DOE OSTI2017
The purpose of this paper is to provide an overview of the development of the approach to addressing embedded digital devices (EDD) in safety-related systems of nuclear power plants in the U.S. and around the world. In April, 2016, the U.S. Nuclear Regulatory Commission (US NRC) issued RIS 2016-05 to heighten awareness that EDDs might exist in procured equipment used in safety-related systems without the devices having been explicitly identified in procurement documentation. Inadequate consideration of these devices in digital technology system upgrades, component replacements, and new equipment applications could lead to an adverse safety consequence. The US NRC request was for addressees to implement early efforts to identify these devices. An area where this is being addressed is in regard to the performance of Diversity and Defense-In-Depth (D3) analyses, as addressed in US NRC Branch Technical Position 7-19. Nuclear facilities have increased their use and reliance on digital technology in systems and equipment (e.g., I and C, electrical systems, and fluid systems). In addition to digital instrumentation and control (I and C) systems, examples of safety-related equipment that may use digital technology include emergency diesel generators, pumps, valve actuators, motor control centers, breakers, priority logic modules, time-delay relays, and uninterruptible power sources. In the U.S. and around the world, engineering and licensing activities in standards and guidance have been, and are being developed to address this important consideration in protecting safety-related systems. This paper addresses development of an extended approach to evaluating common-cause failure vulnerability and mitigation in regard to equipment with an EDD. (authors)
22 GENERAL STUDIES OF NUCLEAR REACTORS↗