[en] A responsibility of the Nuclear Regulatory Commission auditors is to provide assessments of the quality of the safety systems. For software, the audit process as currently implemented is a slow, tedious, manual process prone to human errors. While auditors cannot possibly examine all components of the system in complete detail, they do check for implementation of specific principles like functional diversity. This paper describes an experimental prototype Computer Aided Software Engineering (CASE) tool, UNRAVEL, designed to enable auditors to check for functional diversity and aid an auditor in examining software by extracting all code relevant to a computation identified for detailed inspection