[en] An analysis is made of the current standard documents giving requirements to the nuclear reactors and determining the scope of the metrology assurance of the NPPs. The issues of metrological and technical nature are discussed. The importance of governmental inspection of the equipment is stressed. The main tasks of the metrology are determined. A description of the neutron fluence instruments and internal reactor control system is given. The instrumentation for metrology assurance consists of PC-based consumer-made modules and software. The laws of specimen signals alteration are obtained as a module output, simulating any potential modes of the nuclear reactor operation in real time, including accidents (V.K.)