IEEE 379-2014 pdf free.IEEE Standard for Application of the Single-Failure Criterion to Nuclear Power Generating Station Safety Systems.
A design basis event (hat results in the need for safety functions may cause consequential failures of system components, modules, or channels. In order to provide protection from these failures, the safety equipment is designed. qualitied and installed to provide protection from such anticipated challenges. An analysis shall be performed to determine the consequences of safety system failures resulting from design basis events. For a system to meet the single-failure criterion, it shall be shown that the required safety function can be performed in the presence of these event-caused failures, all identifiable nondetectable failures, and any other single failure.
Thc requirement for a safety system to function in the presence of common-cause failures (CCFs) is beyond the scope of the application of single-failure criterion and, therefore, this standard. However, it is important to screen out the potential (‘CFs when performing a single-failure analysis. As part of evaluating the ovcrall reliability of safety systems. IEEE Std 352 extends the qualitative analysis beyond that which is done for failure modes and effects analysis (FMEA), or fault tree analysis, by considering CCFs. Therefore, an extended qualitative analysis described in IEEE Sid 352 should be used to identify and screen out common-cause failure mechanisms not normally considered in an analysis of independent component failures.
Common-cause failures not subject to single-failure analysis include causative factors from external environmental efTects (e.g., voltage. frequency, radiation, temperature, humidity, pressure, vibration, and electromagnetic interference). Also, equipment qualification and quality assurance programs are intended to afford protection from external environmental effects, design deficiencies, and manufacturing errors. Personnel training: proper control room design: and operating, maintenance, and surveillance procedures are intended to afford protection from maintenance and operator errors. Finally, for digital safety systems, vulnerabilities to (.‘CFs are assessed via the diversity and defense-in-depth associated with the safety system. IEEE Std 352 includes these causative factors contributing to CCFs and the possible preventative measures used to screen out these potential CCFs. The screening process is shown in Figure 1. Other failures may be identified that do not have preventative measures. These failures should be treated as single failures and should be included in the single-failure analysis
Digital safety system vulnerabilities to CCFs are assessed via the diversity and defense-in-depth associated with the safety system. Guidance on using diversity and defense-in-depth to address CCFs in digital computers is provided in IEEE Std 7-4.3.2.IEEE 379 pdf download.