Patent ID: 7997471
Filing Date: 2011-08-16
Classification: G21C,Y02E,Y10T

Abstract:
1. A method for production of spacers to hold a number of elongated fuel rods in a fuel unit for placement in a reactor, wherein each spacer encloses a number of cells each of which has a longitudinal axis (x) and is arranged to receive a fuel rod in such a way that the fuel rod extends parallel to the longitudinal axis (x), wherein each of the cells comprises a number of abutment surfaces which extend essentially parallel to the longitudinal axis (x) for abutment against the fuel rod which is to be received in the cell, the method comprising the steps of; providing at least two spacers, providing a set of mandrels comprising a plurality of mandrels each having a longitudinal axis, which mandrels are arranged on a common base and which mandrels are mutually arranged with their longitudinal axes essentially parallel, arranging the at least two spacers one on top of another such that the at least two spacers have corresponding cells thereof arranged one atop another, and arranging the set of mandrels so that the mandrels are received through the cells in one of the spacers and through the corresponding cells in each of the other spacers, with the longitudinal axes of the mandrels essentially parallel to the longitudinal axes (x) of the cells, so that cells which are arranged on top of each other are intersected by a common mandrel, and heat treating the spacers when they are arranged on the set of mandrels so that internal tensions in the spacers are released and relative distances between the cells in the spacers are adapted to relative distances between the mandrels.