MONITORING METHOD AND MONITORING PROGRAM FOR BOILING WATER REACTOR, AND ACOUSTIC DAMPING METHOD FOR BOILING WATER REACTOR

• US 20110280358A1
• Filed: 07/28/2011
• Published: 11/17/2011
• Est. Priority Date: 02/28/2006
• Status: Active Grant

• Current Assignee: Kiyoshi Fujimoto, Masaaki Tsubaki, Masaya Ohtsuka
• Original Assignee: Kiyoshi Fujimoto, Masaaki Tsubaki, Masaya Ohtsuka
• Inventors: OHTSUKA, Masaya, Fujimoto, Kiyoshi, Tsubaki, Masaaki
• Granted Patent: US 8,571,163 B2
• Time in Patent Office: Days
• US Class Current: 376/247
• CPC Class Codes: G21C 17/00 Monitoring; Testing measuring in general G01; Maintaining
• CPC Class Codes: G21C 17/02 Devices or arrangements for monitoring coolant or moderator
• CPC Class Codes: G21D 3/001 Computer implemented control
• CPC Class Codes: G21D 3/08 Regulation of any parameters in the plant
• CPC Class Codes: Y02E 30/00 Energy generation of nuclear origin
• CPC Class Codes: Y02E 30/30 Nuclear fission reactors

Abstract

A method for monitoring and acoustic damping a boiling water reactor which includes: a reactor pressure vessel; a steam pipe for transporting steam out from a steam dome of the reactor pressure vessel; a high pressure turbine driven by the steam; a feedwater heater which heats feedwater supplied to the reactor pressure vessel using bleed steam from the high pressure turbine; a bleeding valve which adjusts a flow rate of the bleed steam; and a pressure sensor provided in a main steam line including the steam dome and the steam pipe. The method includes monitoring a fluctuating pressure in the main steam line and controlling an opening degree of the bleeding valve based on a magnitude of the fluctuating pressure.

Claims

1. An acoustic damping method for a boiling water reactor which comprises:

a reactor pressure vessel;

a steam pipe for transporting steam generated in the reactor pressure vessel out from a steam dome positioned at an upper part of the reactor pressure vessel;

a high pressure turbine connected to the steam pipe and driven by the steam;

a feedwater heater which heats feedwater supplied to the reactor pressure vessel using bleed steam flowing from the high pressure turbine to the feedwater heater;

a bleeding valve which adjusts a flow rate of the bleed steam supplied to the feedwater heater; and

at least one pressure sensor provided in a main steam line including the steam dome and the steam pipe,

wherein the method comprises the steps of;

detecting fluctuating pressure caused by acoustic resonance generated in the main steam line;

controlling an opening degree of the bleeding valve such that the fluctuating pressure to be detected becomes minimum; and

further controlling the opening degree of the bleeding valve such that a product of a formula given by Es×

Q is constant,

where Es is an enthalpy difference based on a difference between a temperature of the feedwater that is supplied to the reactor pressure vessel and a temperature of steam that is transported out from the reactor pressure vessel, and Q is a flow rate of steam that is obtained by controlling the opening degree of the bleeding valve.

2. An acoustic damping method for a boiling water reactor which comprises:

a reactor pressure vessel;

a steam pipe for transporting steam generated in the reactor pressure vessel out from a steam dome positioned at an upper part of the reactor pressure vessel;

a high pressure turbine connected to the steam pipe and driven by the steam;

a feedwater heater which heats feedwater supplied to the reactor pressure vessel using bleed steam flowing from the high pressure turbine to the feedwater heater;

a bleeding valve which adjusts a flow rate of the bleed steam supplied to the feedwater heater;

at least one pressure sensor provided in a main steam line including the steam dome and the steam pipe; and

a control rod drive which drives and controls control rods for controlling a nuclear fission reaction of uranium fuel in the reactor pressure vessel;

wherein the method comprises the steps of;

detecting fluctuating pressure caused by acoustic resonance generated in the main steam line;

controlling an opening degree of the bleeding valve as well as controlling the control rod drive such that the fluctuating pressure to be detected becomes minimum; and

further controlling the opening degree of the bleeding valve such that a product of a formula given by Es×

Q is constant,

where Es is an enthalpy difference based on a difference between a temperature of the feedwater that is supplied to the reactor pressure vessel and a temperature of steam that is transported out from the reactor pressure vessel, and Q is a flow rate of steam that is obtained by controlling the opening degree of the bleeding valve and controlling the control rod drive.

3. A monitoring method for a boiling water reactor which comprises:

a reactor pressure vessel;

a steam pipe for transporting steam generated in the reactor pressure vessel out from a steam dome positioned at an upper part of the reactor pressure vessel; and

a high pressure turbine connected to the steam pipe and driven by the steam;

wherein the method comprises the steps of;

monitoring by a monitor system a fluctuating pressure signal from at least one pressure sensor provided in a steam line including the steam dome and the steam pipe; and

monitoring the boiling water reactor based on this monitoring result.

4. A monitoring method according to claim 3, wherein the monitor system executes the steps of:

an analytical studying step for analytically studying an acoustic resonance phenomenon in the steam line and calculating resonance frequency and sound pressure distribution in the steam line;

a detected signal analyzing step for processing the fluctuating pressure signal from the pressure sensor and calculating resonance frequency and fluctuating pressure distribution;

a determination step for comparing results obtained by the analytical studying step and the detected signal analyzing step and determining whether or not a difference in the comparison is equal to or lower than an allowable difference value;

an analytical studying condition changing step for changing an analytical studying condition in the analytical studying step if the difference in the comparison is more than the allowable difference value;

a fluctuating pressure distribution calculating step for calculating fluctuating pressure distribution applied to a surface of a structure in the steam line by the analytical studying step if the difference in the comparison is equal to or lower than the allowable difference value;

a stress distribution calculating step for calculating stress distribution caused in the structure by the fluctuating pressure distribution applied to the surface of the structure;

a threshold pressure amplitude calculating step for calculating a threshold pressure amplitude of the pressure sensor that is required for the structure to reach a fatigue fracture free stress; and

a monitoring step for monitoring whether or not fluctuating pressure amplitude obtained by the fluctuating pressure signal from the pressure sensor is equal to or lower than the threshold pressure amplitude.

5. A monitoring method according to claim 3, wherein the monitor system executes the steps of:

an analytical studying step for analytically studying an acoustic resonance phenomenon in the steam line and calculating resonance frequency and sound pressure distribution in the steam line;

a detected signal analyzing step for processing the fluctuating pressure signal from the pressure sensor and calculating resonance frequency and fluctuating pressure distribution;

a determination step for comparing results obtained by the analytical studying step and the detected signal analyzing step and determining whether or not a difference in the comparison is equal to or lower than an allowable difference value;

an analytical studying condition changing step for changing an analytical studying condition in the analytical studying step if the difference in the comparison is more than the allowable difference value;

a fluctuating pressure distribution calculating step for calculating fluctuating pressure distribution applied to a surface of a structure in the steam line by the analytical studying step if the difference in the comparison is equal to or lower than the allowable difference value;

a stress distribution calculating step for calculating stress distribution caused in the structure by the fluctuating pressure distribution applied to the surface of the structure; and

a monitoring step for monitoring whether or not a stress obtained by the stress distribution calculating step is equal to or lower than a fatigue fracture free stress of the structure.