Patent Number: 056429550
Section: abstract

A strongback for lowering a tie rod into the downcomer annulus of a boiling water reactor during a shroud repair operation. The tie rod strongback is suspended from a cable via a cable adaptor at its upper end. The lower end of the strongback is coupled to a tie rod adaptor, which in turn couples to the top of the tie rod. The strongback is a welded assembly of square tubes, channels for reinforcing the joints of the welded tubes, and upper and lower couplings. In particular, the strongback has mutually parallel first and second rigid linear members which are disposed vertically when the strongback is suspended from a plumb cable. The second rigid linear member is connected to the first rigid linear member by a relatively obliquely disposed third rigid linear member. The first and second rigid linear members lie in a vertical plane which is offset from the axis of a plumb cable to allow the strongback assembly to circumvent the core spray downcomer piping when the tie rod/lower spring assembly is in its final position in the annulus. The first rigid linear member is further offset from the second rigid linear member cable axis to allow the strongback assembly to circumvent the feedwater sparger and the core spray header. This facilitates proper positioning of the bottom of the tie rod/lower spring assembly relative to the gusset plate to which the assembly will be anchored.