraction burnup increases, which is advantageous in terms of fuel economy.

According to the present invention, there is no need to replace the control rod pattern during operation, the number of control rod operations is reduced, the operation is simplified, the availability rate is improved, and at the same time, the soundness of the fuel can be ensured. In addition, there is no need to use a large amount of low-reactivity fuel in the WfiI@l cell circle, which has the effect of improving fuel economy.

[Brief explanation of the drawing]

Figure 1 is an explanatory diagram of a nuclear reactor using a control cell, and Figure 2 is an illustration of a nuclear reactor using a control cell.
FIG. 3 is an explanatory diagram of a non-control cell made up of 8×8 type fuel, and FIG. 3 is an explanatory diagram of a control cell made up of 9×9 type lighting material. 1... Control rod for operation, 2... Control rod for stopping, 3...
・Fuel (Fortune - 1 cow of grass 2 30 grass 5 / 475

Claims (1)

[Claims] 1. As the large number of fuel assemblies with large external dimensions that make up the reactor core, there are two types: one consisting of a square lattice arrangement 1 of fuel rods with a small outer pole and a large number of fuel rods, and the other consisting of a square lattice arrangement 1 of fuel rods with a large outer diameter and a small number of fuel rods. In addition to using a square grid arrangement, +t11 @l salary to be operated during output operation is specified, and for these specified control points, the A nuclear reactor that is waiting to be loaded with a fuel lI + east combination consisting of a number lattice arrangement.