Abstract: A data providing system includes a first communication apparatus and a plurality of second communication apparatuses that provide data to the first communication apparatus using a communication protocol capable of performing authentication by identification information. The first communication apparatus includes an identification information request sending section, an individual identification information receiving section, a first data request sending section, a first common identification information storage section, a second data request sending section, and a data receiving section. At least one of the second communication apparatuses includes an individual identification information storage section, a second common identification information storage section, an identification information request receiving section, an individual identification information sending section, a data request receiving section, a first data sending section and a second data sending section.

Abstract: A wear resistant material containing no cobalt is used for a sliding portion of a control rod driving mechanism of a nuclear plant for reducing the exposure dose due to elution of cobalt and ensuring smooth driving of a control rod under a high load for a long time. A control rod driving mechanism employs a roller and a pin, each of which is made of a wear resisting alloy comprising coarse particles of a hard phase, having a particle size of from 20 to 100 .mu.m, and dispersed in a soft matrix made of an iron-based or nickel-based alloy containing chromium and having a hardness of 300 Hv or less. A nuclear reactor employs this control rod driving mechanism.