Abstract: A chemical decontamination method capable of improving the decontamination efficiency of chemical decontamination of a steam dryer in the RPV is provided. In particular, the decontamination method includes feeding a chemical decontamination aqueous solution into a reactor pressure vessel in which a steam dryer is arranged, and after chemical decontamination of the steam dryer, the water level of the chemical decontamination aqueous solution existing in the reactor pressure vessel is lowered to a first water level below the lower end of the steam dryer.

Abstract: A sound pickup apparatus, which can control directionality and has a simple structure, and in which a plurality of microphones can be provided so as to be floated by using the small number of parts, is provided. Three support columns 13A to 13C having the same length are provided upright on a top surface of a housing 11 of a sound pickup apparatus 1. The support columns 13A to 13C are equidistantly arranged away from a center position of the housing 11 and equally spaced 120 degrees apart from each other. A frame 4 having microphone frames 14A to 14C in which microphones are fitted is arranged above the top surface of the housing 11. In addition, the microphone frames 14A to 14C are coupled to the support columns 13A to 13C of the housing 11 by elastic rubbers 15A to 15C in a state where tensile stress passes the center of the housing 11 and is generated in an outward direction.

Abstract: The invention provides a sound collection device having little error in a desired directivity. The sound collection device includes a unidirectional microphone 12A, a unidirectional microphone 12B, and a unidirectional microphone 12C which are arranged on one plane. Each of the unidirectional microphones has the maximum sensitivity direction directed toward the inside of the arrangement. Each of the unidirectional microphones has a rear surface (direction of the minimum sensitivity) being open acoustically. Since the maximum sensitivity direction of each of the unidirectional microphones is directed toward the inside of the arrangement, the oscillation plane of each of the unidirectional microphones can be positioned substantially at the center of the arrangement. Thus, by adjusting the gain of the sound collected by the respective unidirectional microphones, the directivity can be freely formed on a flat plane with little error.

Abstract: The invention provides a sound collection device having little error in a desired directivity. The sound collection device includes a unidirectional microphone 12A, a unidirectional microphone 12B, and a unidirectional microphone 12C which are arranged on one plane. Each of the unidirectional microphones has the maximum sensitivity direction directed toward the inside of the arrangement. Each of the unidirectional microphones has a rear surface (direction of the minimum sensitivity) being open acoustically. Since the maximum sensitivity direction of each of the unidirectional microphones is directed toward the inside of the arrangement, the oscillation plane of each of the unidirectional microphones can be positioned substantially at the center of the arrangement. Thus, by adjusting the gain of the sound collected by the respective unidirectional microphones, the directivity can be freely formed on a flat plane with little error.

Abstract: A sound pickup apparatus, which can control directionality and has a simple structure, and in which a plurality of microphones can be provided so as to be floated by using the small number of parts, is provided. Three support columns 13A to 13C having the same length are provided upright on a top surface of a housing 11 of a sound pickup apparatus 1. The support columns 13A to 13C are equidistantly arranged away from a center position of the housing 11 and equally spaced 120 degrees apart from each other. A frame 4 having microphone frames 14A to 14C in which microphones are fitted is arranged above the top surface of the housing 11. In addition, the microphone frames 14A to 14C are coupled to the support columns 13A to 13C of the housing 11 by elastic rubbers 15A to 15C in a state where tensile stress passes the center of the housing 11 and is generated in an outward direction.

Abstract: An audio feedback suppression device is provided that outputs a sound while changing a phase so as not to generate audio feedback without performing a relatively complicated process. A phase control section 2 generates a phase adjustment value ? gradually varying with the lapse of time and gives the value ? to an adjustment signal generation section 121 of a phase shifter 1. Phase adjustors 111 and 112 of the phase shifter 1 output two first stage adjusted signals having phases which are shifted from each other by ?/2 in accordance with a shifter input signal. An adjusting signal generation section 121 generates a cosine value cos(?) and a sine value sin(?) of a phase adjustment value 0 and gives the values to respective multipliers 123A and 123B. The multiplier 123A multiplies one of the first stage phase adjusted signals to the cosine value cos(?) and the multiplier 123B multiplies the other first stage phase adjusted signal to the sine value sin(?).