Defining and Characterizing Methods, Tools, and Computing Resources to Support Pseudo Exhaustive Testability of Software Based I&C Devices
- Virginia Commonwealth Univ., Richmond, VA (United States)
Under the Department of Energy’s Light Water Reactor Sustainability Program, within the Plant Modernization research pathway, the Digital I&C Qualification Project is identifying new methods that would be beneficial in qualifying digital I&C systems and devices for safety-related usage. One such method that would be useful in qualifying field components such as sensors and actuators is the concept of testability. The Nuclear Regulatory Commission (NRC) considers testability to be one of two design attributes sufficient to eliminate consideration of software-based or software logic-based common cause failure (the other being diversity). The NRC defines acceptable “testability” as follows: Testability – A system is sufficiently simple such that every possible combination of inputs and every possible sequence of device states are tested and all outputs are verified for every case (100% tested). [NUREG 0800, Chapter 7, Branch Technical Position (BTP) 7-19] This qualification method has never proven to be practical in view of the very large number of combinations of inputs and sequences of device states for a typical I&C device. However, many of these combinations are not unique in the sense that they represent the same state space or in that that they represent state space that would not affect the critical design basis functions of the device. Therefore, the state space of interest might possibly be reduced to a manageable dimension through such analysis. This project focuses on a representative I&C device similar in design, function, and complexity to the types of devices that would likely be deployed in nuclear power plants as digital or software based sensors and actuators (e.g. Smart Sensors). Analysis will be conducted to determine the feasibility of testing this device in a manner consistent with the NRC definition. This report describes acceptable test methods, needed tools (existing or new), and computing resources, all based on engineering and computer science principles. This information will then be used in a later phase of this project to develop a test specification for I&C device testability that can be used in a future phase of this project to demonstrate digital qualification with respect to common cause failure. Following that, testing will be conducted and the results analyzed to determine if the methods employed are sufficient to eliminate consideration of software common cause failure in accordance with the concept of testability.
- Research Organization:
- Idaho National Lab. (INL), Idaho Falls, ID (United States)
- Sponsoring Organization:
- USDOE Office of Nuclear Energy (NE)
- DOE Contract Number:
- AC07-05ID14517
- OSTI ID:
- 1495188
- Report Number(s):
- INL/EXT-18-51521-Rev000
- Country of Publication:
- United States
- Language:
- English
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