IEC 61874:2025

IEC 61874:2025 applies to equipment consisting of: - a borehole logging probe equipped with a collimated radioisotope (gamma) source (during the actual measurements only) and a detector unit to measure scattered gamma radiation; - a hoisting system and depth measuring system; - other instruments and devices (power supply, pulse converter/amplifier, ratemeter, recorder, signal processing and readout units). This document defines the terminology, specifies the types of apparatus, design and general technical requirements, specific radiation performance, electrical, mechanical, safe and environmental performance requirements. It also defines test and calibration procedures and covers electrical safety and radiation protection issues. Further, it gives recommendations about items included in the manufacturer's operation and maintenance documentation (or certificate). The purpose of this document is to specify design requirements and performance characteristics of nuclear instrumentation used in boreholes to determine bulk rock density in situ. With suitable response charts the measurements can be equated to rock lithology and porosity.