Apparatus for repairing cracked core spray supply piping in a boiling water reactor

• US 5,964,029 A
• Filed: 05/29/1998
• Issued: 10/12/1999
• Est. Priority Date: 11/27/1996
• Status: Expired due to Term

• Current Assignee: MPR Associates, Inc. (Research Triangle Institute)
• Original Assignee: MPR Associates, Inc. (Research Triangle Institute)
• Inventors: Sylvester, William E., Weems, Sterling J.
• Primary Examiner(s): Cuda, I
• Application Number:
  US09/086,416
• Time in Patent Office: 501 Days
• Field of Search: 29/723, 29/727, 29/726, 29/890.031, 29/402.15, 29/402.14, 29/402.09, 29/402.01
• US Class Current: 29/723
• CPC Class Codes: B23P 6/04 Repairing fractures or cracked metal parts or products, e.g. castings
• CPC Class Codes: B25B 5/08 using cams
• CPC Class Codes: B25B 5/147 for pipes
• CPC Class Codes: F16L 55/172 the ring, band or sleeve being tightened by a tangentially arranged threaded pin and a nut
• CPC Class Codes: F16L 55/179 specially adapted for bends, branch units, branching pipes or the like
• CPC Class Codes: G21C 15/00 Cooling arrangements within the pressure vessel containing the core; Selection of specific coolants
• CPC Class Codes: Y02E 30/30 Nuclear fission reactors
• CPC Class Codes: Y10T 29/49352 Repairing, converting, servicing or salvaging
• CPC Class Codes: Y10T 29/49739 Mechanically attaching preform by separate fastener
• CPC Class Codes: Y10T 29/531 Nuclear device
• CPC Class Codes: Y10T 29/53122 including deforming means

Abstract

An apparatus for repairing cracked core spray supply piping in a boiling water reactor vessel includes a pair of clamps extending circumferentially around the piping on opposite sides of a crack and a preloading mechanism urging the clamps toward one another to apply and maintain an axially compressive load on the piping tending to close the crack. For vertical sections of core spray supply piping, the clamps are secured at vertically spaced locations with each of the clamps including a first jaw extending circumferentially around a first portion of the piping and including a first opening oriented substantially parallel to a longitudinal axis of the piping and an elongate passage or channel oriented substantially perpendicular to and in communication with the first opening. A second jaw extends circumferentially around a second portion of the pipe in horizontally opposed relation to the first jaw and includes an elongate extension slidably received in the elongate channel and defining a second opening partially aligned with the first opening, with a wedge being movably disposed in the aligned openings to cause the second jaw to move relative to the first jaw in a direction substantially perpendicular to the longitudinal axis of the piping in response to straight, vertical operations. For horizontal sections of core spray supply piping, the clamps are secured at horizontally spaced locations with each of the clamps having a pair of jaws extending circumferentially around the piping in opposed relation and a horizontal preloading mechanism extending between the jaws in tension, the horizontal preloading mechanism being similar to the clamping mechanism used for vertical sections to facilitate installation using straight, vertical operations.

Claims

1. An apparatus for repairing cracked piping in a boiling water reactor comprising

a pair of clamps secured to the piping on opposite sides of a crack;

a bolt connected between said clamps to exert an axially compressive force along a longitudinal axis of the piping tending to close the crack during operation of the reactor; and

bias means disposed between said bolt and at least one of said clamps for maintaining a tensile preload on said bolt during thermal transients when the piping tends to contract due to the introduction of cold core spray coolant water.

2. An apparatus for repairing cracked piping in a boiling water reactor as recited in claim 1 wherein said bolt includes a bolt head and said bias means includes a spring disposed around said bolt and held in compression between said bolt head and one of said clamps.

3. An apparatus for repairing cracked piping in a boiling water reactor as recited in claim 1 wherein said bolt is held in tension between said clamps to apply an axially compressive force along a longitudinal axis of the piping.

4. An apparatus for repairing cracked piping in a boiling water reactor as recited in claim 1 and further comprising a cross-bar adjacent one of said clamps and a plurality of bolts extending through said cross-bar to connect said clamps, wherein said bias means includes a first spring disposed in compression between said cross-bar and said clamp adjacent said cross-bar.

5. An apparatus for repairing cracked piping in a boiling water reactor as recited in claim 4 wherein said first spring is disposed around a first of said bolts and wherein said bias means further includes a second spring disposed around a second of said bolts.

6. An apparatus for repairing cracked piping in a boiling water reactor as recited in claim 5 wherein at least one of said springs includes a plurality of stacked Belleville springs.

7. An apparatus for repairing cracked piping in a boiling water reactor as recited in claim 1 wherein at least one of said clamps extends circumferentially around the piping.