JPS59154392A - Method of detecting inactivity of fuel cladding tube in water cooled 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 invention provides that each of the fuel rod cladding tubes is provided between two ultrasonic inspection huffs 1 for inspection, and one ultrasonic inspection huff 1 is provided between each of these fuel rod cladding tubes. A sonde equipped with a sonic inspection head is moved and - 10,000 transmitting inspection - \ inspection formed as a throat, the throat irradiates ultrasonic waves onto the cladding tube, and the other formed as a receiving inspection head. The inspection node receives the ultrasonic signal arriving from the cladding tube, and at this time, the echo and intensity of the ultrasonic signal are mainly transmitted through the cladding tube wall and the two upper H. covered a
This is done in such a way that the water present between the tubes is mapped to a visible state on one column and evaluated.
The present invention relates to a method for detecting a failure state of a fuel cladding tube having a bundle of fuel rods fixed to one fuel element in a water-cooled nuclear reactor.

Such a method is
der Jahrestagp, r+gKerntech
Nik 8 D (1980, Annual Report of the Annual Conference on Nuclear Technology), pp. 827 onwards.

Honification, Deutsche A, tom? It is publicly known since the orum federation edition 1 publication.

In the technique described in this document, the inspection head is continuously guided through the intermediate space of the fuel element. The continuous movement of the sonde carrying the test head results in echo time fluctuations and fluctuations in the emitted signal. On one hand, the ultrasound signal is made visible and documented with a pencil. Ultrasonic signals (rotating echoes) reaching the receiving inspection head from the cladding tube in the evaluation area recorded as a gate
It is necessary to separate the direct emitting signal 1 from the signal (water signal) which passes only through the cooler from the test head and reaches the receiving test head. , but U7, this approach often leads to failure. Due to the different diameters of the cladding and guide tubes and the flexible design of the test head carrier, the spacing between the test heads is such that these heads can be adjusted to the individual cladding tubes and guide tubes for the control rods. This is because it generally fluctuates significantly while moving alongside the .

This changes the echo time of the sound waves, and - the signal reaching directly from the force test head l' to the other test head (water signal) is displayed as the signal reaching the receiving test head from the cladding tube (rotating echo). It is from. Furthermore, if amplitude fluctuations occur outside the gate or at the edges of the gate, and the display is not or only incompletely displayed,
The above documentation using a writing instrument is inappropriate.

This inaccuracy did not adversely affect the evaluation of what was documented at a later point in time.

For this reason, in the present invention, as stated at the beginning/
The purpose of this method is to ensure signal allocation to the sonde travel path and to improve signal documentation and evaluation.

The above-mentioned problem is solved by the present invention by detecting and storing the cytographic image at each stop of the sonde and by comparing the detected value with the stored index of the fuel element cross-section. resolved.

Since the open signal is not lost during detection and the stepwise motion of the sonde eliminates temporal fluctuations and purity of the signal, an accurate and complete evaluation is achieved. 7. Fuel element memory. The signal allocation′, /
Make it easier.

In particular, the range of movement of the sonde is approximately the same as the wall thickness of the cladding tube in order to obtain a sufficient number of oscillographic images for accurate reporting.

2 The invention will be explained in detail below with reference to embodiments illustrated in the attached drawings.

In FIG. 1, a subregion designated 1 of a fuel element of a water-cooled nuclear reactor can be seen. Reference numeral 2 designates the cladding of the fuel rod 6, which contains fuel in the form of a tufflet (not shown). The guide tube 4 has a larger outer diameter than the cladding tube 2 and serves to guide a control rod (not shown). between the cladding tubes.

Sondes 5 and 6 are moving step by step in the space and in the space between the guide tube and the cladding tube. In this case, sonde 5 is moving the transmitter test head door, and sonde 6 is the receiver test head relative to the transmitter test head. The head 8 is carried. The distance of the flexible sonde 5° is indicated by a broken line 9. Code A
, B, C and D indicate some inspection head positions. From these test head positions, changes in the spacing between the transmitting test head and the receiving test head 7.8 can be observed. Each time the stepwise displacement movement of the probe is stopped, an oscillographic image corresponding to the respective examination position is detected and stored1, thereby obtaining a quarter of the wall thickness of the cladding tube.
A large number of different recordings are made in the range of the movement of the sonde from half to half. FIG. 2 symbolically shows the three-dimensional signal mountain range J i 0.11. These 1, 4
The "Mountain Range" is later stored for the purpose of evaluation after it has been quantified in advance.

i41] FIG. 2 shows the pedestal sheet metal formed within the tire crumb seen in the storage unit Uniso I-. The curve shows the sonde's travel path 12 (C) depending on the time axis of the acoustic wave 13 and the intensity and amplitude axes of the main signal or the corresponding cycle signal T4f. The interval between 1 and 7 indicates the progress width of this index. [Signal Mountains J
iO,11 is formed from a large number of oscilloscope images stacked one after another, and these oscilloscope images are detected each time the sonde is at rest. In the amplitude cylinder, 1 signal mountain range J 1o is the set of main signals (to the reception test of transmission test heso l' 7] l-" 8 is a direct progression), and [-signal range" 11 is the set of rotation signals (The signal progresses through the cladding wall.)

: Two rotational echoes 11 are shown for each of the two main signals 10, each for one cladding wall section.

The detected and stored value is compared with the value of the fuel element IJ stored in the same device. Any deviation from the normal value is considered to be a faulty pipe. Known fraudulent sources. It is not necessary to determine the evaluation area.

[Brief explanation of drawings]

Figure 1 is a cross-sectional view of a part of the fuel element, and Figure 2 is a measurement diagram.The code in the diagram is 5.6...Sonde agent: Hikaru Esaki Good agent: Hikaru Esaki Fumiteh'G 'j'jll ilE 'jM O, -, r
. 1...'' (Delivery/13/7?-:l Director General of the Patent Office Young 4 Yu Jll Husband 1, Indication of the middle matter 2nd year, Ma'-- 1″′
) 0 bow 3, supplementary 1 person ('1 connection 111, applicant n 1 cho] death 1, 7. □1.1), □--
)' Mr. Shin Nto... Case 21. zl
, 7i. , 1.1.7.2. 2.7. 5, Wa, 7 da 41, Agent 5, El application for the order, (G's invention Hana Yokoda application) (No change in content) 7, hn17-', as shown in the attached document 512-

Claims (2)

[Claims] (1) Each of the fuel rod cladding tubes is installed between two ultrasonic inspection heads for inspection, and a sonde each equipped with one ultrasonic inspection head passes between these fuel rod cladding tubes. The extractor is moved, and the inspection throat formed as a transmitting inspection head on one side irradiates the cladding tube with ultrasonic waves, and the inspection navel 1~ formed as a throat on the other receiving inspection head reaches from the cladding tube. receive the ultrasonic signal 7;
At this time, the echo time and intensity of the ultrasonic signal are transmitted through the tube wall and the two above-mentioned objects during the arrival process of this signal.
This is done in such a way that the water present between the i-tubes is mapped to a visible state on the ontograph and evaluated.
A method for detecting a failure condition of a fuel cladding tube having a bundle of fuel rods assembled into one fuel element body in a water-cooled nuclear reactor, in which the probes (5, 6) are moved in full steps; The above detection method is characterized in that each time the sonde is stationary, an onlograph is detected (and this image 'fc is stored) and the detected values are compared with a stored matrix of fuel element cross sections. (2) The detection method according to item 1, wherein the range of the % tolerance requirement is set to be one-quarter to one-half of the wall thickness of the entire cladding tube (2).