Special Treatment For Important To Safety Structures, Systems And Components (SSCs) In The Licensing Of Light Water Reactors

摘要

In the interest of developing an efficient and effective licensing process for light water reactors, there is a need to understand and better define the term "special treatment" and how it should be applied to new reactor applications. New passive reactors are particularly impacted by special treatment due to the large number of Structures, Systems and Components (SSCs) that do not perform any safety-related function, but may be important to safety. This paper addresses the evolution of the term special treatment, its relation to other similar terminology applicable to ensuring quality for improving the reliability and availability of risk-significant and important to safety SSCs and how it should be applied to the design of new reactors. To encourage development of readily endorsable industry consensus standards that capture NRC requirements and guidance concerning special treatment, this paper identifies types of non-specificity in design information, the need for clarity in definitions and regulatory basis for acceptancein the review of new reactor applications. This paper is part of a continuing effort by the NRC staff regarding the application of special treatment requirements for SSCs that have an importance to safety.