Abstract: A retaining tool for a telescoping refueling arm in a nuclear reactor, the retaining tool includes a plurality of support members coupled to a plurality of plates. The retaining tool includes a first plate having a first and a second side, a second plate spaced apart from the first plate, and a third plate having a first and a second side The third plate is spaced apart from the second plate so that the second plate is located between the first and third plates. The second side of the first plate engages the roller housings of the mast outer tube assembly, and the first side of the third plate engages the roller housings of one of the intermediate tube assembly to prevent the intermediate tube from extending and thus permitting the inner tube of the mast to fully extend.