Monitoring method and monitoring program for boiling water reactor, and acoustic damping method for boiling water reactor

• US 8,571,163 B2
• Filed: 07/28/2011
• Issued: 10/29/2013
• Est. Priority Date: 02/28/2006
• Status: Expired due to Fees

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Ohtsuka, Masaya, Fujimoto, Kiyoshi, Tsubaki, Masaaki
• Primary Examiner(s): Brainard, Timothy A
• Application Number:
  US13/192,606
• Publication Number:
  US 20110280358A1
• Time in Patent Office: 824 Days
• Field of Search: 376/247, 376/245, 376/241
• 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. 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 position 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 steam line including the steam dome and the steam pipe to detect a fluctuating pressure in the main steam line to produce a fluctuating pressure signal; and

a monitor and control system connected to the at least one pressure sensor for controlling the bleeding valve by monitoring the fluctuating pressure signal,

wherein the method comprises the steps of;

monitoring the fluctuating pressure signal from the at least one pressure sensor;

monitoring the boiling water reactor based on the fluctuating pressure signal monitored by the monitor and control system,

wherein the monitor and control 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.

2. 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 position 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;

at least one pressure sensor provided in a steam line including the steam dome and the steam pipe to detect a fluctuating pressure in the main steam line to produce a fluctuating pressure signal; and

a monitor and control system connected to the at least one pressure sensor for controlling the bleeding valve by monitoring the fluctuating pressure signal,

wherein the method comprises the steps of;

monitoring by the monitor and control system the fluctuating pressure signal from the at least one pressure sensor;

monitoring the boiling water reactor based on the fluctuating pressure signal monitored by the monitor and control system;

wherein the monitor and control 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.