Regulatory aspects of reactor shutdown systems

Provision of shutdown system is primary and essential requirement for ensuring safety of a nuclear reactor. The shutdown function has to be performed reliably and adequately as and when called for. The reactor design must establish and provide the shutdown system with required reactivity worth, the required reactivity insertion rate and assure adequate shutdown margin. Reliability of the shutdown system must be assured by proper system design and by provision of redundancy and diversity. For reliable operation of shutdown system it is essential that the quality assurance requirements are identified and met during all the stages of design, fabrication, commissioning and operation. This paper highlights relevant regulatory requirements laid down by Atomic Energy Regulatory Board (AERB) in its safety codes on design, operation as well as on quality assurance of nuclear power plants. The paper also elaborates some of the activities which should be performed for effective compliance of the requirements. (author)