Environmental Engineering Reference
In-Depth Information
ANALYSIS ASPECTS OF FPGA-
BASED NPP I&C SYSTEMS
Combined Usage of
Analysis Techniques
Verification and Validation of
FPGA-Based NPP I&Cs
There are a lot of well-known techniques that can
be used for NPP I&CS dependability analysis and
assessment of its attributes. Using these techniques
it is possible to perform quantitative and/or qualita-
tive assessments. Qualitative assessments though
lacking the ability to account, are very effective in
identifying potential failures within the I&CS. We
have performed some work to identify possible
combination of techniques, results are shown in
Figure 12. To carry out dependability analysis it is
necessary to have I&CS technical documentation
(this information is obtained from I&CS project)
and reliability data of I&CS components (is ob-
tained from component vendors).
The first stage of NPP I&CS dependability
analysis is FMECA (Failure modes, effects and
criticality analysis). During this stage all possible
failure mechanisms and failure rates for all com-
ponents involved and quantify failure contribution
to overall NPP reliability and safety are analyzed.
In FMECA qualitative and quantitative results
(see Figure 13) are obtained. Failure mode in
FMECA refers to the way a failure might occur.
Failure effect is the consequence of failure from
the system's point of view. Failure criticality is
assigned to each failure mode to get quantitative
parameters.
FMECA is carried out early in the NPP I&CS
development life cycle to find ways of mitigating
failures and thereby enhancing reliability through
design.
A traditional FMECA uses potential compo-
nent failures as the basis of analysis. Component
failures are analyzed one by one, and therefore
important combinations of component failures
might be overlooked. Environmental conditions,
external impacts and other such factors are ana-
FPGAs were first introduced in non-safety sys-
tems in NPPs, where no specific process over
general FPGA development process is required.
However, to use FPGAs for safety systems, more
strict processes are imposed by nuclear regulators
to ensure the reliability and safety of the systems.
Since the development process of FPGA is
similar to that of software for microprocessor-
based systems, the conventional safety software
development process including V&V methods
can be applied. I&C systems supplied by the RPC
Radiy were subjected to V&V processes to ensure
their reliability and safety.
For example, for US commercial NPPs, the
US NRC endorses IEEE Standard 7-4.3.2-2003
as the methods for high functional reliability and
design requirements for computers, whereas IEEE
Standard 1012-1998 as the methods of V&V.
IEEE Standard 1012-1998 postulates a phased
software life cycle, and defines a number of V&V
activities to be performed throughout the software
lifecycle. The V&V activities include the follow-
ing types of activities:
• Software requirements evaluation.
• Design evaluation.
• Interface analysis.
• Requirements traceability analysis.
• Source code and source code documenta-
tion evaluation.
• Validation testing.
• Hazard analysis.
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