Improving Software Reliability in Nuclear Power Plants via Diversity in the Requirements Phase: An Experimental Study

High software reliability is essential for safety-critical systems in nuclear power plants. To improve the quality of software following the requirements phase, requirements inspections are conducted to detect defects. Traditional approaches enhance inspection outcomes by employing more effective techniques or by increasing team redundancy. This study investigates an alternative approach: introducing diversity within the inspection team. Inspection technique diversity and inspector background diversity are considered in this paper. We hypothesize that an inspection team in which the inspectors use diverse inspection techniques or have diverse backgrounds will have a better performance in defect detection compared to an inspection team with no diversity. This is because diversity can reduce the number of dependent failures in an inspection team. In this study, a controlled experiment is designed and conducted to examine our hypothesis. In the experiment, research subjects with different backgrounds inspect a software requirements specification using different inspection techniques. The results are collected and analyzed statistically. The experiment shows that using diverse techniques in an inspection team can improve the performance of the inspection team; however, using inspectors with diverse backgrounds will not affect the performance of an inspection team significantly.