News Column

Patent Issued for Nuclear Reactor Vibration Surveillance System and Its Method

July 23, 2014



By a News Reporter-Staff News Editor at Electronics Newsweekly -- Kabushiki Kaisha Toshiba (Tokyo, JP) has been issued patent number 8774340, according to news reporting originating out of Alexandria, Virginia, by VerticalNews editors.

The patent's inventors are Sato, Michio (Kanagawa, JP); Kuroda, Hidehiko (Kanagawa, JP); Izumi, Mikio (Kanagawa, JP); Enomoto, Mitsuhiro (Kanagawa, JP); Yoda, Masaki (Kanagawa, JP).

This patent was filed on March 23, 2009 and was published online on July 8, 2014.

From the background information supplied by the inventors, news correspondents obtained the following quote: "The present invention relates to a nuclear reactor vibration surveillance system for structural integrity monitoring of a nuclear reactor internal component and its method.

"As a technique for checking the structural health of a nuclear reactor internal component, there is known a method that measures the vibration amplitude or vibration frequency of the reactor internal component and evaluates the measurement values or trend thereof. In order to measure the vibration of the reactor internal component, a method is generally adopted in which a vibration sensor is installed in the reactor, and a signal from the vibration sensor is sent outside the reactor by means of a signal cable.

"However, in this method, it is necessary to lay the signal cable inside and outside the nuclear reactor, so that it takes quite a lot of work to prepare for the measurement.

"In order to cope with this problem, an ultrasonic vibration measurement system has been proposed as disclosed in Japanese Patent No. 3,782,559 (the entire content of which is incorporated herein by reference).

"In this ultrasonic vibration measurement system, an ultrasonic sensor is placed on the outer surface of a reactor pressure vessel, and an ultrasonic pulse is allowed to propagate in the reactor through the reactor pressure vessel. The ultrasonic pulse propagating in the reactor collides with and reflected by a reactor internal component such as a shroud or jet pump under water. The reflected ultrasonic pulse is retuned once again to the ultrasonic sensor through the reactor pressure vessel.

"If the reactor internal component such as a shroud vibrates, the propagation time of the returned reflected ultrasonic pulse is slightly changed due to the vibration. Assuming that the change in the propagation time of the ultrasonic pulse is .DELTA.t (sec), the vibration amplitude L (m) of the reactor internal component such as a shroud is calculated by using the following equation (1).

".DELTA..times..times..times..times..DELTA..times..times. ##EQU00001##

"'C' is the acoustic velocity (m/sec) of reactor water.

"By plotting the .DELTA.L in time series, the vibration waveform of the reactor internal component such as a shroud can be synthesized.

"In the conventional nuclear reactor vibration surveillance system and its method, an ultrasonic sensor employed is configured both as a transmitter and receiver of the ultrasonic. Thus, for example, in the case where the reactor internal component such as a jet pump is arranged inclined relative to the reactor pressure vessel, the ultrasonic pulse is obliquely reflected by the jet pump, so that the reflected ultrasonic pulse is not returned to the ultrasonic source position. As a result, the ultrasonic sensor cannot receive the reflected ultrasonic pulse, making it impossible to measure the vibration of the reactor internal component.

"The present invention has been made to solve the above problem, and an object thereof is to provide a nuclear reactor vibration surveillance system for structural integrity monitoring of a nuclear reactor internal component and its method capable of measuring the vibration of an in-reactor stricture arranged inclined relative to a reactor pressure vessel."

Supplementing the background information on this patent, VerticalNews reporters also obtained the inventors' summary information for this patent: "According to a first aspect of the present invention, there is provided a nuclear reactor vibration surveillance system comprising: a first ultrasonic transducer for transmission which is arranged on the outer surface of a reactor pressure vessel and is configured to convert a transmission signal into an ultrasonic pulse signal and allow the ultrasonic pulse to be transmitted to a reactor internal component; an ultrasonic transmitter which is electrically connected to the first ultrasonic transducer and is configured to transmit the transmission signal; a second ultrasonic transducer for reception which is arranged on the outer surface of the reactor pressure vessel and is configured to receive a reflected ultrasonic pulse reflected by the reactor internal component and convert the received reflected ultrasonic pulse into a reception signal; an ultrasonic receiver which is electrically connected to the second ultrasonic transducer and is configured to receive the reception signal; a signal processor which is electrically connected to the ultrasonic transmitter and ultrasonic receiver and is configured to input a signal to the ultrasonic transmitter and receive a signal from the ultrasonic receiver so as to apply signal processing to the signal; and a display unit which is configured to display vibration information of the reactor internal component obtained as a result of the signal processing by the signal processor.

"According to a second aspect of the present invention, there is provided a nuclear reactor vibration surveillance method comprising: allowing an ultrasonic pulse to be transmitted to a reactor internal component using a first ultrasonic transducer for transmission which is arranged on the outer surface of a reactor pressure vessel; receiving a reflected ultrasonic pulse reflected by the reactor internal component using a second ultrasonic transducer for reception which is arranged on the outer surface of the reactor pressure vessel; and applying signal processing to the received reflected ultrasonic pulse signal to measure the vibration of the reactor internal component."

For the URL and additional information on this patent, see: Sato, Michio; Kuroda, Hidehiko; Izumi, Mikio; Enomoto, Mitsuhiro; Yoda, Masaki. Nuclear Reactor Vibration Surveillance System and Its Method. U.S. Patent Number 8774340, filed March 23, 2009, and published online on July 8, 2014. Patent URL: http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PALL&p=1&u=%2Fnetahtml%2FPTO%2Fsrchnum.htm&r=1&f=G&l=50&s1=8774340.PN.&OS=PN/8774340RS=PN/8774340

Keywords for this news article include: Electronics, Signal Processing, Kabushiki Kaisha Toshiba.

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Source: Electronics Newsweekly


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