JPS59214795A - Neutron detector for measuring nuclear away from 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 This invention relates to neutron monitoring of nuclear reactors.

Conventionally, there was a persimmon device shown in Fig. 1. In FIG. 1, 11 is a reactor vessel, and (2) is a curve representing the neutron flux distribution ψ in the height direction (X direction) of the reactor vessel. (3) A four-part neutron detector for external nuclear measurement placed parallel to the height direction of the reactor vessel (11);
(41 to (7) are detection elements built into the detector (31); in conventional devices, these detection elements are arranged at equal intervals from each other and symmetrically with the center of the detector (31). Bottom position e x = Or top position f of container (1)
If x=t, the center point position of elements 141 to (7) is
For example, they are located at +15, 2t15, and 3115°4t15, respectively.

By the way, the form of
Omitting the following terms, ψ(x) = C1stnπ-10C25in 2πT0C3
81n 3π7+ C45ln4π−=−= (11) If the coefficients C1, c2, c3, and C4 are appropriately determined, a relatively good approximation can be achieved. In the example shown in Figure 1, x = +15, 2t15, 31
ψ at the four points of 15,4115 (respectively)
'-V-)' +1 2 3 y4) is the detection element fa', 'i5+, 1
61, +71, and from this simultaneous equation (2), the coefficient C C21
C31C4'tl-can be determined. Since the conventional equipment is configured as above, it is possible to avoid the axial offset (axia) of the neutron flux distribution, which is important during reactor operation.
This method has the disadvantage that it is not suitable for accurately measuring lof f se. Axial offset is ψ (in the phantom distribution range x = 0 to x = 1, x (t/2 part and x > L/2 part). As is clear, the coefficient C2+
04, but C2+04 is originally a relatively small number, and c2.04 in each equation of simultaneous equations (2). ' Coefficient of c4 (stn2π; 15. Sin
4π15.5ln6π15°self8π15. l, (Yu 4
π15. Aggression 8π15. Gang 1st grade 15. There is not necessarily a significant difference between the equations (16π15), and therefore the simultaneous equations (2
) determined from C2. The C4 value had the disadvantage of insufficient accuracy.

This invention was made in order to eliminate the drawbacks of the conventional method as described above, and by arranging the center point of each detection element at the most appropriate position for calculating the axial offset e of the neutron distribution, The overall purpose of this invention is to provide a neutron detector for measuring outside the reactor that can accurately emit neutrons.

Hereinafter, the 111VC of this invention will be explained.

FIG. 3 is a diagram showing one embodiment of the present invention,
The same reference numerals as in FIG. 1 indicate the same or corresponding parts, and (8; is the neutron detector for measuring the outside of the reactor according to the present invention, and the detector 1B+
In this case, the center positions of the detection elements +41 to (7) are t/8, t/4, 3t/4, and 7t/8, respectively. Therefore, πx/L = π/8. π/4, 3π/4,
7π/8, and the value of ψ at these four points is y1□s '11□.

If y and y are 13 14, the coefficient of C2*04 is (thπ/4, 1,
-1.

- π:/4), (1, 0, 0, 1) changes relatively significantly, so the coefficient 02 + C4k can be determined with relative accuracy, and the axial offset of the neutron flux distribution)? According to the present invention, the center point of the detection element is set to t/8, L
/4, 31/4. Since it is placed at 'It/8, the axial offset of the neutron flux distribution)'tl- can be detected accurately.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing a conventional device, FIG. 2 is a diagram fully explaining Fourier decomposition of a neutron flux distribution, and FIG. 3 is an explanatory diagram showing an embodiment of the present invention. (1)...Reactor vessel, (21...Neutron flux distribution,
181...Neutron detector for measurements outside the reactor. In addition, the same reference numerals in each figure indicate the same or corresponding parts. Agent: Masuo Oiwa Figure 1 Figure 2 Procedural amendment (voluntary) Commissioner of the Japan Patent Office 2 Name of the invention Neutron detection for core measurement outside the reactor 3. Relationship with the case of the person making the amendment Patent Applicant Address: Chiyohi, Tokyo 2-2-3 Okihi-no-uchi Name (601) Hitoshi Katayama, Representative of Mitsubishi Electric Corporation 8th Department 6, Amendment Content tl+ The claims at the bottom of the specification are corrected as shown in the attached sheet. (2) Akira, fil, page 5, line 9, "can do." should be replaced with "can do."Furthermore, since there is no detecting element near t/2 of the detector, there is no detecting element in this part. For example, it also has percentage characteristics that can be easily incorporated into neutron detection gains in the source or intermediate region.'' 7. List of attached documents (11 amended claims 1 copy (at least)) Attachment 2: Claims The above claims are arranged outside the reactor vessel, parallel to the height direction of the reactor vessel, In the outer core side neutron detector, which is equipped with four detection elements to measure the distribution of neutron flux emitted from the reactor in the height direction, the height of the bottom of the reactor is set to 0. The height of each detection element is t/
8. A neutron detector for nuclear measurement outside the reactor, characterized in that it has a t/4.31/4°7t/8.

Claims (1)

[Claims] Four units arranged outside the reactor vessel in parallel to the height direction of the reactor vessel to measure the distribution of neutron flux emitted from the reactor in the height direction. In a neutron detector for an ex-core nuclear program, in which the height of the bottom of the reactor is O, and the height of the top of the reactor is t, the number of detection elements of the four detection elements is Total height L/8 each
, t/4. 31/4.71/8 Neutron detector for ex-core nuclear program with all the features.