Method for electromagnetic ultrasonic conversion for monitoring the fill level and bubble formation in enclosures containing liquid

Method for monitoring fill level and bubble formation through electromagnetic ultrasonic conversion in a cylindrical boiling water reactor pressure vessel of a nuclear power plant having an interior (3.0) for containing reactor coolant water having a normal fill level and following a water route (3) adjacent a wall (1) having an inner boundary surface (1.1) as well as a reflector (2) in the form of a built-in component within the water route, which comprises coupling at least one transmission converter (SE1, SE2, S) from outside onto the wall at least at one location just below the normal fill level, coupling at least one receiver converter (SE1, SE2, E, E.sub.1, E.sub.2, E.sub.21, E.sub.3) to the wall (1), generating ultrasonic vibrations in the wall inducing ultrasonic echo signals differing by at least one of amplitude and phase in the at least one receiver converter (SE1, SE2, E, E.sub.1, E.sub.2, E.sub.21, E.sub.3), depending on whether the interior (3.0) contains liquid (3), liquid (3) containing steam or gas bubbles (4), or only a fluid in the form of vapor or gas, while reflecting the signals on the inner boundary surface (1.1) or striking the reflector (2) after entering the liquid (3) and traveling a distance therein, and reflecting the signals back from the reflector through the fluid (3) and through the wall (1) to the receiver converter (SE1, SE2, E, E.sub.1, E.sub.2, E.sub.21, E.sub.3),

• returning the ultrasonic transmitted beam (S.sub.W, S.sub.1W) traveling through the container wall (1) as well as the adjacent water route (3) of the reactor water and striking the built-in component (2) to the outside (1.2) of the container wall (1) in the form of an echo signal of a first type (E.sub.1W) where it is received as a "water present" signal by a receiver converter (SE1, SE2, E), while reflecting the transmitted beam (S.sub.1) on the inside (1.1) of the container wall (1) where it is received as an echo signal of a second type (E.sub.1S) at the receiver converter or at another receiver converter as a "no water present" signal, in the absence of water, the echo signal of the second type (E.sub.1S) having a shorter transit time and a greater amplitude than the echo signal of the first type (E.sub.1W), and
• converting the "water present" echo signal of the first type to a "water containing bubbles present" echo signal of a third type (E.sub.2W) being scattered into a plurality of partial echo signals and reduced in amplitude, if vapor or gas bubbles (4) are present in the monitored water route (3) up to a threshold of the bubble volume proportion.

Method for monitoring fill level and bubble formation through electromagnetic ultrasonic conversion in a cylindrical boiling water reactor pressure vessel of a nuclear power plant having an interior (3.0) for containing reactor coolant water having a normal fill level and following a water route (3) adjacent a wall (1) having an inner boundary surface (1.1) as well as a reflector (2) in the form of a built-in component within the water route, which comprises coupling at least one transmission converter (SE1, SE2, S) from outside onto the wall at least at one location just below the normal fill level, coupling at least one receiver converter (SE1, SE2, E, E.sub.1, E.sub.2, E.sub.21, E.sub.3) to the wall (1), generating ultrasonic vibrations in the wall inducing ultrasonic echo signals differing by at least one of amplitude and phase in the at least one receiver converter (SE1, SE2, E, E.sub.1, E.sub.2, E.sub.21, E.sub.3), depending on whether the interior (3.0) contains liquid (3), liquid (3) containing steam or gas bubbles (4), or only a fluid in the form of vapor or gas, while reflecting the signals on the inner boundary surface (1.1) or striking the reflector (2) after entering the liquid (3) and traveling a distance therein, reflecting the signals back from the reflector through the fluid (3) and through the wall (1) to the receiver converter (SE1, SE2, E, E.sub.1, E.sub.2, E.sub.21, E.sub.3),

• returning the ultrasonic transmitted beam (S.sub.W, S.sub.1W) traveling through the container wall (1) as well as the adjacent water route (3) of the reactor water and striking the built-in component (2) to the outside (1.2) of the container wall (1) in the form of an echo signal of a first type (E.sub.1W) where it is received as a "water present" signal by a receiver converter (SE1, SE2, E), while reflecting the transmitted beam (S.sub.1) on the inside (1.1) of the container wall (1) where it is received as an echo signal of a second type (E.sub.1S) at the receiver converter or at another receiver converter as a "no water present" signal, in the absence of water, the echo signal of the second type (E.sub.1S) having a shorter transit time and a greater amplitude than the echo signal of the first type (E.sub.1W), and
• converting the "water present" echo signal of the first type to a "water containing bubbles present" echo signal of a third type (E.sub.2W) being scattered into a plurality of partial echo signals and reduced in amplitude, if vapor or gas bubbles (4) are present in the monitored water route (3) up to a threshold of the bubble volume proportion,
• transmitting, vertically polarized free transversal or SV waves inward at an oblique angle (.alpha.) relative to an incident vertical (1.sub.0) with the at least one transmitter converter (S), refracting the obliquely transmitted beam (S.sub.1W) toward the vertical at the boundary surface (1.1) of the container wall and the water route, and converting the transmitted beam into a longitudinal wave being reflected at the built-in component (2), traveling once again through the boundary surface (1.1) between the water route and the container wall and then being converted back into an SV wave and refracted back toward the vertical and received as an echo signal of the first or third type (E.sub.1W or E.sub.2W) by the receiver converter (E), the transmitted beam being distinguished in terms of amplitude and phase from the echo signal of the second type (E.sub.1S), which is totally reflected at the inner boundary surface (1.1) of the container wall (1) and from there reaches the receiver converter (E) unrefracted, in the absence of water.