Keywords: electromagnets, soft iron, 316LN stainless steel, ERNiCr-3, overlay, gas tungsten arc welding, GTAW, dissimilar welding, diverse safety rods, fast breeder reactors, nuclear reactors, nuclear energy, nuclear power, leak testing, electromagnet welding
Development of joining procedure for pole pieces of the electromagnet of the diverse safety rod in a fast breeder reactor
In the prototype fast breeder reactor, the electromagnet for the diverse safety rod is welded using a non-magnetic filler to separate the magnetic poles. The pole pieces are made of soft iron, and the non-magnetic nickel base ERNiCr-3 was chosen as non-magnetic filler wire. The procedure followed for joining the pole pieces consisted of weld build-up of the inner and outer core pieces with ERNiCr-3 filler material and machining to the required dimensions. The final joining of the electromagnet was by a circular joint at the contact end. The joints were qualified by stringent inspection procedures, including leak testing.