Environmental testing of a prototypic digital safety channel, phase I: System design and test methodology

A microprocessor-based reactor trip channel has been assembled for environmental testing under an Instrumentation and Control (I ampersand C) Qualification Program sponsored by the U.S. Nuclear Regulatory Commission. The goal of this program is to establish the technical basis for the qualification of advanced I ampersand C systems. The trip channel implemented for this study employs technologies and digital subsystems representative of those proposed for use in some advanced light-water reactors (ALNWS) such as the Simplified Boiling Water Reactor (SBNW) and AP600. It is expected that these tests will reveal any potential system vulnerabilities for technologies representative of those proposed for use in ALNWS. The experimental channel will be purposely stressed considerably beyond what it is likely to experience in a normal nuclear power plant environment, so that the tests can uncover the worst-case failure modes (i.e., failures that are likely to prevent an entire trip system from performing its safety function when required to do so). Based on information obtained from this study, it may be possible to recommend tests that are likely to indicate the presence of such failure mechanisms. Such recommendations would be helpful in augmenting current qualification guidelines