During, for example, servicing and replacement of fuel assemblies in reactor tanks, the reactor tank is open. There is a risk that metal particles of different kinds, such as metal chips, may fall down into the reactor tank from work performed in connection with the reactor tank with, for example, cutting machining tools. Sometimes, work is also performed inside the reactor tank with cutting machining tools. In this case, machining tools can be brought down in the reactor tank and be attached to a wall surface in the reactor tank or the internal parts of the reactor tank by means of a suction cup device or another mechanical attachment device. After such a device has been attached to the wall surface, the tool can be activated in order to process the wall surface. It is of great importance that the metal chips and similar particles formed during the work are collected in an efficient manner.
During a subsequent operation, such small metal particles are circulated around in the reactor with the reactor water. The particles can cause abrasion damage to sensitive parts of the reactor tank such as the fuel rods. The particles can essentially not leave the reactor, but they accumulate over time in a growing number inside the reactor tank.
However, it is known to provide reactor tanks with different types of filters in which such particles are captured. Such filters need to be emptied and there is always a risk that loose particles have time to get stuck in an inappropriate place in a reactor tank before they are captured in such a filter.