We reconstructed the rail track for the fuel handling machine at the Dukovany NPP
During the spring of 2021, we successfully completed the reconstruction of the rail-track for the fuel handling machine at the main production unit I at the Dukovany NPP (units 1 and 2) within the required deadline. The wheels of the fuel handling machine were also exchanged, including the preventive replacement of double-row spherical roller bearings. The extent of the reconstruction included replacing the old track with new one without interfering with the floor of the unit base.
This machine weighing about 57 tons ensures the handling of nuclear fuel in the reactor. One machine alternately operates two blocks. Thus there are a total of 2 fuel handling machines at the Dukovany NPP. It is a handling device with electronic control which moves along the track on the unit base. This track provides a connection between three working areas - the reactor core, the exchange pool and the spent fuel storage pool.
When handling fuel, the wheels and rails are extremely stressed and the result of more than 30 years of operation is their excessive wear. As part of a feasibility study from 2018, prepared by our company, the condition of the wheels and rails was evaluated as unsatisfactory for the technical conditions. Based on the operating parameters and the service life requirement (min. 30 years), a suitable material was selected as well as its heat treatment, ensuring service life of the rail-track of min. 38 years and service life of the wheels of min. 11 years, with the possibility of their replacement according to the results of periodic inspections.
The total length of the track is 23,730 mm. It is divided into 6 segments with a length of 3955 mm, which are seated in rail beds. The basic requirement of the customer is the straightness of the rail head of both the side guiding surface and the upper running surface. In order to achieve the required straightness, it was necessary to adjust the individual beds in the vertical and horizontal directions. In the vertical direction, the height was compensated by base plates. In the horizontal direction, the adjustment consisted in widening the in-bed groove using a special milling machine, made by our company for this particular purpose.
The project at the main production unit I at Dukovany NPP is thus successfully over and now we are already preparing for an identical event at the main production unit II at the Dukovany NPP, which is expected to occur in the summer of 2021.