Claims
- 1. A preventive maintenance apparatus of a structural member in a reactor pressure vessel for reducing a tensile residual stress on a surface thereof, comprising:
a fixing apparatus for fixing the preventive maintenance apparatus between a shroud upper body and the reactor pressure vessel; a nozzle head comprising a nozzle for discharging a water jet into core water, a deflector having a plane surface which is impinged by said water jet to change direction of flow of said water jet discharged from the nozzle and impinge the water jet after being deflected onto a target portion of a lower water-level measuring nozzle, and a support maintaining a predetermined distance between the nozzle and the plane surface of the deflector; and a driver for positioning said nozzle head at the position of the target portion of the lower water-level measuring nozzle.
- 2. A preventive maintenance apparatus of a structural member in a reactor pressure vessel according to claim 1, wherein said driver comprises a structure extendable and contractible in the axial direction of the lower water-level measuring nozzle.
- 3. A preventive maintenance apparatus of a structural member in a reactor pressure vessel according to claim 1, wherein said fixing apparatus comprises a structure extendable and contractible in the axial direction of said nozzle head.
- 4. A preventive maintenance apparatus of a structural member in a reactor pressure vessel according to claim 1, wherein an outer diameter of said nozzle head is smaller than an inner diameter of the lower water-level measuring nozzle.
- 5. A preventive maintenance apparatus of a structural member in a reactor pressure vessel according to claim 1, wherein said support maintains the distance between the nozzle and the plane surface of the deflector at most 100 times as large as a hole diameter of the nozzle.
- 6. A preventive maintenance apparatus of a structural member in a reactor pressure vessel for reducing a tensile residual stress on a surface thereof, comprising:
a fixing apparatus for fixing the preventive maintenance apparatus between a shroud upper body and the reactor pressure vessel; and a nozzle head comprising a nozzle for discharging a water jet into core water, a deflector having a recess which is impinged by said water jet to change direction of flow of said water jet discharged from the nozzle and impinge the water jet after being deflected onto a target portion of a lower water-level measuring nozzle, and a support maintaining a predetermined distance between the nozzle and the plane surface of the deflector; and a driver for positioning said nozzle head at the position of the target portion of the lower water-level measuring nozzle.
- 7. A preventive maintenance method of a structural member in a reactor pressure vessel for reducing a tensile residual stress on a surface thereof using the preventive maintenance apparatus claimed in claim 1, comprising the steps of:
fixing the preventive maintenance apparatus between a shroud upper body and the reactor pressure vessel using the fixing apparatus; positioning the nozzle head at the position of a target portion of a lower water-level measuring nozzle using the driver; impinging a water jet from the nozzle of the nozzle head onto the plane surface of the deflector to thereby change direction of flow of the water jet; and impinging the water jet after being deflected directly onto the target portion of the lower water-level measuring nozzle.
- 8. A preventive maintenance method of a structural member in a reactor pressure vessel for reducing a tensile residual stress on a surface thereof, comprising the steps of:
fixing a preventive maintenance apparatus between a shroud upper body and the reactor pressure vessel; positioning a nozzle at the position of a target portion of a lower water-level measuring nozzle; impinging a water jet from the nozzle onto a plane surface of a deflector to thereby change direction of flow of said water jet; and impinging the water jet after being deflected directly onto the target portion of the lower water-level measuring nozzle.
- 9. A preventive maintenance method of a structural member in a reactor pressure vessel according to claim 8, wherein a driver extendable and contractible in the axial direction of the lower water-level measuring nozzle is used for positioning the nozzle at the position of the target portion.
- 10. A preventive maintenance method of a structural member in a reactor pressure vessel according to claim 8, wherein a fixing apparatus extendable and contractible in the axial direction of the nozzle is used for fixing the preventive maintenance apparatus.
- 11. A preventive maintenance method of a structural member in a reactor pressure vessel according to claim 8, wherein a distance between the nozzle and the plane surface of the deflector is at most 100 times as large as a hole diameter of the nozzle.
- 12. A preventive maintenance method of a structural member in a reactor pressure vessel for reducing a tensile residual stress on a surface thereof, comprising the steps of:
fixing a preventive maintenance apparatus between a shroud upper body and the reactor pressure vessel; positioning a nozzle at the position of a target portion of a lower water-level measuring nozzle; impinging a water jet from the nozzle onto a recess of a deflector to thereby change direction of flow of said water jet; and impinging the water jet after being deflected directly onto the target portion of the lower water-level measuring nozzle.
Priority Claims (2)
Number |
Date |
Country |
Kind |
10-227838 |
Aug 1998 |
JP |
|
11-225953 |
Aug 1999 |
JP |
|
Parent Case Info
[0001] This is a continuation-in-part (CIP) application of U.S. Ser. No. 09/373,213 filed Aug. 12, 1999, now allowed, the entire disclosure of which is hereby incorporated by reference.
Continuation in Parts (1)
|
Number |
Date |
Country |
Parent |
09373213 |
Aug 1999 |
US |
Child |
10045087 |
Jan 2002 |
US |