JPH1184065A - Reactor output measuring device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To densely and accurately measure a temperature distribution in the axial direction within a reactor by installing a γ-ray thermometer for each fuel assembly pitch in the axial direction of a detector assembly. SOLUTION: Four local output detectors 3 that are constituted of a neutron flux detector and a plurality of γ-ray thermometers 4 are inserted and arranged for formation corresponding to four levels in a vertical direction within a reactor. The thermometers 4 are arranged corresponding to a fuel assembly pitch. For example, the number of thermometers 4 is equal to 24 when an assembly pitch is 150 mm and the axial length of the assembly 6 is equal to 3,708 mm. The thermometers are mounted in an axial direction corresponding to the fuel assembly pitch in a vertical direction inside the reactor. The output of the 24 thermometers 4 is inputted to an axial direction output distribution measuring device via a signal cable. Since a reactor output distribution for indicating a larger output at a center part than an edge part in axial direction can be obtained, the output of the reactor can be measured accurately.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reactor power measuring apparatus having a gamma ray thermometer in a reactor.

[0002]

2. Description of the Related Art Reactor power measurement by a local power detector composed of a neutron flux detector of a boiling water reactor is described below.
It is known to perform calibration using a γ-ray thermometer. For example, as described in JP-A-3-65696, a local output detector and a γ-ray thermometer are arranged while being separated from each other along the axial direction of the detector assembly, and the γ-ray thermometer is usually used. A method has been proposed for simplifying the calibration system of the local power detector by using it together with the reactor heat balance.

A γ-ray thermometer measures a reactor power based on a calorific value generated by γ-rays in a reactor core.
4 or 8 in a detector assembly that includes
It is supposed to be implemented.

As described in Japanese Patent Application Laid-Open No. Hei 6-289182, a plurality of fixed neutron detectors are installed at intervals in an axial direction in a detector protection tube,
In the same protective tube, the installation position of the fixed neutron detector and the radial position are different, so that a larger number of γ than the fixed neutron detector is used.
It has been proposed to set a linear thermometer at an axial center position of a core roughly and an interval at an end portion in the same direction more densely than a coaxial center position.

[0005]

However, the above prior art does not consider the relationship between the arrangement of the γ-ray thermometer and the accuracy of the reactor power measurement.

An object of the present invention is to realize a reactor power measurement with high accuracy.

[0007]

In order to solve the above problems, a gamma ray thermometer is provided for each fuel assembly pitch in the axial direction of the detector assembly. By doing so, the temperature distribution in the axial direction in the reactor can be measured densely, so that the reactor power can be measured with high accuracy.

It is preferable that a plurality of γ-ray thermometers are installed at the same axial level in the protective tube. According to this, the reliability of the temperature measurement in the reactor by the γ-ray thermometer can be increased.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a structural diagram of a main part of an embodiment of a reactor power measuring apparatus according to the present invention. As shown in the figure, the reactor power measurement device of the in-reactor detector fixed type includes a detector assembly 1 corresponding to a fuel assembly 6.

Four local output detectors 3 composed of neutron flux detectors and a plurality of γ-ray thermometers 4 corresponding to the four levels in the axial direction of the protection tube 2, that is, in the vertical direction in the reactor.
And are inserted and arranged. The output of the local output detector 3 is input to a local monitoring device (not shown) via a signal cable. The fuel assembly 6 includes a plurality of fuel rods 5.
, And the fuel rods 5 are partitioned for each fuel assembly pitch.

The gamma ray thermometer 4 is arranged corresponding to the fuel assembly pitch. For example, if the fuel assembly pitch is 1
50 mm, the axial length of the fuel assembly 6 is 3708 mm (= 1
46 inches), the number of γ-ray thermometers 4 is 3708
/ 150 = 24 (pieces). The twenty-four γ-ray thermometers 4 are mounted in the axial direction corresponding to the fuel assembly pitch in the vertical direction in the reactor.

The outputs of the 24 γ-ray thermometers 4 are input to an axial power distribution measuring device (not shown) via a signal cable. Next, the reactor power distribution obtained by the axial power distribution measuring device according to the outputs of the 24 γ-ray thermometers 4 will be described with reference to FIG. As shown in the figure, it is possible to obtain a dense reactor power distribution showing a larger output at the axial center than at the axial end. The neutron flux detector is affected by the water gap.
Can be measured without being affected by the water gap due to its measurement principle.

[0013]

As described above, according to the present invention,
Since the axial power distribution of the reactor can be obtained densely,
Reactor power measurement can be realized with high accuracy.

[Brief description of the drawings]

FIG. 1 is a main part configuration diagram of an embodiment of a reactor power measuring apparatus according to the present invention.

FIG. 2 is a reactor power measurement distribution diagram obtained from a γ-ray thermometer according to an embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Detector assembly 2 Protection tube 3 Fuel rod 4 Local output detector 5 γ-ray thermometer 6 Fuel assembly

Claims (2)

[Claims] A local power detector for measuring a thermal neutron flux in a reactor and a gamma ray thermometer are inserted and arranged in a protective tube to form a detector assembly. In a reactor power measuring device installed in a reactor to measure a reactor power, the reactor power measurement is characterized in that the γ-ray thermometer is installed at every fuel assembly pitch in the axial direction in the protection tube. apparatus. 2. The reactor power measuring apparatus according to claim 1, wherein a plurality of said γ-ray thermometers are installed at the same axial level in said protection tube.