Method and apparatus for repairing boiling water reactor shrouds.

摘要

A method of repairing a nuclear reactor core shroud with a horizontal crack in a weld joining adjacent shroud segments involves first shutting down the reactor, followed by the application of axially compressive forces to the shroud along its entire length to urge the surfaces of the crack toward one another. Application of these forces is then maintained after operation of the reactor has been restored. Several tie rods (120) are secured to the shroud (113). The bottom of each tie rod (120) has a hook (121) which engages bracket (115). The top of the tie rod (120) is secured to beam (123) which is supported between angularly spaced lugs (117) and fastened to them. A hole in beam (123) receives tie rod (120) which may then be axially tightened by nut (124). As the nuts (14) are tightened, upward forces are exerted against brackets (115) and downward forces are exerted by the nuts on beams (123). The surfaces of horizontal cracks are urged toward each other, sealing the cracks and preventing adverse effects on the shroud structure. Horizontal spacers between shroud and vessel may be used to resist horizontal seismic loads whilst vertical spacers can resist vertically upward loads resulting from main steam line breaks.