Realization of a Automated T-Way Combinatorial Testing Approach for a Software Based Embedded Digital Device

Abstract

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).

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

“…A demonstration of the proposed method is conducted on various systems. The first system is a smart sensor platform [31] with a lightweight operating system (ChibiOS) [32]. The ChibiOS is an example of an all-purpose multiuse resource management system.…”

“…The exact details of the VCU smart sensor system can be found in references [31,33]. A full analysis using RESHA is conducted for clarity on each step.…”

“…The VCU smart sensor's primary function is to provide readings for the adequate control of altitude [31]. Therefore, the assigned top event for this assessment is "autonomous drone crashes into ground due to failure of flight controller."…”

“…In this case study, the ORCAS was applied to an embedded smart sensor developed by VCU. The sensor is a barometric pressure and temperature sensing device that originates from the VCU Unmanned Aerial Vehicle (UAV) Laboratory [31]. The device consists of mature design and code, including the SRS and SDD documentation, with over 10,000 hours of tested flight time.…”

“…The device consists of mature design and code, including the SRS and SDD documentation, with over 10,000 hours of tested flight time. The software is written in GNU11 C programming language for the application code and runs on top of the ChibiOS Version 17.6.4 Real-Time Operating System (RTOS) [31]. The software was tested extensively using a pseudo-exhaustive test-based approach developed by VCU [33] and incorporates methodologies such as combinatorial testing, boundary value assessment, equivalence partitioning, and MCDC structural path coverage.…”