Safety Classification of Items in Tianwan Nuclear Power Plant

The principle of integrality,moderation and equilibrium should be considered in the safety classification of items in nuclear power plant.The basic ways for safety classification of items is to classify the safety function based on the effect of the outside enclosure damage of the items（parts） on the safety.Tianwan Nuclear Power Plant adopts Russian VVER-1000/428 type reactor,its safety classification mainly refers to Russian Guidelines and standards.The safety classification of the electric equipment refers to IEEE-308（80） standard,including 1E and Non 1E classification.The safety classification of the instrumentation and control equipment refers to GB/T 15474-1995 standard,including safety 1E,safety-related SR and NC non-safety classification.The safety classification of Tianwan Nuclear Power Plant has to be approved by NNSA and satisfy Chinese Nuclear Safety Guidelines.