Quantitative evaluation of common cause failures in high safety-significant safety-related digital instrumentation and control systems in nuclear power plants

An Integrated Framework for Risk Assessment of High Safety Significant Safety-related Digital Instrumentation and Control Systems in Nuclear Power Plants: Methodology and Demonstration

“…The hybrid method provides a means to overcome limitations of conventional methods. A formalized process that relies on the modified BFM and PBF-2 is shown in Figure 47, which has been demonstrated in [28] [92]. The subsequent section will demonstrate this process as with a case study.…”

“…This approach has been demonstrated and applied for the hazard analysis of a four-division digital RTS [16] and a four-division, digital, ESFAS [17]. These efforts have been included in the LWRS-RISA milestone report for FY-20 [2] and FY-21 [3].…”

“…Finally, the probability of specific UCA/UIF classes can be determined by multiplying the conditional probabilities of each class with the failure probability per hour per class probability, as shown in Equation (3). Recall that the conditional probability was pre-determined through the historical defect data of multiple different pieces of software.…”

“…In [92], various software defects were detected and classified based on operational data from NUREG/CR-7042 [93]. In the report, software-operating data was collected over a period of 281 months from multiple NPPs on the two separate microprocessors (p) and on the communications module (CP).…”

“…This report documents the activities performed by Idaho National Laboratory (INL) during fiscal year (FY) 2022 for the U.S. Department of Energy (DOE) Light Water Reactor Sustainability (LWRS) Program, Risk Informed Systems Analysis (RISA) Pathway, digital instrumentation and control (DI&C) risk assessment project [1] [2] [3]. The LWRS program, sponsored by the U.S. DOE and coordinated through a variety of mechanisms and interactions with industry, vendors, suppliers, regulatory agencies, and other industry research and development (R&D) organizations, conducts research to develop technologies and other solutions to improve economics and reliability, sustain safety, and extend the operation of nation's fleet of nuclear power plants (NPPs).…”