Doryokuro Kakunenryo Kaihatsu Jigyodan

Yokogawa Electric Works, Ltd.

Nobumi Ohyama

Koichiro Nakamoto

Hajime Kuwahara

Kiyoshi Adachi

Kiyokazu Ishii

A multiple-sheathed sodium leakage detection apparatus capable of detecting a small amount of leakage of sodium due to a breakage of a well for temperature measurement at an early stage of the leakage. The apparatus is a combination of a multiple-sheathed sodium leakage detector having a sheathed thermocouple and sodium leakage detection element wires, which are disposed in an insulating material filled in a multiple sheath; a sodium leakage judgment device which judges whether or not there is a leakage of sodium by a signal from the multiple-sheathed sodium leakage detector; an alarm device which gives an alarm when it is judged that there is a leakage of sodium; and signal lines which connect these devices. The multiple-sheathed sodium leakage detector is designed in conformity to the sheath outer diameter so that it can be inserted into a well which has already been installed on an existing piping without changing the well.

Multiple-sheathed sodium leakage detection apparatus

A method for monitoring flow condition of a liquid metal which employs a detector consisting of an excitation coil applied with an a.c. current and at least two detection coils disposed on both sides of said excitation coil. The detector is disposed in the flowing direction of the liquid metal and a peak point of the cross-correlation function of fluctuation signals occurring in said detection coils is examined. By detecting the moving direction, the polarity and the magnitude of the peak point, the flow condition can be comprehensively ascertained, such as a change in flow velocity, a change in void fraction, the presence of voids and transit velocity of void.

Method for monitoring flow condition of liquid metal

A detector to be inserted into a flowing conductive fluid, e.g. sodium coolant in a nuclear reactor, comprising at least one exciting coil to receive an a-c signal applied thereto and two detecting coils located in the proximity of the exciting coil. The difference and/or the sum of the output signals of the detecting coils is computed to produce a flow velocity signal and/or a temperature-responsive signal for the fluid. Such flow velocity signal or temperature signal is rectified synchronously by a signal the phase of which is shifted substantially .+-. 90.degree. with respect to the flow velocity signal or temperature signal, thereby enabling the device to detect voids in the flowing fluid without adverse effects from flow velocity variations or flow disturbances occurring in the fluid.

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Oarai-machi, Japan

Nobumi Ohyama