System and method of confirming operation of a steam relieving safety valve for a water-cooled nuclear reactor

• US 4,648,425 A
• Filed: 08/20/1980
• Issued: 03/10/1987
• Est. Priority Date: 09/10/1979
• Status: Expired due to Term

• Current Assignee: Japan Nuclear Cycle Development Institute (Japan Atomic Energy Agency)
• Original Assignee: Doryokuro Kakunenryo Kaihatsu Jigyodan
• Inventors: Kurahashi, Takashi, Takiyama, Masashi, Uchikawa, Tadashi, Watanabe, Kenshu
• Primary Examiner(s): Chambers, A. Michael
• Application Number:
  US06/179,879
• Time in Patent Office: 2,393 Days
• Field of Search: 137/524, 137/577, 176/19 R, 176/19 J, 176/19 LD, 176/65, 116/264, 116/266, 116/70, 73/39, 73/40, 73/40.5, 60/644, 60/646, 60/657
• US Class Current: 137/557
• CPC Class Codes: F16K 37/00 Special means in or on valves or other cut-off apparatus for indicating or recording operation thereof, or for enabling an alarm to be given
• CPC Class Codes: G21C 9/004 Pressure suppression
• CPC Class Codes: Y02E 30/30 Nuclear fission reactors
• CPC Class Codes: Y10T 137/8326 Fluid pressure responsive indicator, recorder or alarm

Abstract

A system and a method of confirming the operation of a steam relieving safety valve for a water-cooled nuclear reactor are provided. Acoustic vibration generated by steam relieved from the safety valve when the latter is opened is detected by an acoustic emission sensor. The acoustic emission sensor is mounted on the safety valve or a steam relief pipe connected to the safety valve.

Claims

1. In a water cooled nuclear reactor of the type in which water is used as a primary coolant and including a steam drum, a steam relief pipe, and a steam relieving safety valve disposed between said steam drum and said relief pipe, said safety valve being opened to relieve the internal pressure in said steam drum when said interval pressure increases over a predetermined maximum pressure, the improvement comprising:

means for detecting an opened condition of said safety valve and thereby for confirming proper operation thereof, said detecting and confirming means comprising contact type acoustic emission sensor means, mounted solely on the exterior of at least one of said safety valve and said steam relief pipe, for detecting acoustic vibrations which are generated by steam being relieved from said safety valve when said safety valve is opened and which are transmitted through a solid material of said at least one of said safety valve and said steam relief pipe.

2. The improvement claimed in claim 1, wherein said acoustic emission sensor means is directly fastened to said at least one of said safety valve and said steam relief pipe.

3. The improvement claimed in claim 1, wherein said acoustic emission sensor means is connected to said at least one of said safety valve and said steam relief pipe by means of a solid waveguide member.

4. The improvement claimed in claim 1, wherein said acoustic emission sensor means is electrically connected to a voltmeter via an amplifier, whereby said acoustic vibrations generated by steam relieved from said safety valve are converted into an electric signal by said acoustic emission sensor means and then measured by said voltmeter after said electric signal is amplified by said amplifier.

5. A method of confirming the operation of a steam relieving safety valve installed between a steam drum and a steam relief pipe of a water cooled nuclear reactor of the type in which water is used as a primary coolant, said safety valve being opened to relieve the internal pressure in said steam drum when said internal pressure increases over a predetermined maximum pressure, said method comprising:

mounting a contact type acoustic emission sensor solely on the exterior of at least one of the safety valve and the steam relief pipe;

detecting by means of said acoustic emission sensor vibrations which are generated by steam being relieved from said safety valve when said safety valve is opened and which are transmitted through a solid material of said at least one of said safety valve and said steam relief pipe;

converting the thus detected vibrations into an electrical signal; and

detecting said electrical signal.

6. A method as claimed in claim 5, further comprising amplifying said electrical signal, and measuring the thus amplified electrical signal by means of a voltmeter.